Similar at-sea behaviour but different habitat use between failed and successful breeding albatrosses

K Delord,A Ponchon,A Gamble,JMJ Travis,H Weimerskirch,J Tornos,T Boulinier,C Barbraud

doi:10.3354/meps13880

Abstract

Breeding failure is expected to induce behavioural changes in central place foragers. Indeed, after a failed reproductive attempt, breeding individuals are relieved from having to return to their breeding site for reproductive duties and thus are less constrained than successful breeders in their movements during the remainder of the breeding season. Accordingly, they are expected to adjust their behaviour, travelling longer in distance and/or time to reach foraging grounds. They are also expected to use different foraging areas to decrease local intra-specific competition with successful breeders. We compared the at-sea behaviour and habitat use of successful and failed Indian yellow-nosed albatrosses nesting in Amsterdam Island, Southern Indian Ocean, during 2 chick-rearing seasons. Failed breeders exhibited the same at-sea foraging behaviour, travelling as far and as long as successful breeders. They also spent the same amount of time on their nest between at-sea trips. Nevertheless, habitat models revealed partial spatial segregation of failed breeders, which used specific foraging areas characterized by deeper and colder waters in addition to the areas they shared with successful breeders. Our study shows the importance of combining a range of analytical methods (spatial analysis, behavioural inferences with advanced movement models and habitat models) to infer the at-sea behaviour and habitat use of seabirds. It also stresses the importance of considering individual breeding status when aiming to understand the spatial distribution of individuals, especially when this information may have conservation implications.

Highlights

Seabirds are currently one of the most threatened groups of birds, with nearly 50% of all species showing a decline in population size in recent years (Croxall et al 2012, Dias et al 2019)
During the breeding season, successful breeders may allocate the majority of their time to foraging for themselves and their offspring, making multiple trips between the colony and foraging areas, whereas failed breeders are not restricted in such a way and may be free to engage in longer and/or further at-sea trips (e.g. Fijn et al 2014, Ponchon et al 2017)
As breeding failure is overlooked in tracking studies compared to other factors such as breeding stage within the breeding season, we investigated the at-sea behaviour and habitat use of Indian yellow-nosed albatrosses nesting on Amsterdam Island based on their breeding status during 2 chick-rearing seasons: 2015−2016 and 2018−2019

Summary

Introduction

Seabirds are currently one of the most threatened groups of birds, with nearly 50% of all species showing a decline in population size in recent years (Croxall et al 2012, Dias et al 2019). One major factor likely to affect the at-sea distribution and foraging behaviour of seabirds is breeding status, namely whether an individual is currently succeeding or failing at reproduction (Phillips et al 2017a). Likewise, breeding failure may lead individuals to leave the colony earlier and use different wintering grounds, leading to spatial segregation during the non-breeding season (Phillips et al 2005, Catry et al 2013, Clay et al 2016), with potential negative consequences on subsequent reproductive success (Desprez et al 2018). The short- and long-term consequences of breeding failure are still overlooked in movement studies because failed and non-breeders are generally more challenging to capture and track They are not as attached to their nesting site as successful breeders are and may leave their colony earlier They are not as attached to their nesting site as successful breeders are and may leave their colony earlier (e.g. Catry et al 2013, Ramos et al 2018)

Methods

Results

Conclusion