[CT Birds] What birders do on a snowy morning...

Carrier Graphics carriergraphics at sbcglobal.net
Sat Jan 24 19:47:45 EST 2015


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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