Breeding ecology of Richard's Pipit (Anthus novaeseelandiae) in the Snowy Mountains

摘要

We studied the breeding biology of Richard's Pipit (Anthus novaeseelandiae) in the Snowy Mountains during 1979-2003; intensive field work occurred in 2000-01. In this region Richard's Pipit is an altitudinal migrant, and its nesting cycle was affected by patterns of snowmelt and arthropod abundance. Date of first observation above winter snowline was positively related to date of last snowcover. Adults arrived in the main study area in October, and began nesting in early November, when the ground was similar to50% snow-free. Many pipits apparently were double-brooded; young of first and second broods fledged when arthropod abundance was near maximum levels. Post-breeding flocking began in mid-February. Most nests were placed below shrubs less than or equal to30 cm in height; orientation was non-random, with nest entrances 100-200 from prevailing cold fronts. Clutch size for pipits in the Snowy Mountains was 2.91 +/- 0.34 (s.d.), significantly greater than for clutch size data from the Birds Australia Nest Record Scheme. In 2000-01, 54.1% of the nests (n = 41) fledged at least one young; nest survival probability was 0.636. The major cause of nesting mortality was predation (70.6% of losses). Nest success increased with increasing vegetation cover within 1 m of the nest. Differences in the breeding biology of Richard's Pipit, compared with the alpine-breeding American Pipit (Anthus rubescens), include smaller clutch size, smaller clutch mass as a percentage of female mass, and high frequency of double-brooding. These differences may be due to the shorter duration of snowcover and the longer growing season in the alpine zone of the Snowy Mountains compared with the North American alpine, which allows for multiple breeding attempts in a single season. Given possible decreases in snow cover and duration due to predicted warming in Australian mountain areas, Richard's Pipit represents a 'model organism' that could be used for a long-term study on effects of climate change on high-altitude ecosystems in the region.