In this article, we discuss some of the various land mammals found on Mayne Island and their role in our local ecosystems. Not only are these animals essential to the balance and function of our ecosystems, but they also have some fascinating behaviours!
Northern river otter (Lontra canadensis; weasel)
A common sight around Mayne Island and other coastal areas in the Strait of Georgia is the Northern river otter. Sometimes confused with sea otters, river otters are semi-aquatic and smaller than their cousins, who are not in this region.
On Mayne Island, river otters usually go back and forth between the ocean and freshwater, where they feed on various fish, birds, small mammals and shellfish. You may see them both playing and rolling with each other on the beach or on a solo hunt. These otters often leave quite the mess while resting and eating, but these messes play a crucial role in nutrient transfer and seed dispersal.
Through both their feces and food scraps, river otters deposit nutrient-rich material up into the vegetation past the rocky shores. By doing this, they provide food for various plant species. Seeds are also passively dispersed on their fur from island to island.
American mink (Neovison vison; weasel)
Unlike the Northern river otter, American minks are primarily solitary and have distinct territories. Like river otters, minks are semi-aquatic. They can even dive down to 30 metres! These cunning carnivores are very successful hunters and have a diverse diet of amphibians, snakes, small mammals, birds, fish, crabs, mussels, and often domestic fowls.
Minks will often kill more than they can eat and store the rest for later on. These long, thin hunters are very good at squeezing through tiny openings less than 1 inch in cages and fences. This article outlines a few mink-proofing strategies you can try to keep your winged livestock safe.
One considerable threat to both river otters and mink is environmental pollutants. Because they are higher up on the food chain, these two species are exposed to higher levels of contaminants like heavy metals (ex: lead) and hydrocarbons (ex: petroleum). By eating large numbers of small prey that have a low amount of contaminants, these two predators become loaded up over time with the accumulation of chemicals. This process is called biomagnification. This can be fatal or cause reproductive issues. Other top predators, like the Southern resident killer whales, are also affected by biomagnification.
Beaver (Castor canadensis; rodent)
Although beavers can seem like pesky dam builders, they have a vital role as environmental engineers. By building dams and forming ponds, beavers create ecosystems that provide many different services for the surrounding communities, including for humans. Some of these ecosystem services include water storage and filtration, rivers and stream restoration, flood reduction, and providing habitat for a wide diversity of organisms.
While these creatures are essentially wetland restoration managers, their management strategies can butt heads with human plans and developments. One way to protect your trees from being chewed down is with tree cages surrounding the base, which can be very effective if maintained.
Beavers are primarily nocturnal and are herbivorous, eating the tender parts of trees and aquatic plants. They have large webbed feet and can swim underwater for up to 15 minutes! These large aquatic rodents are busy year-round and do not hibernate.
Red squirrel (Tamiasciurus hudsonicus; rodent)
The red squirrel is our resident tree squirrel in Mayne Island forests. During the day, red squirrels are active, collecting and eating conifer seeds, mushrooms, fruits, bird eggs, nuts, and sometimes insects and small vertebrates. One can identify them by their small grey to olive-brown coloured bodies and red-tipped, bushy tails.
When these squirrels eat various seeds and fruit, they play an essential role in the dispersal of plant seeds in the forest. Seeds have higher success when dispersed away from areas that have high amounts of plant competition for resources like light and soil nutrients.
Vagrant shrew (Sorex vagrans; shrew)
Vagrant shrews are commonly found in wetlands, grasslands and meadows, but can also be in open woodland forests. They live mostly in solitude and protect their territories from other intruding shrews with loud shrieks and squeaks.
Like most shrews, vagrant shrews have a high metabolism (they breakdown and use energy very quickly). Reports have found that they eat 160% of their body weight per day! Adult vagrant shrews weigh between 4-8 grams. They eat all kinds of insects, earthworms, slugs, spiders and the occasional small salamander.
These 10-centimetre-long rodents can use echolocation when they are in unfamiliar areas and orient themselves by emitting a series of low-intensity sounds. While hunting for invertebrates using their very sensitive whiskers, they are also hiding and running from the various predators, like owls, other raptors and domesticated cats.
Check out this article for some Strange and Unbelievable Facts About Shrews.