Date: 2/23/26 12:17 pm From: David McNeely via Inland-nw-birders <inland-nw-birders...> Subject: Re: [inland-NW-birders] Crossbills
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.
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 > _______________________________________________ Inland-nw-birders mailing list send email to: <Inland-nw-birders...> manage subscription: https://mailmanlists.us/mailman/listinfo/inland-nw-birders
