3
COMMUNICATIONS FROM THE MAMMAL SOCIETY-NO. 72 387 Robertson, C. P. J. (1994). Movement behaviour of wild and rehabilitated juvenile foxes (Vulpes vulpes). Unpubl. PhD Steigers, W. D. & Flinders, J. T. (1980). A break-away expandable collar for cervids. J. Mammal. 61: 150-152. Strathearn, S. M., Lotimer, J. S. & Kolenosky, G. B. (1984). An expanding break-away radio collar for black bear. J. Wildl. Manage. 48: 939-942. Weber, J.-M. & Meia, J. S. (1992). The use of expandable radio collars for radio-tracking fox cubs. In wildlije telemerry- remote monitoring and tracking ofunimals: 698-700. Priede, I. G. & Swift, S. M. (Eds). Chichester: Ellis Horwood. thesis, University of Bristol. J. Zool., Lond. (1996) 239, 387-389 Leucistic hedgehogs on the island of Alderney P. A. MORRIS AND A. TUTT Biology Department, Royal Holloway, University of London, Egham, Surrey TW20 OEX Introduction Alderney is one of the Channel Islands, situated about 15km off the north coast of France. It is approximately 6 km long and up to 3 km wide. The hedgehog (Erinaceus europaeus) is present but unlikely to be native to the island. The date of its introduction is unknown, but seems to be after 1810 when Martin (quoted by Coysh, 1974) explicitly stated that hedgehogs were absent. Information from three elderly residents confirms that normal-coloured hedgehogs were present about 1910-1920. Other accounts suggest these had probably died out by the Second World War. In 1989, a questionnaire was distributed to all households on the island. The 95 completed returns revealed little further on the origin of the hedgehog population, except that 10 respondents reported seeing them before 1970. Several gave details implying that an introduction had taken place shortly before that time. Anecdotal information suggests at least three local residents imported pairs of normally-coloured hedgehogs in the 1960s (one pair from Harrod’s London pet shop ‘after the War’). Freeman (1980) asserted that there had been recent introductions (from neighbouring Guernsey), and that ‘fawn’ animals were common. Alderney residents now report ‘blond’ hedgehogs to be frequent there. Inspection reveals these to be leucistic animals, with pale creamy-white spines and fur, black eyes and pink skin, claws and feet. We have been unable to trace any records of pale Alderney hedgehogs prior to 1960. Of the 95 respondents to the questionnaire, 64 (67%) said they had seen ‘blond’ hedgehogs and 48 offered estimates of their prevalence. Twenty-three suggested that the proportion of the population was 50% or more. A second questionnaire, seeking details of animals visiting gardens, reported 60 leucistics out of 132 hedgehog sightings (45.5%), but this may reflect repeated observations of the same animals returning to the gardens under observation. Nevertheless, leucistic hedgehogs are clearly unusually abundant on the island. In 1993, we returned to Alderney to study the hedgehogs and to estimate numbers. Twelve transects, ranging from 175 to 2750 m in length, were established in grassland areas. These were

Leucistic hedgehogs on the island of Alderney

Embed Size (px)

Citation preview

Page 1: Leucistic hedgehogs on the island of Alderney

COMMUNICATIONS FROM T H E MAMMAL SOCIETY-NO. 72 387

Robertson, C. P. J. (1994). Movement behaviour of wild and rehabilitated juvenile foxes (Vulpes vulpes). Unpubl. PhD

Steigers, W. D. & Flinders, J . T. (1980). A break-away expandable collar for cervids. J . Mammal. 61: 150-152. Strathearn, S. M., Lotimer, J. S. & Kolenosky, G. B. (1984). An expanding break-away radio collar for black bear.

J . Wildl. Manage. 48: 939-942. Weber, J.-M. & Meia, J. S. (1992). The use of expandable radio collars for radio-tracking fox cubs. In wildlije telemerry-

remote monitoring and tracking ofunimals: 698-700. Priede, I. G. & Swift, S. M. (Eds). Chichester: Ellis Horwood.

thesis, University of Bristol.

J . Zool., Lond. (1996) 239, 387-389

Leucistic hedgehogs on the island of Alderney

P. A. MORRIS A N D A. TUTT Biology Department, Royal Holloway, University of London, Egham, Surrey TW20 OEX

Introduction

Alderney is one of the Channel Islands, situated about 15 km off the north coast of France. It is approximately 6 km long and up to 3 km wide. The hedgehog (Erinaceus europaeus) is present but unlikely to be native to the island. The date of its introduction is unknown, but seems to be after 1810 when Martin (quoted by Coysh, 1974) explicitly stated that hedgehogs were absent. Information from three elderly residents confirms that normal-coloured hedgehogs were present about 1910-1920. Other accounts suggest these had probably died out by the Second World War.

In 1989, a questionnaire was distributed to all households on the island. The 95 completed returns revealed little further on the origin of the hedgehog population, except that 10 respondents reported seeing them before 1970. Several gave details implying that an introduction had taken place shortly before that time. Anecdotal information suggests at least three local residents imported pairs of normally-coloured hedgehogs in the 1960s (one pair from Harrod’s London pet shop ‘after the War’). Freeman (1980) asserted that there had been recent introductions (from neighbouring Guernsey), and that ‘fawn’ animals were common.

Alderney residents now report ‘blond’ hedgehogs to be frequent there. Inspection reveals these to be leucistic animals, with pale creamy-white spines and fur, black eyes and pink skin, claws and feet. We have been unable to trace any records of pale Alderney hedgehogs prior to 1960.

Of the 95 respondents to the questionnaire, 64 (67%) said they had seen ‘blond’ hedgehogs and 48 offered estimates of their prevalence. Twenty-three suggested that the proportion of the population was 50% or more.

