Save our songbirds
My first trip to Point Pelee National Park was one spring about 25 years ago. The peninsula, which juts out into Lake Erie, is world-famous as a stopping-off place for songbirds during spring migration. As soon as we entered the park gates, it seemed that nearly every branch along the barely budding trees was alive with fiery reds, sky blues, yellows and browns – the breeding plumage of scarlet tanagers, indigo buntings, yellow warblers and wood thrushes, among others. The trees were vibrating with color, and it amazed us not only to find such exotic-looking birds in southern Ontario but so many in one fairly small area.
Years later, I realized that the huge number of birds present that day wasn’t a normal event but a fallout, a phenomenon that occurs when migrants crossing a large body of water are battered by bad weather or forced down by fog and alight, exhausted, on the nearest piece of land that can provide them with sustenance and a place to rest before they continue their journeys. Point Pelee is one of those places, not only because of its location on Lake Erie and its funnel shape, both of which act as a migrant trap, but becae it retains its natural habitat.
That first year, I felt I was experiencing Christmas in springtime, seeing the multicolored songbirds that decorated the trees. But even then, there were harbingers of doom. Older birders talked about the good old days, when the waves of birds were bigger, when numbers were greater. Twenty-five years later, birders continue to worry that the big spring waves aren’t what they used to be and that the numbers and variety of birds have been on a steady decline. But is there proof of declining numbers or have our memories exaggerated the problem?
Two of the best sources of information for tracking population trends are the North American Breeding Bird Survey (BBS) and Bird Studies Canada (BSC). BSC, a non-profit group, is one of the arms of Long Point Bird Observatory (LPBO), which has been monitoring bird populations since the 1960s. LPBO has a vast data base on birds that breed in northern Canada and valuable information on which species have been increasing over the years and which are decreasing and might be in trouble. Jon McCracken, the program manager for Bird Studies Canada says the picture is mixed: “About half the species are decreasing and half are increasing. Some of the declines are more serious than others.”
In the songbird category, grassland species such as eastern meadowlarks and lark sparrows are in serious decline. Certain species of warblers are decreasing in number, and several of the thrushes are losing ground. “There’s often more than one reason for decline [of a species],” says McCracken, though he points out that habitat loss, both in southern wintering grounds and on the northern breeding grounds, generally ranks as the number 1 problem. “Predation is certainly an issue,” he notes, “though it depends on the species.” Ground-nesting species are often hit by feral cats, which are a big problem in many areas, and by nest raiders such as raccoons.
“And then there are tall buildings. Certain species of migrating birds are prone to flying into tall buildings that are lit up at night. Some species, like ovenbird and white-throated sparrow, are declining, and they’re also two of the species that consistently turn up in the biggest kills at skyscrapers. Toxins, though still an issue, aren’t nearly as much of a problem as they were in the ’60s, ’70s and early ’80s, when we were still getting DDT out of the system. But toxins certainly haven’t gone away.”
It’s clear that many variables influence bird population decline; not surprisingly, the human factor figures directly or indirectly in all of them. Let’s take one bird’s eye-view of migration and the perils that it could face on its long journey.
The wood thrush is one of the poster boys of songbirds. A bit smaller than a robin, it’s elegant and handsome: rusty-brown above and whitish below, its sides, breast and throat are punctuated by large dark spots. But it’s the bird’s vocalizations that make thrushes favourites of nature lovers. During breeding season, the bird’s rich liquid song rings evocatively through the woods at dawn and dusk. But we are hearing the song less and less. Data from the North American Breeding Bird survey (a census that has been monitoring breeding populations since 1966) shows the wood thrush population has been declining rapidly since the 1980s. The reason? Wood thrushes nest in hardwood forests from the eastern half of the United States to southern Ontario, Quebec and parts of the Maritime provinces, and as most of us have noticed, these forests have been reduced to mere fragments of their former size, victims of logging, farming, roads and suburban development. The decrease in woods has resulted in an increase in forest edges, areas in which mammals, such as raccoons, chipmunks and cats, and birds, such as jays and crows, thrive. Unfortunately for the wood thrush, these creatures are predators, and forest-nesting birds are their prime targets. The wood thrush also dines on insects, but our forests are often sprayed with pesticides that kill caterpillars and other insects and can harm birds. Researchers also suspect the large variety of agro-chemicals we use could affect the reproductive tracts of birds.
Let’s say our wood thrush thrives on its summer breeding territory. In late July or early August, its genetic programming lures it south, sending it on a migratory flight of thousands of kilometres to Mexico or Central America. Amazingly, birds find their way by tracking the sun, moon and stars and, apparently, by perceiving sensations such as weak magnetic fields, faint odours and barometric pressure.
