Grey seal pup production for North Wales, 2002

Westcott, S.M. & Stringell, T.B.

Marine Monitoring Report No: 5

This is a report of research commissioned by the Countryside Council for Wales. The Council has a programme of research in scientific and other areas, which supports the development of policies and practical work and helps point the way to new countryside legislation. However, the views and recommendations presented in this report are not necessarily those of the Council and should, therefore, not be attributed to the Countryside Council for Wales. No part of this report may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior permission of the Countryside Council for Wales.

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Report Number: 5 Publication Date: September 2003 Contract Number: FC-73-02-183A Nominated Officer: T.B. Stringell

Title: Grey seal pup production for North Wales, 2002

Authors: Westcott, S.M. & Stringell, T.B.

Series editor: W.G. Sanderson Restrictions: None Distribution List CCW: T. Stringell CCW HQ x5 M.McMath, CCW HQ x1 B.Sanderson CCW HQ x1 R. Holt, CCW HQ x1 L. Kay, CCW NWA x1 Mike Camplin, CCW, H'FordW x1 Blaise Bullimore, CCW H'fordW x1 Paul Day, CCW NE x1 Neil Smith, CCW NE x1 CCW HQ Library x1 CCW NWA Library x1 CCW Cardiff Library x1 CCW Mold Library x1 CCW HfordW x1 CCW Skomer MNR x1 Others: JNCC Peterborough, Library x1 Mark Tasker, JNCC Aberdeen x1 Jim Reid, JNCC Aberdeen x1 J. Davies, JNCC Peterborough x1 Jenny Hill, JNCC/EN, Peterborough x1 EN Peterborough Library x1 Victoria Copley, EN, Peterborough x1 Eleanor Hill, EN, Peteborough x1 R. Covey, EN Cornwall x1 SNH Edinburgh, Library x1 John Baxter, SNH Edinburgh x1 Graham Saunders, SNH Edinburgh x1 National Library Wales x1 National Assembly for Wales Library x1 C. Duck, SMRU x1 P. Hammond, SMRU x1 Martin Bradley DoENI x1 PML, Library, Plymouth x1

S. Westcott x5 M. Baines x1 S. Stansfield, Bardsey Bird Observatory x1 A. Moralee, RSPB South Stack x1 C. Sharpe, Manx Bird Atlas x1 T. Johnston, Exploris, Portaferry, NI x1 E. Rogan, UC Cork x1 C. Liret, Oceanopolis, Brest, Brittany x1 R. Penrose, Marine Env Monitoring x1 Ivor Rees, Uni. Wales, Bangor x1 John Gould, Uni Wales Bangor x1 Peter Hope Jones x1 David Mawer, IoS Wildlife Trust x1 T. Nicholson, Cornwall Wildlife Trust x1 Marine Awareness North Wales x1 J Davies Ceredigion CC x1 Simon Avery, RSPB x1 Ian Bullock x1 Jim Poole x1 Powell Strong x1 David Thomas x1 Michelle Dunn, WTSWW x1 Chris Richardson, x1 Hilbre Island Observatory x1 K. Abt, Wadden Sea, Germany x1 R. Witte, Texel, Netherlands x1 Liverpool University Library x1 Port Erin Marine Lab Library x1 UCW Cardiff Library x1 UCW Swansea Library x1 UCW Aberystwyth Library x1 UCW Bangor Library x1 British Library, Document Supply Centre, Boston Spa x1

Recommended citation for this volume: Westcott, S & Stringell, T.B. 2003. Grey seal pup production for North Wales, 2002. Bangor, CCW Marine Monitoring Report No: 5. 55pp.

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PREFACE Under the Council Directive 92/43 EEC on the Conservation of natural habitats and of wild fauna and flora (the Habitats Directive), member states are required to designate and conserve Special Areas of Conservation (SACs). The purpose of this is to maintain or restore habitats and species listed in Annex I and Annex II to Favourable Conservation Status. The grey seal Halichoerus grypus Fabricus is a species listed in Annex II of the Habitats Directive and in Wales they are interest features of the Pembrokeshire Marine, Lleyn Peninsula and the Sarnau and Cardigan Bay candidate SACs.

The work presented in this report is the second study of its type to investigate pup production as an indicator of the condition of grey seals in North Wales. Overall, the work has contributed to the development of methods and procedures for monitoring SACs as well as a dataset that will help to inform how targets should be set for the management of the Lleyn Peninsula and the Sarnau SAC.

Over the last few years many other reviews, surveys, surveillance and monitoring projects have been initiated in Wales for Annex 1 and II habitats and species. Further CCW reports in this series will therefore be prepared on the results of this ongoing programme to develop marine monitoring work that underpins the management of conservation sites.

RHAGAIR O dan Gyfarwyddeb y Cyngor 92/43 EEC ynghylch cadw cynefinoedd naturiol a chadw ffawna a fflora gwyllt (y 'Gyfarwyddeb Cynefinoedd'), mae'n ofynnol i'r aelod-wladwriaethau ddynodi a chadw Ardaloedd Cadwraeth Arbennig (ACA). Diben hyn yw cadw neu adfer y cynefinoedd a'r rhywogaethau sydd wedi'u rhestru yn Atodiad I ac Atodiad II i 'Statws Cadwraeth Ffafriol'. Maer morlo llwyd Halichoerus grypus Fabricus yn rhywogaeth sydd wedi'i rhestru yn Atodiad II i'r Gyfarwyddeb Cynefinoedd ac yng Nghymru mae'r morloi hyn yn 'nodweddion o ddiddordeb' mewn tri safle sy'n ymgeiswyr am statws ACA, sef Sir Benfro Forol, Pen Llŷn a'r Sarnau a Bae Ceredigion.

Y gwaith a welir yn yr adroddiad hwn yw'r ail astudiaeth o'i math i edrych ar enedigaethau morloi bach fel dangosydd o gyflwr morloi llwyd Gogledd Cymru. Yn gyffredinol, mae'r gwaith wedi cyfrannu at ddatblygu dulliau a gweithdrefnau ar gyfer monitro ACA yn ogystal â set ddata a fydd yn helpu i ddangos sut y dylai targedau gael eu pennu ar gyfer rheoli ACA Pen Llŷn a'r Sarnau.

Dros yr ychydig flynyddoedd diwethaf, mae llawer o adolygiadau, arolygon a gwaith arolygu a monitro wedi'u cychwyn yng Nghymru ar gyfer cynefinoedd a rhywogaethau Atodiad 1 a II. Gan hynny, bydd rhagor o adroddiadau yn y gyfres hon gan CCGC yn cael eu paratoi ynghylch canlyniadau'r rhaglen barhaus hon i ddatblygu gwaith monitro morol i fod yn sail ar gyfer rheoli'r safleoedd.

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SUMMARY

The results of a full census of pup production for the 2002 season, carried out between July 29 and December 18, 2002, are presented here. The repeatability of survey methods used in 2001 (Westcott, 2002) was simultaneously tested. The coasts surveyed lie between Aberystwyth in the south to the Dee Estuary in the east, including the coasts of Ynys Môn/Anglesey. Also included are all the islands adjacent to these coasts.

Sea cave sites in the vicinity of Ynys Arw/North Stack, which could not be examined in the 2001 survey due to adverse weather, were explored and mapped during the present survey. Two Trwyn Cilan sites missed in 2001 were discovered, explored and mapped in the present work.

110 pups were located between August 18 and November 11, of which 9 died before weaning. Of these, 5 were stillborn.

The main period of pup production in 2002 was September to October and similar to that of the 2001 season, being weeks 36 to 45 in 2002 compared with weeks 36 to 44 in 2001. In both 2001 and 2002, there was a secondary (lesser) peak in pup production, almost exclusively due to the late onset of pup production at Ynysoedd y Moelrhoniaid/The Skerries, where the two breeding seasons began late and were more compressed than in other districts.

Where possible, seal mothers were photographed, in order to initiate a study examining the fidelity of seals using North Wales nursery sites, and to help identify unweaned pups which move from one nursery site to another in the company of their mothers.

CRYNODEB Cyflwynir yma ganlyniadau cyfrifiad llawn o'r morloi a anwyd yn nhymor 2002, sef cyfrifiad a wnaed rhwng 29 Gorffennaf a 18 Rhagfyr 2002. Rhoddwyd cynnig ar yr un pryd ar ailadrodd y dulliau arolygu a ddefnyddiwyd yn 2001 (Westcott, 2002). Mae'r arfordiroedd a arolygwyd yn gorwedd rhwng Aberystwyth yn y de ac aber Dyfrdwy yn y dwyrain, gan gynnwys arfordir Ynys Môn. Cynhwysir hefyd yr holl ynysoedd sy'n gyfagos â'r arfordiroedd hyn.

Cafodd ogofau môr yn ymyl Ynys Arw, nad oedd modd edrych arnyn nhw yn arolwg 2001 oherwydd tywydd gwael, eu harchwilio a'u mapio yn ystod yr arolwg presennol. Daethpwyd o hyd i ddau safle ar Drwyn Cilan a gollwyd yn 2001, eu harchwilio a'u mapio yn y gwaith presennol.

