Thanks to everyone who jumped in with explanations for me! The links and additional searches made for some interesting (although somewhat confusing with all the scientific words) reading. I don't know if I came away with a clear answer, but I now know a bit more than I did before.
On Mon, Feb 23, 2026 at 12:15 PM David McNeely <davmcneely40...> wrote:
> Probably not. Genetics is suspected, though not proven, despite my > earlier assertion that it is well known. Red crossbill chicks show > morphological differentiation of the bill crossing phenotype BEFORE they > start feeding on their own, that is, while the parents are still feeding > them partially digested seed mash in the nest. But there is evidently no > definitive genetic data. > > https://bootstrap-analysis.com/2005/12/crossbills.which.html > > On Mon, Feb 23, 2026 at 8:41 AM Ken Pitts via Inland-nw-birders < > <inland-nw-birders...> wrote: > >> Hi Catherine! >> >> Your question about the curve direction of Red Crossbills is really >> interesting. I did a quick Google search of Red Crossbill photos and saw >> that some go to the left and some go to the right. I then found an >> explanation that when the Red Crossbills are young, they have pretty >> typical finch beaks. As they attempt to get seeds out of cones, they tend >> to always pry one direction that is not the same for all the others. >> Constant prying in the same direction causes the beak to warp that >> direction, thus determining the lifelong result. >> >> The best! >> >> Ken >> >> On Sun, Feb 22, 2026 at 10:42 AM Catherine Temple via Inland-nw-birders < >> <inland-nw-birders...> wrote: >> >> > Yesterday I saw a pair of red crossbills gathering grit in the road so I >> > took some lovely photos of them. Later I noticed that each birds bill (a >> > male and female) curved in a different direction. I know a lot has been >> > said about the difference in bill size and the different "types" based >> on >> > the types of cones they eat. But if the birds are the same species or >> type >> > shouldn't the bills curve in the same direction? Or is it common to have >> > left and right curved bills within the same type? Or is this a >> difference >> > between male and female? I'm really curious as this is the first time >> I've >> > been able to get close enough to see the differences. I've attached a >> photo >> > of the pair. Thanks in advance if you can enlighten me. >> > Catherine >> > >> > >> > -- >> > >> > *Catherine Temple* >> > >> > *Pet Portrait and Wildlife Artist* >> > >> > *Clarkston, WA.(208) 791-7052* >> > <ctemple99...> >> > >> > www.catherinetemple.com >> > www.flickr.com/photos/ctemple/ >> > _______________________________________________ >> > Inland-nw-birders mailing list >> > send email to: <Inland-nw-birders...> >> > manage subscription: >> > https://mailmanlists.us/mailman/listinfo/inland-nw-birders >> > >> _______________________________________________ >> Inland-nw-birders mailing list >> send email to: <Inland-nw-birders...> >> manage subscription: >> https://mailmanlists.us/mailman/listinfo/inland-nw-birders >> >
--
*Catherine Temple*
*Pet Portrait and Wildlife Artist*
*Clarkston, WA.(208) 791-7052* <ctemple99...>
www.catherinetemple.com www.flickr.com/photos/ctemple/ _______________________________________________ Inland-nw-birders mailing list send email to: <Inland-nw-birders...> manage subscription: https://mailmanlists.us/mailman/listinfo/inland-nw-birders
