COS 184-1 - Improving the understanding of animal habitat selection and resource use with the time model and the time-explicit step selection function (tSSF)

Abstract: 1. Understanding the relationship between animals and their environment is a central focus of ecological science, with important implications regarding how animals will be affected by environmental change and how these impacts can be mitigated. In particular, insights on landscape use can help define priority conservation areas for the establishment of reserves and also potential dispersal routes for the establishment of corridors in fragmented habitats.

2. We describe how complementary information regarding how animals use landscapes can be obtained by separately assessing the drivers of time to traverse the landscape and the drivers of selection strength. More specifically, we describe a new model which enables inference on the time taken to traverse landscapes and we show how it can be combined with a selection function to form a time-explicit step selection function (tSSF) model. The tSSF model accounts for resource availability through time and generates probabilistic outcomes that can be directly used to understand dispersal patterns.

3. These models are illustrated using GPS-tracking data from giant anteaters (Myrmecophaga tridactyla) in the Pantanal wetlands of Brazil. The time model revealed that the fastest movements tended to occur between 8 pm and 5 am, suggesting a crepuscular/nocturnal behavior. Giant anteaters moved faster over wetlands while moving much slower over forests and savannas, in comparison to grasslands. We found that wetlands were consistently avoided whereas forest and savannas tended to have higher preference. Importantly, this model revealed that selection for forest increased with temperature, suggesting that forests may act as important thermal shelters when temperatures are high. Finally, we illustrate how the tSSF results can be used to simulate movement and connectivity within a fragmented landscape.

4. Landscapes across the world are changing at ever increasing rates due to habitat degradation and loss associated with land use change. The ideas and methods proposed here may be useful to improve the understanding of how animals will be affected by these changes and in developing strategies to mitigate these impacts.