EACH fall AT POINT PELEE, Ontario, huge flocks of birds, their numbers swollen with the year's young, arrive and depart in waves as they travel south. On the great prairie flyways, countless skeins of geese, swans and cranes sweep north each spring and south each fall. Watching glistening white tundra swans in a deep blue autumn sky may be the closest I ever come to glimpsing angels. Smaller travellers pass this way, too, and their annual journeys fill me with awe. For a few weeks every spring, my yard echoes with unfamiliar songs as warblers pass through on their way to nest in the north. Blackburnian, Cape May, and a surprising number of other warbler species decorate newly green branches, causing us to grab our binoculars and bird book. When a Blackpoll Warbler appeared this year, nothing about his appearance indicated he was in the midst of travelling thousands of kilometres. The Blackpoll Warbler, named for the breeding male's dark crown and forehead, nests in a variety of habitats in western Alaska, across Canada to Newfoundland and northern Nova Scotia, and into the mountains of northern New England. About 65 percent of the population nests in Canada's boreal forests. After raising their young, blackpolls begin their journey to wintering grounds in Brazil and northern South America: a trip that may total more than 8,000 kilometres (4,970 miles). The majority of blackpolls, from both eastern and western breeding populations, travel down the Atlantic coast to North Carolina. After that, they endure a non-stop flight across the ocean, covering perhaps 3,500 kilometres (2,170 miles) and lasting 88 hours. How does a bird the length of a ballpoint pen (14 centimetres or 5 inches) and weighing about as much as two loonies manage such a feat? It eats insects-a lot of insects. Blackpoll Warblers have an exceptional ability to accumulate and retain body fat. They may nearly double their body weight before beginning their journey. Migrating blackpolls also take advantage of prevailing winds to help them on their way. But, don't forget, this isn't a "once-in-a-lifetime" trip. Each spring, the cycle begins anew. Billions of other birds make similar pilgrimages. Nearly three billion warblers, sparrows, thrushes, flycatchers, hawks and other land birds travel to Canada's boreal forests every spring. A third of these have wintered in the United States. The rest, known as neotropical migrants, come north from South or Central America. Each fall, the same birds, plus their two million new offspring, migrate south. Finding habitat in which to rest and feed on the way south is critical for the migrants, especially the young, inexperienced birds. About 90 percent of each year's songbird hatch fails to reach maturity. For the survivors, the long autumn migration is their first big test. Besides decreasing habitat, migrating birds face hazards including collisions with plate-glass windows, estimated to kill as many as one billion birds annually, and predation by domestic cats, which kill hundreds of millions of birds every year. Vehicles, utility wires, and communication towers add an increasing number of casualties. In addition, such natural risks as storms, sudden drops in temperature, water crossings and normal predation take their toll. Seemingly, we can do little to protect birds from these perils. However, preserving habitat on a large scale-in national and provincial parks as well as wildlife refuges-is vital. Every bit helps. By offering food, water and shelter in my yard year-round, I hope to increase the odds that some of these tough little travellers survive another trip. My hospitality is repaid with a constantly changing stream of visitors, and with some summer lodgers like the house wrens busily stuffing their babies with bugs as I write this. When you read these words, the migrations will be nearly finished. One kilometre after another on soft-feathered, hollow-boned wings. Wave after wave pouring down from the north until the last Vs of big Canada geese bring up the rear. Some chilly nights, as moonlight and the smell of wood smoke drift in through my window, I hear them honking far overhead. I fall asleep easily then, wishing them well on their remarkable journey. - REBECCA L. GRAMBO