Understanding how biological communities respond to global change is important for the conservation of functioning ecosystems as anthropogenic environmental threats increase. National parks within the United States provide unique ecological and cultural resources that can help conserve biodiversity and maintain ecological integrity, especially in heavily urbanized environments. Parks within the National Capital Region (NCRN) and Mid-Atlantic (MIDN) Networks, representing federally protected areas located within a mixed landscape of rural to urban areas, have been monitoring forest and grassland birds annually to evaluate long-term trends in bird community dynamics. Given increasing rates of decline in forest- and grassland-breeding songbirds in North America, understanding community-level trends in parks will help their preservation for future generations. We used point count data collected between 2007 and 2015 from 640 sampling locations to calculate a bird community index (BCI) to infer relative estimates of ecological integrity. Our objectives were to (1) quantify BCI in 17 national parks in the mid-Atlantic region, (2) test for relationships between BCI and the proportion of forest and developed land cover types, (3) assess temporal variation in BCI, and (4) additionally test for differences in estimates of species detection probability between volunteer citizen scientists and paid observers. Mean BCI scores and ecological integrity ranks among parks ranged between 33.5 (low integrity) and 58.3 (high integrity), while the majority of parks had BCI scores ranging between 40.1 and 52.0 (medium integrity). For both networks, we found that BCI was positively related to the extent of forest cover, and for NCRN, the more heavily urbanized network, we found that BCI was negatively related to developed land cover. Assessment of temporal changes in BCI within parks indicated that BCI was stable for 12 parks, increased in four parks, and decreased in one park within our study. Lastly, we detected no differences in species detection probability between citizen scientist- and paid observer-collected data which lends support for the future comparison of bird monitoring data in regional analyses across NPS I&M Networks. The continued evaluation of ecological integrity, through measuring bird community dynamics at regional scales, is important for conserving biological diversity.
All Science Journal Classification (ASJC) codes
- Ecology, Evolution, Behavior and Systematics