Why are the C. Sparrowhawk & B. Goshawk so similar?

["Philip Veerman" <>]

Many of these bird species mentioned are entirely unknown to me and I'm not going to try to find all of them in books but I will at least guess that for many of them they are hard to identify because they are closely related, as in have not diverged much, in which case there is no mystery about it. Also mostly they are still almost the same in morphology and size (which the C. Sparrowhawk & B. Goshawk certainly are not). There will of course be variants in things like bill length among otherwise similar hummingbirds. Also I would guess that for many of them it is the young, female and non-breeding plumages that are similar. With often the breeding males (the ones with the signalling functions) are often very distinct. So these are mostly different situations to what I was asking. Besides, my question was not about birds that are difficult to identify (that is not very interesting) but about why these two species show the same plumage pattern. As in I am not at all asking about our human perception, although some may see that there could be an element of circular reasoning in that. 

 

Philip

 

-----Original Message-----From: David Adams [ Sent: Saturday, 12 January 2013 3:31 PM
To: COG line; Birding-Aus      Subject: [canberrabirds] Re: [Birding-Aus] [canberrabirds] Why are the C. Sparrowhawk & B. Goshawk so similar?

> One minor point (I am also a Northern Hemispherian): Which birds are so

> difficult to identify in Europe and North America? Apart from maybe some

> Empidonax in North America and maybe some Phylloscopus, Acrocephalus and

> Hippolais in Eurasia/Africa I can't think of many species that are that hard

> to ID there. "Hard" birds are certainly not the norm there.

Fair comment. I guess confusing is in the eye of the beholder ;-) Empidonax are hard, for sure...I'd list some of the other tyrants as tough, depending on how far afield you go. Apart from hawks, terns, gulls, pelagic species, and shorebirds, I'd also say that in the New World there are hard pairs of hummingbirds, alcids, flycatchers, ducks (e.g. Scaup), some of the New World blackbirds, and New World warblers. And vireos...and plenty of young/female tanagers. And sparrows...and finches. It's fair to say that corvids are probably harder here. (Unless you accept that they should all be lumped into C. indistinctus, as proposed last year...)  Even some of the loons Old World warblers are tough in Europe.