Two species of legless, fossorial skinks (Typhlosaurus) are partially sympatric in the Kalahari Desert. Typhlosaurus lineatus occur both in the sandridge and flatland geographic provinces of the Kalahari, in dune streets and on sandridgesmicrogeographically in sympatry, and primarily under log and leaf litter microhabitats. Typhlosaurus gariepensis, always microgeogrphically, and primarily in basal roots of bunch grass microhabitats. Microhabitat overlap in sympatry is low. Morphologically, T. lineatus differ from T. gariepensis in being longer and in having a longer and wider head. Snout—vent lengths, head dimensions, and proportional head lengths of sympatric T. lineatus are larger than those of allopatric T. lineatus; thus T. lineatus displace from T. gariepensis in sympatry. Both species are viviparous, have one brood per year, and give birth in summer after a 5—mo gestation period. Maturity is reached at minimum ages of one and two—thirds yr. Mean litter size of T. lineatus is 1.6, whereas T. gariepensis have but one young. A response to competition between the two species is suggested by the facts that offspring of sympatric T. lineatus are significantlyheavier than those of allopatric females, and that fewer sympatric T. lineatus females are reproductive than allopatric females. Because Typhlosaurus are termite specialists (92.4% of diet by volume), termitesin guts were identified to species and caste. Compared with sympatric T. lineatus, T. gariepensis eat more Psammotermes workers, fewer Allodontermes major workers, and scarcely any Hodotermes. Sympatric T. lineatus eat fewer Psammotermes workers and more Allodontermes major workers than do allopatric T. lineatus. Prey size differences parallel lizard size differences. Because of dietary shifts by T. lineatus in sympatry, dietary overlap with T. gariepensis is substantially reduced for females and immatures, although not for males. Strong morphological and dietary evidence support, for T. lineatus females and immatures, the hypothesis that behavioral and morphological character displacement has occurred which reduces dietary overlap with T. gariepensis. Dietary data for male T. lineatus are possibly conflicting.
Gray fox (Urocyon cinereoargenteus Schreber, 1775) populations in portions of the eastern United States have experienced declines whose trajectories differ from those of other mesocarnivore populations. One hypothesis is that gray fox declines may result from interspecific interactions, particularly competition with abundant coyotes (Canis latrans Say, 1823). Alternatively, gray foxes may respond negatively to increased urbanization and reduced forest cover. To evaluate these hypotheses, we used single-species occupancy models of camera trap data to test the effects of habitat covariates, such as the amount of urbanization and forest, on coyote and gray fox occupancy. Additionally, we test the effect of an n-mixture based index of the number of coyotes at each camera trap site on gray fox occupancy. Results indicate that occupancy probabilities of coyote and gray fox relate positively to the amount of forest, but they provided no evidence urban cover impacts gray foxes. Additionally, gray fox occupancy was negatively related to the index of the number of coyotes at each site. Our models support the idea that interactions with coyotes impact gray fox occupancy across the eastern U.S. These results illustrate how large scale studies can relate mechanisms identified within specific landscapes to phenomena observed at larger scales.
COVID-19 lockdowns in early 2020 reduced human mobility, providing an opportunity to disentangle its effects on animals from those of landscape modifications. Using GPS data, we compared movements and road avoidance of 2300 terrestrial mammals (43 species) during the lockdowns to the same period in 2019. Individual responses were variable with no change in average movements or road avoidance behavior, likely due to variable lockdown conditions. However, under strict lockdowns 10-day 95th percentile displacements increased by 73%, suggesting increased landscape permeability. Animals’ 1-hour 95th percentile displacements declined by 12% and animals were 36% closer to roads in areas of high human footprint, indicating reduced avoidance during lockdowns. Overall, lockdowns rapidly altered some spatial behaviors, highlighting variable but substantial impacts of human mobility on wildlife worldwide.
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