Sample size required to characterize area use of tracked seabirds

Abstract

Conflicts in resource use between humans and wildlife populations are increasingly determined through quantitative approaches. To better understand interactions between birds and human activities in the marine environment, telemetry is routinely used to characterize the area use of species, but evaluations are often based on a small number of individuals taken as representative of a local population studied. Furthermore, the relative importance of the number of animals required and for what duration they should be tracked has received little attention. We examined the central‐place foraging movements of 24 lesser black‐backed gulls (Larus fuscus) from a protected population from 1 March to 31 August during 2010–2013. Using bootstrapping and non‐linear modeling, we investigated whether sample sizes were sufficient to characterize offshore area use by considering the cumulative area use for an increasing number of birds and duration of tracking. Box‐and‐whisker analysis suggested a minimum of 13 birds and a precautionary upper maximum of 41 birds were needed to describe 95% of the estimated area use of the population (defined by 100% occupancy). Tracking fewer birds for longer was more important than tracking more birds for less time. A period of 145 days was required to characterize area use for 13–41 birds; however, offshore areas were used primarily after May, meaning that a 97‐day tracking period from May onwards was also representative. Predicted and observed areas were strongly correlated, and the predicted area of 15 birds for 151 days was 91% of the total estimated for the population. These findings suggest that the data were suitable for determining interaction with offshore developments, and were characteristic of the population. This study has revealed the power of a long‐term tracking dataset, and has uncovered further complexities surrounding study design and analysis that may shape conclusions drawn. The method and considerations raised have wider applicability for other datasets where human‐wildlife resource use conflicts need to be assessed. © 2017 The Wildlife Society.

Making room for the 3Rs principles of animal use in ecology: potential issues identified through a survey

“…These responses are in accordance with other studies looking into awareness of the 3Rs principles among researchers working or intending to work with animals (Franco & Olsson, 2014;Franco et al, 2018). Van Luijk et al (2013) pointed out that the information about the 3Rs principles and their implementation may be difficult to access. The issue with effective searching for the 3Rs principles was highlighted also in the study by Leenaars et al (2009), in which 67 scientists said that they have limited knowledge of the 3Rs databases and access to information is limited.…”

“…Another important source of information about the 3Rs principles and animal welfare are colleagues (Fig. 4B) and strengthening communication among researchers might be one of the strategies to distribute knowledge about the 3Rs (van Luijk et al, 2011;van Luijk et al, 2013).…”

“…3C), which is the most straightforward way to implement the principle of Reduction. While the calculation of the minimum sample size in ecological research has not been enforced (Field et al, 2019), several pioneering studies have been recently published, e.g., in seabirds (Thaxter et al, 2017) or moose (Girard et al, 2002).…”

Methods to quantify avian airspace use in relation to wind energy development

“…2018) and the limitations associated with sample size and deployment duration (Thaxter et al . 2017b), which may affect the use of the data collected to determine collision risk accurately.…”

Assessing integration of black cockatoos using behavioral change point analysis

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