Drivers and fitness consequences of dispersive migration in a pelagic seabird

Abstract

Lay SummarySex segregation, competition and differences in individual quality may drive dispersive migration in birds and affect their fitness. Atlantic puffins tracked for up to 6 years followed remarkably different migration routes, but individuals followed the same route every year. Although random dispersion and sex segregation could not explain the patterns observed, birds visiting the Mediterranean Sea foraged more and had a higher breeding success than birds remaining locally or visiting the Atlantic Ocean.

Within-pair similarity in migration route and female winter foraging effort predict pair breeding performance in a monogamous seabird

“…No obvious impact was observed on any of the pairs, and all continued behaving normally after handling. The breeding success and survival of puffins tracked with geolocators on our study site are similar to control birds (Fayet et al 2016).…”

“…Chicks fledge from late June to midJuly, and soon after, the adults leave the colony and start their migration. Migratory patterns are very diverse and can include successive trips to different wintering sites (Fayet et al 2016). The timings and locations of moult are unknown but likely to vary widely within populations (Harris et al 2014).…”

“…However, the spatial variables estimated are only used for comparison between individuals, so it is their relative value which is considered, which will be less affected by any systematic over-or under-estimation than the absolute values. We also processed the data to minimise error, using the following methods (described in Fayet et al 2016). Two-day median positions were calculated from the geolocation light data for all migration tracks, using a speed filter of 500 km d −1 and removing data close to the equinoxes.…”

“…The NND was calculated over a 20 d window to add a temporal aspect to our calculation of route similarity; in other words, the tracks of 2 birds visiting similar locations months apart would not count as being similar. As in Fayet et al (2016), a 20 d window was chosen as a good compromise between short enough to compare synchrony between birds and long enough to ensure a reasonable range of locations from which to find a nearest neighbour (due to the spatial resolution of geolocation, there may be gaps in the data on particular days).…”

“…Here, we use geolocation tracking data, combined with individual at-sea activity budgets to provide estimates of daily behaviour and energy expenditure, to examine the within-pair dynamics of migration both spatially and behaviourally in a long-lived monogamous dispersive migrant, the Atlantic puffin Fratercula arctica (Guilford et al 2011, Fayet et al 2016). More specifically, we investigate how certain measures of a pair's reproductive success are related to the non-breeding behaviour of each mate and of the pair as a whole by testing (1) whether pair members migrate together or separately and synchronise their arrival to, and departure from, the colony and if there is any fitness advantage for mates to follow similar routes (in terms of timing of breeding and reproductive success); (2) whether sexes differ in their non-breeding behaviour (which would indicate distinct foraging strategies or niches that may promote separation of partners during non-breeding); and (3) the extent to which each pair member's foraging effort during the non-breeding season predicts the pair's subsequent breeding performance.…”