Daethpwyd o hyd i 110 o forloi bach rhwng 18 Awst a 11 Tachwedd, y bu 9 ohonynt farw cyn cael eu diddyfnu. O'r rhain, cafodd 5 eu geni'n farw.

Y prif gyfnod ar gyfer genedigaethau morloi yn 2002 oedd mis Medi i fis Hydref, yn debyg felly i dymor 2001, sef rhwng wythnos 36 ac wythnos 45 yn 2002 o'i gymharu ag wythnos 36 ac wythnos 44 yn 2001. Yn 2001 a 2002, cafwyd uchafbwynt eilaidd (llai) yn nifer y morloi oedd yn cael eu geni, a hwnnw'n deillio bron yn llwyr o'r ffaith bod y genedigaethau'n dechrau'n hwyr ar Ynysoedd y Moelrhoniaid, lle dechreuodd y ddau dymor bridio yn hwyr a lle roedden nhw'n fyrrach na'r ardaloedd eraill.

Pan oedd yn bosibl, cafodd lluniau'r mamau eu tynnu, er mwyn dechrau astudiaeth i edrych ar ffyddlondeb y morloi sy'n defnyddio safleoedd meithrin y Gogledd, ac i helpu i adnabod morloi heb eu diddyfnu sy'n symud o'r naill safle meithrin i'r llall yng nghwmni eu mamau.

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Grey seal pup production for North Wales, 2002 Westcott, S1 & Stringell, T.B.2

1 Nancherrow Cottage, Nancherrow, St Just-in-Penwith, Cornwall, TR19 7PW

2 Countryside Council for Wales HQ, Plas Penrhos, Ffordd Penrhos, Bangor, LL57 2LQ, UK

Contents

PREFACE / RHAGAIR 3

SUMMARY / CRYNODEB 5

1 INTRODUCTION 9 1.1 OBJECTIVES ......................................................................................................... 10

2 METHODS 11 2.1 Study area ................................................................................................................ 11

2.2 Site access................................................................................................................ 12

2.3 Pup production ........................................................................................................ 12

2.4 Dye marking ............................................................................................................ 12

2.5 Condition ................................................................................................................. 13

2.6 Data storage............................................................................................................. 13

2.7 Minimising disturbance ........................................................................................... 13

3 RESULTS 15 3.1 Overall pup production in North Wales, 2002 ........................................................ 15

3.2 Weekly pup production in North Wales, 2002........................................................ 15

3.3 Weekly pup production at Penrhyn Llŷn/Lleyn Peninsular sites ............................ 15

3.4 Weekly pup production at Ynys Enlli/Bardsey sites ............................................... 16

3.5 Weekly pup production at Ynys Cybi/Holy Island sites ......................................... 17

3.6 Weekly pup production at Trwyn y Gader/Carmel Head sites................................ 17

3.7 Weekly pup production at Ynysoedd y Moelrhoniaid/The Skerries sites ............... 18

3.8 Comparison between timing and numbers of pups produced in the 2001 and 2002 seasons in North Wales ....................................................................................................... 18

3.9 Comparison between timing and numbers of pups produced in the 2001 and 2002 seasons in Penrhyn Llŷn/Lleyn Peninsular.......................................................................... 19

3.10 Comparison between timing and numbers of pups produced at Ynys Enlli / Bardsey sites, 2001 and 2002 ............................................................................................................ 20

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3.11 Comparison between timing and numbers of pups produced at Ynys Cybi / Holy Island sites, 2001 and 2002 ................................................................................................. 21

3.12 Comparison between timing and numbers of pups produced at Trwyn y Gader/Carmel Head, 2001 and 2002 ................................................................................... 21

3.13 Comparison between timing and numbers of pups produced in the 2001 and 2002 seasons at Ynysoedd y Moelrhoniaid/Skerries.................................................................... 22

3.14 Comparison between timing and numbers of pups produced in the 2001 and 2002 seasons at The Ormes .......................................................................................................... 23

3.15 Births at sea cave and open shore sites ................................................................. 23

3.16 Habitat features of nursery sites, 2002 .................................................................... 24

3.16.1 Ynys Arw/North Stack sites ............................................................................ 24

3.16.2 Trwyn Cilan sites............................................................................................. 25

3.17 Pup mortality ........................................................................................................... 25

3.18 Dye marking of pups ............................................................................................... 26

4 DISCUSSION 28 4.1 Pup production at North Wales sites, 2001 and 2002.............................................. 28

4.2 Weekly pup production at Penrhyn Llŷn/Lleyn Peninsular sites, 2001 and 2002... 30

4.3 Weekly pup production at Ynys Enlli/Bardsey sites, 2001 and 2002 ..................... 30

4.4 Weekly pup production at Ynys Cybi/Holy Island sites, 2001 and 2002................ 31

4.5 Weekly pup production at Trwyn y Gader/Carmel Head sites, 2001 and 2002 ...... 32

4.6 Weekly pup production at Ynysoedd y Moelrhoniaid/The Skerries sites, 2001 and 2002 ................................................................................................................................. 32

4.7 Weekly pup production at the Ormes sites, 2001 and 2002 .................................... 32

4.8 Timing and extent of the breeding seasons, 2001 and 2002.................................... 32

4.9 Habitat features of nursery sites used, 2001 and 2002 ............................................ 33

4.10 Pup mortality ........................................................................................................... 34

4.11 Dye marking of pups ............................................................................................... 34

5 ACKNOWLEDGEMENTS 36

6 REFERENCES 37

7 APPENDICES 38 8 CAVE PLANS 47

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1 INTRODUCTION

The UK populations of grey seals represent about 40% of the world population and 95% of the EU population (Davies et al., 2001). At the start of the 2000 breeding season, Great Britain held some 124,000 grey seals with a further 300-400 around the Isle of Man and Northern Ireland (SCOS 2000). The grey seal colonies of Wales represent over 2% of annual UK pup production (SCOS 2000).

A survey of grey seals in North Wales was conducted in 2001 for the Countryside Council for Wales (CCW). It provided baseline data on seal distribution at haul-out sites and on pup production (Westcott, 2002). In 2001, 102 pups were recorded born, of which 20 were stillborn, or otherwise died before the completion of the period of lactation. The timing of a North Wales breeding season was described for the first time in Westcott (2002). The 2001 season began on August 1, peaked in September and October, and ended on November 19. One other pup was located in January 2002 but was regarded as being outside the breeding season. Throughout their range, grey seals are known to be capable of giving birth to a pup in any month of the year although this rarely occurs outside of the main breeding season.

The sole previous pup production study for North Wales was made in 1974 (Anderson, 1977), when annual pup production was estimated at 55. Since then, only at Ynys Enlli has pup production been recorded during recent years, where a slow rise appears to have been observed during the past decade (Bardsey Observatory Reports, 1988-2002).

Westcott (2002) tentatively estimated a North Wales grey seal population size of 365 based on pup data collected during the 2001 survey and a multiplication of 3.5 (a ratio of one pup to three and a half adults (Duck, pers. comm. 2002)). However, the number of grey seals present in the waters of North Wales at all haul-out sites was, at all times, greater than this, with no less than 700-750 seals in winter and the maximum figure (June, July, August) at c. 1100 (Westcott, et al., 2003). This reflects the extent to which seals circulate around the Irish Sea and perhaps beyond.

Work on the current project began on 29 July 2002. This survey set out to examine the representativity of pup production data collected in North Wales in 2000-2001 by means of a more focussed follow-up survey and also to develop and test protocols (Standard Operating Procedures) for monitoring grey seal pup production.

The present work also generated images for photographic identification to provide initial insights into the identity of the breeding population size, site fidelity and movement between sites. This aspect of the work contributes to the compilation of a site- and time-specific photographic identification catalogue for all seals photographed or filmed at nursery sites during the project and is reported elsewhere (Westcott, in prep. 2003).

During the 2002 survey, the first east Atlantic phocine distemper epizootic since 1988 progressed from the Danish island of Anholt, in May, around the North Sea basin and as far as the north Irish Sea coast. Although principally causing heavy mortality among common (harbour) seals, some grey seals also died on British coasts (SMRU, 2002). Concern that the phocine distemper virus might affect seals using the North Wales coast meant that close attention was given to the physical condition of the seals, with any abnormalities being noted.

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1.1 OBJECTIVES

To record pup production on Ynys Enlli/Bardsey, Ynys Môn/Anglesey and Pen Llŷn/Lleyn Peninsular for the 2002-2003 season.

To evaluate the dye marking of pups (in order to prevent multiple counting of the same pups on successive visits, as practised in south-west Wales) in the context of North Wales sites during pup production work.

In conjunction with CCW, and with reference to methods employed in south-west and north Wales, to produce a site based Standard Operating Procedures for future monitoring of pup production in north Wales (Westcott, in prep 2003b).

