| Patuxent Science Meeting 2006 Poster Abstract |
| | Effects of habitat fragmentation and landscape context on mammalian |
| | predators in Northeastern National Parks |
| | Talancy NW (URI), Husband T (URI), O'Connell AF, Gilbert AT, Annand E (IAP) |
| | Human disturbance is a significant source of land use change around the world, specifically in |
| | the northeastern United States, where expanding human populations are causing increased |
| | landscape development, habitat fragmentation, and pressure on wildlife populations. The effects |
| | of fragmentation on a number of wildlife species have been well-documented, but for species |
| | like medium-sized mammalian predators that are often cryptic and elusive, these effects are |
| | difficult to evaluate and not well understood. Medium-sized mammalian predators occupy an |
| | important niche in most ecosystems and because they are wide ranging may be more sensitive |
| | than other taxa to landscape scale influences. In 2004, we used remote cameras, track |
| | plates, and hair traps to collect presence/absence data on medium-sized mammalian predators |
| | in 8 National Park Service (NPS) sites in the northeastern United States. We collected data |
| | on environmental variables at multiple spatial scales and modeled the responses of 10 |
| | mammalian species to these variables using site occupancy models that incorporate the |
| | probability of detection for each species. Detection probabilities for medium-sized mammalian |
| | predators varied among time, space, and species, were all <1 and most frequently <0.4. |
| | Cumulative detection probabilities showed that the number of days of sampling will range |
| | between 18 and 174 to detect the target species with a 95% level of confidence. Using site |
| | occupancy models to account for this variation in detection, we determined that landscape |
| | scale variables were good at describing differences in the occurrence of predators. Variables |
| | that focused on the amount of human disturbance, such as the amount of landscape |
| | development, fragmentation, and distance to the nearest occupied building, were the most |
| | important in describing the probability of site occupancy. At the local scale, habitat variables |
| | such as canopy closure, coarse woody debris, and habitat edge were more important to the |
| | target species than the proportion of non-native vegetation or vegetation diversity. Overall, |
| | models that included variables from multiple spatial scales increased the accuracy of site |
| | occupancy estimates, but no single spatial scale was consistently better than others. This |
| | research suggests that landscapes surrounding NPS sites should be considered as important |
| | sources of variation in species presence and patterns of distribution. Detection is an important |
| | parameter to incorporate when sampling wildlife populations because detectability varies over |
| | time and space, and non-detection of a species does not imply absence. This study provides |
| | statistically valid occupancy estimates for 10 medium-sized mammalian predators that will |
| | Friday, September 22, 2006 |