Synchronisation of parental behaviours reduces the risk of nest predation in a socially monogamous passerine bird

K Leniowski,E Węgrzyn

doi:10.1038/s41598-018-25746-5

Abstract

Social monogamy with bi-parental care is the most common breeding pattern in birds, yet cooperation between mates has not been intensively studied to date. In this study we investigate synchronisation of parental behaviours in the blackcap Sylvia atricapilla, a species characterized by bi-parental care and high nest predation. We test the hypothesis that mates synchronize their behaviours to decrease total activity at the nest, which is known to affect predation rate in birds. We examine if blackcap parents synchronise their feeding trips more when nestlings are at the poikilothermic stage, and they may be more vulnerable to nest predation due to their inability to escape and survive outside the nest without parental brooding. We also investigate the alternation of feeding trips by parents. We show that blackcap parents synchronise the majority of their feeding trips during the whole nestling period, and the level of parental synchrony is higher before nestlings develop endothermy. The alternation of male and female feeding trips was much higher than would be expected by chance and was positively related to parental synchrony. We have demonstrated that synchronisation of parental feeding trips significantly decreased parental activity at the nest, and nest survival time increased with the synchrony of parental feeding trips.

Highlights

Social monogamy occurs in 92% of bird species[1] but it is not necessarily associated with both parents involved in the raising of offspring
A high level of synchronisation was characteristic for the majority of blackcap pairs - two-thirds of pairs synchronised over 50% of feeding trips (Fig. 1A)
Comparison of the real disturbance at the nest (RD – caused by both synchronous and asynchronous parental feeding trips) to the theoretical maximum disturbance (TMD - that would be generated if all parental feeding trips were asynchronous), revealed that the reduction of the disturbance at the nest (RoD) caused by parental synchrony was 36% ± 7.8

Summary

Introduction

Social monogamy occurs in 92% of bird species[1] but it is not necessarily associated with both parents involved in the raising of offspring. An individual may withhold provisioning until the partner has provisioned, which leads to alternation of provisioning[13] and more equal distribution of work between parents This kind of conditional cooperation requires integration of information about the mate’s investment, which may be obtained indirectly from nestling condition[14] or directly from watching their partner. We test the hypothesis that blackcap parents synchronize their behaviours to decrease disturbance at the nest caused by parental activity, which is known to affect nest predation rate in numerous bird species[10]. We examine if blackcap parents put more effort into synchronising their feeding trips to reduce disturbance at the nest at the stage of poikilothermic nestlings, which may be more vulnerable to predation. As non-random alternation of provisioning requires the monitoring of a mate we assume that alternation of feeding trips will increase with parental synchrony

Methods

Results

Conclusion