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May 4, 2006  Where Do They All Come From Its 5:45 a.m. and the thermometer stands at -7 Celsius. I look out the window and my first chore of the morning becomes obvious; the sugar water in the hummingbird feeder looks thick and frosty like the contents of a slushy dispenser. To solve the problem I mix new warm sugar water and replace the old stuff. Next, I head outside to catch the first rays of sun. Usually I sit to the left of the driveway with a cup of coffee but today I seek out the strong sunlight and choose to prop myself against the biggest poplar tree off to the right of the driveway. From this vantage point I can see down the length of the valley to the Canim Lake hills that look like gauzy blue bumps facing off against one another. The distant sky is platinum yellow in the haze. Pastures spread from my boot tips to the distant horizon. The closest pasture features cows and calves. The impact of each bovine is doubled as they all cast a strong dark shadow on the grass. On a power line above the road Tree Swallows sit and jostle. At other times they dash off to buzz one of the many bird boxes positioned along the fence line. I've now built so many bird boxes, which have not yet been put up, that I feel like a bird box miser. If I build more I'll be like the Montgomery Burns character from The Simpsons TV show. When asked what he'd do if he won another million dollars on a bet, he replied "Just throw it on the pile, I guess." As I looked over the pastoral landscape my mind travels further east down the valley to Canim Lake. A few miles more, and an elevation drop, takes you to Mahood Lake. From the east end of Mahood lake flows the Clearwater River until dropping in steep turbulent passages to the North Thompson River. As my mind went east, I thought of the birds going north, and speculated on the birds' use of the natural corridor up to the plateau. By what routes do the birds' go when migrating to this area. And by what routes do those north of us travel? I often wonder and have developed several theories. I don't believe the migrant songbirds now here came to us over the Rocky Mountains. There does not seem to have been enough time for the migrants to come up the eastern coast of North America and swing across Canada into Alberta and British Columbia. We are now swamped with yodeling flocks of White-crowned Sparrows. They winter somewhere south of us but because they are hardy that wouldn't be too far south across the 49th parallel. The same goes for Juncos; they simply fly north and come up to the Cariboo plateau without a need to follow low forgiving valleys to survive an early incursion. Song Sparrows, now ensconced and singing in many spots along the creek and other riparian areas, probably move straight north from some southern, not very far off, wintering areas. Most expected species of Swallow have returned to the Cariboo. Tree, Rough-winged, Cliff, Violet-green and Barn Swallows have all sent their Spring representatives, and greater numbers will follow later. Only the Bank Swallow has not yet shown up, but I suspect that I saw one about a week ago. I extrapolated the Swallows route to the plateau when reading about Violet-green Swallow migration which follows the Pacific coast north from California then turns inland, possibly coming up the Fraser River or even over the coastal mountain ranges. So my theory is that our Swallows come from the west, not the east. What about Hummingbirds? Though not yet here in great numbers, the Calliope and Rufous have both put in a showing. They come from much further south than any previously mentioned bird, possibly Mexico or further, but they also stay on the west side of the Rockies in their flight north. The Yellow-rumped Warbler, first of its clan to return, also comes to us from south of the 49th parallel and the west side of the Rockies. The next Warbler species to return usually is the Wilson's Warbler, or the Orange-crowned Warbler, and yesterday I saw my first Wilson's. Though it is startlingly exotic in buttercup-yellow plumage with a little tam of black, I suspect it is not one of the migrants coming with the eastern influx over the Rockies, but follows a route similar to the birds already mentioned. So on what do I base my theories of migration? Do I pull them from the thin air? No, of course not. First, I consult a good bird book that contains current information on the wintering areas of each bird species. The Wilson's Warbler for instance, according to Sibley's it winters on both coasts of Mexico and the coast of Texas. Noting distribution one can see that the Wilson's Warbler blankets North America from side to side, so it is likely that the Wilson's we see migrate straight up the continent from Mexico. So far, the Hammond's Flycatcher is the only one returned. I counted three in scattered locations on my walk today. Hammond's is truly a western bird and winters, according to Sibley's Bird Guide, in central Mexico. Their return would definitely take place up the western side of North America. The Hermit Thrush returned to our area at least a week ago. There is still no sign of the Swainson's Thrush. Again, this makes sense if you consult wintering territory; in winter the Hermit is found right across the southern third of North America, whereas the Swainson's is right off the map and probably comes to us from Central America or even further south thus taking longer to arrive. In general, I believe that the birds migrating to the Cariboo each spring are not the same birds that flood across the Great lakes in May and make bird watching in Point Pelee so famous. This is not to say that none of the birds made that long trek. One example, that springs to mind if you count the Clearwater area east of the Canim Lake trench, is the Magnolia Warbler. Another is the Grey Catbird. Both come to us from the east. So why do I speculate on the swirling movement of birds as they arrive in the Cariboo? I guess it's similar to thinking about where one's food comes from, and upon reflection, giving thanks to the earth. The tenuous infrastructure necessary to bring a fresh lettuce to our local store is a miracle of sorts, and requires a thousand things to go right, including variables as diverse as political will, and weather. The same with birds; migration corridors shrink each year as humans erode what is left of habitats in order to build roads, houses, and all the things that mean comfort, life and prosperity for humans. How long the birds keep coming is anyone's guess. So far, another spring is here and the birds are arriving as usual and that my friend, is worth giving thanks for and pausing to watch. To e-mail Tom CLICK HERE To look at previous column CLICK HERE |
