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UPDATE: 20th March 2012 - for the information of ECAOAC members & local landholders across the Lower Gwydir floodplain.

GWYDIR FLOWS UPDATE 9th – 20th March 2012

Flood waters across the wider floodplain continue to recede and dry off. As a result, ground access to agricultural lands has continued to improve in many areas. Since last (6th March) update) water levels in the wetlands have slowly dropped, as natural inflows also reduced over the period. In response to continuing falling inflows and the need to support the current Ibis breeding event, environmental water commenced delivery into the Gingham watercourse from Tyreel on or about the 9th March. A review of recent flows shows a continual increase in flow delivery since commencement, now nearing the desired target @ the downstream Teralba gauge. The Tillaloo Bridge gauge (nearest

upstream wetlands gauge) has generally followed a similar volume and flow pattern to the upstream Teralba gauge. The Gingham Bridge gauge, (loc. between the Upper & Lower Gingham Ibis rookeries)

has continued to fall for most of the period, although around the 16th March flows made a turnaround with flows now progressively increasing since that time. Current water levels at both rookery sites remain within acceptable ranges, increasing slowly in most recent days. It is expected that wetland water levels will continue to rise slowly and increase their passage through the upper & into the lower rookeries sites. During field visits to the rookery sites (13-16th March) Departmental staff installed a number of water height gauge plates and attached time series cameras. Regular monitoring of inflows and water levels in and around the rookery sites will be undertaken until Ibis chicks fledge, poss. late April 2012.

Flows @ Gingham Gauges

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2/03

/201

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4/03

/201

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6/03

/201

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/201

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10/0

3/201

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12/0

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Dates

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day Teralba

Tillaloo Bridge

Gingham Bridge

Figure 1. Recent flow rates at relevant gauges in the Gingham watercourse.

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Waterbird observations & nesting requirements (prov. By Dr. Jen Spencer NSW OEH) Staff from NSW Office Environment Heritage (OEH) are currently undertaking a program of ground surveys of major waterbird colonies in the Gingham watercourse, Gwydir wetlands over March and April. The aim of these surveys are to determine an estimate of total nests per species, colony extent, nesting stage in each colony and also estimate breeding success. Surveys to date have indicated that the egret colonies are extensive, spreading widely and joining smaller egret colonies together. A survey of sites on the 12 March indicated that nesting is at a later stage, with many intermediate egrets near fledging/fledged. This indicates that most birds nested following the Nov-Dec flooding rather than the February flooding. Small numbers of white ibis, royal spoonbills, great egrets and night herons were also observed nesting in River Cooba and Belah at the sites. Water depth ranged from 20-40 cm. The western straw-necked ibis colony is spread over a large area in the Lower Gingham. This is a very large rookery and birds are nesting in stands of cumbungi and reed. During surveys on the 13-14 March most nests contained eggs or recently hatched chicks (ranging from about 1 – 7 days old). There were also areas of glossy ibis nests containing eggs or very recently hatched chicks, a number nesting in River Cooba as well as reed bed. Water depth at this site ranged from 10-40cm. Nest densities were counted in the upper and mid region of this colony where accessible on foot. These counts will help ground-truth high resolution aerial photography that OEH captured on 8 March. This imagery will be analysed to provide an estimate of total numbers of nests and colony extent. Approximately 2,600 active straw-necked ibis nests were counted in clumps of lignum in the upper Gingham rookery, during a survey on the 15 March. These nests were at a later nesting stage than the western ibis colony, with most nests (95%) containing chicks and very few nests containing eggs. Small numbers of intermediate egrets (182 nests), royal spoonbills (65 nests), white ibis (38 nests) were also nesting in cooba around the edge of the bis colony. Approximately 3,036 juveniles were counted in this colony. These juveniles were a result of nesting in January before the large flood. These birds survived the February flood by rafting on tall clumps of lignum. It was also apparent that some birds from the January breeding event did not survive the flood, with 514 dead juvenile straw-necked ibis observed in the colony. Water depth in this colony ranged from 20-50cm, but there were a small number of nests on the edge of the colony which were dry underneath. Water levels are rising slowly at this site since environmental water commenced. It will be vital that water levels are maintained under the nesting ibis to prevent large-scale desertion of the active nests. Further surveys of these colonies, including the large egret colonies at the eastern & western colonies will be surveyed from 19-30 March. Water levels in all sites are being closely monitored at all times.

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Pic 1. Ibis Rookery nests with eggs

Pic 2. Ibis nest (egg hatching)

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Final & Important Note The staff from NSW Office of Environment & Heritage takes this opportunity to commend and sincerely thank the landowners, on whose properties the current waterbird breeding events are occurring. These landowners have allowed continued access to the sites by staff, for the purpose of monitoring the breeding event. Without this level of support and acknowledgement of both the importance of the event and monitoring it throughout its cycle, a successful outcome could not be assured. The local wetland landowners understand the cycle of waterbird breeding in the Gwydir, however the wider public need to be aware that access to these rookery sites and waterbird breeding event is restricted, due to the impact that disturbance can have on breeding success and chick survival. It is paramount that disturbance of rookery sites must be kept to a minimum; for adults will abandon both eggs and young if their fears are heightened. Flightless Ibis chicks will jump from nests when disturbed, often drowning as a result of their inability to return to the nest. NSW OEH with the support of Border Rivers Gwydir CMA have hosted a series of regular updates, as the season has unfolded, in an attempt to better inform the wider public and local landowners, of flooding, wetlands state and the current waterbird breeding event. In addition, a series of slide shows will soon be hosted with the regular updates so that the breeding event, chick development and final fledging will be known by all.

Pic 3. Ibis nest (Chicks @ 5- 7 days)

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Pic 4. Ibis Rookery (adults, nests & young)

Provided as advice to ECAOAC members and landowners in the Gwydir Watercourses and Floodplain Areas by Daryl Albertson - Gwydir Environmental Water Manager NSW Office of Environment & Heritage Email: daryl.albertson@environment.nsw.gov.au or jane.humphries@environment.nsw.gov.au

http://brg.cma.nsw.gov.au/index.php?page=ECA