To count or to catch: Do walk-in traps lead to a biased measure of wader productivity?
53 – 56
1 August 07
Avian Ecophysiology Unit, Dept. of Vertebrate Ecology & Zoology, Univ. of Gdansk, Al. Legionów 9, 80-441 Gdansk, Poland.
Data on the proportion of juveniles in three wader species on autumn migration along the Baltic coast of Poland were collected in two ways: daily counts and constant trapping using walk-in traps. For each species, both methods revealed similar patterns of productivity from year to year. However, depending on local conditions, the age structure of waders caught with walk-in traps may be biased towards juveniles or adults. Therefore determining proportion of juveniles from regular counts may be the better method of assessing wader productivity at stop-over sites during autumn migration than walk-in trap catching