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2 METHODS

2.1 Study area

The grey seal survey was conducted in North Wales and in the course of writing up the records, the nursery sites were grouped under the heading of the 5 'districts' in which all pups were concentrated. These were:

1. Penrhyn Llŷn/Lleyn Peninsular, consisting overwhelmingly of sites on the south coast of the peninsular, west of Pwllheli

2. Ynys Enlli/Bardsey.

3. Ynysoedd y Moelrhoniaid/The Skerries.

4. Ynys Cybi/Holy Island, consisting of sites between Ynys Lawd/South Stack and the harbour at Holyhead

5. Trwyn y Gader/Carmel Head, consisting of sites between Cemlyn Bay and Church Bay.

It is recognised here that these might as well be regarded as just two broad areas: one set of sites on Pen Llŷn/Lleyn Peninsular and at neighbouring Ynys Enlli/Bardsey (A, Map 1); the other at the triangle of sites along the north-west rim of Ynys Môn/Anglesey (B, Map 1).

Map 1. Grey seal nursery sites, 2003 and the two broad pupping areas: (A) Pen Llŷn/Lleyn Peninsular including Ynys Enlli/Bardsey, and (B) Ynys Môn/Anglesey.

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2.2 Site access

As in the 2001 survey (Westcott, 2002), this survey was mainly seaborne, during which a wave ski was used to transport the fieldworker and survey equipment to and from sites that were mainly inaccessible from land. With the North Wales pupping sites being confined mainly to relatively short stretches of coastline, and with sea conditions being benign through the survey periods, it was not necessary to use a boat to reach sites. Investigating sites using a wave ski was quicker than swimming to and from sites and allowed near-silent approach to be made to each site, thus keeping the disturbance to mother and pup to a minimum.

In order to gain access to Ynys Enlli/Bardsey and Ynysoedd y Moelrhoniaid/The Skerries, it was necessary to make the sea crossing using the Enlli charter boat (MV Highlander) and a Skerries lighthouse supply boat (Girl Kilda). As a result of the timetables being operated and sea state limitations, the number of visits made to both islands was less than would have been ideal. However, on Ynys Enlli/Bardsey, weekly circuits of the Island were made by Dave and Libby Barnden, the tenant farmers, in order to report the appearance of pups, thereby ensuring that gaps in data collection did not occur. Sites at Trwyn y Gader/Carmel Head, Carreg Ddu, Rhosgor and Glanllynnau Skerries were visited by foot.

2.3 Pup production

The term nursery site is used throughout this report to describe the place where an unweaned seal pup is located because, although this site may be the place where the pup was born, it may not always be so.

Visits were made within two hours of low tide, except in a small number of instances, because low tide is that time when it is most possible to avoid disturbing mother and pup. Binoculars (10x50) were used, whenever necessary, during counts. On site, information was recorded in a waterproof notebook at the time the observation was made. Later in the same day, information was entered into a custom-built Access database (the grey seal database).

Based on Westcott (2002) it was reasonable to assume that all pups born during the North Wales breeding season in 2002 could be counted between July and mid-December. Every actual and potential nursery site was visited as many times as possible, generally weekly, from July until mid-December. The number of visits that can be made to potential nursery sites was entirely dependent on wind direction and speed and on the sea state. A total of 128 days of fieldwork were conducted between July 29, when contract started, and December 19 2002.

Pups were aged according to the 5-phase system devised by Smith (1966), so that a birth date could be recorded for each seal. The presence of a warm placenta indicated that the pup was newborn. The identity of the pup was reinforced where it was possible to identify the mother (using still or moving film). This was particularly helpful in the identification of pups that moved between different nursery sites.

2.4 Dye marking

Every pup was aged when located, and given a reference number (see above) and any distinguishing marks were noted. A small number of pups were also dye-marked using an ethanol base (95%) and rhodamine dye. Each of these pups were marked on the lower back/lower flanks region of the body, mainly using an ex-washing-up liquid container to

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make the application of dye. The garden spray used to make the initial application proved less effective in making the different patterns of markings.

In sea caves, in particular, the lack of space available made the application of the dye problematic, sometimes impossible. The presence of a seal mother also complicated the procedure, especially where she lay between the researcher and her pup. In that case, it was not possible to mark the pup without causing unnecessary disturbance and so the pup was left unmarked.

2.5 Condition

While this survey was taking place, a phocine distemper epizootic progressed from the Danish island of Anholt, in May, around the North Sea basin and as far as the north Irish Sea coast (http://www.smru.st-and.ac.uk/pdv/pdvgen.htm). Concern that it may affect seals using the North Wales coast meant that close attention was given to the physical condition of the seals. Any abnormal conditions (in particular, signs of discharges and lesions, or of unnatural lethargy) were noted.

2.6 Data storage

An MS Access database was set up to record information pertaining to seals at every nursery site where they occur. This includes:

• A reference number, Ordnance Survey co-ordinates, orientation, ease of access, a description of the site including the nature of access, the shape of the entrance, type(s) of substrata, potentially perilous, hazardous or otherwise unexpected features of the site as well as a scanned plan view if it is a sea cave site.

• The nearest launching points for both a canoe or wave ski and for a RIB are identified.

• Human use of the land and sea in the vicinity of the site.

• An indication of levels of disturbance at the time of every visit.

• Each seal pup is given a reference number and a precise or estimated date of birth based on the key devised by Smith (1966). During subsequent site visits, a history is recorded for the development (or otherwise) of every pup. There is a section for notes in which detail of the pup can be recorded.

• Any seals present at or just offshore from the nursery site are recorded as male, female, juvenile or unidentified. There is a section for notes in which detail of adult and juvenile seals can be recorded. This might include information about identification marks or reference to identification photographs or film taken.

2.7 Minimising disturbance

Some disturbance was caused at nursery sites by the survey, and so time on site was always kept to a minimum. Sites were approached as discreetly as the conditions permitted, to avoid

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attracting the attention either of the seals or the general public. All landings were made, wherever possible, out of the line of sight of the seals. Movement on site was made, wherever possible, out of line of sight of the seals. As far as possible, movements were quiet, mindful of the acute sense of hearing of the seals. Their sense of smell is also acute, and so effort was made, where the lie of the land permitted, to approach them upwind.

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3 RESULTS

3.1 Overall pup production in North Wales, 2002

Overall, in 2002, 110 pups were located at North Wales sites between August 18 and November 11. Nine stillbirth and pre-weaning mortalities were recorded. Full datasets are presented in Appendices 1 and 2.

3.2 Weekly pup production in North Wales, 2002

Production of pups peaked between early to mid-September and the first third of October. There was a secondary peak in late October, early November (Figure 1).

Figure 1. Weekly pup production at North Wales sites, 2002

3.3 Weekly pup production at Penrhyn Llŷn/Lleyn Peninsular sites

In 2002, 45 pups were located between August 18 and November 11 (Figure 2). 37 were born in sea caves, 8 were born on open beaches. Six of 7 mortalities occurred in September, during a period of quiet sea conditions. Five of these mortalities were stillbirths. See Appendix 3 for full dataset.

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Figure 2. Weekly pup production at Penrhyn Llŷn/Lleyn Peninsular sites, 2002

3.4 Weekly pup production at Ynys Enlli/Bardsey sites

In 2002, 13 pups were located between September 8 and November 3 (Figure 3). Two pups were born in sea caves, 11 were born on open beaches. Two pups died before weaning. See Appendix 4 for full dataset.

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Figure 3. Weekly pup production at Ynys Enlli/Bardsey sites, 2002

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3.5 Weekly pup production at Ynys Cybi/Holy Island sites

In 2002, 35 pups were located between September 5 and November 7 (Figure 4). All pups were born in sea caves. No pups died before weaning. See Appendix 5 for full dataset.

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Figure 4. Weekly pup production at YnysCybi/Holy Island sites, 2002

3.6 Weekly pup production at Trwyn y Gader/Carmel Head sites

In 2002, 2 pups were located between September 25 and October 14 (Figure 5). Both were born on open beaches. Neither pup died prior to weaning. See Appendix 6 for full dataset.

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Figure 5. Weekly pup production at Trwyn y Gader/Carmel Head sites, 2002

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3.7 Weekly pup production at Ynysoedd y Moelrhoniaid/The Skerries sites

In 2002, 15 pups were counted at Ynysoedd y Moelrhoniaid/The Skerries between 16 October and 8 November, all being born on open beaches (Figure 6). No pre-weaning mortalities occurred. See Appendix 7 for full dataset.

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Figure 6. Weekly pup production at Ynysoedd y Moelrhoniaid/The Skerries sites, 2002

3.8 Comparison between timing and numbers of pups produced in the 2001 and 2002 seasons in North Wales

All sites of the 2001 survey were examined repeatedly during 2002, as were sites where seals were said to have nursed pups in previous years and those sites which appeared to be potential sites i.e. sites which resembled existing nursery sites but were not yet known to have been used for that purpose. One potential site, Ogof Morlo a sea cave on the east side of Ynys Enlli/Bardsey was subject to a cliff fall that rendered access unsafe.

In 2001, 102 pups were located between August 1 and November 19. One other late pup was subsequently located on January 25. In 2002, 110 pups were located between August 18 and November 11. In both years, the main periods of pup production were similar (Figure 7). However, in 2001, the main period was between weeks 36 and 44, with a steady rise to a peak in week 41, followed by a secondary (lesser) peak in weeks 43 and 44, whereas in 2002, the main period was between weeks 36 and 45, with a sharp rise from quiet beginnings to a sustained peak between weeks 37 and 41, followed by a secondary (slightly lesser) peak in weeks 44 and 45.

