Mammals of the Macoun Field Club’s nature-study area in Ottawa, Ontario
What are the most important mammals of the Study Area?
HUMANS! Because historically they have changed the whole character of the landscape through clear-cut logging, farming, habitat fragmentation, trail-making, and the introduction of destructive invasive species.
BEAVERS, because they have created extensive wetland ecosystems that flourish where none did before.
DEER, because right now their over-browsing is bringing an end to most natural forest regeneration.
All three agents of change are operating in the area shown here.
(This is a 1987 aerial view looking SE across beaverponds V and VI, with the thin line of Richmond Road across the top of the photo, and Bells Corners at left.)
What other mammals are out there?
RABBITS, HARES, AND LARGER RODENTS
REALLY BIG ANIMALS
What can we say about them?
Really small mammals — mice, voles, and shrews — are seldom and only fleetingly seen, but they do sometimes leave tracks on the snow surface. On this basis, we can say that these animals do regularly occur in the Study Area, with no significant change over the past 30 years.
Our only estimate of abundance was made in June of 1989, when an overnight live-trapping exercise (with 100 live-traps) yielded a scant four White-footed Mice (one of them at right) in a 10-acre hardwood forest. It was believed that numbers would have been much higher later in the season, after the mice had raised families.
Gray Squirrels (which are commonly black) appear to be much more common than 30, or even 15 years ago. With the introduction of improvised private bird feeders everywhere along the trails, these and other small rodents now have a much better chance of getting throught the winter. This may be why ten Gray Squirrel nests were observed in the above-mentioned 10 -acre forest in 2000, where there had been only one in 1992. It is probable that squirrel numbers have seen a real increase.
The growth of Red Pine plantations into signifcant cone-bearing trees has provided an abundance of seeds in winter that only the Red Squirrels exploit. Their habitat has thus expanded by almost 50 % in the last 30 years. They are stil most common, however, in the natural coniferous forests.
Eastern Chipmunk numbers are harder to assess. In some years, we hardly see or hear them; in others, they seem quite common.
Rabbits, hares, and larger rodents
Snowshoe Hares are the common lagomorph here. Their numbers fluctuate dramatically in a famous 11-year cycle. They were at a low (one dozen total) in 1994, and were moderately numerous in 2002 (probably more than a hundred).
Cottontail and Domestic Rabbits have had only a minor and possibly brief presence here.
Muskrats thrive in the marshiest parts of the beaverponds; without looking for them, we see easily a dozen Muskrat houses in the winter. There are probably several, or even many times that number.
We have studied Porcupines more than any other mammal, and between 1987 and 1991 documented an increase from 21 to 49 animals in the square mile. From casual sightings (which we still record in detail), we believe that the numbers leveled out at close to 100 around the year 2000. In 2015-16, we realized that we were seeing fewer animals and suspect the population has gone back down.
Beavers are in a sense new to the Study Area, in that they had been wiped out across the whole region long ago by hunting and trapping, and only reappeared here about 1960. Right away they began damming up the two small seasonal streams that cross the Study Area, creating a dozen ponds, some of them as much as 25 acres (10 hectares) in extent. The Sarsaparilla Trail’s observation dock is on the biggest one, which we call Pond I.
For food and building materials, beaver cut down poplar, birch and maple trees around the shores of their ponds. By selecting some tree species over others, they alter the compostion of their own food resource so that it becomes less favourable to them over time.
This is a rather mixed bunch, as half of these ‘carnivores’ are actually omnivorous and readily eat insects and berries. Two of them aren’t even wild animals. But all can and do hunt and kill other animals from time to time.
Coyotes and Red Foxes are best known by their tracks, though we have had short encounters with both species. In recent years, we have been finding the remains of deer that have been at least scavenged, if not killed, by Coyotes. In some cases, we are sure from the tracks that Coyotes were the predator.
