Browsing the blog archives for May, 2011.

Winter Kill in the South March Highlands

Green Reality, Legislative Gaps, South March Highlands

There are laws to protect nesting birds in Ontario, but incredibly no law protects nesting mammals!  This post uses tabs, so be sure to click on each one to see the entire article.

Protecting Birds

The Federal Migratory Bird Convention Act was passed as long ago as 1917 as a result of an agreement between Canada and the United States (the U.S. passed an identical act, the Migratory Bird Treaty Act, in 1918).  This law enables the Migratory Birds Regulations that further prohibit the destruction of nests for a wide variety of birds anywhere in Canada.  Penalties for violating the Act are stiff – up to $500 K for corporations and up to $100 K for individuals.

This effectively prevents the clearing of trees between April and the end of July in Ontario since it can be difficult to ensure that no breeding birds are nesting within a forested area.

In Ottawa, the City has published Standard Mitigation Measures that clearly sets out that no clearing of trees and vegetation is permitted between April 15 and July 31 unless a qualified biologist has conducted a pre-clearing survey within 5 days prior to the removal of trees.

Mammal Dens

In winter, most mammals either hibernate or den in a torpor-like state.  They will find dens (i.e. nests) for that purpose in trees, caves, fallen logs, or or create suitable dens in trees and other protected areas such as abandoned buildings.

Porcupine Den in South March Highlands

Hibernating mammals include bats, some species of ground squirrels, mice and several species of rodents,  some species of rabbit, skunks, chipmunks, woodchucks, ground hogs, etc.  Mammals that truly hibernate will slow their heart and breathing rates to conserve energy and allow their body temperatures to drop to near zero.  Many of these mammals will hibernate while pregnant so that they are ready to give birth by spring.

Many mammals that don’t truly hibernate will conserve energy by limiting movement by sleeping deeply and for long periods of time, but will wake up during warmer periods to find food.  Examples of these denning mammals include bears, raccoons, porcupine, some species of ground squirrels, shrews, mink, otter, fox, weasels, beaver, etc.

Some denning species will also slow their heart rates during sleep (but not as much as hibernating species), making them appear slow and lethargic when awake during winter.  Bears and raccoons are examples of species that do not truly  hibernate but come close to it.  Females of these mammals are also likely to be gestating over the winter so that they are ready to give birth when spring arrives.

Porcupine in Den

Vulnerable

Denning and hibernating mammals are as vulnerable as nesting birds.  If their dens are threatened, hibernating animals cannot be awakened to flee, and denning animals have no where to go during winter.

Many mammals have a limited range due to the territorial needs of others in its species.  For example a porcupine generally stays within a 100 m radius in winter and within 1.5 km in summer .  Most mammals will fight to defend their territory from invaders of their own kind.

Within it’s range, a replacement den may not be available and raw materials that could otherwise be used to construct a den (such as twigs, logs) are usually frozen or covered with snow.  This means that a displaced mammal is exposed to the elements.

Exposed Porcupine That Lost It's Den

The photo above was taken in Beaver Pond Forest shortly after tree clearing had begun in extremely cold temperatures.  Despite it’s protective fur, every non-hibernating mammal is vulnerable to cold during the dead of winter and can freeze to death without shelter.

Winter Clearing

The operator of heavy equipment, such as the one shown below employed by KNL to clear-cut the Beaver Pond Forest in winter, is not able to see if mammals are hibernating or denning and in any case is certainly not likely to exit the warm cab in winter to examine every tree prior to cutting it down.

Heavy Tree Clearing Equipment

The City of Ottawa’s mitigation guidelines state “Avoid the use of heavy equipment in wetlands and watercourses during the winter, when fish, amphibians and reptiles may be hibernating.” but is silent on the protection of mammals in winter when they are most vulnerable.

The City’s only mention of mammal protection is  ”Avoid vegetation clearing during sensitive times of the year for local wildlife, such as spring and early summer (when many animals bear their young).” which ignores the winter-long gestation period for mammals.

Winter Kill

The result of winter tree clearing is inevitably death.  Either via direct injury caused by crushing the animal when the tree is felled by heavy equipment, or by freezing to death from exposure as a result of being homeless in winter.

Female Porcupine Frozen To Death

Based on the acreage  of the Beaver Pond Forest (30 hectares), and the average number of Porcupines within a given area (12 porcupines / km 2), it is possible to estimate the size of the porcupine population prior to tree clearing in Beaver Pond Forest to be approximately 4 porcupines.  A field study conducted immediately after tree clearing completed, located 3 of those porcupines and found 2 of them dead – both females who were likely pregnant and less likely to survive without shelter.

In other words, the winter tree clearing approved by the City and conducted by KNL killed at least half of the population of porcupines and possibly 2/3 of them (allowing for the possibility that there were only 3 at the outset).  Other mammals were undoubtedly killed too, however, porcupines are more readily found as they are less likely to be consumed by carnivorous birds and other mammals because of their quills.

So why do we have laws that protect nesting birds and not nesting mammals?

  • Why has Ontario not passed effective wildlife protection laws?
  • Why has the Canadian Wildlife Federation not pressed for protection of mammals?
  • Why does the SPCA not object to the winter slaughter of animals?
  • Why does the City of Ottawa authorize the winter slaughter of mammals, reptiles, and amphibians?
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