Abstract
Dierschke (2003) recently published a paper entitled,
``Predation hazard during migratory stopover: are light
or heavy birds under risk?¿¿ He measured the body
condition of 11 species of passerine migrants depredated
by feral cats and raptors at an offshore stopover
site, and used these data to address two hypotheses: (1)
predation risk is higher for heavy birds because it
decreases the take-off ability, and (2) predation risk is
higher for lean birds because their need to feed increases
their exposure to predators. Dierschke found
that lighter weight individuals were strongly disproportionately
represented among the victims, and concluded
that ``it seems that the importance of reduced escape
performance caused by the carrying of fuel loads is
overestimated and possibly not biologically significant
in terms of predation risk¿¿. We found Dierschke¿s data
and analysis interesting and exciting, and believe that
fundamentally, we interpret his results much as he does:
lighter birds are killed disproportionately because they
spend more time feeding and/or do so in ``riskier¿¿
habitats. But we disagree with the inference that massspecific
``predation risk¿¿ is therefore of little ecological
importance or biological significance. In this commentary
we consider the reasoning behind his conclusions,
focusing particularly on the meaning of ``predation
risk¿¿.
Original language | English |
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Pages (from-to) | 225-228 |
Journal | Journal of Avian Biology |
Volume | 34 |
Issue number | 3 |
DOIs | |
Publication status | Published - 2003 |
Keywords
- blackcaps sylvia-atricapilla
- body-mass
- birds
- sandpipers
- selection
- behavior
- fat