Mad about Science: Western Tanager

By Brenden Bobby
Reader Columnist

Astute bird-watchers and casual backyard feeders may have the occasional good fortune to witness a brilliant feathered neighbor darting between the branches: the western tanager.

This bird is relatively common throughout the late spring and summer, but they’re a tricky-to-spot forest denizen, unless you really know where to look. The western tanager has a striking appearance, with brilliant yellow plumage punctuated by inky black wing feathers while the males sport bright red faces. The darkness of the wings vanish into the shadows of the conifers while the yellow blends right into the greens of the canopy. 

The females are even more well camouflaged, with green-gray along their wings and back, and a dull and dirty yellow along the underbelly, head and tail. The females blend right into the boughs of trees.

This bird isn’t particularly fond of seeds and vastly prefers insects and fruit when it’s time to feed. Suet blocks flavored with berries are a great way to attract them to your yard, while bird baths give them a reprieve from the summer heat and a reliable source of water to keep the birds hydrated and interested in your yard. 

The stark red feathers of the male are actually attributed to their diet, as they don’t produce the rhodoxanthin pigment naturally. Rather, it’s believed to be processed from the insects the tanager consumes. Rather than excrete the pigment as waste, it becomes a glorious mating display to showcase the tenacity and virility of the breeding males.

Western tanagers have a staggering range during the breeding season, with some staying as far south as western Texas and others traveling as far north as Canada’s Northern Territories. Preferring coniferous forests, they will actively avoid much of the high desert, including vast swaths of northern Nevada, central Oregon and the Columbia River Basin of Washington state. Filled to bursting with conifers, Bonner County provides ample seasonal housing for the western tanager. During the fall and winter seasons, the bird prefers the sunny climes of southern Mexico, straying as far south as Nicaragua and Costa Rica.

The females will lay between three and five eggs per nest. The eggs are pale blue in color and speckled with brown blotches. The female will sit on her eggs for roughly two weeks. Once the eggs have hatched into tanager chicks, both parents will contribute to feeding the young until they’re ready to leave the nest — around two weeks after they’ve hatched.

Unafraid of heights, western tanagers will seldom build a nest lower than 15 feet from the base of a tree — preferably a conifer — while nesting up to 65 feet up at the highest. The female is the premier architect of a tanager pair, creating an open cup from whatever she may find as a suitable material. They like to build the nest where a branch horizontally forks, providing a natural support on two sides.

As mentioned above, these birds like fruit and insects and will do the majority of their foraging in the canopies of trees. They are graceful and agile birds and will actively pursue insects in flight. They also feed on the nectar from flowers, as well as the pollinators that frequent them. Wasps and bees are a favorite of the western tanager, though it’s not particularly picky when it comes to meaty insects, as it will also consume grasshoppers, beetles and cicadas. Curiously, western tanagers enjoy citrus fruits, which is rare in the natural world, especially in locations where citrus doesn’t naturally grow.

The call of the western tanager is one you would likely recognize, especially this time of year. It’s a short and undulating chirp with frequent pauses. To my ear, it sounds like the bird is saying: “Whip it, whip it, beer!” The call is easily mistaken for that of the robin, especially if the source of the call is invisible from the canopy of the forest.

Western tanagers face similar climate challenges to other birds. Rising temperatures throughout the North American West has increased the risk of fire, which directly endangers young tanagers and nesting locations. Destroyed forest canopies deprive the birds of places to forage and cover from raptors. Heat waves in the spring endanger the nest-bound chicks. Harsh winters don’t bother the tanager, as they spend that time in the tropics anyway.

Are you hoping to track down and spot a western tanager with your own eyes? Now is a great time to get outside and do some casual birdwatching. Come visit me at Pine Street Woods in the main lot on Friday, Aug. 9 between 10 a.m. and 2 p.m. to check out the library’s mobile science center. I’ll have a number of field guides available to explore local flora and fauna, as well as invasive species. Birding backpacks will also be available to check out on the trailhead if you have your library card with you — these are a part of our Library of Things that contain a pair of Vortex binoculars, a copy of Sibley’s Guide to Birds West, and a community birding journal to mark down any birds you see to share with your community. It’s the only book the library will let you check out that we encourage you to write in!

This citizen science initiative is a great and free way to spend a couple of hours exploring your local ecosystem and learning more about which critters call this place home. It’s a great way to discover local plants and find what is actually invasive and out of place for our area. 

Did you know the white oxeye daisies that sprout everywhere around here are actually invasive? It’s an introduced ornamental flower that spreads aggressively throughout local ecosystems. It isn’t noxious like tansy or knapweed, but it still outcompetes native plants for precious space and resources.

Stay curious, 7B.