What is a season to an oryx? Movement rates identify three seasons for scimitar-horned oryx reintroduced into their native range.

Abstract

Background: Abundant evidence exists that mobile animals exhibit different movement behavior during different seasons, especially in landscapes with strong seasonal variation in climate and resource availability. Quantifying seasonal movement dynamics is critical for making accurate inferences and appropriate recommendations for species conservation and landscape management. Using empirical approaches to characterize seasonal variation in animal movement minimizes assumptions about the timing of seasonal transitions, environmental proxies, and effects of spatiotemporal variation.

Methods: We calculated 57,255 mean daytime hourly movement rates for 104 scimitar-horned oryx (Oryx dammah) released into a large protected area in central Chad from 2016 to 2022. We used these movement data to build generalized additive mixed models of movement rates over a generic calendar year to detect potential seasonal variation in oryx movement behavior.

Results: Our final model indicated that reintroduced oryx experience three seasons per year, exhibiting dramatically lower daytime movement rates during the hot, dry season and higher movement rates during the rainy and cool, dry seasons. Reproductive status also affected oryx movement rates, notably females 1-4 months into pregnancy.

Conclusions: Captive-born oryx exhibited transitions in movement behavior aligned with regionally characteristic seasonal variation, a promising indicator for an ongoing reintroduction effort. Females 1-4 months pregnant, particularly those accompanied by neonates, exhibited consistently elevated daytime movement rates, suggesting substantial energy allocation to foraging in early pregnancy. The three seasons delineated by this study will be used to manage the reintroduced oryx population, for example to identify priority areas and time periods for enhanced monitoring and enforcement actions, as well as to investigate the potential re-emergence of historical seasonal migrations.