[va-bird] Re: follow up Mystery Hawk Revealed

Hi,

It was indeed an educational exercise to try and id
the hawks and more so when the explanations were
offered by the birder who posted the photos and then
the expert comments by another birder who followed it
up.

This resulted in me pondering "again" about a question
which has been perturbing me for some while which is:

"How then does a bird of a particular bird species
recognize another bird of either the same/different
species?"

A bird needs to identify:
-- between birds of the same species and different
species
-- between genders of the same species


We need to leave out the breeding season wherein the
differences in certain species between the males and
the females visually is pronounced.

If visual identification itself is not reliable (and
after so much of experience we have so many doubts
yet)then how do birds recognize species,gender and
perhaps age within themselves visually?

An easy answer would be that perhaps identification is
need based only. E.g.: a male would need to identify
the female only in the mating season and thus there
are other visual clues developed in the mating season.

So within the same species, perhaps the gender
identification is specific to seasons and one can
perhaps postulate that the need to identify is only in
some seasons and in the rest their is no need for the
birds to identify gender.

But this still leaves us with the question, how do
confusing species (confusing visually) identify each
other when vision is the sole means to identify?
Or is the answer that they don't really need to
identify?

cheers,
-Deapesh Misra.
Fairfax, Va.

(I am purposefully leaving out identification based on
the means of vocalization)

> 
> Sharp-shinned Hawk -- wing chord 215 mm or less,
> outer tail feather less than 12 mm shorter than
> longest tail feather.
> 
> Cooper's -- wing chord 220 mm to 290 mm. outer tail
> feather more than 13 mm shorter than longest tail
> feather.
> 
> Goshawk -- wing chord 300 mm or more.


                
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