Skip to main content

Table 3 Cowbird parasitism frequencies on common host species in Berks County, Pennsylvania

From: Egg rejection behavior does not explain the lack of cowbird parasitism on an eastern North American population of Red-winged Blackbirds

Host speciesScientific name2018 breeding seasonLate 19th centurya
n% parasitizedn% parasitized
Willow FlycatcherbEmpidonax traillii20.0
Eastern PhoebeSayornis phoebe1100unkcunk
Red-eyed VireodVireo olivaceus1030.0
Wood ThrushHylocichla mustelina130.0310.0
American RobinTurdus migratorius100.0130.0
Gray CatbirdDumetella carolinensis190.0450.0
Brown ThrasherToxostoma rufum10.0360.0
Chipping SparrowSpizella passerina425.02441.7
Field SparrowSpizella pusilla333.33321.2
Song SparrowMelospiza melodia812.53321.2
Eastern TowheePipilo erythrophthalmus260.0
Yellow WarblerSetophaga petechia250.010.0
Northern CardinalCardinalis cardinalis60.040.0
Indigo BuntingPasserina cyanea2924.1
Totals 687.428511.9
  1. aData from Levi Mengel egg collection (1884–1900) in the Reading Public Museum (Uhrich 1997)
  2. bNo nests of the Willow Flycatcher or the very similar Alder Flycatcher were previously reported in Berks County, although birds of both species were observed during the breeding season (Uhrich 1997)
  3. cTotal number of nests and parasitism frequency unknown but 8 nests recorded as parasitized and this species was noted as a common host
  4. dSpecies lacking data from the 2018 breeding season (indicated by dashes) were present in our study areas but at a low density and no nests were located