Sunday, August 23, 2015

FOS: Least Flycatcher, Yellow Warbler, and Brown-headed Cowbird

It was another warm and humid morning out at the banding station today.  Despite the uncomfortable weather we still had a decent selection of migrants including our first Least Flycatcher and Yellow Warbler of the season.  We also had good numbers of Northern Waterthrush, Common Yellowthroat, and Red-eyed Vireo.  The highlight of the day was our first of the season Brown-headed Cowbird.  The Brown-headed Cowbird is a brood parasite which means it lays its eggs in the nests of other birds.  Cowbirds evolved this behavior back when they depended on buffalo herds and needed to have the ability to follow the herds.  When a female lays an egg in her host nest she will usually remove one or more of the host eggs.  Their eggs require less incubation time which allows the cowbird to hatch out first and out compete the host’s offspring.  If a cowbird egg is noticed, some host species will either abandon the nest or try to remove the egg.  Eastern host species are a less equipped to deal with cowbird parasitism than Mid-Western species.  Cowbirds stayed in the open grasslands of the Mid-West up until 1800’s when humans began expanding farmland westward and opened up a whole new eastern range for cowbirds.  Over 200 species have been recorded as being parasitized by cowbirds.     


Yellow Warbler

1 Least Flycatcher
4 Red-eyed Vireo
1 Worm-eating Warbler
5 Northern Waterthrush
2 Black and White Warbler
6 Common Yellowthroat
2 Yellow Warbler
4 Prairie Warbler
3 Painted Bunting
1 Brown-headed Cowbird

3 Carolina Chickadee
1 Northern Mockingbird
3 Northern Cardinal
2 Painted Bunting

# of Birds Banded:  31
# of Recaptures:  9
# of Species:  13
Effort:  125.0 net-hours
Capture Rate:  32.0 birds/100 net-hours

Aaron Given
Mattie VandenBoom
Michael Gamble
Jen Tyrrell