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Weekend Science Fun is a bit late this weekend because it has been one of “those” weeks. Yesterday we spent the day at a FIRST robotics competition. The day before we visited the Pima Air and Space Museum. You get the idea…

Keeping with the bird theme, let’s take a look at….Pigeons! Have you ever really spent a few minutes and looked closely at a pigeon (also called rock dove)? Check out their plumage. The feathers around the pigeon’s neck are often gorgeous iridescent purple or green. They really are a glamorous as peacocks in their own way.

I can hear you saying now, is she really talking about pigeons? Maybe she’s been out in the sun too long at the FIRST competition. Aren’t pigeons pests?

I have to say I didn’t think too much about pigeons until a book came out called
Pigeons: The Fascinating Saga of the World's Most Revered and Reviled Bird by Andrew D. Blechman.

After my son and I read the book, our attitude changed a lot. In fact, one his favorite parts of our trip to Washington, DC last summer was checking out all the different-colored pigeons on the Mall. I have to say the variety of colors was definitely greater than anywhere else we have visited.

Pigeons came back to mind when I saw an article in the newspaper recently about how many different species of birds have the ability to see the color ultraviolet, which is invisible to humans. That was pretty cool to me, because I know that many insects can also see ultraviolet.

The article didn’t mention pigeons, but I had an idea those brilliantly colored feathers might have some ultraviolet. Sure enough, it turns out that some of the earliest studies on birds’ abilities to see ultraviolet were carried out with pigeons. More recent work has shown that the purple or green feathers have a complex mix of colors and ultraviolet.  Pigeons are walking billboards of color we can’t see.

If I’ve convinced you that pigeons might be worth investigating, then take a look at a cool project at the Cornell Laboratory of Ornithology called Project Pigeonwatch.

Here’s a quick link to the free educational resources.

I’ll dig up some pictures and add later this weekend if I get a chance. Have a good weekend.


We were doing a bit of yard work when we came across this leaf-footed bug. These insects get their name from the leaf-like flanges on their hind legs.

leaf-footed bug

Note the light-colored zig-zag marking across the middle of its back.

Leaf-footed bugs have sucking mouthparts and sometimes feed of fruit such as cactus fruit, oranges or peaches. Although we do have citrus, I think this one is a visitor from our neighbors’ yard. Our neighbors have a pomegranate bush. Pomegranates are one of the leaf-footed bugs' favorite foods.

Like many of their relatives, these true bugs can give off an odor when handled.


I was asked a question last week about what white-lined sphinx moth caterpillars eat. I had read that they eat wild relatives of the four-o'clock, a garden plant. A few weeks ago we visited Boyce Thompson Arboretum State Park and I got some great first-hand information about what kind of plants the caterpillars feed on.

At the arboretum we found caterpillars on a native plant that is being used as a landscape perennial called pink guara (Guara lindeimeri). I noticed, however, the caterpillars were only eating the flowers. Often the flowers lack toxins or feeding deterrents found in the leaves or stems, although I don’t know for sure this is the case here.

whitelined sphinx moth

Some of the caterpillars were working on a plant called white ratany (Krameria grayi).

whitelined sphinx moth

whitelined sphinx moth

I needed a friend’s help to identify that one. The plant has pretty purplish-pink flowers, but they are inconspicuous. She said the plant is a partial parasite that takes food from the roots of fellow desert plants like bursage or creosote bush. I also found out that the flowers produce an oily substance rather than nectar (weird!), but that some native bees will take it to mix with pollen.

whitelined sphinx moth

Finally, we cheered the caterpillars when we found this batch eating the noxious weed, spotted spurge. Go white-lined caterpillars, go! (Sorry, the photo isn't all that great).

For more information about white-lined sphinx moths and their caterpillars, check these previous posts:

Raising Caterpillars, which also has a photo of the adult

More About White-lined Sphinx Moth Caterpillars

Bug of the Week:  White-lined Sphinx Caterpillars