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Agassiz's desert tortoise (Gopherus agassizii) populations are exposed to a variety of anthropogenic threats, which vary in nature, distribution, severity, and frequency. Tortoise management in conservation areas can be compromised when the relative importance of these threats is not well understood. We used HexSim to develop simulation models for desert tortoise populations occupying 2 study areas in the western-central (Superior Cronese in California, USA) and the eastern (Gold Butte-Pakoon in Nevada and Arizona, USA) Mojave Desert, each with a distinct set of site-specific threats. We developed threats models that were parameterized from published information, and conducted independent simulations of threats at varying levels of severity for each study area. Modeled tortoise populations in both study areas were subjected to simulations of threats associated with human presence and subsidized predators. Additional simulated threats in the Superior Cronese model included disease and habitat degradation on land in-holdings, whereas tortoise populations in the Gold Butte-Pakoon model were further exposed to simulations of wildfire, livestock grazing, and feral burros. We used our 2 study area-specific simulation models to rank the threats' relative importance to desert tortoise population viability. Threats more widely distributed in time and space within the modeled conservation areas significantly limited tortoise population growth more than threats that were patchily distributed or temporally dynamic. Our use of a spatially explicit population model allowed us to evaluate and prioritize the effects of threats over site-specific, dynamic, simulated landscapes, which differed from previous modeling efforts for desert tortoises. Our threat prioritization will inform and improve ongoing management efforts attempting to increase desert tortoise population viability by altering anthropogenic disturbance regimes. Ó 2016 The Wildlife Society.

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Saragossa Plantation is located in Natchez, Mississippi. It was established in 1823 by one of the wealthiest cotton planters in the Old South, Stephen Duncan. Between 1823 and 1865, Saragossa was home to numerous enslaved African Americans who faced dangers of abuse at the hands of their overseer, sundered and reconstituted families, disease, overwork, and lack of autonomy. Hunting by members of the slave community is suggested as one of the more effective mechanisms for coping with meager rations, but it also functioned to reinforce male gender identity and to incorporate strangers into the quarter community. Overall, hunting strengthened slave family and community bonds and made these social institutions better able to cope with violence, lack of autonomy, and other risks faced by slaves. [slavery, hunting, risk management] * Archaeological site Vicksbg Mississippi Mississippi River