to Challenge Question #10:
The Case of the Missing Eggs
Photo Richard Urbanek, ICF, USFSW
time we asked:
crane pair that nested in 2005 and 2006 has not yet learned how
to keep eggs safe? Based on your work in Nesting
Errors: Learning from Mistakes,
why do you think they’re having trouble keeping eggs safe?”
high fives to
sixth grade homeschooler Marcus. He clearly knows
what the future crane parents cranes need to learn:
pair #101 and #202 is the pair that nested in 2005 and 2006 and has
not yet learned how to keep their eggs safe. It seems that they keep
leaving the nest unattended, and either the eggs get cold so the
chicks inside die or a predator gets the eggs while the parents aren't
over them. They need to learn to make sure that at least one parent
stays with the eggs at all times to keep them safe and warm. Another
problem cranes have to be careful about is accidentally stepping
on their eggs and crushing them."
Marcus F., Sixth grade, home schooled, Mt. Airy, Maryland
three experts add their thoughts:
birds SORT of learn from their mistakes. Eggs can get smashed if the
birds walk on them, or crunch them when hunkering down to incubate,
or mess up when trying to turn them. The bird may have done one of
things wrong last year, and a different thing wrong this year. It may
not have known what went wrong last year, not connecting it to its
own behavior, or it may be rather ... stupid. But really, even though
all learn from our mistakes, just because a person tries to be careful
after spilling milk once doesn't mean s/he will never again spill milk,
does it? Cranes have long gangly legs and a long, piercing bill;
learning to coordinate them properly can be tricky. It may be a little
more difficult for these birds than for wild cranes raised by their
parents because these birds haven't experienced a parent keeping them
or gently touching them with its beak, too, though that's hard to be
about unless we were to do some very difficult, long-term experiments."
Duff, Operation Migration
"The behaviour of all birds is based on instinct and experience.
Instinct motivates them to migrate, and experience shows them the route.
For them, pair bonding and breeding is a whole new adventure.
"Can you imagine
what it is like for them the first time they lay an egg? Whooping cranes
are formidable birds and I can't imagine they
off a nest by a raccoon, or many other predators for that matter. More
likely they wandered too far to forage and their eggs were snatched in
their absence. Once this has happened a few times, they will learn to be
more attentive, and that is why most new parents are successful only on
their second or third attempt. In the Aransas/Wood Buffalo flock, young
birds usually fledge their first chick in their fifth or sixth year, generally
bringing one offspring south with them only every other season."
Sara Zimorski, ICF carries
a whooping crane in its travel box.
Zimorski, Aviculturalist at the International Crane Foundation
is definitely disappointing that those the nests were predated, but it
was not totally unexpected. These birds are still young and pretty inexperienced.
I'm not sure what to think about them re-nesting. They definitely have
time to re-nest. Lots of sandhills and many of the Florida non-migratory
whooping cranes re-nest. In fact, one pair nested a third time, after
their first and second nests were predated. However, neither of these
pairs re-nested last year after they lost their nests. So far they aren't
showing any signs of re-nesting. I guess we'll just have to wait and
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