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Figure 7. Weekly pup production at North Wales sites, 2001 and 2002

In both years, the secondary peak is almost entirely composed of pups born at Ynysoedd y Moelrhoniaid/The Skerries, the northernmost nursery site in the region, where the onset of pupping did not occur until after the middle of October. The season of pup production here was strikingly more compressed than in any other district in both years.

3.9 Comparison between timing and numbers of pups produced in the 2001 and 2002 seasons in Penrhyn Llŷn/Lleyn Peninsular

In 2001, 51 pups were born between August 1 and November 14. 37 were born in sea caves, 14 were born on open beaches. In 2002, 45 pups were born between August 18 and November 11 (Figure 8). 37 were born in sea caves, 8 were born on open beaches. See Appendix 3 for full dataset.

During both North Wales breeding seasons, the largest numbers of pups were born in this district, although numbers fell in 2002.

During both seasons, the highest pre-weaning pup mortality rates were recorded here, but the 2001 mortality rate was higher than in 2002 (13 compared with 7). Furthermore, in 2001, 11 of 13 mortalities occurred in October, when violent sea conditions prevailed. In 2002, 6 of 7 mortalities occurred in September, during a period of calm sea conditions. Five of these mortalities were stillbirths.

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Figure 8. Weekly pup production at Penrhyn Llŷn/Lleyn Peninsular sites, 2001 and 2002

3.10 Comparison between timing and numbers of pups produced at Ynys Enlli / Bardsey sites, 2001 and 2002

In 2001, 16 pups were born between September 10 and January 25. All were born on open beaches. In 2002, 13 pups were born between September 8 and November 3. Two pups were born in sea caves, 11 were born on open beaches. See Appendix 9 for full dataset.

Pup production at Ynys Enlli/Bardsey sites fell slightly in 2002, from 16 to 13, with most pups born between weeks 37 and 43 in both years (Figure 9). This contradicts the general impression locally that pup production at these sites is increasing. Survival rates to weaning were high in both years.

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Figure 9. Weekly pup production at Ynys Enlli/Bardsey sites, 2001 and 2002

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3.11 Comparison between timing and numbers of pups produced at Ynys Cybi / Holy Island sites, 2001 and 2002

In 2001, 9 pups were counted between September 21 and October 30. All were born on open beaches. In 2002, 35 pups were counted between September 5 and November 7. All pups were born in sea caves. No mortalities were recorded. See Appendix 10 for full dataset.

The contrast in numbers for the two seasons (Figure 10) is due to the inaccessibility of most sites through the 2001 season, all of which remained accessible through the 2002 season.

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Figure 10. Weekly pup production at Ynys Cybi/Holy Island sites, 2001 and 2002

3.12 Comparison between timing and numbers of pups produced at Trwyn y Gader/Carmel Head, 2001 and 2002

In 2001, 9 pups were born between August 29 and October 12. All were born on open, beaches. In 2002, 2 pups were born between September 25 and October 14. Both were born on open beaches (Figure 11).

No pre-weaning mortality occurred in either year. See Appendix 11 for full dataset.

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Figure 11. Weekly pup production at Trwyn y Gader/Carmel Head sites, 2001 and 2002

3.13 Comparison between timing and numbers of pups produced in the 2001 and 2002 seasons at Ynysoedd y Moelrhoniaid/Skerries

The same number of pups (15) was found at Ynysoedd y Moelrhoniaid/ The Skerries in both 2001 and 2002 breeding seasons, all being born on open beaches (Figure 12). Pups born here made the same contribution in the two years to the late season secondary peak. In both years, pupping began very late in the season and took place over a very short period. It is possible that, during both years, late-born (late December or January) pups were missed as the island was, for long periods, storm-bound. One pre-weaning mortality occurred in 2001, none in 2002. See Appendix 12 for full dataset.

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Figure 12. Weekly pup production at Ynysoedd y Moelrhoniaid/The Skerries sites, 2001 and 2002

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3.14 Comparison between timing and numbers of pups produced in the 2001 and 2002 seasons at The Ormes

No pups were located at the Ormes in 2002, compared with 1 in 2001 (the 2001 pup was reported by a member of the public but this sighting was not confirmed).

3.15 Births at sea cave and open shore sites

In 2002, 74 pups (67.3%)were born on sea cave beaches (Figure 13) and 36 pups (32.7%) were born on open shores (Figure 14). See Appendices 13 and 14 for full dataset.

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3.16 Habitat features of nursery sites, 2002

Due to the predominance of south-easterly winds during the breeding season, sea caves in the vicinity of Ynys Arw/North Stack on Ynys Cybi/Holy Island became accessible to survey. In 2001, however, south-westerlies and north-westerlies had predominated, rendering most of them inaccessible. Consequently, they could be mapped (see Cave Plans 1 7) and monitored for the first time.

Near Aberdaron, two sites identified in 2001, Ogof Meudwy (SH16272543) and Ogof Gwynion West (SH18742532), were mapped for the first time (see Cave Plans 8 and 9).

In addition, two important sites on Trwyn Cilan were identified in 2002 (Grid references: Ogof Mulfran West: SH28792378, Ogof Mulfran East: SH28902373), which had been missed in 2001. These, also, were mapped (see Cave Plans 10 and 11) and monitored for the first time.

All sites were as described in the Westcott (2002), except for the 9 sites described below. All were important nursery sites.

3.16.1 Ynys Arw/North Stack sites

These sites are both remote and relatively difficult to access and monitor. Not only are there fierce tide races close to their entrances, but also even a gentle onshore breeze generates a considerable swell in the caves to the south of the headland.

Pups found at the Ynys Arw/North Stack sites were born between September 5 and November 7.

The sole open shore (beach) site here, Parliament House (See Cave Plan 3 for Arw Cleft and Arw Headland Cave), is a cove with a mixed substratum of sand, pebbles, cobbles, boulders of varying size and bedrock. It is overhung by high cliffs and has cavelets along the higher shore.

The higher shore also offers access to a cleft through the headland off which run other parts of what is a relatively complex sea cave system. This complex is relatively sheltered compared with the neighbouring sites, some of which are extremely exposed to swells from either south-west (south of the headland) or north-west (north of the headland). Among the sites both north and south of Ynys Arw, are the longest sea caves used by seals in North Wales, including those two sites where the most pups were nursed in the 2002 season: Ogof Arw and Ogof Morlo (see Cave Plan 4). Here, 8 and 14 pups respectively were identified.

The substrata of these caves vary, but nearly all of the 35 pups born here were nursed on sand or cobble beaches, or at least on the part of the cave substrata that consisted of sand or cobbles. The exceptions were Arw Cleft and Ogof Ddeuddrws (see Cave Plan 5), where pups were nursed on flat slabs.

The largest number of seal pups found at any single site during any site visit was 6, in Ogof Morlo. At the same time, unusually, 8 adults were present, including 2 males.

Pups here spend part of most tide cycles in the sea because nursery beaches are covered by the tide at high water. Often during site visits (nearly always made within 90 minutes of low

25

tide), pups were wet.

This relatively small but remote locality is subject to minimal disturbance. Only climbers and sea canoeists are known to make site visits, these being rare. However, it is only a matter of time before people discover that several of the sites are accessible without great difficulty from cliff tops.

Pups, as well as other seals, are subject to one unique (to the region) form of disturbance at these sites, but particularly at and south of Ynys Arw/North Stack. The high speed ferries using Holyhead, although reducing speed in the approaches to and from the port, yet generate a dramatic wake which has a magnified effect in the caves and, in particular, upon their beaches, several times each day.

These notes complement and supercede those for the locality made in the 2001 report (Westcott, 2002).

3.16.2 Trwyn Cilan sites

In 2001, Trwyn Cilan (the largest headland on Penrhyn Llŷn) was explored. At that time, only one nursery site was identified, the assumption being that all other sites must be too exposed and the pups too vulnerable to the south-westerly swells to be so used.

In 2002, standard practise included a continued search for new nursery sites, mainly in the vicinity of known sites. This revealed three sites used by seals, two of which proved to be sites where pups were born and nursed. These are Ogof Mulfran (West) and Ogof Mulfran (East).

Both sites, especially Ogof Mulfran (East), are sea caves. However, Ogof Mulfran (West) is only a true cave for the mid- and high water stages of the tide cycle. Also, unusually, both caves are most easily accessible at mid-tide. At low water, both sites are screened by large rocks, which make access to the sea more difficult (arduous) for the seals. Both sites are open to the south-west. The substrata consist mainly of boulders of varying size, periodically accumulating into dune formations at the back of the beaches due to wave action. For plan views of the two sites, see Cave Plans 10 and 11.

Of 45 pups born at Penrhyn Llŷn sites, 20% or 9 individuals were born at these two sites.

