Seabird species vary in behavioural response to drone census

Émile Brisson-Curadeau,David Bird,Paul Pace,Chantelle Burke,David A Fifield,Richard B Sherley,Kyle H Elliott

doi:10.1038/s41598-017-18202-3

Abstract

Unmanned aerial vehicles (UAVs) provide an opportunity to rapidly census wildlife in remote areas while removing some of the hazards. However, wildlife may respond negatively to the UAVs, thereby skewing counts. We surveyed four species of Arctic cliff-nesting seabirds (glaucous gull Larus hyperboreus, Iceland gull Larus glaucoides, common murre Uria aalge and thick-billed murre Uria lomvia) using a UAV and compared censusing techniques to ground photography. An average of 8.5% of murres flew off in response to the UAV, but >99% of those birds were non-breeders. We were unable to detect any impact of the UAV on breeding success of murres, except at a site where aerial predators were abundant and several birds lost their eggs to predators following UAV flights. Furthermore, we found little evidence for habituation by murres to the UAV. Most gulls flew off in response to the UAV, but returned to the nest within five minutes. Counts of gull nests and adults were similar between UAV and ground photography, however the UAV detected up to 52.4% more chicks because chicks were camouflaged and invisible to ground observers. UAVs provide a less hazardous and potentially more accurate method for surveying wildlife. We provide some simple recommendations for their use.

Highlights

The number of organisms in a population has long been recognized as a key parameter in population ecology[1,2,3]
To develop an effective method for counting cliff-nesting Arctic seabirds using unmanned aerial vehicles, we examined the effect of the vehicles on breeding seabirds and compared counts made from the vehicles with those made from observer-based photography
Continuing the earlier research on k-ratios developed from observer-based counts, we addressed a series of questions: How do seabirds respond to Unmanned aerial vehicles (UAVs)? Do they habituate, and how quickly? Does the approach direction or distance matter? Are UAV counts comparable to those derived from traditional census techniques and are they more or less variable?

Summary

Methodology and Results

The study was conducted on thick-billed murres (Uria lomvia), a model-species for Arctic seabirds. As a polar bear (Ursus maritimus) eliminated all eggs on two plots prior to the first UAV flights, we eliminated those two plots from statistical analyses of reproductive success. Those two plots were kept in the analysis of murre’s response to UAV, as they represented a good opportunity to study plots with low k-ratio. Two variables were not included directly in the model, but rather in a separate analysis: 1- habituation over a long period (days) which was not included directly in the models, as high winds allowed us to only repeat the flights for three days or more at two plots 2- time of day, which could be consistently recorded at different time only in Digges Island, due to the conditions at Coats Island.

Results

Discussion