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Autumn in the Rouge: changing colours is just the start

The Rouge National Urban Park is transformed during autumn not only by vibrant colours. (Photo by Ken Jones)

It’s that time of the year again. There’s a chill in the air, the days are getting shorter and the city is painted with a cascade of changing autumn colours.

Perhaps no other place in Toronto are these changes more evident that then the Rouge National Urban Park. With its accessible trails and abundant biodiversity, it’s a popular spot for nature walkers and bird spotters alike, especially in the fall. 

As the primary research and education partner with Parks Canada, U of T Scarborough has many experts who use the Rouge to conduct research and take class trips to explore the many species that live in the park. Some of those experts shared insights on what’s taking place in the park throughout autumn.

The park is unique in that it’s situated in a transition zone between the Carolinian forest and northern forests, and also happens to be located in Canada’s largest city, notes Associate Professor Marc Cadotte, an expert on urban forest conservation and biology.

“Since the Rouge is in a transition zone it has a high diversity and unique combination of species,” he says.

That diversity can be experienced with a quick walk around the park, he adds. If you’re near the Glen Rouge camp ground you will see plenty of maple, oak and hickory forests but as you move to more hilly terrain you will start to see spruce, pine and cedar. This also means the animals and birds will be different from one location to the next.

You’ll also notice different colours in the leaves because, as Cadotte points out, there’s considerable variation in leaf colour even within the same species of tree.

“The colours are produced by the chemistry of the leaves. They’re typically green in the spring and summer because of chlorophyll, which drives photosynthesis,” he says.

“As the days begin to shorten trees prepare for the winter by drawing in the important chemicals of the leaves. What’s left behind can be quite colourful.”

The reason they eventually fall and die is that even though leaves are food source for a plant, once winter rolls around they become a burden. Cadotte says if you’re out for a stroll you may also notice that some leaves remain green and don’t fall. That’s because they’re either invasive, like the garlic mustard plant, or they’re evergreen trees like pine that have evolved in harsher climates.

Morning is a great time to see insects, notes Cadotte. The most obvious will be the monarch butterfly, which is preparing for its long migration south to Mexico. There will also be plenty of wolly bear caterpillars, which are preparing for their long hibernation for the winter.

“During autumn mornings you’re more likely to see insects resting on bark or the side of trees. You can walk right up to them and they won’t take off because they need to warm up before they can move,” he says.  

Mornings are also a great time to see mammals being active, says Ecology Professor Rudy Boonstra, an expert on animal behaviour.

“The best time is either early morning or right before dusk when human activity is low,” he says.

While there’s a whole range of animals to see throughout the Rouge including cottontail rabbits, raccoons, squirrels, chipmunks, woodchucks, foxes, coyotes, white-tailed deer, striped skunks, and even mink along the shores of Highland Creek and the Rouge River, each have a unique strategy when it comes to preparing for winter, notes Boonstra.

Some hibernators like chipmunks, spend all fall storing food in an underground cache. They will wake up every few weeks in winter to replenish body stores before going back in hibernation. Others, like woodchucks, store food internally in the form of fat, he adds. They also wake up every few weeks during the winter but replenish their needs from their fat stores. Both species will lower their metabolism to a few degrees above 0 C in order to conserve energy. 

Other mammals prefer the “sit and take it” approach, says Boonstra. Animals like white-tailed deer, red fox, red squirrels, greys squirrels and raccoons do not hibernate. Some remain active and can be seen, while others like the raccoon and skunk become inactive in a burrow or tree hollow and may reduce their body temperature slightly

He adds that male deer in the rut, also called bucks, can be dangerous from October to early November since it’s the mating season. 

“If males have a look where they aren’t afraid or are eyeing you up, it’s a good idea to stay away,” he says. “It’s very rare for them charge but it does happen… just check out YouTube.”

Boonstra adds that a great resource for those wondering what mammals and birds they can see along Highland Creek and the Rouge River can be found through the City of Toronto’s Biodiversity in the City series.

One of the more obvious signs of autumn is migrating birds, adds Associate Professor Jason Weir, who does research on the biodiversity of new world birds.

“There are big wetlands where the Rouge empties into Lake Ontario so you will see all sorts of birds,” he says.

At this time of the year birds, many of which live in pairs or small groups during the summer, aggregate in flocks in order to migrate south. In the forests along the Rouge he lists songbirds like warblers, sparrows and blue jays as some that can be seen.

On recent class trips Weir says he’s come across wood ducks, gadwalls and northern shovelers as well as great egrets and caspian terns in the wetlands. 

Walking through the Rouge you may also come across fish like migrating chinook salmon and rainbow trout that have been stocked and are now naturalized in the area, says Associate Professor Nicholas Mandrak

“There’s a good chance of seeing these species, particularly after a rainfall, which triggers them to swim upstream,” says Mandrak, an expert freshwater fish.

So when you’re out for a stroll through the Rouge and enjoying the autumn colours, spare a thought for the all the species that are preparing for a long cold winter ahead. 


© University of Toronto Scarborough