Winter Bird Population Study (WBPS) in Downtown Rockingham, North Carolina: High Species Richness, Dominance by Resident Generalists, and Low Compositional Change

Abstract

Abstract - I conducted a winter bird population study (WBPS) in a commercial district of downtown Rockingham, NC. I recorded 44 avian species (40 native suburban adapters, 4 exotic urban invaders) over 10 surveys conducted 20 December 2021 to 19 January 2022 within a 42.4-ha plot containing 25 city blocks. Thirty-one species (including all exotic urban invaders) were residents (74% of observations), whereas 13 native species were winter visitors (26%). Average winter bird species richness was 22.8 and average abundance was 143.5/40 ha. The median difference in species richness and abundance of suburban adapters was greater than exotic urban invaders among all 25 blocks, except species richness in 1 block and abundance in 4 blocks. A vegetation index (measure of the amount of vegetation) was a positive predictor of species richness for all suburban adapters and abundance for 3 species of suburban adapters (Mimus polyglottos [Northern Mockingbird], Cardinalis cardinalis [Northern Cardinal], Thryothorus ludovicianus [Carolina Wren]). Building area was a negative predictor of species richness for all suburban adapters and abundance for Northern Mockingbird. Average abundance was lower than the number of blocks in which each species was detected, except for the 3 most abundant birds (Passer domesticus [House Sparrow], Sturnus vulgaris [European Starling], Zonotrichia albicollis [White-throated Sparrow]) and Bombycilla cedrorum (Cedar Waxwing), all flocking species. Two exotic urban invaders (House Sparrow, European Starling) and 4 suburban adapters (Northern Mockingbird, Northern Cardinal, Carolina Wren, Zenaida macroura [Mourning Dove]) were also among the most abundant species (i.e., those whose average counts were ≥5 birds) and were resident species that nested within the plot the previous breeding season. The degree of compositional change of the avian community during early winter 2021–2022 compared to the last 3 decades was low in downtown Rockingham, NC.