Date: 6/22/25 7:05 pm From: Ian MacGregor <00000489141846bd-dmarc-request...> Subject: Re: Barn Swallow cooperative breeding
I think non-subscribers to the Birds of the World website can see the range maps. Surprisingly there’s a section of Argentina where they breed. These birds are breeding twice a year, once somewhere in their normal breeding range and again in Argentina.
Ian MacGregor Bella Vists
On Sun, Jun 22, 2025 at 6:23 PM, Ragupathy Kannan <[<0000013b0ad14faf-dmarc-request...>](mailto:On Sun, Jun 22, 2025 at 6:23 PM, Ragupathy Kannan <<a href=)> wrote:
> You learn something new everyday. Today I learned that Barn Swallows can breed cooperatively.
>
> It started when I observed 3 adults building a nest in my porch. I looked up Birds of the World.
>
> So, yes, a nonparent adult can help a pair build a nest and attend to other chores.
>
> But before you go "awww"--it becomes sinister the more you dig into it.
>
> Some male helpers kill nestlings to induce divorce among the parents. They then take over the brooding female.
>
> As I often tell my ornithology students, DNA evidence has unearthed a lot of "dirty laundry" in the bird world.
>
> For more on this, click [here](https://birdsoftheworld.org/bow/species/barswa/cur/breeding#coopbr).
>
> Kannan
> Ft. Smith
>
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