Forest bird monitoring in the National Capital Region Network: Summary report 2007–2017

Ladin, Zachary; Tymkiw, Elizabeth; Roberts, Samuel; Shriver, W.

doi:10.36967/nrr-2287175

This report presents 11 years of data from forest bird monitoring efforts in the National Capital Region Network (NCRN). Forest bird monitoring began in 2007 and was implemented annually at 385 (initial) and 410 (current) sampling points within the 13 parks of the NCRN that include Antietam National Battlefield (ANTI), Catoctin Mountain Park (CATO), Chesapeake and Ohio Canal National Historical Park (CHOH), George Washington Memorial Parkway (GWMP), Harpers Ferry National Historical Park (HAFE), Manassas National Battlefield Park (MANA), Monocacy National Battlefield (MONO), National Capital Parks–East (NACE; including Greenbelt/Baltimore Washington Parkway [GREE] and Fort Washington/Piscataway Park [PISC/FOWA]), Prince William Forest Park (PRWI), Rock Creek Park (ROCR), and Wolf Trap National Park for the Performing Arts (WOTR). The objectives of this monitoring program are to: (1) document distributions of forest-breeding bird species including mean occupancy, abundance, and density, (2) use bird community indices to assess ecosystem-level dynamics at both park and regional levels, (3) detect annual variation in species abundance with special attention paid to species of conservation concern, and (4) provide data that will allow the assessment of the importance of habitat quality for long-term trends in bird abundance, density, and community dynamics. Throughout the report, we refer to bird species using a four-letter code designated by the American Ornithological Society (Chesser et al. 2019) and now maintained by the Institute of Bird Populations (https://www.birdpop.org/pages/birdSpeciesCodes.php). These “alpha” codes are presented with common and scientific names, along with conservation status in the Glossary. After completing a five-year report (Ladin and Shriver 2013), we are continuing to follow standard operating procedures (Dawson and Efford 2013). We document results on annual probability of site occupancy and abundance along with associated variances for all forest-breeding species detected in the NCRN from 2007 to 2017 at regional and park unit scales. The parks within the NCRN boast a high diversity of forest-breeding birds, and provide important habitat for species of both continental and regional conservation concern. In addition to supporting common forest-breeding species, NCRN parks provide important breeding habitat for many species of conservation concern. For example, Cerulean Warblers (Setophaga cerulea), Rusty Blackbirds (Euphagus carolinus), Red-headed Woodpeckers (Melanerpes erythrocephalus), Olive-sided Flycatchers (Contopus cooperi), Henslow’s Sparrows (Centronyx henslowii), Chimney Swifts (Chaetura pelagica), and Wood Thrushes (Hylocichla mustelina) are all Partners in Flight watch list species of continental concern (Panjabi et al. 2017) that have been detected within the NCRN. These species should be given special consideration during planning and management within the NCRN. Based on a guild analysis using bird community assemblages, we calculated a bird community index (BCI) to evaluate habitat integrity within NCRN as a region and within each park (O’Connell et al. 2003). We were able to detect variation in BCI among park units and years. Within the NCRN there is a considerable range in BCI scores among park units, with larger forested parks (i.e., Catoctin Mountain Park and Prince William Forest Park) having the highest forest habitat integrity and smaller parks in more urban settings (i.e., Wolf Trap National Park for the Performing Arts) having a lower habitat integrity. We include additional analyses (methods described in most up-to-date protocol SOPs, available at https://irma.nps.gov/DataStore/Reference/Profile/2170024) for each species including those of continental concern to estimate abundance using the ‘unmarked’ package (Fiske et al. 2011), implemented using the statistical software program R (R Core Team 2017). These corrected abundance estimates can be...

Forest bird monitoring in the National Capital Region Network: Summary report 2007–2017

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