Today a beautiful bird came to my window, a male Northern Cardinal (Cardinalis cardinals). I only had time to take a quick shot through a window, and the composition is not very artistic.
However, in the mouth of this cardinal you can see a dragon/damselfly.
I consulted the literature to see if I could find anything interesting to tell you about Northern Cardinals. I did find a study by Abernathy and Peer  that looked at the rejection rate of Brown-headed Cowbird eggs from Cardinal nests. They thought that UV reflectance of the egg might have something to do with this. They tested various Brown-headed Cowbird eggs in Cardinal nests, some of which were coated by a UV-blocking gel—there were of course control eggs with a gel that did not block UV reflectance. They found no differences in the rejection rates between the unmodified and gel-coated eggs.
Brown-headed Cowbird eggs look similar to Northern Cardinal eggs, but it looks like Cardinals don’t use UV to check whether the egg belongs to them. The authors did remark that Cardinals will more frequently reject more different-looking eggs, so it’s not as those Cardinals will just keep anything in the nest. In any case, good news for the Brown-headed Cowbird!
 Abernathy, Virginia E., and Brian D. Peer. “Reduced ultraviolet reflectance does not affect egg rejection by Northern Cardinals (Cardinalis cardinalis).” The Wilson Journal of Ornithology 128.2 (2016): 334-342.