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Gruebler, M. U.

Publications and source records attributed to Gruebler, M. U..

3 recordsLinked to original sources

Integrating learning in movement using step-selection analyses

1. Understanding how animals acquire and use information from the environment is critical for linking movement to population dynamics, species distributions and conservation. Advances in tracking technologies and growing interest in learning processes have opened opportunities to study behaviours such as habitat exploration in translocated animals or ontogeny of migration and dispersal movements. However, accessible statistical methods for studying these behavioural processes are lacking. 2. We present a learning-explicit step-selection analysis (SSA) that integrates movement, habitat selection, and learning into a single evolving process. At the start of the movement trajectory, the animal is assumed to have no knowledge of the landscape, i.e. its internal habitat quality map is initialized to a constant. As the animal moves, this map is updated dynamically: with each step, only the habitat within its perceptual range becomes known and contributes to future decisions. 3. Through simulations, we show that this method separates true habitat preferences from learning effects and reveals when large-scale behaviours, such as attraction to resources or avoidance of risks, emerge as knowledge accumulates. Critically, we demonstrate that ignoring learning, as in traditional SSA, can lead to biased estimators of habitat selection. 4. Finally, we apply our approach to a real-world GPS dataset of naive individuals, consisting of 10 juvenile red kites dispersing in Switzerland. Using leave-one-individual-out cross-validation, we show that learner SSFs consistently outperform traditional SSFs in predicting movement decisions. 5. We conclude by discussing methodological considerations and future directions for integrating learning into movement ecology. By explicitly modelling the formation of memory that integrates both spatial information and habitat quality, our approach advances process-based movement ecology while remaining compatible with standard SSA workflows, offering practical tools for both theoretical research and applied wildlife management.

animal behavior and cognition↗

Cascading carry-over effects of early activity phenotypes in golden eagles

1.Early-life conditions are often associated with fitness of animals later in life. Although recent studies show that environmental conditions during development affect the formation of early behavioural phenotypes we have a limited understanding of the cascade of life-history transitions from early phenotypes to fitness relevant behaviours in later life stages. Here, we used GPS and body-acceleration data of 35 juvenile golden eagles (Aquila chrysaetos) to investigate the association between nestling body condition and activity levels (ODBA), the relationship of nestling activity with the timing of fledging and post-fledging activity, and the effects of post-fledging activity on post-fledging movements and the timing of dispersal. We found that nestlings with good body condition also showed increased activity levels. Active nestlings fledged earlier and remained more active after fledging than passive nestlings during early post-fledging. Increased post-fledging activity levels were related to an increased number of pre-dispersal forays and an early timing of dispersal. Even though some effects showed reduced certainty, our results provide evidence for downstream effects of behavioural differences due to early-life conditions. They suggest that early activity phenotypes of nestlings drive the timing of subsequent life-history transitions, thereby representing a key mechanism that links early life conditions with future performance.

ecology↗

Gaining proficiency in flight transforms energy landscapes during ontogeny

The heterogeneity of the physical environment determines the cost of transport for animals, shaping their energy landscape. Animals respond to this energy landscape by adjusting their distribution and movement to maximize gains and reduce costs. Much of our knowledge about energy landscape dynamics focuses on factors external to the animal, particularly the spatio-temporal variations of the environment. However, an animals internal state can significantly impact its ability to perceive and utilize available energy, creating a distinction between the "fundamental" and the "realized" energy landscapes. Here we show that the realized energy landscape varies along the ontogenetic axis. Locomotor and cognitive capabilities of individuals change over time, especially during the early life stages. We investigate the development of the realized energy landscape in the Central European Alpine population of the golden eagle Aquila chrysaetos, a large predator that requires negotiating the atmospheric environment to achieve energy-efficient soaring flight. We quantified weekly energy landscapes using environmental features for 55 juvenile golden eagles, demonstrating that energetic costs of traversing the landscape decreased with age. Consequently, the potentially flyable area within the Alpine region increased 2,170-fold during their first three years of independence. Our work contributes to a predictive understanding of animal movement by presenting ontogeny as a mechanism shaping the realized energy landscape.

animal behavior and cognition↗