What is it again

The bird in yesterday's post was a female brown-headed cowbird. A female cowbird doesn't make a nest of her own but instead is a brood parasite. She lays her eggs in the nests of other bird species, who then raise the young cowbirds. Not only that, but the female cowbird will often even destroy or eat the other birds' eggs.
Nature can be so harsh.

If this were a cowbird, I'd think she was saying to me, "Screw you and your judgment of me as a bad parent and a bad bird." But it's just a little junco who appears to be mooning me for my own pleasure.
And here's today's "what is it" photo. It's very exciting.
Scroll down for the answer.
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I told you it was exciting. I hope your heart stops beating fast enough to let you get some sleep. I know that between my random bird facts and photos of exercise equipment my blog can be a little overstimulating.