3.17 Pup mortality

Known mortalities for 2002 (n=9, 8.2%) were lower than for 2001 (n=20, 19.4%). The 2002 mortalities (see Appendix 15) occurred between August 31 and October 25, mainly in the first half of the breeding season. One died in August, 6 in September and 2 in October. No pups were known to have died outside this period. By contrast, the 20 mortalities recorded in the 2001 season occurred between September 28 and the first week of November (Figure 15). Two died in September, 17 in October and 1 in November.

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Figure 15. Weekly pup mortality, 2001 and 2002

3.18 Dye marking of pups

21 pups were marked with red dye at sites on Penrhyn Llŷn (10 pups) and Ynys Arw (11 pups). Every pup reacted against being sprayed as well as against the disturbance involved. The dye marks faded quite quickly, i.e. were no longer visible on repeat visits, a week or more later. In every case, the dye mark had to be refreshed at subsequent visits.

Perhaps because nearly all marking took place in September, a time of generally quiet seas, no single dye-marked pup moved from one site to another, although a small number (less than 5) of unmarked pups certainly did move between sites at this time something that could be confirmed either by distinguishing marks on the pup (for example: partial facial moult; tar stain or wound) or by the markings or scars or wounds of the mother.

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(a)

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Plate 1. North Wales grey seal pup production monitoring 2002. (a) Stephen Westcott surveying on a waveski. (b) Mother suckling pup in cave habitat. (c) Pup in cave habitat. (d) Pup swimming. (e) Juvenile in cave. (f) Two day old pup. All photos ©Stephen Westcott, 2002, except (a) ©Bill Sanderson, 2002.

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4 DISCUSSION

The aims of the North Wales pup production surveys of 2001 and 2002 were to: study potential and known breeding sites all year round, most intensively between the beginning of July and the end of December, in order to establish the timing and extent of the breeding season; identify sites where pups were born; monitor the fate of pups and photo-identify as many seal mothers as possible. 121 sites were identified as candidate pupping sites and were monitored through the two breeding seasons, except when wave action made those sites inaccessible.

In 2002, 110 pups were located at 35 different North Wales sites, with 74 born at sea cave sites, and 36 at open beach sites. This compares with 103 located in 2001 at 38 different sites, when 37 were cave-born, 65 were born at open beaches and the origin of one was unknown. In both seasons, all except one pup were born between the beginning of August and the end of November, with the great majority born in September and October. However, within those limits, there was considerable local variation in the timing of pup production for the region. This is similar to patterns recorded in Cornwall (Westcott, unpubl.) and south-west Wales (Baines et al., 1995). It should be remembered, however, that the occasional pup is born outside the breeding season. The author has found grey seal pups at the not dissimilar Cornish sea cave and remote beach sites in every month of the year except February, although the timing and extent of the breeding season is very similar to that for North Wales

Important nursery sites at Ynys Arw/North Stack were inaccessible in 2001 due to wave action and two other sites at Trwyn Cilan were passed undetected in that year. It is therefore probable that the 2001 pup production figure should be higher by as many as 35 pups. Every site inaccessible or overlooked in the 2001 survey was a sea cave. This suggests it is reasonable to revise the estimate of pup production for the 2001 season upward to around 140. The 110 pups discovered in 2002 is believed to represent a truer reflection of total pup production for the year because sea conditions allowed generally easier and more complete access to all candidate sites. Therefore, in 2002 it appears that there may have been a decrease in pup production.

Ynys Enlli dropped from second to fourth place in importance for North Wales in 2002, with 13 pups (11.9%) born and 2 (22.2%) mortalities. Together, 58 pups (54.1%) were born at these westernmost nursery sites of the region, and all recorded mortalities (9) were also recorded here.

The phocine distemper epizootic affecting common and grey seals in the north-east Atlantic during 2002 but had no apparent impact upon North Wales grey seals. There is no way of determining whether the apparent drop in pup production for 2002 was due to the epizootic impacting on North Wales seal mothers at sites outwith the region, affecting their condition in such a way as to have a negative impact on pup production. In future, however, if greater effort were made to photo-identify all seal mothers producing pups in the region, and if some dead seals are of a condition to make photo-identification feasible, it may become possible to make informed judgements about the influence of future epizootics on the regional/local population.

4.1 Pup production at North Wales sites, 2001 and 2002

Sites used were mainly sea caves or remote beaches where people never normally landed. Indeed, many individual sites were used by the seals themselves only during the period of pup production. However, Ynys Enlli/Bardsey (where people live throughout the year) and Ynysoedd y Moelrhoniaid/The Skerries (where RSPB wardens live from May to August, and

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to which lighthouse maintenance workers come for day- or periodic visits) are two important exceptions to the rule outlined above. However, at Ynysoedd y Moelrhoniaid/The Skerries, people are rarely visiting the island at the time the pups are born and reared.

A direct comparison has not been made between the two pup production seasons because the 7 sites in the vicinity of Ynys Arw/North Stack visited through the 2002 season had not be visited during the 2001 season due to wave action. In addition, 2 sites at Trwyn Cilan had been overlooked in 2001 (when they were thought to be too exposed for successful rearing of pups to take place) but were visited through the 2002 season.

The main periods of pup production were similar in both years, although the shape of the 2 seasons varied slightly. In 2001, the main period was between weeks 36 and 44, with a steady rise to a peak in week 41, followed by a secondary (lesser) peak in weeks 43 and 44. In 2002, the main period was between weeks 36 and 45, with a sharp rise from quiet beginnings to a sustained peak between weeks 37 and 41, followed by a secondary (slightly lesser) peak in weeks 44 and 45.

At all sites except Ogof Morlo, just south of Parliament House at Ynys Arw/North Stack, where 14 pups were born, pup production is very low, especially by comparison with sites in West Wales (Baines et al., 1995). At 7 sites, between 5 and 8 pups were born in 2002, which represents (in the regional context) the high end of pup production for any site. At no other site were 5 or more pups born. Similarly, at 13 sites, only one pup was born at each site through the entire season. Therefore, nursery sites are fewer and smaller than in West Wales (Baines et al., 1995) but otherwise resemble those in south-west Wales inasmuch as they are generally found in clusters. However, although pup production for clusters is considerably higher than for individual sites, there are only 5 cluster sites in North Wales, with occasional pups born elsewhere.

As in south-west Wales, all sites except those at Ynysoedd y Moelrhoniaid/The Skerries and at Henllwyn on Ynys Enlli/Bardsey are extremely vulnerable to wave action and to inundation at high tide. Indeed, a feature of nursery sites at Penrhyn Llyn /Lleyn Peninsular and Ynys Arw/North Stack is the length of time pups must spend swimming in the sea over the high tide period while the nursery beach is covered by the tide.

It might be argued that the swimming of pups at this time means that they will attain weaning with a lesser body mass than if they had not entered the sea during this period, and therefore suffer a reduced prospect of survival to age one, larger pups having a higher probability of survival (Hall et al., 2003). However, an alternative hypothesis is that pups which swim daily during the suckling period become more adept not only to swimming but at foraging by the time of weaning and may lose less body mass in the intermediate stage during which they are achieving adequate swimming and foraging abilities.

Hall et al., (2003) also suggests that the average survival of pups will vary between years according to the average condition of the breeding females: when most females are in poor condition, pup survival will be lower than average. In this survey, mortality rates of pups prior to weaning were either relatively or very low (19.4% in 2001, 8.2% in 2002) compared with figures collected for Skomer in 1975 (Davis and Anderson, 1976) and Ramsey in 1976 (Anderson et al., 1979), where mortality rates of 43% and 35% were recorded. The 2002 figure compares closely with the 1995 data collected by the West Wales grey seal survey (Baines et al., 1995). The higher 2001 figure was due mainly to a three and a half week interlude of heavy seas close to the peak period of pup production.

In both years, the secondary peak in pup production is composed almost entirely of pups born at Ynysoedd y Moelrhoniaid/The Skerries, the northernmost breeding station in the region, where the onset of pupping did not occur until after the middle of October. The season of pup

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production here was strikingly more compressed than in any other district in both years.

4.2 Weekly pup production at Penrhyn Llŷn/Lleyn Peninsular sites, 2001 and 2002

Two previously undiscovered sites located in 2002 (Ogof Mulfran West and Ogof Mulfran East) were identified along the west face of the great headland, Trwyn Cilan, on the south coast of the Peninsular. In the preliminary examination of sites, made in 2001, the possibility that this might be a nursery site was discounted because it is open to the south-west and because it was hard to imagine pups surviving there if a rough sea state prevailed. However, this was not the way the seal mothers regarded the sites. Nine pups were born here, just east of the already identified sea cave site, Carreg y Tir. Among them, not a single mortality was recorded. Therefore, it is likely that the figure for the 2001 season was underestimated by about 10 pups. In that case, the apparent drop in pup production in 2002 may have been, in fact, an increase of about 5 pups.

Elsewhere on the peninsular, pup production was markedly down on the 2001 season, although individual sites only recorded slight falls in numbers. This was the case at Ogof Lleiddiad (previously incorrectly named Ebolion Great Cave in the 2001 season (Westcott 2002)), Ogof Lwyd West, Ogof Ebolion (Mast) and Ogof Trwyn y Penrhyn (S) and Clog Cidwm (E) (previously incorrectly named Porth Cidwm (E) in the 2001 season). The sites named above are the nursery sites at which the largest numbers of pups were located on the peninsular. They include seven sites at which only a single pup was born.

