Among parasitized nests, an average of 1.4 Brown-headed Cowbird
eggs were counted (range 1-4; SE = 0.34), none of which hatched.
The first thing you should know about Keriann Dubina is that she likes brown-headed cowbirds
. In fact, she's a local authority on the species most birders love to hate.
Additionally, expansion of agriculture and logging into Michigan brought with it brown-headed cowbirds
(Molothrus ater), "nest parasites" that lay eggs in the nests of unsuspecting host birds who then go on to raise the cowbird chicks as their own.
The main sources of nest mortality for North American songbirds include predation (Martin, 1988, 1993; Martin and Li, 1992) and brown-headed cowbird
parasitism (Friedmann and Kiff, 1985; Ortega, 1998).
This month's cover image,  Plate 99 from Birds of America (printed in stages during 1827-1838) by American ornithologist, naturalist, and painter John James Audubon (1785-1851), shows a pair of oft-vilified brown-headed cowbirds
. This painting appears in the book as one of 435 life-sized watercolors that were reproduced from Audubon's hand-engraved plates.
While other studies in the central United States have reported relatively high abundances of brown-headed cowbirds
(Cully and Winter 2000, Powell 2008, Rahmig et al.
(Molothrus ater) in Florida's breeding bird atlas: A collaborative study of Florida's birdlife.
are a New World blackbird, which - like cuckoos - lay their eggs in the nests of other birds, though evolution made no attempt to make their eggs look like those of their hosts.
The North American brown-headed cowbird
, which is not a cuckoo but a member of the blackbird family, and the common cuckoo mentioned earlier are probably the world's most successful and well-known brood parasites.
(Molothrus ater): Smaller blackbird; males have a brown head.
Sonny was a fledgling brown-headed cowbird
, (Molothrus ater) ugly and noisy, there was no mistaking that.
These great forest fortresses buffer nesting birds from nest parasites like the brown-headed cowbird
and the killing forays of neighborhood house cats that make sorties into suburban-rimmed woodlands.
She then discusses the introduction and eventual impact of two alien invaders, cheat-grass and the brown-headed cowbird
. The chapter concludes with an exposition o f interdisciplinary considerations, and humans as geographic agents.
Nesting buntings that evade these predators must contend with the starling- sized brown-headed cowbird
, another prime suspect in the case of the disappearing bunting.
The brown-headed cowbird
is one species that Breeding Bird Survey census-takers hope not to find on their routes.