[CT Birds] What Birders do on a snowy morning...
Carrier Graphics
carriergraphics at sbcglobal.net
Thu Dec 27 10:46:19 EST 2012
What Birders do on a snowy morning...
I look out at the 6 new inches of snow, and find the birds
are all over the feeders. On my window screen feeder are 3 Mourning Dove, and
4 Junco. I notice how the Doves seem to be eating many more seeds per second
that the juncos. I know this happens because all those in the Dove and Pigeon
Family
do not need to crack open seeds, just eat them whole, and let their crop do the
cracking/digestion.
So: I count how many seeds are picked up per minute for each species, then
average out the short periods of time they are not picking up seeds per min. Ex-
walking over to a new seed area, head lifting for danger, etc. And here is what
I came up with...
MOURNING DOVE:
On average, a Dove picked up 5 seeds per second X 60 = 300 seeds per minute.
minus 6 intervals of 2 sec each = 12 seconds, 12 X 5= 60 seeds
So 300 seeds per minute, minus 60 seeds less for intervals =
The MOURNING DOVE eats 240 seeds per minute!
JUNCO:
On average, a Junco picks up 1 seed and cracks it open and swallows
it at one per second X60 = 60 seeds per minute.
The Junco takes 10 intervals of 2 seconds each = 2 X 10 = 20 seconds = 20 seeds.
So 60 seeds per minute, minus 20 seeds less for intervals =
The JUNCO eats 40 seeds per minute.
Conclusion:
The efficient DOVE eats 200 more seeds per minute. And this gives this much
larger bird a less chance of being taken by a predator from less time spent in
the open finding food than a JUNCO, because they do not need to crack open each
seed at the site of the food, but can digest them from the safety of a tree or
such that affords them safety from a predator. Yes?
Paul Carrier - Harwinton
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