Do ringing numbers reflect true migratory activity of nocturnal migrants?

Citation
S. Zehnder et L. Karlsson, Do ringing numbers reflect true migratory activity of nocturnal migrants?, J ORNITHOL, 142(2), 2001, pp. 173-183
Citations number
40
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Animal Sciences
Journal title
JOURNAL FUR ORNITHOLOGIE
ISSN journal
0021-8375 → ACNP
Volume
142
Issue
2
Year of publication
2001
Pages
173 - 183
Database
ISI
SICI code
0021-8375(200104)142:2<173:DRNRTM>2.0.ZU;2-8
Abstract
In autumn 1998, nocturnal bird migration at Falsterbo was recorded over a p eriod of three months by means of a passive infrared device. At the same pl ace a standardised trapping scheme is in operation. This study reveals for the first time a positive correlation between the migratory intensity of bi rds aloft and the numbers of trapped birds. By relating the migratory patte rns of single species with the nocturnal. migratory intensities, we show th at the species composition aloft can at least partly be deduced from the nu mber of grounded birds. The numbers of trapped pre-Saharan migrants were re lated more strongly to the migratory intensity of the preceding night than were the numbers of trans-Saharan migrants. Assuming that the number of tra pped birds varies according to the weather to the same extent as the migrat ory intensity of birds aloft, we conclude that in shorter range migrants th e decision to engage in a migratory flight is influenced more strongly by w eather conditions, and that the migratory activity of trans-Saharan migrant s is possibly more intensely controlled by their endogenous. migratory urge .