Thursday, August 8, 2013

The family drama of birds

"Papa can you hear me?"
Male great egrets, as well as other birds, practice chickiside with blithe regularity. In The Private Lives of Birds, Bridget Stutchbury describes watching a firstborn egret chick peck his younger sibling to death while the pater stood by unconcernedly preening. Apparently, the second chick was insurance and this gruesome occurrence is just another example of survival of the fittest.
 Stutchbury, a biologist at York University in Toronto, has researched such exotics as the endangered albatross and tufted puffin (above), but she specializes in the behavior of a group with which most of us are intimately familiar—songbirds. She's spent 20 years following them in the Hemlock Hill Forest in Northwestern Pennsylvania.

Her favorite is the splendid scarlet tanager, whose female mating call is so subtle that it's not even found on bird identification CDs. The male also has a very quiet "whisper song" to announce that he's bringing home the bacon (or caterpillar, as the case may be) for her and the little ones. By watching one pair and performing a brief test, Stutchbury precipitated a moment of high drama. When the male did not attend to her angry calls for food during the hour they kept him in a cage, the vociferously rageful female flew off and left him and nest for good (suburban housewives of Hemlock Hill Forest?) In her defense, the nestlings do have to be fed several times an hour for 3 to 4 weeks, so she must have been driven by biological imperative to cut her losses and start over.
 Other winning and losing behaviors in the evolutionary sweepstakes are addressed in chapters discussing such grabby themes (for birdlovers, that is) as "mate choice by ear," "why birds divorce," "how birds parent," "territory defense and aggression," "why birds live in groups," "the demands of migration," and more. 
"I am a bird detective,"  Stutchbury says, "revealing the behind-the-scenes details of the social lives of birds to understand why females cheat on their mates, what makes a male attractive, why some pairs divorce, how birds claim a territory...and what all this means not only for our avian friends, but for us as well."
Here's an example of the latter, as pointed up in a Science News review of her book: "At sewage-treatment plants in England, fearthworms reveling in sludge pick up traces of estrogen-mimicking chemicals that are passed along to starlings. In a surprise twist, the hormones give males unusually fine singing powers, possibly misleading females into selecting hormone-laden males as prime mates."
"The chestnut-sided warbler cheerfully greeted me at the forest edge with a raspy pleased pleased pleased to meet cha."

"Birdsong is music to our ears," says Stutchbury, "but to birds the love song is also a sophisticated weapon to keep competitors at bay.... In many birds the voice of the male is even more revealing to a female than his colors. Songbirds are well-known for their impressive dawn chorus, a symphony of song that often begins before daybreak and dwindles to a whisper after sunrise. The best time for a female to judge a male's energy level and stamina is after a period of fasting, in other words, at daybreak. Singing is energetically expensive and females judge male quality simply by listening to the quantity and quality of song."
Below, a rose-breasted grosbeak does his thing. This is one of the birds our author studied in the PA forest.
 Do tell: what are some of your favorite birds and bird songs? I am partial to the semi-ubiquitous cardinal.
Ornithologists' delight: Tim Dee, the author of A Year on the Wing: Four Seasons in a Life with Birds has spent 40 years devoted to avian pursuits (10 more than Stutchbury!). Middleton Evans' beautiful photographic collection Rhapsody in Blue: A Celebration of North American Water Birds reflects nearly 40 trips to view and capture these magnificent creatures on film. Picking up on Stuchbury's theme of the complex communications in bird vocalizations is What the Robin Knows: How Birds Reveal the Secrets of the Natural World by naturalist and tracking expert Jon Young.

10 comments:

  1. I don't know if I have a favorite birdsong, but I do prefer when they are not too loud too early. :)

    I wish I could live in blissful ignorance about birds who kill their siblings or mothers who abandon the nest to start over. But unfortunately, that stuff does happen and while it seems sad, I guess it is part of natural behavior to keep the ecosystem in check.

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    1. I hear you Molly! Birds look so lovely in appearance and sweet and for the most part gentle but a great deal of them are kind of jerks. As for bird songs, I am more of a whale song type of gal. I like the occasional tweet (not too early), but I really live for the marine mammal's ambient cry.

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  2. Wilhelmina FinkelsteinAugust 8, 2013 at 5:07 PM

    Haha, very true! As odd as may seem, I've always loved the turkey vulture. Maybe it's because the best Disney movie of all time is Robin Hood, but they've been given the avian-stepchild treatment:) Apparently, they don't have the necessary vocal components to sing. Instead, all they can muster is either low and guttural or whiny.

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  3. Wilhelm, is that you??

    My favorite bird song would be the soulful cry of the loon. It sings of twilight in lonely places, an odd mixture of tranquility and longing.

    The poets always make birds into free spirits. But the truth is they live in the limits of their society and their physical capabilities. I've seen a parent refuse to feed a nestling who hatched badly and could not lift up its neck. It soon died. What was disheartening was the parents then turned on the remaining, healthy nestling, and killed her. Then they left. The weather was still warm enough to start over, so maybe they wanted to, elsewhere.
    Anyone care to write a poem about that?

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  4. I never really thought that what the loon — of which we have many around this neighborhood — does could be called a song; it’s more like a cry. (I guess people usually refer to it as a 'call.') But then again, my favorite bird to listen to is the red-winged blackbird, and that’s more a call too, not a song.

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    1. I wonder what the birds would call it. The Hollywood Finch who graced my terrace for a while had a 16-note signature which he sang 3 times, faithfully, after dawn. Then he would fly off.
      About a year later, his family moved to a fire escape on the next block, and a similar bird was singing the same song, but with a variance at the end.
      Whenever another bird sat on the terrace, the finch would sing his signature, more rapidly, and then spit a coda of 3 notes. I imagine he was giving notice that this was his place--"And YOU get out!"

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  5. I also love the sound of a loon, but my favorites are the raptors. I live in rural, northern Illinois, so we get a lot of red-tails, but every once in a while I'll glimpse a kestrel or a Prairie Hawk. That's always exciting.

    We have these little, dark, swallow-looking creatures thick in our neighborhood. One in particular always sits on the edge of my roof, in the same spot just outside my office window, and just talks a blue streak. No singing, but he's clearly carrying on quite the conversation with himself.

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