Whooping Crane Whooping Crane
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Responses to Challenge Question #10:
The Case of the Missing Eggs

Photo Richard Urbanek, ICF, USFSW

Last time we asked:

  • “Which 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?”

Kudos and high fives to sixth grade homeschooler Marcus. He clearly knows what the future crane parents cranes need to learn:

"Crane 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 watching 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

And three experts add their thoughts:

Laura Erickson, Ornithologist
"Well, 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 these 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 we 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 warm or gently touching them with its beak, too, though that's hard to be sure about unless we were to do some very difficult, long-term experiments."

Joe 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 can be forced 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."

Aviculturalist Sara Zimorski, ICF carries a whooping crane in its travel box.

Sara Zimorski, Aviculturalist at the International Crane Foundation
"It 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 see."


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