New Zealand Journal of Zoology abstracts

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Effect of changes in water level on numbers of black stilts (Himantopus novaezelandiae) using deltas of Lake Benmore

MARK D. SANDERS

Department of Zoology
University of Canterbury
Private Bag 4800
Christchurch, New Zealand
email: msanders@clear.net.nz

Present address: Department of Conservation, Private Bag, Twizel, New Zealand

Abstract  The black stilt (Himantopus novaezelandiae) is a critically endangered wading bird that inhabits rivers, wetlands and lake deltas in the Upper Waitaki Basin, South Island, New Zealand. Changes in numbers of black stilts using the Ahuriri and Tekapo/Ohau Deltas of Lake Benmore, during temporary drawdowns in 1982, 1992, and 1994, were investigated. Numbers of black stilts on the deltas increased during all drawdowns for which data are available, even though the drawdowns varied in magnitude and duration, and occurred at different times of year. Habitat conditions, food supplies, and foraging behaviour at these deltas were measured during the 1994 drawdown, when highly suitable physical habitat, and abundant aquatic invertebrate food supplies for black stilts, were exposed. Invertebrate biomass comprised mainly larval Chironomidae, Oligochaeta, and Gastropoda (Lymnaea spp.). Feeding rates of black stilts on the exposed deltas were high in comparison with feeding rates at other sites in the Upper Waitaki Basin. Management implications of these results are discussed.

Keywords  water level; lake level; black stilt; Himantopus novaezelandiae; shorebird; wader; habitat selection; Chironomidae; Lake Benmore

Z98021
Received 18 June 1998, accepted 29 January 1999

PDF file of entire paper: medium quality (697K); (scanned from paper original: notes about this process)

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