To Mexico and Back Again Southeast’s Smallest Migrants by Bob Armstrong and Marge Hermans from Southeast Alaska's Natural World In early summer in South- Tracking birds as small as hummingbirds east Alaska, one of the great pleasures to answer such questions is difficult. But for residents is keeping bright red sugar- some insights have come from the work of Adult male water feeders filled with nectar to feed ru- Bill Calder, a researcher and professor at the hummingbirds have fous hummingbirds. Buzzing and sparring, University of Arizona, who studied rufous brilliant red “gorgets” glinting in shades of red-brown and metallic hummingbirds for more than 30 years. (throat feathers). green, the birds often jockey noisily with Calder found that hummingbirds stop Tiny barbules on each other for the chance to sip their next to refuel in high mountain meadows just as the feathers reflect meal. They seem like tiny miracles—and in- certain alpine and subalpine flowers are at increased light at deed they are. They have traveled thousands the peak of blooming. In July and August certain angles, so the of miles from their wintering grounds in some appear in meadows of the Coast and bird’s gorget seems to Mexico to nest in Southeast Alaska. Sierra Mountains at elevations of 5,500 flash brilliant color as Hummingbirds begin arriving in early to to 7,000 feet, perhaps visiting the same it moves about. mid- April, but by late June the males will be patches of flowers they visited during past on their way south again. Females and young fall migrations. Others turn up in the Rocky of the year will leave in mid-July/early Au- Mountains, where summer flowers typically gust. All the birds will travel 1,700 to 2,700 reach their prime during the monsoons. miles to reach their wintering grounds by That birds so small have journeyed even September. this far is quite remarkable. In fact, Calder What routes do they follow? Where do likes to calculate their trips in hummingbird they stop to refuel? What affects their ability body lengths—which total almost 49 mil- to survive the long journey? lion, the longest migration of any bird by such a standard.

23 Calder wrote in the book Gatherings of An- gels—Migrating Birds and Their Ecology: Small size is . . . a disadvantage for seasonal In early spring rufous home-changing. Small size puts limits on hummingbirds leave fat storage and flight speed, and that reduc- their wintering grounds es endurance and range between refuelings. in Mexico and head Hummingbird A Canada goose, for example, can fly six north to nest and raise times as far between fueling stops, at two their young. Traveling migration or three times the hummingbird’s 25-mph up the west coast of speed (no tail wind). . . . If the fuel sup- North America, some routes ply runs short, the weather changes, or the turn inland toward migrating hummingbird is blown off course Idaho, Montana, and or forced down unexpectedly, the unlucky Alberta, Canada. bird might be far from a flowering meadow. Others continue north to British Columbia In situations such as these it may be dif- and coastal Alaska ficult, or impossible, for the bird to recover as far north as Prince enough to continue its journey. William Sound. “Social” birds like Canada geese have other advantages, Calder said. Geese pool In mid-July and their experience and route knowledge with August, first the flock mates and relatives, and they reduce males then the females energy costs by flying in V-formation. “Anti- and young of the social” hummingbirds lack these advantages, year fly south. Some because they develop no social ties, even at travel along the Coast the family level. Each bird is on its own. Range and the Sierra Nevadas. Others travel farther east along the Hummingbirds stop to Rocky Mountains. refuel in high mountain meadows. Most hummingbirds from Southeast Alaska And what about the young of the year? probably follow the How do juvenile hummingbirds—barely a Coast Range/Sierra month out of the nest—manage this long, Nevada route. dangerous migration? Calder believed in- structions for the migratory flight must be Breeding Range encoded in the genes. Juvenile birds get no guidance from their parents on migration Winter Range routes. By the time they begin to head south Based on a map their parents have already left. by William A. Calder In preparation for only one leg of the

24 (Above left) Hummingbirds are attracted to several species of paintbrush, some of which are trip to Mexico, hummingbirds may increase flowers die or wither, birds face tremen- quite common in their body weight by two-thirds. Calder dous competition for nectar sources, and Southeast Alaska writes, “Once fully-fattened, a hummingbird they may be unable to refuel successfully. meadows. the size of a rufous could fly an estimated Describing his observations of just such a 610 miles of its migration route without situation in 1996 and 1997, Calder wrote, (Above right) refueling. With a tail wind it could fly even “Two consecutive years is long enough for Western columbine farther.” a generation of hummingbirds to have died, flowers have evolved But refueling stops are crucial, and and such sustained climatic vicissitudes, if specifically to attract widespread, could have a significant impact hummingbirds, rather “Once fully fattened, on the species’ population.” than bees or other insects, as pollinators. a hummingbird the size While habitat protection is important, he noted, “the greatest vulnerability may come They are usually of a rufous could fly from the effects of climate change.” bright red or orange, an estimated 610 miles Here is a theme that keeps repeating colors conspicuous to of its migration route itself as we learn about many species of hummingbirds but not without refueling.” migratory birds: Everything is connected. to bees. And events far from us can tremendously affect the birds we enjoy no matter where Calder notes that “timing and amount of we live. It’s a story borne out by Southeast’s precipitation must often determine the smallest migrants, and perhaps those most success of migratory nectar-feeders. If widely anticipated each spring. there is summer drought, so that seasonal

25 Learning about hummingbirds Most of what we know about hum- mingbirds has come from the dedicated “We could . . . stand and painstaking work of Bill Calder, who in awe of a naïve, researched hummingbirds for 30 years before his death in April 2002. For several month-old bird with years Bill and his wife Lorene came to little more than Southeast Alaska to study and band ru- 1/10,000 of our fous hummingbirds. One of their regular brain volume bravely stops was Bob Armstrong’s back porch setting forth and in Juneau. successfully navigating Each hummingbird Bill caught he to Mexico for the weighed, banded, and examined for fat handled. The female in the photo above winter.”—Bill Calder content and a characteristic pattern of laid quietly in Bill’s hand until he gave it a wear on the tail feathers that would gentle nudge and it buzzed off. indicate it was feeding nestlings. He also removed a tail feather for later DNA You can see the numbered aluminum analysis. leg band and the temporary blue mark Bill used to distinguish birds that had been Rufous hummingbirds are very docile recently handled. and do not put up a struggle when they’re

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