Rouge Valley Conservation Centre
Nature Notes
By Steve Gahbauer
September 2009
For everything there is a reason.
In nature, everything is interconnected and there is a purpose to all things. Nothing exists in isolation. A year ago I wrote about the importance of saving grasslands. They are recognized globally as one of the most imperiled ecosystems. And the shrinkage of this flora also affects birds, insects and ground dwellers that depend on it. Grassland bird populations have shown steeper declines than any other of North America's birds, according to Bird Studies Canada. In the past decade alone, the Short-eared Owl population has decreased by 25 per cent.
Many grassland birds depend on this habitat for their livelihood. Two of these are the Eastern Meadowlark and the smaller but feisty Bobolink, our only songbird that is solid black below and largely white above, with an unruly black tuft. You can still observe both of these lovely birds in the meadows of the Rouge Valley.
In the Summer edition of Birdwatch Canada Becky Stewart wrote this about Bobolinks:
“It's hard to get noticed when you live in a hayfield. Maybe that's why the male Bobolink has such striking plumage, and why he bursts into song while circling above the grass. How else could he get a female's attention? Once paired, the male continues to look out for rival males while the female builds the nest. By August they will begin a breathtaking 10,000 km journey to the native grasslands of Central America, where they spend the winter. Grassland birds, like the Bobolink, are experiencing the most severe population declines of any North American birds. These declines are largely attributed to the disappearance of native grasslands in the prairies. Some 400 years ago, grassland and open country birds were few and far between, restricted to beaver meadows, flood plains and barrens. It was only after pioneer settlements that large tracts of suitable nesting habitat were created. As a result, some grassland species expanded their ranges and populations. But now, Bobolinks are absent from areas where they were once abundant. Hay cutting now occurs two or three weeks earlier than in the past and overlaps directly with the peak breeding season of ground-nesting grassland birds. And large-scale monocultures have reduced crop diversity and thus the availability of suitable breeding habitat. Compounding the problem is the fact that conservation for grassland birds has received little attention to date.”
The disappearance of grassland habitat because of changes in land use is also responsible for a 5% decline across Canada, from 1968 to 2007, of the Eastern Meadowlark, a member of the Blackbird family. This beautiful bird, sturnella magna, is widely distributed in open grassy areas throughout eastern North America and comprises 15 subspecies. The Eastern Meadowlark has a chunky body, a bright yellow breast with a black bib, and prominent white outer tail feathers. Its song is a burst of several slurred whistles. Males often fight aggressively to establish territories. Male courtship behaviours include several methods of wooing females, such as puffing out their chests, bill tilting, tail flashing and wing fluttering. The mating systems are rather complex because males can be either polygamous or monogamous. Breeding success appears to be bigger when females mate with polygamous males, probably because the latter are older and more experienced. Eastern Meadowlarks nest from April to July and build cave-like grass structures on the ground. Only the female incubates the clutch of three to seven eggs.
Other grassland inhabitants are snakes. In the Rouge we have harmless Green Snakes, Garter Snakes and the small Red-bellied Snakes. Like spiders, snakes don't have a favourable press. Some people actually dislike them, others fear them – ophidiophobia is the fear of snakes – yet some have them as pets. Whatever your sentiments, snakes, like all creatures, have their place and their usefulness in ecosystems. Take a closer look and you'll find that they are really magnificent and adorable animals. They are extremely beneficial, as they eat slugs, snails, grubs, mice, rats, and leeches and keep pest populations under control.
Snakes are reptiles and live anywhere in the world, except in Antarctica. Some adders can even be found as high as 3,000 m in the European alps. The most northerly of the many species of snakes are the Red-sided Garter Snakes (thamnophis sirtalis parietalis) who, like most snakes, inhabit aquatic environments and dry land. (There are also some tree and some water snakes). Adult Red-sided Garter Snakes are 85 – 100 cm long, have a slender dark body with conspicuous yellowish stripes with red markings on its side, and are most active between April and mid-October. They are one of a dozen species of common Garter Snakes that can be found in every province in Canada, as well as in the Northwest Territories. Garter Snakes may move up to 18 km to reach their summer feeding areas. Most other snakes are less ambitious travellers.
