Allochrony is shaped by foraging niche segregation rather than adaptation to the windscape in long-ranging seabirds

• Published in: Movement Ecology
• Main Authors: Francesco Ventura, José Pedro Granadeiro, Paulo Catry, Carina Gjerdrum, Federico De Pascalis, Filipe Viveiros, Isamberto Silva, Dilia Menezes, Vítor H Paiva, Mónica C Silva
• Format: Article in Journal/Newspaper
• Language: English
• Published: BMC 2024
• Subjects: Allochrony; Ecological segregation; Flight behaviour; Foraging niche; Pterodroma; Seabird; Biology (General); QH301-705.5; North Atlantic
• Online Access: https://doi.org/10.1186/s40462-024-00463-z; https://doaj.org/article/106fa2a5451d4b85a4158e4a5f051f59

Abstract Background Ecological segregation allows populations to reduce competition and coexist in sympatry. Using as model organisms two closely related gadfly petrels endemic to the Madeira archipelago and breeding with a two month allochrony, we investigated how movement and foraging preferences shape ecological segregation in sympatric species. We tested the hypothesis that the breeding allochrony is underpinned by foraging niche segregation. Additionally, we investigated whether our data supported the hypothesis that allochrony is driven by species-specific adaptations to different windscapes. Methods We present contemporaneous tracking and stable isotopes datasets for Zino’s (Pterodroma madeira) and Desertas (Pterodroma deserta) petrels. We quantified the year-round distribution of the petrels, characterised their isotopic niches and quantified their habitat preferences using machine learning (boosted regression trees). Hidden-Markov-models were used to investigate the effect of wind on the central-place movement speed, and a simulation framework was developed to investigate whether each species breeds at times when the windscape is most favourable to sustain their trips. Results Despite substantial spatial overlap throughout the year, the petrels exhibited diverging isotopic niches and habitat preferences during breeding. Both species used a vast pelagic region in the North Atlantic, but targeted two different mesopelagic ecoregions and showed a preference for habitats mostly differing in sea surface temperature values. Based on our simulation framework, we found that both species would perform trips of similar speed during the other species’ breeding season. Conclusions The different breeding schedules between the species are underpinned by differences in foraging habitat preferences and adaptation to the local environment, rather than to the windscape. Nevertheless, the larger Desertas petrels exploited significantly windier conditions, potentially unsustainable for the smaller Zino’s petrels. ...