David Sibley looks at American Avocets

These illustrations show the differences between male and female American Avocets. Art by David Sibley

I often say that I learn new things every time I go bird watching and the learning opportunities will never end. One of the keys to this is being an “active” observer and asking questions, and for this column I thought it would be helpful to outline my approach and recent experience.

On a recent April day in Texas, I was happy to see a tight herd of resting American avocets. I took the opportunity to think about questions I might ask about the American Avocet. The first thing that came to mind was, “What about the few grey-headed (non-breeding color) birds among the many orange-headed (breeding color) birds?” I have wondered about this variation in the past, and with views this close, I can now confirm that all grey-headed birds were immature, less than a year old, while all older birds had their heads orange. (New info number 1!)

Now that I had identified these few birds as immature, I wondered, “Does the sex difference in beak shape apply equally to all ages?” (A female’s beak is more curved, the male is more straight.) A little scanning and comparison confirmed that even immatures show distinctive differences in beak shape, just like older birds. (New info number 2!)

In comparing beak shapes, I asked another question: “Do adult males and females show any differences other than beak shape?” After identifying several males and females by beak shape, then comparing details between them, I concluded that there was no consistent difference in plumage color, size, leg color, etc. . (New info number 3!)


But there was something about the head. The females seemed to have a more bulbous forehead, the males more sloping. It was variable and hard to pinpoint, and I left it at that. Later that evening, I looked at my photos and worked on some designs, and that process revealed some other differences and a few specific things to look for when I meet again.

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A return visit the next day was more conclusive: males and females seem to have different head shapes! The feathers can be raised or lowered, reducing the differences when you observe them in the field, but I think there is a real difference. (New info number 4, and an exciting question to ask the next time I see avocets.)

Admittedly, these are only details, but the great discoveries take place in the same way. The simple act of asking questions, looking for patterns, and observing carefully can lead to revelations, even in your own backyard.


This column originally appeared in the July/August 2022 issue of Bird watching magazine.