If weather conditions are good and our bird finds safe and appropriate habitat to rest in along the way, migration should go without a hitch. But migrating can be fatal when a bird that weighs as little as 1.6 ounces (47 grams) meets up with a storm or a relentless cold front while crossing a big body of water such as Lake Erie or the Gulf of Mexico. Alan Wormington, an avid birder who, has worked as a naturalist in various Canadian parks for years, spent one spring and two autumns on an oil rig in the Gulf of Mexico, taking a census of migrating birds for the University of Louisiana.
“By studying birds off the platform, you can see exactly where a bird’s coming from and where it’s going, if it’s feeding, what it’s eating, how long it stays,” says Wormington, who talks about one day on the rig on Oct.18, 1999, when a cold front came through. “On that one day, I recorded 74 different species, pretty impressive from the platform of a hunk of metal in the ocean.” How many birds might have died trying to cross the Gulf under those adverse conditions? “When a cold front comes through and there’s a downpour, tens of thousands of birds are killed,” says Wormington. “Birds that are out on the ocean are expecting perfect conditions to get them across, and if they crash into a front with heavy rains and fierce winds, there are massive die-offs.”
If our thrush breezes across on a tailwind and arrives at its home in Mexico, what then? By conservative estimates, between one and four per cent of forest is being cleared for pasture or farmland every year in Latin America. Forest loss is greatest in Mexico and Central America, the most important winter migratory bird areas, and though some birds thrive in second-growth forests, others, like the wood thrush, adapt poorly to them and do even worse in cultivated landscapes. Until recently, for instance, coffee was grown under a canopy of shade trees, and coffee plantations resembled rainforest habitat well enough to attract and nurture migrants. Increasingly, however, industrial coffee farmers are clearing the lush vegetation off their land to grow coffee in full sun. This conversion to sun-grown coffee has produced a dramatic decrease in migratory bird species. More than 90 per cent fewer species are found on sun-grown coffee farms than on shade farms.
On the other hand, when a forest is cleared for cultivation, some species benefit: the forest birds will disappear, but the birds that live in fields or forest edges will increase. Despite the 50/50 balance, Kenn Kaufman, a bird expert and author of books including Birds of North America (Houghton Mifflin, 2000), has concerns. “What worries me,” says Kaufman, “is that the birds that are increasing tend to be the ones that are really generalized, really adaptable, while the ones that are more specialized are tending to disappear.” His fear is of ending up with a world that’s a lot more generic. “Birds like the house sparrows out on your patio are now on every continent,” he says. “They’re highly adaptable and can live easily alongside humans in cities – and more power to them. But the birds that need a particular kind of habitat are becoming less common.”
Like most naturalists, Kaufman likes the idea of diversity. “It’s a healthier ecosystem if you have a lot of species interacting independently, not only with other birds but with the plants and insects and everything else in the environment. If you get down to just a few species, it’s a lot easier for things to seriously get out of balance.
Kaufman’s appreciation for the esthetic value of birds is shared by many; he thinks one of the reasons may be in the bird’s being. “There isn’t much in our surroundings as intensely alive as a bird,” he says. “Their senses are so much more finely tuned than ours. Some little songbirds may have a heartbeat when they’re excited that goes at 200 or 300 times a minute or more, but they don’t explode. And you get this little bird, which doesn’t weigh much more than a loonie, migrating thousands of miles every year going from Canada to Mexico or the Caribbean and back again the following spring. There’s so much energy in that tiny bird. If people paid attention, they couldn’t help but be interested in these wonderful creatures.”
WHAT YOU CAN DO
While we can’t do much to protect birds from inclement weather, there are many things we can do to help alleviate some of the problems we’ve created that threaten birds.
Support FLAP. Bird species that migrate at night are often attracted to lights shining from tall structures such as skyscrapers and broadcast towers. Confused, they either collide with the object or flutter around the lights until they collapse with exhaustion. About half the birds found die from injuries suffered in the collision; others require medical attention while some are simply stunned but have a slim chance of making it out alive. Gulls, crows, cats and other opportunistic predators have learned they can have an easy meal at the base of tall buildings. The Fatal Light Awareness Program (FLAP) is a Toronto-based charity that rescues live birds and works with tower management and staff to turn off tower lights during migration.
If you want to volunteer for FLAP or donate funds, call 905-831-FLAP; write to 65 Front St. W., Ste. 0116-207 Toronto M5J 1E6 or go to www.flap.org.
Keep your cat indoors. Research conducted in the U.S. a few years ago concluded that domestic cats kill hundreds of millions of birds nationwide each year. Canadian figures would be lower but no less shocking. In response, the American Bird Conservancy has launched a Cats Indoors campaign to convince cat owners to keep their pets indoors.
For more information, contact Cats Indoors!, American Bird Conservancy, 1250-24th Street N.W., Ste. 400, Washington, D.C. or e-mail: [email protected].
For information on bird associations and volunteer opportunities, go to www.birding.com/BestWebSites.asp