Abundance and Community Composition of Waterbirds Using the Channelized Kissimmee River Floodplain, FL

Abstract

We conducted aerial surveys during 1996–1998 to estimate abundance and species composition of waterbirds using the channelized Kissimmee River to help understand how river channelization has altered bird use. For waterfowl, mean monthly species richness was 1.5 ± 0.3 (mean ± SE, n = 11 surveys); mean monthly abundance was 86 ± 43, 191 ± 70, and 13 ± 16 birds in 1996–97, 1997–98, and 1998–99, respectively. Blue-winged Teal (Anas discors Linnaeus) were the most abundant duck (74%) followed by Mottled Ducks (Anas fulvigula Ridgway, 21%). Mean wading bird species richness was 8.48 ± 0.35 (n = 20 surveys). Cattle Egret (Bubulcus ibis Linnaeus) were the most abundant wading bird species during the wet season (64 ± 22% of individuals); White Ibis (Eudocimus albus Linnaeus) were most common during the dry season (39 ± 23%). Mean total wading bird abundance was greater during the wet than dry season (F1,15 = 6.29; P = 0.02), with the increase driven by increases in Cattle Egret (F1,15 = 5.46, P = 0.03) and large-prey visual foragers (F1,15 = 5.47, P = 0.03). Compared to the 1950s, waterfowl species richness has declined 70% and abundance has declined 95%. For wading birds, mixed species breeding colonies no longer occur in the floodplain, and the community composition is dominated by the largely terrestrial foraging Cattle Egret during the wet season.