In both years, the Peninsular had the largest number of births and of pre-weaning mortalities for any district in North Wales. However, while most pre-weaning mortalities in 2001 occurred during periods of stormy weather in October, in 2002 most mortality occurred in September during periods of quiet weather. Post-mortems were not carried out, but it is possible that these deaths were due to poor condition of the mothers who may have been affected at a sub-lethal level by the phocine distemper epizootic.

45 pups (42.2% of pups born at North Wales sites) were located at Penrhyn Llŷn/Lleyn Peninsular sites in 2002, and as in 2001, this district also recorded the highest mortality rate for unweaned pups: 7 (77.8%). 51 pups (49.5%) were located in 2001 with a pre-weaning mortality of 13 pups (65%). With neighbouring Ynys Enlli, this is the main pupping district in North Wales.

4.3 Weekly pup production at Ynys Enlli/Bardsey sites, 2001 and 2002

The dip in 2002 pup production apparent in the Penrhyn Llŷn/Lleyn Peninsular data was also found at neighbouring Ynys Enlli/Bardsey sites. Pup production at Ynys Enlli/Bardsey (including the late-born pup located on January 25) fell from 16 (15.5% of pups born at North Wales sites) in the 2001 season to 13 (11.8%) in 2002, for no apparent reason. There were 3 pre-weaning mortalities (15%) in the 2001 season, 2 (22.2%) in 2002. Consequently, Ynys Enlli dropped from second to fourth place in importance for the region in 2002. However, together with Penrhyn Llŷn/Lleyn Peninsular, 58 pups (54.1%) were born at these westernmost nursery sites of the region, and all mortalities recorded for the region (9) were recorded here.

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4.4 Weekly pup production at Ynys Cybi/Holy Island sites, 2001 and 2002

South-easterly winds predominated during this breeding season, a detail that contrasts with the prevailing south-westerly and, to a lesser extent, north-westerly winds of the 2001 season. This enabled generally much easier access to the sea cave nursery sites in the vicinity of Ynys Arw/North Stack. Only minimal access to these sites had been achieved during the 2001 season.

Sites noted in the 2001 survey were measured, mapped and subjected to repeat visits through the season in 2002. Between Porth Namarch and Ynys Arw/North Stack, there were 2 sites: Ogof y Nant (joined at mid- to low tide to Porth y Nant, which was subsequently used by pups as a site of refuge during periods of violent sea conditions) and Ogof Arw.

Through the headland at Ynys Arw, there runs a cleft (Arw Cleft), orientated north to south, which is used as a nursery site by seals and as a place of refuge during periods of violent sea conditions. At its southern limit, it adjoins Parliament House. Part way along, a passageway leads off to eastward. Opposite this passageway, another leads off westward to the tip of the headland. Another passageway leads north-eastward off this passageway, thereby creating the most complex site used by seals in North Wales.

Just south of Parliament House are three great caves, all of which were used as nursery sites in 2002 and one of which was by far the most important single nursery site in the 2002 season. Situated immediately south of Parliament, this long sea cave is called Ogof Morlo. 14 pups were born here. To the south of Ogof Morlo is Ogof Arw Midway and to the south of this lies Ogof Ddeuddrws. These 3 sea caves, like Parliament House, are open to the south-westerly swells and also to the (often violent) daily wake of the high speed ferries which use the port of Holyhead. The same is true of Ogof Gogarth, halfway across Gogarth Bay to Ynys Lawd/South Stack

The 2002 site visits revealed this locality to be, arguably, the most important in North Wales. Although as in 2001 more pups were born on the coast of Penrhyn Llŷn/Lleyn Peninsular, they were spread along a much greater length of coastline, between the Tudwals and the Gwylans/Porth Meudwy.

At the Ynys Arw sites, there is the possibility that a very small number of pups was missed at the beginning of the 2002 breeding season. 35 pups (31.8% of pups born in North Wales) were born at Ynys Arw/North Stack sites, with no mortalities. A true comparison with pup production in the 2001 season is impossible, when only 9 pups (8.2%) were recorded with 3 pre-weaning mortalities (15%).

The 2001 figure is almost certainly an underestimate, within which the apparent importance of the Parliament House site is likely to have been exaggerated, inasmuch as this site was used mainly as a place of refuge by pups during stormy interludes in 2002 rather than as a place where pups were born. This appears to be confirmed by the fact that most sightings and counts made in 2001 were from distant (i.e. cliff top) viewpoints whereas counts made in 2002 were made at sites being used by the seals.

Therefore, it is reasonable to conclude that the 2001 Ynys Arw/North Stack data is significantly flawed, failing to convey a true picture of nursery site distribution and of the numbers of pups born. The 2002 data is accurate except for the possibility that the first pups may have been undetected.

Another notable feature of these sites is that all pups discovered in 2002 survived to weaning, all being cave-born, despite sometimes violent sea conditions. In 2001, 3 of 9 pups counted were recorded as having died. This data, also, should be regarded as flawed. Pups lost from

32

Parliament House may, in fact, have taken refuge in (adjacent) Arw Cleft, where they would not be visible to cliff top observers.

4.5 Weekly pup production at Trwyn y Gader/Carmel Head sites, 2001 and 2002

There was a dramatic decline in pup production at Trwyn y Gader/Carmel Head sites in 2002, compared with 2001, from 9 (8.7%) to 2(1.1%), for no verifiable reason. This may reflect the natural variation in pup production, but long-term data is required to establish this. No pre-weaning mortalities occurred in either year at these sheltered sites

The decline in pup production may have been influenced by heavy fly-tipping which occurred in the early part of the breeding season and which impacted directly and for the remainder of the breeding season upon nursery beaches. At the same time, there was also a lot of coastguard activity in the vicinity, due to the return of a ship carrying nuclear waste from Japan to Sellafield, Cumbria and the possibility of seaborne protest. Walkers using footpaths can also easily access these nursery sites.

4.6 Weekly pup production at Ynysoedd y Moelrhoniaid/The Skerries sites, 2001 and 2002

Pup production and pre-weaning mortalities were the same in 2001 and 2002, with 15 pups being born. One pre-weaning mortality (5% of the North Wales total) was recorded in 2001, none in 2002. Due to a small variation in the total number of pups located in North Wales, 15 pups represented 14.6% of the total in 2001, 13.6% in 2002.

Pups born here made the same contribution in the two years to the late season secondary peak for the region as a whole. In both years, pupping began very late in the season and took place over a very short period. It is possible that, during both years, late-born (late December or January) pups were missed as the island was, for long periods, storm-bound.

4.7 Weekly pup production at the Ormes sites, 2001 and 2002

One pup was reported seen here by a member of the public in 2001. It was not located subsequently. None were located in 2002. With high levels of activity on beaches here, this is an improbable nursery site, except where pups are storm-driven to use it as a place of refuge.

4.8 Timing and extent of the breeding seasons, 2001 and 2002

In both years, a very small number of pups were born in August, the great majority of pups were born in September and October while in November, more pups were born than in August, with nearly all late October and November births being recorded at the northernmost breeding station in the region: Ynysoedd y Moelrhoniaid/The Skerries. In 2001, one pup was born in January.

33

Farther south, at some south-west Wales sites (Baines et al., 1995) and some Cornwall, Isles of Scilly and Lundy sites (Westcott, 1997), the main part of the pup production period includes August while sometimes beginning in late July. In Cornwall, in 2002, the first pup was born 07 July; in 2003, the first pup was born 16 July (Westcott, unpubl.). Therefore, it appears that breeding commences a little later at North Wales sites than at sites farther south. However, the cautionary note here is that detailed examination of sites that took place in the 1990s in south-west Wales (Baines et al, 1995) and in south-west England (Westcott, 1997) appear to indicate a drift toward an earlier onset of pup production compared with earlier (less detailed) pup production surveys in both regions, which tended to be based on single sweeps of the entire coast (Summers, 1974; Anderson, 1977);

Therefore, any future survey that aims to identify the full figure for pups born should have commenced survey work by mid-July at the latest and should continue at least until the end of the first week of December. At least the 121 sites identified as actual and candidate sites should be examined regularly through the season.

4.9 Habitat features of nursery sites used, 2001 and 2002

In the 2001 season, if possible uncounted pups are not included, the majority of pups were born at open beach sites. Any reference to open beaches here simply means non-sea cave sites. In 2002, when all potential sea cave nursery sites were for the most part accessible through the breeding season, the majority of pups were born at sea cave nursery sites. It is felt that this reflects reality more accurately.

However, an alternative interpretation is that site preference (i.e. sea cave versus open beaches), and certainly survivorship of pups through the weaning period, may vary from year to year, according to the impact of wave action on nursery sites.

It is certain that the most exposed sea cave nursery sites, such as those in the vicinity of Ynys Arw/North Stack, will continue to keep their secrets some, probably most, years due to access being impossible unless remote monitoring devices are used.