The smaller weasels — Mink and ermines (Long-tailed and Short-tailed Weasels) — have been normal residents of the Study Area all through the years. Signs of Otters have been seen only a few times, years apart. One that was hit by a car while crossing Robertson Road, just north of the Study Area, was 47 inches from nose to tail.
Fishers, like Beaver, were long absent from the Ottawa region. As part of an eastward expansion of their local range, the first Fisher tracks were seen in the Study Area in November 1997. In 1999 there were two of them, distinguished by the size of their footprints. And in the winter of 2001/02, Fisher tracks were easily the most frequent animal track to be found in the woods. We found where one had killed and eaten a Porcupine.
Former members who have been away from Ottawa for many years might be amazed to learn that Fishers, once known only from up toward Algonquin Park, first became common in the Pakenham Hills in the early 1990s, and have now spread east of the Rideau River. They are even being seen in suburban areas around the city.
Striped Skunks are probably more common in the city than here. We found a den once in late winter, and sometimes see skunks ambling through the forest.
Raccoons may also be more common in the city, but they are common enough here. In late winter, their tracks lead from one hollow tree to the next, as they search for each other. We can generally find several den trees if we look for them. They are especially important as they dig up and eat turtle eggs.
Dogs and cats are really just visitors, but both are known to kill wildlife here. People walk their dogs along the trails, and not all of them put their pets on a leash. We seldeom see cat tracks in the snow, and think they are probably deterred by the chain-link fences, with gates, that separate residentail neighbourhoods from the Study Area.
Really big animals
Black Bears have probably not been a significant part of the Study Area any time in the last 40 years, but they have left their tracks on the smooth bark of Beech trees, which they climbed for the edible nuts. Wandering bears still turn up in the Greenbelt and even in the built-up parts of Ottawa every year, so some probably pass through from time to time.
In the last 30 years, the White-tailed Deer population in the Study Area has increased probably 30-fold. About 12 years ago, the deer began wintering here. By the end of the 1990s, they were eating their favourite winter food (White Cedar branches) faster than it could grow back the next year. A pronounced browse line developed. As of 2002, certain wildflowers, notably White Trillium, have been almost eliminated as flowering plants. The whole shrub layer of the forest, where tree regeneration takes place, is under intense browsing pressure summer and winter.
Humans have played several very different roles here. Pre-historically, and even for hundreds of years after European visitors began to keep historical records, people occupied the region as hunter-gatherers. Their populations were small, and humans fitted into the natural ecosystem without greatly altering it. We have no direct evidence of this stage here.
For about a hundred years, from the early 1800s to the mid-1900s, agricultural production dominated what is now our Study Area. Between land-clearing operations and the great fire of 1870, all the original forests were destroyed. Where the land could be cutlivated, the hummocky ground was smoothed out, the organic matter that had accumulated over millenia was plowed under, and the soil was compacted by machinery. Each of these changes has a direct influence on today’s flora and fauna, even though farming ceased here half a century ago. Physical remains include stone piles and rail fences, house foundations, roads, and rubbish heaps that are notably free of plastics.
As agriculturalists, humans introduced hundreds of other organisms that are alien to this place, ranging from crops and weeds to insects, livestock, and predators. Many persist. Allied to agriculture is silviculture, in which trees are treated as crops. Alien tree species, monocultures, and managment practices are involved.
In the present day, as recreationalists, humans are now daily visitors that can number in the hundreds, strung out over several kilometers’ worth of linear trails. Almost all humans withdraw at dark, but occasionally small groups return and penetrate to secluded spots and build bonfires. Forest fire is a genuine threat. Physical signs include well beaten trails and gravelled roads, scattered trash (plastic, bottle glass, paper, and foil), and localized damage to trees (stripped of lower limbs for firewood).
Having formed into vast industrial societies beyond our Study Area borders, humans are also having an impact here in terms of poor air quality, the continuing introduction of invasive plants and animals, and a warmer and drier climate.