Аннотация
Introduction: Animal movements are influenced by landscape features;
disturbances to the landscape can alter movements, dispersal, and ultimately
connectivity among populations. Faster or longer movements adjacent to a
localized disturbance or within disturbed areas could indicate reduced habitat
quality whereas slower or shorter movements and reduced movements may
indicate greater availability of resources. The Mojave desert tortoise (Gopherus
agassizii) is a threatened species that is challenged by anthropogenic disturbances.
Methods: We studied tortoise movements using Global Positioning System (GPS)
loggers at multiple sites in the Mojave Desert of Nevada and California. Tortoises
at our sites encountered localized, linear human infrastructure, including paved
roads, dirt roads, and fences, as well as landscape-scale disturbances wildfire,
off highway vehicle use (OHV), livestock grazing area. We fit two-state (moving
and encamped) Hidden Markov models to GPS logger data to infer how tortoise
movement behavior relates to anthropogenic and natural features.
Results: We found that temporal covariates, individual-level random effects
(intercepts), and sex best explained state transition probability in all sites. We
compared relationships between tortoise movement and linear disturbances,
which varied depending on site and context. Tortoises made longer movements
within the OHV recreation area, near most dirt roads, and near a low-traffic
paved road, indicating that tortoises avoid these habitat disturbances. Conversely,
tortoises made shorter movements in areas of higher slope and near highways,
suggesting that these features may restrict movement or provide resources
that result in prolonged use (e.g., forage or drinking locations). Tortoises that
encountered fences around utility-scale solar installations were more active and
made longer movements near fences, indicative of pacing behavior.
Discussion: These results provide insight into how different disturbances
alter tortoise movement behavior and modify tortoise habitat use, providing
information that can be used to manage tortoise habitat.
Линки и ресурсы
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