Wild great and blue tits do not avoid chemical cues of predators when selecting cavities for roosting.

Gustavo Tomás,Luisa Amo,Irene Saavedra,Marcel E Visser

doi:10.1371/journal.pone.0203269

Gustavo Tomás, Luisa Amo + Show 2 more

Open Access

https://doi.org/10.1371/journal.pone.0203269

Copy DOI

Abstract

Small birds use cavities for roosting to decrease the thermoregulatory costs during the winter nights. The ability of birds to detect and escape from an approaching predator is impaired during roosting and thus the selection of such cavities should take into account the risk that a predator will find the cavity. Previous evidence suggested that birds in captivity are able to detect predator scent and avoid roosting in nest-boxes containing such predator chemical cues. Here, we tested whether birds also show this avoidance response under natural conditions. We performed three studies in three populations of blue and great tits. We added predator scent, a pungency scent or an odourless control to nest-boxes and compared the use of these nest-boxes for roosting. We found no differences between the scent treatments in the use of nest-boxes. Therefore, chemical cues indicating the potential presence of a predator are not enough for birds to avoid roosting in nest-boxes under natural conditions.

Highlights

During winter, bird mortality is reported to be higher than at other moments of the year [1,2] especially after particular bad weather events such as frosts or storms [3]
Under natural conditions, birds did not avoid roosting in nest-boxes containing predator scent
When considering the previous use of the nest-boxes, our results show that birds did not avoid to roost in those nest-boxes that contained predator scent

Summary

Introduction

Bird mortality is reported to be higher than at other moments of the year [1,2] especially after particular bad weather events such as frosts or storms [3]. This increased mortality during winter can have several causes. For instance for insectivorous birds, the decrease in insect abundance in winter leading to increased foraging effort [4] Another potential cause is the increased metabolic costs associated to thermoregulation under low environmental temperatures. Survival of small birds can be seriously compromised during winter, especially during the night, when temperature reaches its minimum

Methods

Results

Conclusion