However, if a sea cave is inaccessible due to wave action, it does not follow that survival by pups is at risk. As in 2001, there were many sightings of pups swimming, of them entering the water of their own volition, and of them being suckled in the shallows. Indeed, in 2002, during late October storms, the survival of all 6 pups using a sea cave that had been inaccessible to surveyors during the 2001 season was the greatest surprise revealed during the 2 years of this survey. They had taken refuge at other sites, slightly less exposed, close by along the coast. Therefore, storm seas running on to sea cave nursery sites do not automatically presage the violent death of the seal pups within.

One very unexpected but significant event occurred during the 2002 breeding season. On October 26 and 27, westerly winds gusting to hurricane force ran mountainous seas against the Ynys Arw coast. It seemed inevitable that all pups at the nursery sites would be quickly battered to death and lost. However, the first site visit made in the wake of this storm revealed that not a single pup had died. All were located, albeit scattered to other non-cave sites close by the cave sites with which they had previously been associated. It was apparent that pups must have vacated the caves early in this period, voluntarily or otherwise, and either ridden out the worst of the storm beyond the wave break or at relatively sheltered open shore sites. Indeed, some were found at a considerable height above the high water mark at Porth y Nant, just east of the easternmost cave in the locality while the remainder were on Parliament House beach or in the adjoining cleft and cave complex. One was in a burrow of boulders, not trapped but seemingly taking shelter there.

34

This demonstrates that pups can survive periods when violent seas are running on to the sites where they are being nursed. It further implies the likelihood that because pups here have to swim over the high water period, they are actually better prepared to swim and survive during stormy interludes. Whether this means that pups are lighter and less well fitted to survive after weaning remains to be clarified.

The perception at the end of the 2001 season was that relatively few sea cave nursery sites are used by seals in the North Wales region and that the sites used are highly localised, being confined to the west Penrhyn Llŷn/Lleyn Peninsular and its outlier of Ynys Enlli/Bardsey and to north-west Ynys Môn/Anglesey and its outlier, Ynysoedd y Moelrhoniaid/The Skerries. That perception holds true in the wake of the 2002 survey.

As in 2001, the breeding season extended from August to late November, peaking strongly in September and October, but including in both seasons a late secondary peak for pup production in late October/November, due to the very late onset of pup production on Ynysoedd y Moelrhoniaid/The Skerries, where very low or zero mortality is probably explained by the fact that pups can haul themselves up grassy slopes that lie behind the nursery beaches, so there is always a potential escape route from heavy seas.

As in 2001, a great number of sea cave sites are used more or less exclusively during the breeding season, and not at all during the remainder of the year. Seal numbers at breeding sites were low everywhere at all times (maximum 3 pups, 3 mothers and one male) except for one site. In 2002, at Ogof Morlo near Ynys Arw/North Stack, one nursery site contained 11 females, 6 pups and 2 males. This was utterly exceptional.

Indeed, Ogof Morlo and neighbouring caves around YnysArw/North Stack used as nursery sites mean that the assertion made in the 2002 report, that only one sea cave nursery site is so-used on Ynys Môn/Anglesey, is incorrect. In fact, the 2002 survey showed that sea cave sites are preferred here.

4.10 Pup mortality

Pup survival to weaning across the region was, even more than in 2001, remarkably high, given that the habitat in which they are born is so exposed, especially to wave action. Furthermore, the breeding season coincides with the time of onset and then the continuation of autumn storms, when sea conditions may be rough for extended periods. However, early in the 2002 season, while slight sea conditions prevailed, 5 of the 9 pups known to have died were identified as having been stillborn and two were abandoned. The cause of death of the remaining two pups was unknown, although neither pup was stillborn. By contrast, the majority at least 75% - of pup mortalities in 2001 was due to wave action during a succession of south-westerly storms in October.

4.11 Dye marking of pups

It is recommended that a month-long study of seal behaviour at sites where pups have been marked with dye be conducted prior to the next dye-marking programme, so that we can be as sure as possible that this method is ethically defensible.

Often, garden mist sprayers are used to apply the dye, with the nozzle set to provide a narrow jet. However, an empty plastic detergent bottle provides a stronger, more reliable jet, will not clog and is therefore a more sensible option.

35

Choice of colours for use in dye marking is subjective. For example, red was not used at Skomer MNR because it was felt that red markings on seal pups could be misinterpreted by members of the public, potentially resulting in spurious records of injured seals or in attempts to rescue injured seals. However, the key details are that they require to be seen, and to be seen as often as possible. Therefore, red and blue are recommended.

Equally subjective, and linked to the choice of colours for dye marking, is the degree to which the help of the public may be enlisted. The strong recommendation here is that they be informed through the various media and potentially interested groups such as inshore fishermen and wildlife trusts of any dye-marking programme. This addresses the concerns raised by the Skomer team and the principal purpose of the dye-marking programme, which is to identify the movements of marked pups, by enlisting extra pairs of eyes to locate pups that wander outside the normal research area.

In applying the dye, the hind parts (back and flanks) and the centre of the back offer the best opportunity for least intrusive (to the seal) marking. The head, neck and fore-flippers should be avoided as a precaution against damaging the (primarily) scent-based.recognition system between mother and pup.

The seal should be approached from the rear, if possible. A head-on approach is likely to provoke the pup to stand its ground, thereby making the act of dye marking problematic. Wind direction and strength will also influence the direction from which the spray is applied. There should be an expectation that the pup is likely to move, probably sharply, in reaction to the first spraying effort. The movement may be aggressive to the fieldworker, may be an attempt to escape or simply a reflex movement to something unexpected. At all times, the fieldworker should maintain awareness of a safe line of retreat in case of seal aggression.

The most effective strategy for dealing with a seal pup that has seen the approach of the fieldworkers is to have the person who is not spraying attract the attention of the pup and hold its attention while the sprayer moves into position. Diversionary tactics must involve movement and, if appropriate, sound: waving fronds of kelp; dancing; singing.

To keep disturbance to the minimum, the period of dye marking should not be extended. If a pup proves impossible to mark, the effort to mark should be abandoned until the next visit.

It is recommended that a pattern of marks be used to distinguish individuals, these to be faithfully recorded on a plan view of a seal. Other marks distinguishing the individual should also be recorded at this time (for example, pattern on face, wound, tar mark).

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5 ACKNOWLEDGEMENTS

I am grateful to CCW for funding this work.

I am particularly grateful to: Mandy McMath, Tom Stringell and Bill Sanderson for their support in general and their patience while cajoling this final version of the report out of me.

Sion Roberts and Tom for helping me to produce the site-based database on which this and future pup production data will be recorded.

Dave and Libby Barnden

Reg Biddlecombe

Bardsey Island Trust

The Williams Family

Al Moralle

All the enthusiasts, naturalists and scientists who went before me, those who shared these adventures and those who explore these places when I have gone from them.

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6 REFERENCES

Anderson, S.S. 1977. The grey seal in Wales. Nature in Wales 15 (3): pp.114-123

Anderson, S.S., Baker, J.R., Prime, J.H. & Baird, A. 1979. Mortality in grey seal pups: incidence and causes. J.Zool., Lond. 189: 407-417.

Baines, M.E., Earl, S.J., Pierpoint, C.J.L. and Poole, J. 1995. The West Wales Grey Seal Census. CCW Contract Science Report No.131. 238pp.

Bardsey Observatory Annual Reports, 1988-2002.

Davies, J., Baxter, J. Bradley, M., Connor, D., Khan, J., Murray, E., Sanderson, W.G., Turnbull, C., & Vincent, M. (Eds.). 2001. Marine Monitoring Handbook March 2001. Peterborough, Joint Nature Conservation Committee 405pp.

Davis, J.E. & Anderson, S.S. 1976. Effects of oil pollution on breeding grey seals. Mar. Poll. Bull. 7: 115-118.

Hall, A.J., McConnell, B.J. and Barker, R.J. 2001. Factors affecting first-year survival in grey seals and their implications for life history strategy. J. Animal Ecology, 70 (1): 138-149

Kiely, O., Lidgard, D., McKibben, M., Connolly, N, and Baines, M. 2000. Grey Seals: Status and Monitoring in the Celtic and Irish Seas. Maritime Ireland/Wales INTERREG Report No.3: 76pp.

Platt, N.E., Prime, J.H. and Witthames, S.R. (1975) The age of the grey seal at the Farne Islands. Transactions of the Natural History Society of Northumbria 42: 99-106.

SCOS, 2000. Scientific Advice on Matters Related to the Management of Seal Populations: 2002. SCOS 02/2, pp57. [http://www.smru.st-and.ac.uk/CurrentResearch.htm/scos.htm].

Smith, E.A. (1966) A review of the worlds grey seal population. J.Zool., Lond. 150: 463-489.

SMRU. (2002) Sea Mammal Research Unit Phocine Distemper Virus Status Reports, Nos.1-19.

Summers, C.F. 1974. The Grey Seal (Halichoerus grypus) in Cornwall and the Isles of Scilly. Biol. Conserv., vol.6, no.4: 285-291.

