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The Black Rat Snake
"Live and Let Slither"
Big, black and benign
Just how big is Canada's largest snake? Most adults reach 1.5 to
1.8 metres. Shorter black rat snakes would stretch from side to
side of a queen size mattress; longer ones, from top to bottom.
This is about a metre shorter than the record-setting black rat
snake, which stretched in at 2.57 metres (about 8½ feet).
So by just about anyone's standard, an adult black rat snake is
a large snake. And to many of us, any snake, particularly a large
one, is intimidating. But despite their impressive size, black rat
snakes are harmless - unless you are a chipmunk or a small bird.
Neither are they venomous. A grey squirrel is about the largest
creature that a black rat snake could subdue.
Black rat snakes are not aggressive, but when harassed or threatened
they may rear and strike, and will often vibrate the tip of their
tail against dry leaves in imitation of a rattlesnake. Even though
black rat snakes impersonate rattlesnakes, the chance of mistaking
one for the other is remote. They don't look alike, and an encounter
with a rattlesnake within the black rat snake's Ontario range is
highly unlikely.
In spite of their name, not all black rat snakes are solid black.
Though most adults are a shiny black with a white or cream chin
and throat, many retain faint remnants of their juvenile colouration
and patterning. Their backs and sides may have faint irregular blotches
of brown, and the tips of their scales may be edged with white.
Colours between the scales can be shades of yellow, red, white,
green, and brown, making some individuals quite colourful. Their
bellies are generally unpatterned and range in colour from light
cream to almost black, sometimes even orange. Adult black rat snakes
are sometimes confused with large female water snakes, melanistic
garter snakes, or eastern fox snakes. Young black rat snakes are
pale grey with irregular patterns of dark brown to black blotches
along their backs and sides. This patterning darkens and fades with
age. Juveniles are often confused with young watersnakes, milksnakes,
or eastern fox snakes.
Harmless - but becoming homeless
Canada's largest snake lives only in two distinct regions of Ontario
- the Carolinian Forest region, running across the north shore of
Lake Erie in southwestern Ontario, and the Frontenac Axis region
in southeastern Ontario. The black rat snakes in these areas are
at the periphery of the species' range, with those in the Frontenac
Axis being at the very northern edge.
From their range in the eastern United States, they moved northward
with the retreating glaciers. This means that for about 7,000 years
they have made these areas of Ontario their home.
Historical records indicate that prior to European settlement,
black rat snakes lived throughout much of the Carolinian forest
region. Over the past 200 years, the Carolinian forest cover has
been reduced to patches, most of which measure less than three hectares.
The black rat snake population in this area has been fragmented
along with the forest. These snakes now live as a handful of small,
isolated groups.
The Frontenac Axis snakes are confined to an area of approximately
5,000 square kilometres. This area includes a small bit of New York
State, into which the axis extends. The next nearest group of snakes
is 120 kilometres to the south, near Syracuse, New York.
Black rat snake populations in Ontario are isolated from each other
and from other populations in the United States. Since they have
no way of intermingling with the black rat snakes farther south,
they are particularly vulnerable to the pressures of continued loss
and alteration of habitat.
Habitat loss and fragmentation have reduced their geographic distribution
in Ontario by an estimated 75 percent. Most of the reduction has
occurred in the Carolinian region, but there is also evidence of
significant range contraction in the Frontenac Axis region.
The increase in the number of roads through black rat snake habitat,
and the ever-increasing traffic, spell bad news for black rat snakes.
They don't reach sexual maturity until they are 9 or 10 years old.
If individuals are to contribute to their population, they not only
have to avoid natural predators for a decade, but must also avoid
becoming roadkill and being killed or collected by humans.
In 1998, the black rat snake was designated a "threatened"
species in Canada. This designation
means they are likely to become endangered in this country if the
factors affecting their vulnerability are not reversed. If their
7,000-year legacy in Canada is to continue, we must dig down to
the very old - and twisted - roots of the human/snake relationship.
Let's not let them silently slip away
The situation facing Ontario black rat snakes is strikingly similar
to that facing wildlife worldwide. More and more species are being
confined to fragmented remnants of their former range; habitat alteration
is the leading problem facing all vertebrate groups.
About one in four vertebrate species is limited to small and localized
populations, is declining steeply in numbers, or is threatened with
extinction. Most biologists believe that we are presently in the
middle of one of the great mass extinctions of geologic history.
But whereas all of the others were caused by natural phenomena,
this one is unique in being brought about by one species: homo sapiens.
The dubious distinction is ours.
We still have time to avert the collapse of our living world. The
only way to prevent the big picture of mass extinction is to treat
each little picture - like black rat snakes in Canada - as vitally
important.
Live and let slither
Sharing habitat with black rat snakes
Some of us are permanent residents in black rat snake habitat;
some of us are seasonal; and some of us may just pass through. Here
is a list of things we can do to actively share habitat with black
rat snakes.
- Consider supporting or volunteering for black rat snake projects
at provincial or national parks, such as the "Adopt a Snake"
programs run by the Friends of Murphys Point and Friends of Charleston
Lake Provincial Parks.
- Reduce driving speed and increase observational skills during
spring and fall when black rat snakes are most likely to be basking
on roads. At other times of the year, black rat snakes may be
crossing the road just to get to the other side. Be mindful!
- Leave dead or hollow trees on property for basking, shedding
and egg-laying sites. They are also beneficial to other wildlife.
- Leave downed trees and woody debris with rotten cavities because
of their importance as egg-laying sites.
- Start a compost pile for a potential egg-laying site. Don't
turn it in July and August, or eggs may be crushed.
- Leave known hibernacula and the surrounding area undisturbed.
- Create small brush piles on property. These can serve as places
where snakes can escape predators and find prey.
- Perhaps most importantly, let the snakes be!
Recovery Initiatives
In 1999, the Ministry of Natural Resources (MNR) assembled the
Black Rat Snake Recovery Team. It consists of a dedicated group
of experts from MNR, Ontario Parks, Parks Canada, and
Environment Canada - as well as academic researchers from the United
States and Canada, and non-government representatives.
Their overall goal is to ensure that black rat snakes remain a
healthy component of Canadian biodiversity. To this end, they have
developed a recovery strategy and are implementing an action plan.
They have set separate medium-term goals for the two population
regions. For the Frontenac Axis, the aim is to retain current distribution
and connectivity among populations, with no decrease in numbers.
For the Carolinian region, they aim to achieve self-sustaining populations,
with no further decrease in numbers. They also aim to restore connectivity,
or gene flow, among the currently isolated populations.
The recovery team will attempt to coordinate with existing landscape
conservation initiatives such as the Algonquin to Adirondacks (A2A)
project and Carolinian Canada's "Big Picture Project."
Excerpted from the booklet, The Black Rat Snake, Live & Let
Slither, Ontario Ministry of Natural Resources, 2001.
Project supervisor: Chris Burns, Ontario Ministry of Natural Resources
Written by Leslie Work
Project co-ordination and graphic design: Gareth Lind, Lind Design
Illustrations by Nick Craine
Scientific editors: Gabriel Blouin-Demers and Shaun Thompson
Photographs by Gabriel Blouin-Demers and courtesy of Charleston
Lake
Provincial Park and the Ontario Ministry of Natural Resources
Thanks to Rob McAleer, Lithosphere Press
Thanks to the Friends of Charleston Lake Provincial Park and the
Lanark
County Stewardship Council for their assistance in funding this
project.
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