Sunday, September 26, 2010

Odd Hummingbird Behavior

Yesterday afternoon and this morning I saw something I’ve never seen before: two hummingbirds seemingly co-guarding one feeder. The feeder in question dangles from a clothesline in our small “rose garden,” a patio that is covered with shade cloth this time of year.
2 hums 2 good 9-26-2010 8-39-21 AM 3616x2712 I believe they are juvenile Costa’s. Both are often on the clothesline together. Sometimes they seem to take turns drinking from the feeder. Sometimes one will display at the other. Sometimes one will chase the other. Once I saw them “dueling” with their beaks.  But most of the time they just sit there, checking out each other and the general area. Sometimes they sit several inches apart, as in the above photo, and sometimes they sit right next to each other—once about half an inch apart.
2humsA 9-25-2010 5-54-01 PM 3616x2712 Here is my theory: I think they are nestmates, and there is some faint memory that keeps them from inflicting total mayhem on one another. They are obviously uneasy with the situation, but do accept it.
Other hummers have tried to horn in, but these guys so far have chased everyone else away.

3 comments:

  1. Hi, Kathryn,

    I've seen juvenile female Anna's behaving in much the same way (though with less sense of an armed truce) and had precisely the same thought about why they would tolerate each other.

    This is one of those tantalizing mysteries about hummingbird behavior. There are a few other observations that suggest that the relationship between nestmates doesn't end at fledging or independence, but we just don't have enough evidence to say for certain that it happens.

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  2. I've wondered about something similar here. I can't tell for certain, but it looks like two hummers will share and a third is always chased off. I assumed the two were mates, but I can't even say for certain there are three. The chasing is easily spotted, playing nice less so.

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  3. Kathryn,
    Just discovered your blog, which is delightful. Even my mother, who was not a nature lover, became a bird watcher living on the desert. She would have enjoyed your blog.
    -- Pat

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