BirdAnalyst
BBS Route · Colorado · BCR 16

Marshall Pas Bird Survey Route

A standard 50-stop Breeding Bird Survey route. 87 species recorded across 19 survey years, still active.

87Species 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 →
19Years SurveyedYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →
1995–2019Span
5Observers

Bird Species Found on Colorado Marshall Pas

Top 40 of 87 species by most recent count. Each links to its species trend.

Species recorded on the Marshall Pas 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
American RobinTurdidae562019-54%1999
Warbling VireoVireonidae242019+3%1999
Green-tailed TowheePasserellidae162019+0%1999
Western TanagerCardinalidae162019-42%1999
Wilson's WarblerParulidae112014-45%1999
Western Wood-PeweeTyrannidae102019+79%1999
Dusky FlycatcherTyrannidae102008+380%2002
MacGillivray's WarblerParulidae102014+450%2002
Northern House WrenTroglodytidae92019+214%2001
Broad-tailed HummingbirdTrochilidae82019-66%1999
Ruby-crowned KingletRegulidae72019+21%1999
Clark's NutcrackerCorvidae62019-56%1999
Brown-headed CowbirdIcteridae62008+0%2000
Hermit ThrushTurdidae52019-68%1999
Virginia's WarblerParulidae52002+400%1998
Evening GrosbeakFringillidae42011+100%1995
Lincoln's SparrowPasserellidae42019+50%2006
Pygmy NuthatchSittidae42012+50%2000
Mountain ChickadeeParidae42019-29%1999
Black-capped ChickadeeParidae42016+0%2013
MallardAnatidae32013+175%2000
Spotted SandpiperScolopacidae32014+200%2006
Mourning DoveColumbidae32012+967%2000
Hairy WoodpeckerPicidae32019+14%2006
Hammond's FlycatcherTyrannidae32010-25%2006
Steller's JayCorvidae32019-40%1999
Black-headed GrosbeakCardinalidae32019-27%1999
Yellow WarblerParulidae32019-46%1999
Mountain BluebirdTurdidae32018+0%1999
Williamson's SapsuckerPicidae32014+100%2010
Common NighthawkCaprimulgidae22019-33%2000
Canada JayCorvidae22018+117%2003
Common RavenCorvidae22018+40%1999
Pinyon JayCorvidae21995n/an/a
Brewer's BlackbirdIcteridae21995n/an/a
Red CrossbillFringillidae22016-23%2005
Pine SiskinFringillidae22019-65%1999
Song SparrowPasserellidae22019-26%1999
Fox SparrowPasserellidae22011-40%2006
Red-winged BlackbirdIcteridae22012-72%2001

Source: USGS North American Breeding Bird Survey, retrieved 2026-05-22. A route is a sample, not a census.