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Waxwings and Cottonwoods

March 6, 2019

Waxwings arrive in Houston after Christmas and stick around until they eat all the mulberries, which don’t even get going until late March. 

They aren’t large birds, about the size of a starling, but they are dapper. With a red tip on each wing, a yellow band at the tip of their tails and a black mask, they look like doormen at a fancy apartment building. That red wingtip is how they got their name. They secrete a red waxy substance on the tips of their wing feathers. The older they are, the more wax tips they have. The wing tips are thought to play a role in status, the more red, the more breeding opportunities.

Once you know how to listen for them, you can’t miss this bird. They are always in flocks. You rarely see fewer than 10 cedar waxwings in a flock, and I’ve often seen more than 50. They make an incredibly high-pitched sound and they make it nonstop. If they were loud, we would hate them. But they are quiet and that sound of theirs is so high pitched, I think much of it is out of our range of hearing.

If you are a bird watcher, you love cedar waxwings. They will come to your yard for fruit and if you have a mulberry tree, you are their best friend. They love mulberries so much they will eat them even after they are so ripe they have begun to ferment. Then you get drunk waxwings.

Winter can be dull and waxwings are like ornaments that make everything a little brighter. But I’ve always wondered, what do they eat in January and February? Before the mulberry abundance is upon us.

I was surprised this week to find that they love cottonwood flowers. In truth, I was surprised simply by cottonwood flowers. 

The thing with tree flowers is that they are often not showy, and even if they are, they are usually so high up that you need binoculars to enjoy them. Take a good look at a catalpa in bloom and you will be blown away by the orchid-like flowers.

I discovered cottonwood flowers because I was in the Park sitting still and hoping something bloggy would occur. I noticed that there were all these shells at my feet. I poked through them for a while and then, brilliantly, decided to look up. I was floored. Above me were these fat fingers of red and yellow blooms. Cottonwood flowers! Those shells were the casings that the flowers burst out of.

I took a bunch of photos and went home to learn more. I learned that these were male flowers because cottonwoods are dioecious, which means that there are male cottonwoods and female cottonwoods and each has a flower with only male (or female) parts. Most flowering plants produce flowers with both male and female parts. 

With that information in hand, I returned to the Park to find the female trees. I didn’t find any, but I did find flocks of cedar waxwings eating the cottonwood flowers. One mystery solved (what do they eat when mulberries aren’t around), but another one arose. Where are the female cottonwoods?

I can’t say for sure, but I did see a fair number of cottonwoods not in bloom at all. I think those are the females. It makes sense that they would flower second. Cottonwoods produce tons of pollen that is dispersed by the wind. If the female flowered first, she would produce flowers waiting for the pollen that wasn’t yet aloft. By flowering weeks later, female flowers arrive in a world with air full of pollen. Once the pollen contacts the pistil, the tree starts making seeds embedded in cottony fluff that carries them aloft. I’m not sure any birds eat those seeds. A million of them would weigh only three pounds. They were built for flight.