What is that little brown and black bird?

Bird call: Brown-headed cow­birds lay their eggs in the nests of oth­er birds. MARIA POUCH­NIKOVA / TIMES PHOTO

What’s that bird with a shiny black body and neck and head the col­or of dung?

It’s a brown-headed cow­bird. It’s not one that North­east res­id­ents are likely to see at their back­yard feed­ers, or maybe even re­cog­nize when they do see them in open fields or on the edges of woods or parks. 

The brown-headed cow­bird is about the size of the eas­ily re­cog­niz­able European starling, but its black body feath­ers are not speckled like the starling’s, even though those feath­ers have something of the starling’s iri­des­cence.

There are plenty of them around, and their pop­u­la­tion in Pennsylvania is pretty stable, said Di­ane Smith, dir­ect­or of edu­ca­tion with the Bucks County Audu­bon So­ci­ety.

It’s how the cow­bird main­tains its num­bers that’s dif­fer­ent.

It’s a para­site. Fe­male cow­birds lay their speckled blue eggs in the nests of oth­er birds and let those host par­ents raise the cow­bird’s young. 

“It’s a nasty bird over­all,” said Mary Pen­ney, the so­ci­ety’s spokes­wo­man.

It uses the nests of hun­dreds of dif­fer­ent spe­cies, Smith said, but some fe­male cow­birds seem to spe­cial­ize in im­pos­ing on their in­di­vidu­al fa­vor­ites. “They spe­cial­ize in par­tic­u­lar kinds of nests,” she said.

Some host birds re­sent the stranger’s eggs enough to push them out of their nests, she said.

Cow­birds can be seen on farms, of­ten fol­low­ing live­stock so they can pick off the in­sects that stirred up when the an­im­als move through fields, Smith said. It’s thought that, for thou­sands of years, they used to fol­low North Amer­ica’s roam­ing herds of bison for the same reas­on.

Sally Mc­Cabe, Pennsylvania Hor­ti­cul­tur­al So­ci­ety pro­ject man­ager, said she’s seen brown-headed cow­birds in the city and be­lieves there are just as many of them now as there were 25 years ago. She the­or­ized that people are prob­ably more aware of them now.

They don’t seem to be a prob­lem for city garden­ers be­cause they eat seeds and in­sects on the ground and gen­er­ally stay away from feed­ers. They don’t eat young plant leaves, which is something spar­rows do, she said. ••

You can reach at jloftus@bsmphilly.com.

comments powered by Disqus