Change-point models for identifying behavioral transitions in wild animals

Kathleen P Gundermann; D R Diefenbach; W D Walter; A M Corondi; J E Banfield; B D Wallingford; D P Stainbrook; C S Rosenberry; F E Buderman

doi:10.1186/s40462-023-00430-0

Change-point models for identifying behavioral transitions in wild animals

Mov Ecol. 2023 Oct 20;11(1):65. doi: 10.1186/s40462-023-00430-0.

Authors

Kathleen P Gundermann¹, D R Diefenbach², W D Walter², A M Corondi³, J E Banfield⁴, B D Wallingford⁴, D P Stainbrook⁴, C S Rosenberry⁴, F E Buderman⁵

Affiliations

¹ Department of Ecosystem Science and Management, Pennsylvania State University, University Park, PA, USA. kpgund@psu.edu.
² U. S. Geological Survey, Pennsylvania Cooperative Fish and Wildlife Research Unit, Pennsylvania State University, University Park, PA, USA.
³ Pennsylvania Cooperative Fish and Wildlife Research Unit, Pennsylvania State University, University Park, PA, USA.
⁴ Pennsylvania Game Commission, Harrisburg, PA, USA.
⁵ Department of Ecosystem Science and Management, Pennsylvania State University, University Park, PA, USA.

Abstract

Animal behavior can be difficult, time-consuming, and costly to observe in the field directly. Innovative modeling methods, such as hidden Markov models (HMMs), allow researchers to infer unobserved animal behaviors from movement data, and implementations often assume that transitions between states occur multiple times. However, some behavioral shifts of interest, such as parturition, migration initiation, and juvenile dispersal, may only occur once during an observation period, and HMMs may not be the best approach to identify these changes. We present two change-point models for identifying single transitions in movement behavior: a location-based change-point model and a movement metric-based change-point model. We first conducted a simulation study to determine the ability of these models to detect a behavioral transition given different amounts of data and the degree of behavioral shifts. We then applied our models to two ungulate species in central Pennsylvania that were fitted with global positioning system collars and vaginal implant transmitters to test hypotheses related to parturition behavior. We fit these models in a Bayesian framework and directly compared the ability of each model to describe the parturition behavior across species. Our simulation study demonstrated that successful change point estimation using either model was possible given at least 12 h of post-change observations and 15 min fix interval. However, our models received mixed support among deer and elk in Pennsylvania due to behavioral variation between species and among individuals. Our results demonstrate that when the behavior follows the dynamics proposed by the two models, researchers can identify the timing of a behavioral change. Although we refer to detecting parturition events, our results can be applied to any behavior that results in a single change in time.

Keywords: Change-point models; Deer; Elk; Hidden Markov model; Movement behavior; Parturition; Telemetry data.