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The role of allochrony in influencing interspecific differences in foraging distribution during the non-breeding season between two congeneric crested penguin species

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posted on 20.09.2022, 07:12 authored by CP Green, N Ratcliffe, T Mattern, D Thompson, MA Lea, S Wotherspoon, PG Borboroglu, Ursula EllenbergUrsula Ellenberg, KW Morrison, K Pütz, PM Sagar, PJ Seddon, LG Torres, MA Hindell
Mechanisms promoting coexistence between closely related species are fundamental for maintaining species diversity. Mechanisms of niche differentiation include allochrony which offsets the peak timing of resource utilisation between species. Many studies focus on spatial and temporal niche partitioning during the breeding season, few have investigated the role allochrony plays in influencing interspecific segregation of foraging distribution and ecology between congeneric species during the non-breeding season. We investigated the non-breeding migrations of Snares (Eudyptes robustus) and Fiordland penguins (Eudyptes pachyrhynchus), closely related species breeding between 100–350 km apart whose migration phenology differs by two months. Using light geolocation tracking, we examined the degree of overlap given the observed allochrony and a hypothetical scenario where the species commence migration simultaneously. We found that Fiordland penguins migrated to the Sub-Antarctic Frontal Zone and Polar Frontal Zone in the austral autumn whereas Snares penguins disperse westwards staying north of the Sub-Tropical Front in the austral winter. Our results suggest that allochrony is likely to be at the root of segregation because the relative profitability of the different water masses that the penguins forage in changes seasonally which results in the two species utilising different areas over their core non-breeding periods. Furthermore, allochrony reduces relatively higher levels of spatiotemporal overlap during the departure and arrival periods, when the close proximity of the two species’ colonies would cause the birds to congregate in similar areas, resulting in high interspecific competition just before the breeding season. Available evidence from other studies suggests that the shift in phenology between these species has arisen from adaptive radiation and phenological matching to the seasonality of local resource availability during the breeding season and reduced competitive overlap over the non-breeding season is likely to be an incidental outcome.

Funding

This work was supported by donations from the Antarctic Research Trust, Global Penguin Society and National Geographic. The funders provided support in the form of salaries and/or by covering the costs of field work for authors KP, PGB and KWM, but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are articulated in the "Authors' contributions" section. This study forms part of a PhD funded by a British Ornithologists' Union (BOU) John & Pat Warham Studentship from a bequest left to the BOU by the late John and Pat Warham for the study of Sphenisciform and Procellariiform seabirds by a student from Commonwealth countries.

History

Publication Date

09/02/2022

Journal

PLoS ONE

Volume

17

Issue

2 February

Article Number

e0262901

Pagination

22p.

Publisher

PLOS

ISSN

1932-6203

Rights Statement

© 2022 Green et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.