Canada has 25 species of snake, though one, the Timber Rattlesnake, has been killed off. Many others are at risk of extinction. Snakes will generally avoid encounters with humans. Only two – the Eastern Massasauga Rattlesnake and the Western Rattlesnake – are venomous, though usually not aggressive. Both are threatened in Canada. The Massasauga is a species at risk and globally rare. In Canada Missasaugas live only in Ontario.
In the Rouge we have created habitat for Garter Snakes and Green Snakes by provinding rocks in the sun for basking for these cold-blooded creatures, and rock piles and wood warrens in the shade for shelter from the heat in the summer and for use as hibernacula in the winter.
Here are a few more interesting facts about snakes in general, courtesy of Wayne Lynch, a contributing editor to the Canadian Wildlife magazine:
Snakes evolved in the torried tropics. Over millennia they dispersed to colder regions. In the past 30 years the study of the most northerly species, the above-mentioned Red-sided Garter Snake, has shed new light on how some reptiles adapt to cold environments. Snakes cannot withstand prolonged freezing temperatures, so Red-sided Garter Snakes hibernate underground for seven to eight months every year. Often, they overwinter in communal dens, where in the darkended depths of their hibernacula temperatures stay above freezing. When garter snakes enter a hibernaculum in October, they are relatively dehydrated. This may be a purposeful physiological tactic to lower the freezing point of their tissues and in turn provide protection from the lethal cold.
Garter Snakes emerge from hibernation in late April and early May. Like all snakes, they are unable to shiver to warm themselves, so they must rely on their surroundings for warmth. This dependence on an external heat source lures them to the spring warmth above ground. Male Garter Snakes, pencil-thin from months of fasting, are the first to appear. The difference in the way males and females emerge may be biologically significant. With the ratio of males to females around a den entrance as high as 50:1, the probability of a female being fertilized is virtually 100 per cent. Also, if all the females were to emerge together, mate and disperse early in the season, a subsequent sudden cold snap could destroy much of the breeding population. The staggered emergence of the females ensures that some will survive.
The courtship urge in male Garter Snakes is strong. Males will even court dead females. Copulation in Red-sided Garter Snakes lasts 15 to 20 minutes, during which the successful male deposits a gelatinous plug in the female's cloaca, a kind of reptilian chastity belt. The plug acts as a physical barrier to further mating by other males and remains effective for at least 48 hours. Snakes do not eat during their lengthy mating period. A snake's appetite returns only as the courtship urge fades.
Our neglect of the world around us and our reluctance to deal with environmental issues has dire consequences. One of them is eutrophication, the foaming sludge and toxic goo that is killing lakes worldwide and has recently also invaded Canada, bringing some of our freshwater lakes to the tipping point.
Eutrophication is the number one water quality issue we face. The culprit isn't oil spills, toxic waste or pesticides, but nutrient overloading from fertilizers and animal and human waste. Nitrogen and phosphorus do in water precisely what they do on land: cause plant life to run wild and multiply like crazy. The process is accelerated by the channelization of waterways to allow rapid runoff from farm fields, and by the destruction of wetlands and riverbank areas. Already, Lake Winnipeg is in worse shape than Lake Erie was 40 years ago, and the problem is rapidly becoming common in western Canadian lakes. Globally, toxic algal blooms in lakes and coastal systems have been increasing in number, frequency and size.
On the other hand there have been successes, notably in Switzerland, where legislated efforts have kept lakes largely free of algae by reducing agricultural runoff by 50% over the past ten years. And then there is Lake Erie, whose comeback is one of the world's great environmental success stories. It was declared dead in the 1960s, but within a decade the five major cities on the lake's south shore managed to slash phosphorus loading by half – and presto, the lake water revived.
There are also some other good news stories. I will write about a half dozen of them in the Winter edition of Nature Notes in December. Until then, enjoy the autumn, marvel at the coloured leaves when nature uses its magic paintbrush, try to love some snakes, and make an effort to keep the waters clean. Happy hiking!
Sources: Canadian Wildlife Federation, Bird Studies Canada, Nature Conservancy of Canada, Maclean's, The Green Book, and personal field notes.
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