BirdAnalyst
BBS Route · Illinois · BCR 22

Williamsfld Bird Survey Route

A standard 50-stop Breeding Bird Survey route. 99 species recorded across 51 survey years, still active.

99Species RecordedSpecies recordedDistinct species detected on standard-protocol BBS runs here across all years on record — a measure of survey breadth, not a complete checklist.Full methodology →
51Years SurveyedYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →
1971–2025Span
3Observers

Bird Species Found on Illinois Williamsfld

Top 40 of 99 species by most recent count. Each links to its species trend.

Species recorded on the Williamsfld route.
Recent countThe raw number of individuals recorded on this route in its most recent survey year. A single-route tally, not a trend.Full methodology →TrendPercent change in the route-weighted abundance index between a smoothed baseline window and the most recent one. It tracks direction, not absolute population.Full methodology →Baseline yearThe first year of the smoothed window the trend is measured from. An earlier baseline means a longer record stands behind the number.Full methodology →History
Red-winged BlackbirdIcteridae822025+5%1974
American RobinTurdidae612025+436%1974
House SparrowPasseridae372025-74%1974
KilldeerCharadriidae33202521×1977
Brown-headed CowbirdIcteridae282025+28%1977
Canada GooseAnatidae282025+296%1985
DickcisselCardinalidae262025+18%1974
Eastern MeadowlarkIcteridae252025-19%1974
Common GrackleIcteridae232025-14%1974
Chipping SparrowPasserellidae212025+738%1974
European StarlingSturnidae182025+150%1974
Common YellowthroatParulidae152025+129%1974
American CrowCorvidae132025+208%1974
Northern CardinalCardinalidae132025+386%1974
Northern House WrenTroglodytidae132025+475%1976
Indigo BuntingCardinalidae122025+167%1978
Mourning DoveColumbidae112025+231%1974
Barn SwallowHirundinidae112025-8%1974
Warbling VireoVireonidae112025+450%1978
House FinchFringillidae112025+218%1994
Chimney SwiftApodidae102025-51%1978
Cliff SwallowHirundinidae102025+509%1995
Vesper SparrowPasserellidae92025+27%1979
Rose-breasted GrosbeakCardinalidae92025+283%1977
Cedar WaxwingBombycillidae92025+50%1987
Eastern KingbirdTyrannidae72025+280%1974
Purple MartinHirundinidae72025-50%1974
Western MeadowlarkIcteridae62019-56%1977
Rock PigeonColumbidae62024-42%1978
Northern BobwhiteOdontophoridae52025-93%1974
BobolinkIcteridae52014-18%1977
Eurasian Tree SparrowPasseridae52025+211%2005
Eurasian Collared-DoveColumbidae52025+13%2012
Red-headed WoodpeckerPicidae42023-30%1976
Horned LarkAlaudidae42025-61%1976
Song SparrowPasserellidae42025-52%1976
Great Crested FlycatcherTyrannidae42025+233%1983
Eastern Wood-PeweeTyrannidae42025+233%1984
MallardAnatidae32019-65%1977
Tufted TitmouseParidae32025-22%1976

Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14. A route is a sample, not a census.