New Sibley Bird Book and hybridization

[Kenemet]

Anyone who's done any birding is familiar with the Sibley guides. It's a debate as to which is more popular... the older Petersen guides or the more current Sibley guides. Both are preferred by birders to the guides that show pictures of the birds -- the drawn illustrations often show the field markings more clearly than any photograph can, though the photograph reproduces a single specimen very accurately.

Sibley has just released the update of his Birds of North America and I was lucky enough to see him during his recent book tour and get my copy signed. One of the most intriguing things about it is that he's covering the "hybrid species" -- birds that are crossbreeds between two species. Hybrids occasionally occur in nature, but these crossbreed birds are now so common that it is necessary for birders to be able to identify them.

The one that caught my eye was the listing of the three main crossbreeds for mallard ducks. The site, 100000birds.com has a nice article on the crossbreeding and the possibility that it will cause some species to become extinct:

http://10000birds.com/hybrid-mallards.htm

[Sundew]

Male ducks apparently have one of the longest copulatory organs for their body size of just about any animal, and judging by the way they hybridize, they aren't afraid to use it!

[Grandpa Greenman]

Thanks, that is interesting. Fewer birds, fewer mates to be found I would guess.

[Kenemet]

The book sort of hints that climate change and human activity is causing species cross-mixing (Sibley doesn't get into this at all, but another educator mentioned the spread northward of hybridization between the tufted titmouse and another titmouse.)

In some cases, the hybrids don't have a mating behavior that is recognizable by either of the parent species (or so I was told by another birder at the lecture.)

In any case, I thought it was rather interesting.