Laura Erickson's For the Birds

Friday, May 9, 2008

The Rest of the Story about Chickadee Eggs: for Carolyn

Chickadees are rather the Norwegian Bachelor Farmers of the bird world. They are very sociable--ya, sure, you betcha!--but they aren't comfortable getting TOO close to other chickadees. They maintain a rather large personal space, which is why they never sit side-by-side at your feeder. If one chickadee does approach another too closely, the dominant one between them will make a little gargle call which effectively shoos the other bird away like a discreet "ahem!"

The trick is, at least once a year a pair of chickadees must draw very close together indeed, or we'll never have baby chickadees. So chickadees sing, which revs them up hormonally so they can overcome their inhibitions and reserve to finally do what birds and bees and educated fleas do. During the song period, female chickadees get so revved up that they become like teenaged girls at a rock concert who throw their panties on stage--if a particular male chickadee is exceptionally tuneful, many or most of the chickadee families in his neighborhood will have at least a few babies who share his genes. Fortunately, father chickadees never demand paternity tests before raising their babies--they spend weeks feeding all the babies in their brood regardless of parentage.

It takes almost 2 weeks for chickadee eggs to hatch after the brood is complete. The young remain in the nest for another two full weeks, and remain with the parents for another month or so. By the time the young are on their own, there isn't enough time remaining in summer to raise another brood. But many things kill chickadees, so to maintain their numbers, broods contain an average of 6-8 eggs, and some have as many as 13!

If you think this is extreme, the even tinier Golden-crowned Kinglet's average brood normally contains 8 or 9 eggs. In both cases, the eggs are so tiny that they can be brooded in one layer. I love how the eggs are arranged in that chickadee nest!

11 comments :

  1. Laura, tell us more about your job there. Great facts about the Chickadee!
    Cindy

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  2. I'd like to know how those PVC pipe houses are made too.

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  3. I'm the new science editor at the Lab of Ornithology--the first issue of BirdScope under my "editorship" came out last week!

    Lynne, the plans for the artificial nest snags used at Sapsucker Woods were originally developed by some researchers from Ohio who published a paper in The Condor in 1995. The PDF of that paper, with the "snag" plan, is at http://elibrary.unm.edu/sora/Condor/files/issues/v097n04/p1067-p1070.pdf
    If you need a subscription to get access to the page, let me know and I'll get you the plans another way. The Lab's version of these "pipe nests" uses a slightly larger pipe to make them comparable to regular nest boxes, because the Lab built them for another study about chickadees--results of that study (which showed chickadees have a strong preference for the snags over boxes) will be published later this year.

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  4. Laura: Thanks for the explanation! I know that the local female b-c chickadees prefer the few male Carolina chickadees that are around. I wonder if it's their song they like better??? I expect I'll soon have lots of little hybrids around!

    Carolyn H.

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  5. We have chickadees nesting in house on our deck rail. This morning there were six eggs on the deck, apparently pushed out of the nest. All but one or two had cracked shells, and all appeared to contain unhatched chicks, nearly fully-formed. Any ideas why?

    Roger & Jeannie in SW Michigan

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  6. Has a House Wren or House Sparrow taken over the house? That's exactly what both species do.

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  7. The chickadees are still going in and out of the house.

    Roger & Jeannie, SW Michigan

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  8. Indeed, an invasive wren appears to have been the culprit. The chickadees continued to use the house, decreasingly, over several days, with the wren bringing in twigs in what appeared to be an obstruction to the chickadees. I took sides and cleared it out once, but, like the chickadees, I ultimately conceded defeat.

    Roger, SW Mich

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  9. A chestnut-backed chickadee is roosting in a corner of my second story deck. He/she arrives about 15 minutes before dark and leaves a little before sunrise. This has been going on for 10 days. Because of all that I read about them roosting in flocks, isn't this unusual? I can't imagine how this bird ever found this spot, tucked up as it is, and not seen from just flying by. There is a birch tree just a few feet away, but I had never seen it in there. Are chickadees sometimes "loner"?

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  10. Chickadees are extremely social in the daytime, but are very much loners at night. They each pick out a safe little crevice, tiny tree cavity, or other safe spot to sleep on their own. They're not quite as extroverted as one might think!

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  11. What can you tell me about the range of a chickadee's neighborhood? The one I call "mine" is still roosting on my deck, but I wonder where he goes during the day: 1 mile, 2 miles or more? Thanks, Lynne. dorothy

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