A second questionnaire, seeking details of animals visiting gardens, reported 60 leucistics out of 132 hedgehog sightings (45.5%), but this may reflect repeated observations of the same animals returning to the gardens under observation. Nevertheless, leucistic hedgehogs are clearly unusually abundant on the island.

In 1993, we returned to Alderney to study the hedgehogs and to estimate numbers. Twelve transects, ranging from 175 to 2750 m in length, were established in grassland areas. These were

Page 2: Leucistic hedgehogs on the island of Alderney

388 COMMUNICATIONS FROM T H E MAMMAL SOCIETY-- NO. 72

TABLE I Transects in three grassland areas, total di.rtance walked and number of individual marked hedgehogs found

Location of Total transect Number of brown Number of leucistic transects distance walked (m) hedgehogs seen hedgehogs seen % leucisitic

Golf course 45,798 Airport 2 1,250 Cricket pitch 2,800 Rough grass 11.347 Other areas ~

14 14 7

10 5

36 0

42 9

38

Total 81,195 50 17 25.4

walked by two people on 26 nights in September, each transect up to 17 times; a total of 81.2 km. Hedgehogs were sought using powerful torches, captured by hand, weighed, and 67 were individually marked with spray paint, including some found elsewhere on the island.

Results

The sighting distance, perpendicular to the transect line, was similar for both leucistic and normal hedgehogs (Mann Whitney U-test, 2-tailed probability = 0.5925), confirming that the high prevalence of pale animals was not simply due to their greater conspicuousness at night.

The proportion of leucistic animals among the hedgehogs caught in different areas is shown in Table I.

None of the 67 hedgehogs carried fleas, normally an abundant ectoparasite (Brinck & Lofqvist, 1973). This confirms statements from two former staff of the island’s animal hospital and is consistent with human introduction of hedgehogs to the island because flea removal is normal when hedgehogs are transported. New Zealand hedgehogs, translocated from Britain, also have no fleas (Brockie. 1990).

All the pale hedgehogs inspected had black eyes, confirming they were leucistic not albino animals (true albinos also have whiter spines). Leucistic coloration was found in 17 animals, but was not sex-linked (7 males and 10 females; a ratio that did not differ significantly from the normal coloured animals: 2 x 2 x 2 , P > 0.05). The pale coloration was not age-related as leucistic animals ranged from 15Og, to three animals weighing in excess of 1 kg, representing an age range from weaning to at least two years old. Normal brown hedgehogs were found ranging from one at 130 g to five weighing over 1 kg.

Distribution of leucistics appeared patchy. None was found among the 14 hedgehogs caught on 10 visits to the 2.1 km of transect walks around the airport, a statistically significant deviation from the expected 3.09 based on prevalence, elsewhere ( x 2 = 4.848, d$ = 1, P = 0.0277), yet a leucistic individual was found only 1 km away, easily within the distance that a hedgehog can travel in a night (Morris, 1988), and there were no physical barriers to prevent it doing so.

Discussion

Leucistic hedgehogs are very uncommon on the British mainland, only three examples being noted by us in more than 30 years studying this species (two from Aberystwyth, Wales, the other

Page 3: Leucistic hedgehogs on the island of Alderney

COMMUNICATIONS FROM T H E MAMMAL SOCIETY-NO. 72 389

from Fordingbridge, Hampshire). Albinos appear to be more common and are reported in the popular literature comparatively frequently.

There are no predatory mammals on Alderney, so being conspicuously pale probably does not constitute a selective disadvantage there. The genetic basis for coloration in hedgehogs is not known, but the leucistic character may be controlled by a rare recessive gene. This is consistent with the observed facts: it is rarely manifest on the mainland and none of the reported introductions to Alderney were other than normal coloured. But if one of them carried the gene, and there was a back cross mating between the F1 generation and the parent, very likely in a small founder population, this would result in 25% leucistic offspring, exactly the proportion evident today. The patchiness and abundance of leucistic animals in the population might facilitate inbreeding, helping to sustain this high prevalence.

With a confined population, free of predators, this situation might continue, but if there are further introductions, or the genetic basis for spine coloration is more complex, the proportion of leucistic animals may well decline. The purpose of this note is to record the present situation against which a future comparison may be made.

We are very grateful to Barbara Head and the people of Alderney for their enthusiastic assistance; also the Alderney Society and the British Hedgehog Preservation Society who provided financial support for this study.

REFERENCES

Brinck, P. & Lofqvist, J. (1973). The hedgehog Erinaceus europaeus and its flea Archaeopsylla erinacei. Zoonoses (Suppl.)

Brockie, R. E. (1990). European hedgehog. In The handbook of New Zealand mawimals: 99-113. King, C. M. (Ed.).

Coysh, V. (1974). Alderney. Newton Abbot: David & Charles. Freeman, R. B. (1980). Notes on the Fauna ofdlderney. The Alderney Society, St Anne’s. Morris, P. A. (1988). A study of home range and movements in the hedgehog (Erinaceus europaeus). J . Zool., Lond. 214:

1: 97-103.

Auckland: Oxford University Press.

433-449.

J . Zool., Lond. (1996) 239, 389-393

A relationship between echolocation calls and noseleaf widths in bats of the genera Rhinolophus and Hipposideros

M A R K F. ROBINSON 1 I Newton Road, Little Shelford, Cambridgeshire CB2 5HL

Introduction

The production of ultrasound by bats was first recorded by Pierce & Griffin (1938), and later described in more detail by Griffin (1958). Bats of the genera Rhinolophus and Hipposideros emit constant frequency echolocation pulses through their nostrils (Mohres, 1950), which are surrounded by a fleshy, leaf-like structure. The majority of Rhinolophus