Westcott, S.M. 1997. The Grey Seals of the West Country. Cornwall Wildlife Trust. 91pp.

Westcott, S.M. (2002) The distribution of Grey Seals (Halichoerus grypus) and census of pup production in North Wales, 2001. CCW Contract Science Report No.499: 140pp.

Westcott, S.M. in prep (2003). Photo-identification of grey seals in North Wales. CCW Marine Monitoring Report.

Westcott, S.M. in prep b (2003). Standard Operating Procedures for grey seal monitoring in North Wales: towards procedural guidelines. CCW Marine Monitoring Report.

Westcott, S.M., McMath, A.J., Stringell, T.B & Sanderson, W.G. 2003. The distribution, abundance and pup production of grey seals (Halichoerus grypus) in North Wales, UK. Poster presentation at the 17th Annual Conference of the European Cetacean Society, Gran Canaria.

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7 APPENDICES

Appendix 1. Total number of pups born in each week of the 2002 breeding season

Week 34 35 36 37 38 39 40

Starts 18/8 25/8 1/9 8/9 15/9 22/9 29/9

No. of pups 1 2 6 14 13 13 14

Week 41 42 43 44 45 46

Starts 6/10 13/10 20/10 27/10 3/11 10/11

No. of pups 12 10 6 9 9 1

Appendix 2. Pup production by district, 2002

Week 34 35 36 37 38 39 40

Starts 18/8 25/8 1/9 8/9 15/9 22/9 29/9

No. of pups:

Penrhyn Llŷn 1 2 4 11 7 6 8

Ynys Enlli 0 0 0 2 1 1 1

Ynys Cybi 0 0 2 1 5 5 5

NW Ynys Môn 0 0 0 0 0 1 0

Y.y.Moelrhoniaid 0 0 0 0 0 0 0

Week 41 42 43 44 45 46

Starts 6/10 13/10 20/10 27/10 3/11 10/11

39

No. of pups:

Penrhyn Llŷn 3 0 0 1 1 1

Ynys Enlli 4 2 1 0 1 0

Ynys Cybi 5 5 1 3 3 0

NW Ynys Môn 0 1 0 0 0 0

Y.y.Moelrhoniaid 0 2 4 5 4 0

Appendices 3-7: Pup production at each site: estimated or actual dates of birth

* indicates pup that died prior to weaning

Appendix 3. Penrhyn Llŷn/Lleyn Peninsular

Site Co-ordinates Aug Sep Oct Nov Total Pups

Ynys Tudwal West SH33562508 18 24 2

Ynys Tudwal East SH34362588 11 1

Ogof Mulfran (E) SH28902373 8 2 4

22 10

Ogof Mulfran (W) SH28792378 7 9 5

11

21

23

Ogof Carreg y Tir SH28712411 2 3

11

22

Clog Cidwm East SH19402594 8 3

11*

40

16

Ogof Lwyd East SH19242565 5 10 3

18*

Ogof Lwyd West SH19212562 31* 8* 2 7

9 3

13 30

Porth Lwyd SH19202561 23* 1

Ogof Lleiddiad SH19072553 9 2 6 7

15 3

25

29

Porth Ebolion SH18962540 21 1

Ogof Ebolion (Mast) SH18932533 2 2 2

Ogof Ebolion (C) SH18922533 15 1

Ogof Ebolion (S) SH18912530 14* 1

Ogof Gwynion (W) SH18742532 16 1

Ogof Trwyn y Penrhyn (S) SH18642530 29 9* 2

Ogof Hwyaid (N) SH18492462 3 1

Appendix 4. Ynys Enlli/Bardsey

Site Co-ordinates Sep Oct Nov Total pups

Ogof Bae y Rhigol SH11792255 8 1

Henllwyn SH11412080 12 1 3 4

14

First Cove South-east SH11422060 15 6 6

41

24 7

8

19

Ogof Trwyn hwch-fawr SH11512193 10* 1

Porth Solfach SH11432624 25* 1

Appendix 5. Ynys Cybi/Holy Island

Site Co-ordinates Sep Oct Nov Total pups

Ogof y Nant SH21868380 5 8 5

15 17

21

Ogof Arw SH21718394 7 5 3 8

16 12 7

24

28

Ynys Arw: Arw Cleft SH21488401 24 15 2

Ogof Morlo SH21508382 21 2 14

23 3

27 5

28 6

30 9

14

16

29

30

42

Ogof Midway (Ynys Arw) SH21508378 13 14 2

Ogof Ddeuddrws SH21508369 19 9 5 3

Ogof Gogarth SH21538331 25 1

Appendix 6. Trwyn y Gader/Carmel Head

Site Co-ordinates Sep Oct Total pups

Porth Gader Mynachdy SH29949292 25 1

Porth y Dyfn (W) SH29359283 14 1

Appendix 7. Ynysoedd y Moelrhoniaid/The Skerries

Site Co-ordinates Oct Nov Total pups

Helipad (N) Cove SH26829489 22 1 7

25 6

26 8

28

Midway Cove (E) SH26949496 16 4

21

28

31

Isthmus West SH27019504 18 5 2

Isthmus East SH27059502 27 4 2

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Appendix 8. Number of pups born each week at Penrhyn Llŷn sites

(Total: 45 pups 6 died)

Week 34 35 36 37 38 39 40

Starts 18/8 25/8 1/9 8/9 15/9 22/9 29/9

No. of pups 1 2 4 11 7 6 8

Week 41 42 43 44 45 46

Starts 6/10 13/10 20/10 27/10 3/11 10/11

No. of pups 3 0 0 1 1 1

August: 18-29-31*

September: 2-2-5-7-8*-8-8-9*-9-9-11*-11-11-13-14*-15-15-16-16-18*-21-21-22-22-

23-23-24-25-29

October: 2-2-2-2-3-3-3-9-10-10-30

November: 6-11

Appendix 9. Number of pups born each week at Ynys Enlli sites

(Total: 13 pups 2 died)

Week 37 38 39 40 41 42 43 44 45

Starts 8/9 15/9 22/9 29/9 6/10 13/10 20/10 27/10 3/11

No. of pups 2 1 1 1 4 2 1 0 1

September: 8-12-15-24

October: 1-6-7-8-10*-14-19-25*

November: 3

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Appendix 10. Number of pups born each week at Ynys Cybi sites

(Total: 35 pups)

Week 36 37 38 39 40 41 42 43 44 45

Starts 1/9 8/9 15/9 22/9 29/9 6/10 13/10 20/10 27/10 3/11

No. of pups 2 1 5 5 5 5 5 1 3 3

September: 5-7-15-13-16-19-21-21-23-24-25-27-28-30

October: 2-3-5-5-6-8-9-9-12-14-14-15-16-17-24-28-29-30

November: 3-5-5-6-7-8

Appendix 11. Number of pups born each week at Trwyn y Gader/Carmel Head sites

(Total: 2 pups)

Week 39 40 41 42

Starts 22/9 29/9 6/10 13/10

No. of pups 1 0 0 1

September: 25

October: 14

Appendix 12. Number of pups born each week at Ynysoedd y Moelrhoniaid sites

(Total: 15 pups)

Week 42 43 44 45

Starts 13/10 20/10 27/10 3/11

No. of pups 2 4 5 4

October: 16-18-21-22-25-26-27-28-28-31

November: 1-4-5-6-8

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Appendix 13. Number of pups born each month in sea caves

Locality August September October November

Penrhyn Llŷn 2 23 11 1

Ynys Enlli 0 1 1 0

Ynys Cybi 0 14 18 3

NW Ynys Môn 0 0 0 0

Ynysoedd y Moelrhoniaid 0 0 0 0

Total no. of pups 2 38 30 4

Appendix 14. Number of pups born each month on open shores

Locality August September October November

Penrhyn Llŷn 1 6 0 1

Ynys Enlli 0 3 7 1

Ynys Cybi 0 0 0 0

NW Ynys Môn 0 1 1 0

Ynysoedd y Moelrhoniaid 0 0 10 5

Total no. of pups 1 10 18 7

Appendix 15. Week of birth of pups that were stillborn or died, 2002

Week 35 37 38 39 41 43

46

Starts 25/8 8/9 15/9 22/9 6/10 20/10

No. of pups that were stillborn or died 1 4 1 1 1 1

47

Cave Plan 1. Ogof y Nant, Ynys Arw/North Stack

48

Cave Plan 2. Ogof Arw, Ynys Arw/North Stack

49

Cave Plan 3. Arw Cleft and Headland Cave, Ynys Arw/North Stack

50

Cave Plan 4. Ogof Morlo, Ynys Arw/North Stack

51

Cave Plan 5. Ogof Midway, Ynys Arw/North Stack

52

Cave Plan 6. Ogof Ddeuddrws, Ynys Arw/North Stack

53

Cave Plan 7. Ogof Gogarth, Ynys Arw/North Stack

54

Cave Plan 8. Ogof Meudwy, Ynys Arw/North Stack

Cave Plan 9. Ogof Gwynion West

55

Cave Plan 10. Ogof Mulfran West, Trwyn Cilan

Cave Plan 11. Ogof Mulfran East, Trwyn Cilan