The distinctive buzz of the male broad-tailed hummingbird (Selasphorus platycercus ) is one of the surest indications of spring in Rocky Mountain National Park. The green-backed, rosy throated males arrive first and set up territories. When the females arrive, the males put on impressive swooping aerial displays to win them. The male's distinctive humming buzz, reminiscent of a tiny fighter jet, no doubt makes these aerial displays even more exciting for the females. Once mated, females make tiny nests out of lichens, mosses, spider silk, and other soft materials, and usually lay two eggs. The females have all the work - the males do not participate in raising the young.
Broad-tailed hummingbirds usually arrive in the park in April to early May. Their arrival seems to be timed to coincide with the first blooms of the wax current (Ribes cereum), one of their important local nectar sources. Later in the summer, usually early July, they are joined by their slightly smaller, and substantially feistier relatives, the rufous hummingbirds (Selasphorus rufus ). Male rufous hummingbirds are very easy to recognize because they glow red-gold in sunlight. You may want to visit USGS Patuxent National Wildlife Research Center's website for an excellent description and more pictures of broad-tailed hummingbirds, and rufous hummingbirds.
The Continental Divide Research Learning Center at Rocky Mountain National Park is starting a project this summer to band hummingbirds so we can better understand these "flying jewels."