The St. Croix ground lizard, Ameiva polops, is a United States endangered species endemic to St. Croix, U.S. Virgin Islands. It was extirpated from St. Croix Proper by invasive mongooses, and remaining populations are on small, nearby cays. In the summer of 2008, as part of the recovery plan for this species, I worked in a multi-agency effort to translocate a population of A. polops to Buck Island Reef National Monument, U.S. Virgin Islands to focus on two main objectives: 1) examine the detection probability of A. polops and infer the consequences of it on population estimates; and 2) examine whether A. polops may deplete its prey base or alter the arthropod assemblage at the translocation site. We used a soft-release strategy for the translocation, in which 57 lizards were initially contained in a series of eight 10 m x 10 m enclosures in the habitat on Buck Island for monitoring. As part of the initial monitoring I conducted visual surveys through all enclosures, with the known number of lizards, to calculate the detection probability and to demonstrate how many individuals would be estimated using visual encounter surveys of this known population. Adjacent to enclosures housing A. polops were control enclosures, without A. polops, which I used to test whether the translocated lizards would impact their prey base over 6 weeks. I found that the detection probability of A. polops is very low (<0.25), which causes population sizes to be severely underestimated, even using some mark-resight techniques. My study of A. polops on the prey community indicated that the lizards generally had no effect on abundance or diversity of arthropods in general, though they may cause small changes for particular taxa. My results help corroborate other evidence that accuracy of population enumeration techniques needs to be improved in order to adequately understand the status of wildlife populations. Additionally, prey resources do not seem to be limiting A. polops in the short-term, and I expect the population will grow, expanding through Buck Island. Future monitoring will be carried out by the National Park Service using robust mark-resight techniques.

Moose populations in southern Manitoba have declined. Although the primary cause of this decline is unclear, wolf predation is considered a main contributor because wolves have limited moose populations elsewhere. To help understand the role of wolf predation in limiting moose populations we reconstructed the proportional diet of wolves using stable isotope analysis and a Bayesian stable isotope mixing model (MixSIAR). We tested the assumptions of MixSIAR by running sensitivity analyses on trophic discrimination and prior information. We observed differences in wolf diet in areas where moose and deer coexist and are spatially separated, with changes both seasonally and annually. Our results suggest white-tailed deer were preyed on during winter, even in areas where deer are locally rare, suggesting prey catchability is more important than local prey density. Seasonal changes in prey accessibility strongly affect wolf predation rates, and manipulating alternative prey populations could mitigate predation impacts on moose. / October 2015