High-resolution GPS tracking reveals sex differences in migratory behaviour and stopover habitat use in the Lesser Black-backed Gull Larus fuscus

Wendt Müller,Luc Lens,Brigitte C. Heylen,Marwa M. Kavelaars,Eric W. M. Stienen,Jan M. Baert,Roland-Jan Buijs,Judy Shamoun-Baranes

doi:10.1038/s41598-018-23605-x

Abstract

Sex-, size- or age-dependent variation in migration strategies in birds is generally expected to reflect differences in competitive abilities. Theoretical and empirical studies thereby focus on differences in wintering areas, by which individuals may benefit from avoiding food competition during winter or ensuring an early return and access to prime nesting sites in spring. Here, we use GPS tracking to assess sex- and size-related variation in the spatial behaviour of adult Lesser Black-backed Gulls (Larus fuscus) throughout their annual cycle. We did not find sex- or size-dependent differences in wintering area or the timing of spring migration. Instead, sexual differences occurred prior to, and during, autumn migration, when females strongly focussed on agricultural areas. Females exhibited a more protracted autumn migration strategy, hence spent more time on stopover sites and arrived 15 days later at their wintering areas, than males. This shift in habitat use and protracted autumn migration coincided with the timing of moult, which overlaps with chick rearing and migration. Our results suggest that this overlap between energy-demanding activities may lead females to perform a more prolonged autumn migration, which results in spatiotemporal differences in foraging habitat use between the sexes.

Highlights

Long-distance migration has evolved in many genera of birds to cope with spatio-temporal fluctuations in the environment[1,2]
Ringing recoveries revealed that differences in the timing of migration only occur during autumn migration, with males generally arriving on their wintering site before females, despite their simultaneous departure from the breeding area[32]
The wintering areas of tracked Lesser Black-backed Gulls extended from the UK to Senegal (Fig. 1)

Summary

Introduction

Long-distance migration has evolved in many genera of birds to cope with spatio-temporal fluctuations in the environment[1,2]. These trade-offs in energy allocation have been shown to vary among individuals within a population in relation to experience[10,11], sexual maturity[12], size[13] or social dominance[14] Such age-, sex-, or size-dependent variation in the timing of migration, choice of wintering areas, or migration routes, is commonly referred to as ‘differential migration’[15]. Migration is generally considered as a costly stage within the annual cycle[18], as it requires time and energy or increases the risk of predation These costs should be outweighed by the benefits of wintering in favourable areas or of a timely arrival at wintering or breeding sites. We investigated to what extent differences in distance between wintering and breeding areas, in timing of migration, and in habitat use throughout the year, varied according to size and sex

Methods

Results

Conclusion