Western Tanagers arrive in Southwest Colorado shortly after bears come out of hibernation, so setting out orange halves to attract them, as some websites suggest, isn’t a good practice in bear country. Providing a water source, however, particularly a low volume dripper, will often bring them to your home for baths and drinks, and what a breathtaking sight it is to look out the window and see these striking beauties lighting up the backyard.
Males start to sing immediately upon their arrival in May as they stake out their breeding territories. They aren’t trying to attract a lady love – pairing off already happened back home in the tropics, or midway during their migration flight. Their songs are for cementing that bond and telling the other guys in the hood to back off.
Some have compared the burry, sing-song quality of their vocalizations to that of the American robin – with a sore throat! I laughed at that description, but knowing this about them is actually very helpful for tracking them down in the woods, because Western Tanagers like to feed high in the forest canopy and can be easy to miss.
Where do the males get that flaming red head? Western Tanagers are fruit eaters in their tropical homes, but they’re mostly insectivores here on their breeding grounds. One of their favorite foods is the highly destructive western spruce budworm, which is the caterpillar phase of the small brown and gray moth Choristoneura freemani.
These caterpillars voraciously eat the leaf buds of several species of conifers, which contain the rare red pigment rhodoxanthin, and ornithologists believe that by consuming these caterpillars and other conifer bud-eating insects, the red pigment is passed along, similar to flamingoes obtaining their pink feathers by eating brine shrimp and crustaceans.
Of course female Western Tanagers, with their subtle olive green plumage, also eat the caterpillars, but for some reason don’t metabolize rhodoxanthin into their feathers. Which is no doubt a good thing, as a brilliant red-headed female sitting atop a nest in an evergreen tree would be like a flashing neon sign pointing the way for nest predators.
“A thing of beauty is a joy forever,” wrote English poet John Keats, and for that reason alone, these radiant songbirds are worthy of our care and protection. But they also provide vital services, such as keeping insect populations in check and helping disperse seeds in the fall when they return to eating berries.
Migration is risky business, but there’s a few simple things we can all do to help ensure Western Tanagers keep returning to Colorado each spring. Check out the American Bird Conservancy’s “Bird-Friendly Living” at https://tinyurl.com/348cjfck to learn about their “Small Actions, Big Results” campaign. And next time you’re in the woods, remember to look up into the treetops when you hear that robin with a sore throat.
Mary Grizzard is an amateur naturalist and volunteers with the San Juan Mountains Association. You can reach her at [email protected].