BirdAnalyst
BBS Route · Pennsylvania · BCR 28

Mawr Glen Bird Survey Route

A standard 50-stop Breeding Bird Survey route. 135 species recorded across 54 survey years, still active.

135Species 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 →
54Years SurveyedYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →
1966–2025Span
2Observers

Bird Species Found on Pennsylvania Mawr Glen

Top 40 of 135 species by most recent count. Each links to its species trend.

Species recorded on the Mawr Glen 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-eyed VireoVireonidae952025+440%1968
American RobinTurdidae822025+32%1968
Gray CatbirdMimidae482025+663%1968
OvenbirdParulidae392025+232%1983
VeeryTurdidae392025+272%1984
Song SparrowPasserellidae292025+203%1968
Wood ThrushTurdidae282025-52%1968
Mourning DoveColumbidae242025+320%1968
Common YellowthroatParulidae24202515×1975
Yellow-bellied SapsuckerPicidae23202517×1983
Tufted TitmouseParidae222025+336%1984
American CrowCorvidae212025-60%1968
Red-winged BlackbirdIcteridae192025-62%1968
Scarlet TanagerCardinalidae182025+975%1969
Chipping SparrowPasserellidae162025+26%1968
Indigo BuntingCardinalidae162025+500%1968
Black-capped ChickadeeParidae162025+386%1971
Eastern PhoebeTyrannidae152025+457%1968
Yellow WarblerParulidae142025+750%1971
Baltimore OrioleIcteridae132025+275%1969
Common GrackleIcteridae132025-37%1968
Barn SwallowHirundinidae132025-75%1968
Northern House WrenTroglodytidae132025+150%1968
American RedstartParulidae132025-9%1984
Blue JayCorvidae122025+3%1968
Yellow-billed CuckooCuculidae122024+300%1989
Black-throated Green WarblerParulidae102025-29%1984
Wood DuckAnatidae102025+233%1992
Blue-headed VireoVireonidae92025+74%1984
American GoldfinchFringillidae82025-3%1968
Northern CardinalCardinalidae72025-31%1968
Least FlycatcherTyrannidae72025+155%1984
Magnolia WarblerParulidae72025+475%1984
European StarlingSturnidae62025-86%1968
Eastern TowheePasserellidae62025+367%1982
Common RavenCorvidae52025+275%1976
BobolinkIcteridae52025+40%1969
Rose-breasted GrosbeakCardinalidae52025-61%1968
Tree SwallowHirundinidae52025+6%1970
Hooded WarblerParulidae52025+225%1989

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