Effect of Geolocators on Migration and Subsequent Breeding Performance of a Long-Distance Passerine Migrant

• Geolocators are small light-weight data loggers used to track individual migratory routes, and their use has increasedexponentially in birds. However, the effects of geolocators on individual performance are still poorly known. Westudied geolocator effects on a long-distance migrating passerine bird, the northern wheatear (Oenanthe oenantheL.). We asked the general question of whether geolocators affect migratory behaviour and subsequent reproductiveperformance of small passerines by comparing arrival time, breeding time, breeding success and survival ofgeolocator versus control birds of known identity and breeding history. During two years geolocator birds (n=37)displayed a lower apparent survival (30%) as compared to controls (45%, n=164). Furthermore, returning geolocatorbirds (n=12) arrived on average 3.5 days later, started laying eggs 6.3 days later, and had lower nest success (25%)than control birds (78%). Our results suggest that geolocators affect migratory performance with carry-over effects tothe timing of breeding and reproductive success in the subsequent breeding season. We discuss the implications ofsuch geolocator effects for the study of migratory strategies of small passerines in general and suggest how toidentify and investigate such effects in the future.

Ämnesord

NATURVETENSKAP  -- Biologi -- Zoologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Zoology (hsv//eng)

NATURVETENSKAP  -- Biologi -- Ekologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Ecology (hsv//eng)

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