The high cost of movement in an arid working landscape for an endangered amphibian
Data files
Apr 04, 2024 version files 11.10 KB
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README.md
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Salamander.csv
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Abstract
Connectivity is essential for the maintenance of genetic diversity and stability of wildlife populations. Drought and changing precipitation regimes have caused natural aquatic amphibian breeding habitats to disappear or become isolated and have led to the replacement of natural surface water with artificial livestock water tanks. Terrestrial movement is the only means of responding to aquatic threats in arid landscapes and to allow population connectivity. Aridity may present an impenetrable barrier in hydrologically fragmented environments. We used a facultatively paedomorphic and federally endangered salamander to assess the challenges of movement across arid working lands. Sonoran tiger salamanders (Ambystoma mavortium stebbinsi) are endemic to the San Rafael Valley of southeastern Arizona, United States of America, where they depend on livestock water tanks as breeding habitat. The ecology of this species’ metamorphs outside of stock tanks is virtually unknown. To assess survival on the landscape during terrestrial movement we used radio transmitters to track 78 adult metamorphosed salamanders over two years. Sonoran tiger salamanders moved up to 1 km from the tank edge, and average distances moved of over 400 m were higher than most Ambystoma species. However, during the study period, none reached neighboring stock tanks. We found high mortality due to predation and desiccation. Individuals that dispersed to terrestrial habitat in summer survived longer than individuals that dispersed in spring. High mortality suggests terrestrial movement is exceptionally risky and may contribute to isolated subpopulations and elevated levels of inbreeding. Conservation actions that improve and maintain artificial aquatic habitats as well as increase connectivity may improve long-term management for pond-breeding amphibians in arid regions.
Description of data:
ID: animal ID
Tank: tank where the salamander was originally captured
HR (0/1): Home range calculated for the individual. 0=no; 1=yes
Massb4; body mass (g) of the salamander at implantation day
SVL: Snout–vent length (cm)
Left tank (0/1): whether the salamander ever left the tank of origin during the survey period (1=yes) or not (0=no)
ID_Interval: numer of days between implantation date and date when the salamander left the tank. na shoed if the salamander never left the tank
Dispersal_Month: the month when the salamander left the tank (na if it never left the tank)
Dispersal: Date when for the first time the salamander was recorded as away from the tank (na if it never left the tank)
Final: last day of tracking
Days_terrestrial: days in dispersion (na if it never left the tank)
Total_Fixes: number of telemetry locations. na if the transmitter malfunctioned or signal was lost
TD: total distance moved since leaving the tank (na if it never left the tank)
MD: maximum distance moved between telemetry fixes (na if it never left the tank)
SD: the average distance traveled per day (na if it never left the tank)
KDE_95: home range with Kernel Density estimator (na if it never left the tank or if the number of locations collected was < 20)
KDE_50: core area with Kernel Density Estimator (na if it never left the tank or if the number of locations collected was < 20)
Survival (1/0):Fate of each salamander (0=died;1=survived) until the end of the study (na if the individual went missing or the transmitter malfunctioned)