Annually in March-April, a natural phenomenon is occurring across British Columbia - the migratory return of Rufous Hummingbirds after wintering in southwestern USA, western Mexico or Central America. Traveling some 2000 km at a few hundred km per week, hummingbirds are guided by an ancient internal signal to return to northern regions for summer feeding and breeding.

The main south-north route, rich in "roadmap" landscape features, is the coastal Pacific Flyway from Baja, Mexico to Alaska, providing mild weather that enables hummingbirds to arrive along south-coastal BC in mid-March and Osoyoos by early-April. Covering extremes of distance, some Rufous Hummingbirds summer as far north as Alaska and the Yukon!

Such wide range of spring migration requires tolerance to occasional cold temperatures, placing a premium on timing to coordinate with shelter, nectar and insect availability. Arriving at the breeding grounds too early without these factors in place would challenge survival and territorial competition. One wonders if migratory patterns are gradually evolving in a way linked to the climate changes from global warming that affect the timing of flower blooming (nectar), nesting conditions and insect populations.

While in flight, hummingbirds have the highest metabolism of any animal, a necessity supporting their rapid wing beats during hovering and fast forward flight - around 50 flaps per second! With heart rates of 1000 beats per minute and 250 breaths per minute, hummingbirds in flight consume oxygen at a rate 10 times higher than trained athletes running at top speed on a treadmill.

As hummingbirds consume more than their own weight in nectar and insects each day, they must visit hundreds of flowers daily and forage in flight throughout daylight hours. Each night, or in times of low food availability, hummingbirds enter a hibernation-like state called torpor to store energy for the next day's activities.

Many species of hummingbirds produce sounds with their wings or tail, however the harmonics of feather sounds during territory intrusion or courtship dives vary across species. Male Rufous Hummingbirds have a distinctive wing whistle in normal flight that sounds like small coins jingling in your pocket. Research has shown that the whistle results from air rushing through slots between the tapered ends of the ninth and tenth primary wing feathers, creating a sound loud enough for detection by female or competitive male birds over 100 meters in distance. Behaviorally, the whistle alerts females and other males that a male bird is in flight nearby, providing an audible defense of feeding territory and courtship.

Rufous tail-feathers also vibrate during courtship dives, producing a loud chirp apparently to impress females! When courting, the male first ascends in a spiral to some 30 meters high before dramatically diving over an interested female at a speed of 27 meters per second, equal to 385 body lengths per second, causing a high-pitched vibration of the tail feathers. The sound is caused by rapid air flow past tail feather tips, causing them to flutter and vibrate.

Spring is a wonderful time to stop by the Desert Centre to observe hummingbirds in action. Three species of hummingbirds - Rufous, Calliope and Black-chinned - are routinely sighted at our feeders. Their aerial acrobatics are sure to delight visitors of all ages!