Variable Sunbird’s nectar-thieving shenanigans exposed

2009 July 25

NAIROBI, KENYA — This morning, I watched a spectacular male Variable Sunbird (Cinnyris venustus) feeding on the garlic vine (Mansoa alliacea) that’s blooming in our back garden.

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But I noticed something odd. The sunbird, a nectivorous species, was visiting the base of each flower in turn:

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The garlic vine (named for the odor emitted by its leaves when broken) is an ornamental plant introduced from the Neotropics. It’s in the family Bignoniaceae, which also includes Catalpa and the North American trumpet vine, Campsis radicans. Like the latter species, this plant has long, tubular flowers, and the Variable Sunbird (despite its elongated bill and long tongue) can’t possibly reach the nectar inside.

At least, not through the front door. But this is a clever bird — just look at that glint in his eye:

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The bird was slipping his bill beneath the flower’s calyx and piercing the base of the corolla. Then, presumably, he could easily reach the nectar with his specialized tongue.

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This behavior is called nectar thievery or nectar robbing because the plant may not get pollinated when its reproductive structures are bypassed in this way. (But see Are nectar robbers cheaters or mutualists?) Various sunbird species are known to engage in this behavior when needed (see, for example, the mention in Jewels of the bird kingdom from a newspaper in India), and of course the Neotropical flowerpiercers have specially hooked upper mandibles that let them specialize in a life of nectar thieving.

This next shot isn’t great, but it shows the Variable Sunbird’s threadlike tongue.

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I went back later to examine the flowers and found tiny slits, the edges of which had started to brown:

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Related posts:

  1. Variable Sunbirds feeding Klaas’s Cuckoo
  2. Variable Sunbird, Cinnyris venustus
  3. Flycatchers in Nairobi
  4. Sword-billed Hummingbird, Ensifera ensifera
7 Responses
  1. July 25, 2009

    Great shots of a beautiful bird. Lucky that you saw the nectar thievery as it happened.

  2. thainamu permalink
    July 25, 2009

    The internet connection is so bad here in Addis that I can’t see your photos, but my son and I were just discussing this behavior of sunbirds a couple days ago when we observed it while we were at Lake Langano. I had no idea that there was a special name for it. :-) I’ve seen three species of sunbirds while here.

  3. Chivis permalink
    July 25, 2009

    I’m jealous! So nice you could see that. And thanks for sharing it with the rest of us who can’t be there. Good pics of a gorgeous bird.

  4. July 26, 2009

    A gorgeous bird and fabulous shots! Quite a LOVELY little thief :)

  5. July 28, 2009

    I’ve always heard Sunbirds were the Old World equivalent to Hummingbirds. But I suppose they fill the Flowerpecker niche as well, then.

    Cool!

  6. Dave permalink
    August 3, 2009

    How neat. Thanks for the mini-article!

  7. Narendra bhagwat permalink
    September 5, 2012

    Yes, even I see that in my garden regularly in India.

Comments are closed.