The popular conception that most birds in the tropics tend toward the
amazingly colorful is very ably discussed by Steve Hilty in his book "Birds
of Tropical America" (1994, Chapters Pub. Co.) in a chapter titled "Who is
the Fairest? Colorfulness in Tropical and Temperate Birds." There is a lot
more in this chapter than can be summarized in this email, but two points
are especially worth mentioning.
First, the proportion of colorful birds is actually about the same in the
tropics and the temperate zone, but the birds one associates with the
tropics (and more likely sees well) are the glamour birds: colorful toucans,
parrots, tanagers, trogons instead of the hundreds of species of earth-toned
antbirds and ovenbirds (not to mention 360 plus species of flycatchers).
Second, "to see colorful birds, you have to look up into the brightly lit
branches of the rainforest canopy. There, strong sunlight fashions a
high-contrast world of lights and darks that simultaneously dazzle and
confuse. Bright birds move easily in a world where color catches the sun
one moment and then fades in a shadow the next. Color is riotous and often
flaunted with impunity in the rainforest canopy. It may also be adaptive.
Concealing color does not have to be dull and drab . . . anyone who has
squinted into a sunlit rainforest canopy in search of a trogon or jacamar
will appreciate how bright colors can disrupt a bird's shape (p. 132-133)."
This is only a piece of the complex adaptive puzzle discussed in the
chapter, and doesn't even raise the key point that many of the colorful
birds of the tropics rely heavily on fruit. This book and Kricher's "A
Neotropical Companion" go a long way to helping make sense of birding in the
Neotropics for those of us with a temperate zone birding frame of mind; I
get great mileage out of them when leading a tour in Trinidad, Belize, etc.

Bob Sundstrom
ixoreus at scattercreek.com
Tenino, WA

----- Original Message -----
From: "Rob Sandelin" <floriferous at msn.com>
To: <tweeters at u.washington.edu>
Sent: Wednesday, March 05, 2003 8:28 AM
Subject: Color in birds


> I must have missed this lesson in my ornithology class.
>
> Why is it that there are so many species of highly colored birds resident
in
> the tropics, and so few in our area? Once I got over the shock of some of
> the colors I saw in Costa Rica I got to wondering. Territory seems to be
set
> by vocalization, not necessarily color. Why is color a selection force?
Or
> is it? Do brighter males get better territories, or more mates? Do females
> choose males for brightness because that indicates fitness?
>
> While in Costa Rica I watched some kind of bird eating hawk nail a Scarlet
> tanager in midair. It seems in that case, being so contrasting against the
> jungle made for easy pickings. This would seem to make one think bright
> color would be a selective disadvantage.
>
> And to whom do I complain to about getting more color in the northern
> birds? After two weeks of wild electric blue Honeycreepers, and Toucans,
the
> chickadees and juncos and song sparrows are just not satisfactory. Ahhh, A
> stellars jay did liven up my feeder this morning so I feel a little bit
> better......but still, how come northern birds are sooooo uncolorful
> relative to the tropics?
>
> Rob Sandelin
> Sky Valley Environments <http://www.nonprofitpages.com/nica/SVE.htm>
> Field skills training for student naturalists
> Floriferous at msn.com
>
>
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