Re: Yearly SD dig, Pachy skulls, & tree nesting

[jamolnar@juno.com]

On Sun, 29 Jun 1997 23:39:28 +0100 roger@arkansas.net (Roger A.
Stphenson) writes:
>
>During the memorial day weekend holiday I happen to witness a 
>initially sad
>thing. A quick and windy thunderstorm dislodged a baby bird from the 
>top of
>a hickory tree, and it flopped on the ground that seemed very 
>violently to
>me. I dashed out of the truck and rescued it before the wall of rain
>arrived. After the storm passed I located the nest and parents, 50 
>feet up.
>My Mcgyver(sp) mind formulated a simple solution to getting the 
>nesting
>back near its parents. I took an empty 12 ounce beer can attached some
>fishing line to the top, put a few drainage holes in the very bottom, 
>cut a
>smallish hole in the side, being careful to dull the edges, and palced 
>the
>bird inside after packing it with strips of paper towels. I then threw 
>a
>rock over the limb with the nest, with the fishing line tied to it 
>(not on
>the first try!). It was then a simple matter to draw the can, bird n 
>all,
>almost back up to the nest. The mother scarlet tanager(sp) was quick 
>to
>begin feeding the returned baby, but the male was put off by the can. 
>I'm
>not absolutely sure the baby survived, but last time I was at the site 
>the
>nest was empty, and so was the can.
>
>My question(s) to you all;
>If such falls happen in species well designed for tree nesting, is 
>there
>even a remote chance that smallish-supposedly-able-to-climb-trees 
>dinosaurs
>nested in trees? It seems that during that awkward stage, of any young
>animal, such falls would surely be fatal without intervention such as 
>I
>provided.

If the dinosaur was small, and hollow boned, the baby would be fairly
light in weight and the fall would not be fatal.  It is amazing to watch
Wood Duck ducklings fling themselves out of a nest hole up to 50 feet
high in a tree, madly flapping their pin feathered wings away, to land on
the ground with a thud, only to follow momma duck to the nearest water,
unscathed.  Then again, ducks are hatched in an "advanced" state, ready
to walk and swim after parents.

Still, a large brood would allow for such losses, but Mr. 
>Bois's
>placement of nesting site  importance should be considered. Since 
>there are
>so many tree nesting dinosaurs alive today, ie birds, can we assume 
>that
>this aspect of their survival statagey was developed very early in the
>evolutionary processes? If the pre-powered-flying dinosaurs began 
>nesting
>in trees, would tree nesting and the protection provided be a prime 
>force
>in directing the evolutionary path? If so what mechanisms would these 
>early
>dinosaurs use to offset the inheirent danger of falling nestlings? 

Retaining claws on their hands [proto-wings], like a hoatzin, which
clambers back up to a nest if it falls out, or being hatched in a state
where their eyes are open and they can follow their parents in the trees
fairly quickly, clinging with feet, arms, mouth/beak; maybe having air
sacs to cushion them if they fall, hollow bones to make them light, etc.

>Even if
>the fall is survived, which may be easier than I imagined, the 
>squalling
>traumatized baby alerts every predator within earshot.
>

That still happens even today.  Once baby birds get to be of a certain
size, they are tremendously noisy.  It makes one wonder how any of them
survive at all.  All I can guess is that most birds breed all at once,
and there are so many baby birds bawling at once that it just floods the
market enough that even if they are loud, the noise is more adaptive in
getting parent's attention than it is alerting predators.

>Isn't it amazing that a vicious "hunter" such as myself could display 
>such
>concern over a baby bird?

You are not alone.  Konrad Lorenz would say you are merely reacting to a
very conservative and universal signal of a young animal in distress.  I
once watched a mother robin with a mouth full of worms fly over to a
peeping, begging towhee to investigate this pitiful creature.  She was on
her way to feed her own brood, but found the noise and open mouth of the
towhee very compelling.  She stopped, looked the bird over, then decided
it wasn't hers and flew away.  But it was an amusing few minutes to watch
her confused concern.

Judy Molnar
Education Associate, Virginia Living Museum
vlmed@juno.com
jamolnar@juno.com
All questions are valid; all answers are tentative.