Habitat geometry rather than visual acuity limits the visibility of a ground-nesting bird's clutch to terrestrial predators

George R.A. Hancock*, Lizzie Grayshon, Ryan Burrell, Innes C Cuthill, Andrew Hoodless, Jolyon Troscianko

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

Abstract

The nests of ground-nesting birds rely heavily on camouflage for their survival, and predation risk, often linked to ecological changes from human activity, is a major source of mortality. Numerous ground-nesting bird populations are in decline, so understanding the effects of camouflage on their nesting behavior is relevant to their conservation concerns. Habitat three-dimensional (3D) geometry, together with predator visual abilities, viewing distance, and viewing angle, determine whether a nest is either visible, occluded, or too far away to detect. While this link is intuitive, few studies have investigated how fine-scale geometry is likely to help defend nests from different predator guilds. We quantified nest visibility based on 3D occlusion, camouflage, and predator visual modeling in northern lapwings, Vanellus vanellus, on different land management regimes. Lapwings selected local backgrounds that had a higher 3D complexity at a spatial scale greater than their entire clutches compared to local control sites. Importantly, our findings show that habitat geometry—rather than predator visual acuity—restricts nest visibility for terrestrial predators and that their field habitats, perceived by humans as open, are functionally closed with respect to a terrestrial predator searching for nests on the ground. Taken together with lapwings' careful nest site selection, our findings highlight the importance of considering habitat geometry for understanding the evolutionary ecology and management of conservation sites for ground-nesting birds.
Original languageEnglish
Article numbere10471
JournalEcology and Evolution
Volume13
Issue number9
DOIs
Publication statusPublished - 14 Sept 2023

Bibliographical note

Funding Information:
NERC GW4+ NE/S007504/1 funded George R. A. Hancock in a CASE partnership with the Game and Wildlife Conservation Trust. Jolyon Troscianko was funded by a NERC Independent Research Fellowship NE/P018084/1.

Publisher Copyright:
© 2023 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.

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