Rouge Valley Conservation Centre
Nature Notes
By Steve Gahbauer
July – August 2008
Birds and Climate Change.
Summer! The days are longer, the sun is warmer, everything in nature is abundant. The first clutch of Eastern Bluebirds has fledged in the meadows of the Rouge Park and the parents are building a second nest. So do some of the swallows, American Robins and Mourning Doves. It's a great time for hiking and enjoying the bounty of nature.
But not everything is well with nature. We must not ignore the danger signs around us. If we do, it is to our peril. Species, both plant and animal, are disappearing at an alarming rate. The magnitude of the declines within the last couple of decades is staggering.
Many years ago, we used to have bears and porcupines in the Rouge Valley. Not anymore, due to development around the park. Now, even the deer are moving farther north, as our annual deer census shows. In just 30 years time, one quarter of all known mammals are expected to disappear from the face of the earth, due to climate change and human interference with ecosystems. Global warming – no longer just a theory but a proven fact – is rapidly becoming the most serious threat to the planet's biodiversity, according to Dr. J. Malcolm, an associate professor at the University of Toronto.
Among the hardest hit are birds. The 2008 Red List of Bird Studies Canada shows that 1,225 species are threatened with extinction and eight species have been uplisted to critically endangered. Our birds are sending us a frightening signal. They are warning us that climate change can have catastrophic consequences. Of the 428 bird species that breed in Canada, 60 are already at risk of extinction. More than 70% of Northern Pintales, Bank Swallows, Eastern Meadowlarks and Greater Scaups have already gone; more than 60% of Snow Buntings and Common Grackles have disappeared; and there is a more than 50% decrease in American Bitterns, Horned Larks and Ruffed Grouse.
Declines have been so severe that Chimney Swifts, Common Nighthawks and Olive-sided Flycatchers were recently designated as threatened species. Barn Swallows, Bank Swallows and Eastern Wood Pewees may not be far behind. The population of Olive-sided Flycatchers, the largest member of the Wood Pewee genus, which has been seen in the Rouge Valley in the past, has been declining for decades and its numbers are falling faster every year. The current population is only 18% of what it was 40 years ago. Chimney Swift populations have declined by 96% since 1968.
Other threatened birds are the Red-headed Woodpecker and the Whip-poor-will. The latter was once a common part of the cottage experience for many Canadians, but its song is no longer heard in cottage country. Among bird species in the Rouge that are responding to climate change are American Robins, who are arriving at their Canadian breedings grounds earlier; Tree Swallows, who are breeding an average of nine days earlier; and Red-winged Blackbirds, whose population has decreased by 50% since 1972 because of warmer and wetter winters in the southeastern United States. Waterfowl are the most vulnerable to changing climate.
Climate change affects birds in different ways. It alters their distribution, abundance, behaviour, and even their genetic make-up. It also affects the timing of events, like migration and breeding. Global warming can change entire ecological communities – food and nesting material for birds may no longer be there, there may be new parasites and predators to which they are not adapted, new forest pests change food patterns, and in our area we may end up with a dozen fewer warblers than are currently found here in the summer. After all, migrating birds are particularly vulnerable to climate change effects because they depend on multiple habitats. (See also “Understanding climate change” in the February 2008 mini-essay.)
Frogs, Toads and Turtles.
Frogs and toads are also bellwethers of climate change and early indicators of environmental degradation. They live on land and in the water and signal damage to both ecosystems early. Frogs, toads, salamanders and newts, who have managed just fine for the past 360 million years, are now disappearing rapidly. Almost one-third of all amphibian species (there are more than 6,000 of them) are faced with the possibility of extinction; 120 of them have already gone in recent decades. No other class of organisms has faced such high risk of widespread extinction. Habitat loss, fragmentation, chemical pollutants, invasive species, and diseases are pushing amphibians to the brink.
One of the main threats to frogs and amphibians is the spread of a fungus (chytrid) caused by global warming. It has infected more than 100 frog species already. The spores of the fungus attack the outer layer of skin and as frogs absorb air and water through their skin they can no longer take in oxygen and water and they die. The Toronto Zoo launched a breeding program for at-risk species and a rescue centre for frogs, and named 2008 the “Year of the Frog.” Biologists are working with the International Union for Conservation of Nature to set up an amphibian ark. Under this program, threatened frog species will be bred in captivity, but there is no guarantee that the scheme will work. One of the challenges will be to maintain genetic diversity. Another will come when it is time to put the captivity-bred frogs back into the wild. It's worth a try, though. Frogs matter!
Through its Adopt-A-Pond Wetland Conservation Program, the Toronto Zoo is also cooperating with the Rouge Valley Foundation again this year by co-hosting our annual turtle walk (see hike schedule above). Zoo staff will be on hand to talk about turtle life and surveys in the Rouge, answer questions and hand out literature. Some of the Snapping Turtles in the river wear radio collars and the “find the turtle” hunt is always fun. Populating the wetlands are Painted Turtles, one of the most common species in Ontario, but also some species-at-risk Map Turtles and a few threatened Blanding's Turtles.
Among the frogs and toads in the wetlands of the Rouge are Green Frogs, Leopard Frogs, Grey Tree Frogs and early in the season some of the tiny but incredibly noisy Spring Beepers. Around the wetlands you'll also find some American Toads.
We cannot stop climate change, but we can be aware of what's going on and try to mitigate the effects of global warming and slow it down a bit. A good start would be to buy eco-friendly products and produce less waste. Think about it on your next hike in the Rouge, don't miss the popular and informative turtle walk, and contemplate how sad it would be if the birds no longer sang.
Sources: Canadian Wildlife Federation, Nature Canada, Bird Studies Canada, The David Suzuki Foundation, The Toronto Zoo, The Green Book, and personal field notes
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