Avian migration and dispersal

The movements of birds are among their most captivating traits. The regular seasonal movements of avian migrants are remarkably diverse: phalaropes (Phalaropus species) from the high Arctic spend their non‐breeding season in upwelling areas on open tropical seas; Northern Wheatears (Oenanthe oenanthe) traverse most of the northern hemisphere in their back‐and‐forth movements to ancestral wintering areas in Africa; and Resplendent Quetzals (Pharomachrus mocinno) travel from one side of Costa Rica’s mountainous spine to the other and back again in their annual search for fruiting trees. Birds migrate great distances to find suitable habitats, and they also engage in dispersal from the location where they hatched to their adult breeding sites

Distance doesn't matter: migration strategy in a seabird has no effect on survival or reproduction

Migrating animals show remarkable diversity in migration strategies, even between individuals from the same population. Migrating longer distances is usually expected to be costlier in terms of time, energy expenditure and risks with potential repercussions for subsequent stages within the annual cycle. Such costs are expected to be balanced by increased survival, for example due to higher quality wintering areas or lower energy expenditure at lower latitudes. We compared reproductive parameters and apparent survival of lesser black-backed gulls (Larus fuscus) breeding in The Netherlands, whose winter range extends from the UK to West Africa, resulting in one-way migration distances that differ by more than 4500 km. Individuals migrating furthest arrived later in the colony than shorter distance migrants, but still laid in synchrony with the colony and consequently had a shorter pre-laying period. This shorter pre-laying period affected neither egg volumes nor hatching success. We found no relationship between migration distance and apparent survival probability, corresponding with previous research showing that annual energy expenditure and distance travelled throughout the year is similar across migration strategies. Combined, our results indicate an equal fitness payoff across migration strategies, suggesting there is no strong selective pressure acting on migration strategy within this population