Nest monitoring does not affect nesting success of Whinchats Saxicola rubetra

Author(s): Border, J.A., Atkinson, L.R., Henderson, I.G., Hartley, I.R.

Published: December 2017

Journal: IBIS

Digital Identifier No. (DOI): 10.1111/ibi.12574

A new paper, resulting from a collaborative study between BTO and Lancaster University showed that monitoring nests has no effect on daily survival rates of Whinchat nestlings. To ensure that monitoring efforts do not affect survival rate of nestlings and young birds, it is important to assess their impact. Nest monitoring could potentially lead predators to the nest or cause parents to desert or reduce parental care effort to their nestlings. This paper investigated 39 nests to determine whether monitoring has an adverse effect on daily survival rate in Whinchats at Salisbury Plain, Wiltshire.

Nests were either visited only once upon their initial detection, or every two days during the incubation period. The visited nests did not have a lower survival rate than the non-visited nests, suggesting that there are no adverse effects of monitoring on incubation.
During the nestling stage, the nests were monitored once a day on three consecutive days, by using a video camera to record the parents’ behaviour. This part of the study found that nest disturbance by setting up monitoring equipment temporarily reduced the feeding behaviour of the parents, but this only added up to 0.52% of total nestling time; a non-significant portion of the total time a nestling spends with its parents.

In conclusion, this study found that monitoring Whinchat nests every two to three days has no negative effect on survival rate, and although birds can become slightly disturbed, they will soon resettle into normal behaviour. The authors emphasise that precautions to minimise potential impact on nests should always be taken and that guidelines for nest monitoring should always be adhered to.

Abstract

It is important to assess the effect that research activities may have on animals in the wild, especially when key parameters, such as breeding success, could potentially be influenced by observer activity. For birds, some studies have suggested that nest monitoring can increase the chances of nest failure due to predation, while others suggest that human nest visits may actually deter mammalian predators. Nest monitoring visits can also influence breeding success more indirectly by altering parental provisioning behaviour. Here, the influence of monitoring activities on nest success was examined in a ground-nesting, grassland bird, the Whinchat Saxicola rubetra. First, during the egg phase a sample of nests were not visited between the initial finding event and the estimated hatching date; instead the nest status was assessed at a distance. Daily survival rates (DSR) for these nests were compared to nests visited every two days. Second, during the nestling phase, the effects of observer nest visits on parental provisioning behaviour were determined. Nest visits were found not to significantly affect egg DSR and parental provisioning was disrupted for a maximum of 20 minutes (0.52% of the nestling period) following an observer visit. Given the variation in response to nest visits across species, we suggest that consideration should be given to observer impact in all studies where predation risk is high. Here, we illustrate a method for researchers to assess the impact of their nest visits to ensure they are not biasing estimates of breeding success.

Notes

This study was funded by the British Trust for Ornithology and Natural Environment Research Council and is part of a PhD collaboration with Lancaster University and the Ministry of Defence on wider work on the Whinchat.

Staff Author(s)