Male mountain bluebird at Golden Gate Canyon State Park, elevation 7,600–10,400 feet

Mountain Bluebirds in Denver

Mountain bluebirds seek out nest sites in open areas of short grasses, shrubs, and trees at 7,000–12,500 feet above sea level. Typically they migrate through Denver (5,280 feet above sea level) and head toward the mountains where they spend their summer and raise their young. Breeding in Denver is uncommon, but if the habitat is suitable, the food is plentiful, the nest box provided, and the mate is willing…why not? So it happened at the CommonGround Golf Course this spring.

Left: Mountain bluebird feeding a nestling in a nest box at CommonGround Golf Course. Right: The yellow gape makes a perfect target for feeding a nestling in a tree hole nest at Golden Gate Canyon State Park.

On April 12, the CommonGround birders saw a pair of mountain bluebirds at a nest box on the golf course. The birds continued to be sighted on May 10 and May 25. Finally, they documented nestlings begging for food and parents rotating to feed them on May 29 and June 2. The nestling’s open mouth (gape) is a bright yellow, fleshy area—a visual cue for where to deposit food.

Mountain bluebirds do not have blue pigments in their feathers. The blue color is a result of the interaction of light with the feather. The feather barbs have structures that bend light waves and allow only blue light to reflect back to the viewer. This is similar to how we see the sky as blue.

Bird Walks: July 5 and August 2, 7:30am & 8am. Walks are free but you must RSVP at www.blufflake.org/birdwatching. All are welcome. Bring your own binoculars, or borrow a pair from your guide. 11255 MLK Jr. Blvd. Search www.FrontPorchNE.com for “Bird Sightings” to see all the past bird stories and photos from George Ho.