Accounting for behaviour in fine-scale habitat selection:A case study highlighting methodological intricacies

• Published in: Journal of Animal Ecology
• Main Authors: Beumer, Larissa T., Schmidt, Niels M., Pohle, Jennifer, Signer, Johannes, Chimienti, Marianna, Desforges, Jean Pierre, Hansen, Lars H., Højlund Pedersen, Stine, Rudd, Daniel A., Stelvig, Mikkel, van Beest, Floris M.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2023
• Subjects: Arctic; availability domain; context-dependent habitat selection; hidden Markov modelling; muskox; step-selection functions; ungulate; ovibos moschatus
• Online Access: https://pure.au.dk/portal/en/publications/9f929c4d-074c-49aa-ba90-e8c1bb7ba31a; https://doi.org/10.1111/1365-2656.13984; http://www.scopus.com/inward/record.url?scp=85164956879&partnerID=8YFLogxK

Animal habitat selection—central in both theoretical and applied ecology—may depend on behavioural motivations such as foraging, predator avoidance, and thermoregulation. Step-selection functions (SSFs) enable assessment of fine-scale habitat selection as a function of an animal's movement capacities and spatiotemporal variation in extrinsic conditions. If animal location data can be associated with behaviour, SSFs are an intuitive approach to quantify behaviour-specific habitat selection. Fitting SSFs separately for distinct behavioural states helped to uncover state-specific selection patterns. However, while the definition of the availability domain has been highlighted as the most critical aspect of SSFs, the influence of accounting for behaviour in the use-availability design has not been quantified yet. Using a predator-free population of high-arctic muskoxen Ovibos moschatus as a case study, we aimed to evaluate how (1) defining behaviour-specific availability domains, and/or (2) fitting separate behaviour-specific models impacts (a) model structure, (b) estimated selection coefficients and (c) model predictive performance as opposed to behaviour-unspecific approaches. To do so, we first applied hidden Markov models to infer different behavioural modes (resting, foraging, relocating) from hourly GPS positions (19 individuals, 153–1062 observation days/animal). Using SSFs, we then compared behaviour-specific versus behaviour-unspecific habitat selection in relation to terrain features, vegetation and snow conditions. Our results show that incorporating behaviour into the definition of the availability domain primarily impacts model structure (i.e. variable selection), whereas fitting separate behaviour-specific models mainly influences selection strength. Behaviour-specific availability domains improved predictive performance for foraging and relocating models (i.e. behaviours with medium to large spatial displacement), but decreased performance for resting models. Thus, even for a predator-free population ...