BirdAnalyst
BBS Route · Colorado · BCR 16

Castleton Bird Survey Route

A standard 50-stop Breeding Bird Survey route. 112 species recorded across 32 survey years, still active.

112Species 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 →
32Years SurveyedYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →
1988–2025Span
4Observers

Bird Species Found on Colorado Castleton

Top 40 of 112 species by most recent count. Each links to its species trend.

Species recorded on the Castleton 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 BlackbirdIcteridae942025-64%1992
American RobinTurdidae842025-54%1992
Canada GooseAnatidae432025+300%2003
Yellow WarblerParulidae412025-33%1992
Black-billed MagpieCorvidae33202516×1996
Brewer's BlackbirdIcteridae312025-36%1994
White-crowned SparrowPasserellidae312025-6%1992
Lincoln's SparrowPasserellidae282025+92%1994
Western Wood-PeweeTyrannidae252025+150%1992
Pine SiskinFringillidae252025+39%1992
Savannah SparrowPasserellidae242025-32%1994
Wilson's SnipeScolopacidae232025-19%1992
Warbling VireoVireonidae232025+479%1994
Green-tailed TowheePasserellidae212025+156%1994
Broad-tailed HummingbirdTrochilidae202025+16%1992
Song SparrowPasserellidae202025+117%1996
House SparrowPasseridae182025-62%1994
Cliff SwallowHirundinidae142025-85%1994
Western TanagerCardinalidae122025+583%1994
Violet-green SwallowHirundinidae112025-80%1992
Mourning DoveColumbidae102025-75%1992
White-throated SwiftApodidae101991n/an/a
Tree SwallowHirundinidae92025-59%1994
Red-naped SapsuckerPicidae82025+163%1994
Western MeadowlarkIcteridae82025-40%1992
European StarlingSturnidae72025-74%1992
Evening GrosbeakFringillidae72025+0%1998
Mountain BluebirdTurdidae62025-18%1996
Dusky FlycatcherTyrannidae62025-20%1998
Red CrossbillFringillidae62022-47%2003
Brown-headed CowbirdIcteridae52025-83%1994
Ruby-crowned KingletRegulidae52025+16%1996
Western BluebirdTurdidae51992+25%1991
Cinnamon TealAnatidae52021n/an/a
Brewer's SparrowPasserellidae42025+22%1994
Northern House WrenTroglodytidae42025-49%1994
Hermit ThrushTurdidae42025-20%1996
Horned LarkAlaudidae41991n/an/a
Black-capped ChickadeeParidae42024-10%1996
Fox SparrowPasserellidae42025+367%2010

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