Staging Behavior in Red KNOT (Calidris Canutus) in Delaware BAY: Implications for Monitoring Mass and Population Size

The Auk

Allan J. Baker¹  Simon Gillings¹  Karen A. Bennett¹  Philip W. Atkinson¹  Inês De Lima Serrano¹  Lawrence J. Niles¹  Jean L. Woods¹  Kimberly B. Cole¹  Humphrey P. Sitters¹  Patricia M. González¹  Kevin S. Kalasz¹  Ron C. Porter¹  Clive D. T. Minton¹  Nigel A. Clark¹ 

关键词: Calidris canutus;    Delaware Bay;    mark-recapture models;    mass gain;    passage population size;    Red Knot;    staging ecology;    turnover;   

DOI  :  10.1525/auk.2009.06247

学科分类：动物科学

来源: Central Ornithology Publication Office

【 摘 要 】

Many migratory birds use staging sites to gain essential resources to fuel their ongoing migration. Understanding staging strategies reveals much about migration systems and is essential if one is concerned with monitoring population trends and mass gains, two of the principal methods for assessing the “health” of a migratory population. In spring 2004, we investigated the staging behavior in Delaware Bay of Red Knot (Calidris canutus) using mark-recapture techniques and resightings of birds marked in the preceding spring. Individuals staged for 11–12 days, which declined to 8–10 days late in the season. Arrivals were asynchronous, but departures tended to be synchronized. A simple sensitivity analysis showed that the mark-recapture analysis estimated length of stay to within +10% and confirmed biases in monitoring trends and mass gains using peak counts and mass-on-date regressions. Alternative methods using staging duration to estimate passage population size and mass gains were shown to be unbiased. Using these methods, we estimated a passage population size in 2004 of 18,000 Red Knot that arrived at an average mass of 111 g and, on average, gained mass at 7.2 g day^-1. Thus, in 2004, the passage population was substantially smaller than the recent peak count of 50,360 in 1998, which confirms a significant decline in the number of Red Knot staging in Delaware Bay. Use of refined techniques such as these is essential if management decisions such as those in Delaware Bay are to be based on firm scientific advice.

【 授权许可】

Unknown