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Habitat Structures

Photo of Kestrel_on_Raptor_Post
Kestrel on a raptor post.

Raptor Posts and Hawks, Owls and Rodents

Ecosystems involve complex inter-relationships between living things and their environment.

FRW tries to imitate the natural processes and interactions that restore ecosystem health and the balance of nature.

For example, by providing perching posts for owls and hawks, FRW invites these raptors to hunt on our sites and thereby control the populations of rodents that would otherwise ravage the newly planted deciduous trees.

The rodents -- meadow voles, mice and rabbits -- eat the tender bark of these trees during the winter. Meadow voles and moles also eat the roots of some trees such as green ash.

This damage would be acceptable except that the trees are often girdled (i.e. the rodents remove a complete ring of bark from around the tree). When girdling occurs, food cannot move between the tree's leaves and its roots, leading to the tree's death by the following summer.

Owls regurgitate plum sized pellets of
fur and bone after a meal.

Garter snakes like to hibernate in large
numbers in holes below the frost line.

This bird box has been opened for cleaning
after the family moved out.

Red back salamanders live in rotting
wood in the forest.

FRW's “raptor” posts help hawks and owls by allowing them to scan a large area for prey without using much energy. Evidence that hawks and owls regularly use the raptor posts is revealed in regular raptor sightings and the discovery of rodent remains and owl pellets on the ground beside the posts.

Snake Hibernaculums

Some snakes (garter, milk) hibernate together in large numbers below the frost line in underground cavities and tunnels called "hibernaculums".

In the spring, the snakes emerge from the hibernaculum, find a mate, breed and disperse to find good territories to feed themselves and their young.

If the snakes cross roads and cultivated fields to move from their wintering hibernaculum to their summer feeding territory, they are more likely to be killed by a car or eaten by another animal.

FRW builds a new hibernaculum each year at one of our Rouge Park restoration sites to reduce the distance the snakes will have to travel and hopefully reduce snake mortality.

Bob Johnson, the curator of amphibians and reptiles at the Toronto Zoo, has helped FRW to build appropriate snake hibernaculums. The Toronto Zoo’s Adopt-a-pond site has information on the design of snake hibernaculums.

Nesting Boxes for Birds

Some bird and animal populations are limited by the availability of suitable nesting sites. Cavities in old growth trees are the traditional nesting sites for many bird species. Since most of the old growth trees have been cut in the GTA, cavity nesting sites are in short supply.

Fortunately, many bird species will use appropriately designed and placed wooden boxes as a substitute nesting site. For more information see the Links below.

Bluebird Success Story: With reduced pesticide use and increased nesting boxes, the eastern bluebird is making a come-back in the Rouge. When nesting sites are scarce, starlings out-compete bluebirds in areas where the habitat is otherwise suitable for bluebirds. By placing hundreds of bird boxes around meadow areas, people like Bill Lewis have encouraged the eastern bluebird to breed in the Rouge Park after a three decade absence.

Nesting boxes which are not used by bluebirds are often used by tree swallows, chickadees and other interesting species. Nesting boxes are opened in the winter to determine if they were used and by which species of bird. Soiled nesting material is removed to reduce the spread of diseases and pests (bot flies).

Wood Duck Success Story: A small beautifully coloured duck, the wood duck, has become less common because its preferred habitat (wetland pond surrounded by forest), has been greatly reduced. FRW restoration projects are creating new habitat for wood ducks. Frw has also placed wood duck boxes in suitable wetland areas and this small habitat improvement is increasing the number of wood ducks nesting in the Rouge Park.

Information on building, placing and maintaining wood duck, blue bird and bat boxes:

Piles of Logs and Wood Chips

The diversity of old growth forests is at least partly due to many fallen and rotting logs and the diverse habitat niches thus created for plants and animals.

With this in mind, the City of Toronto Forestry department helps FRW to improve habitat diversity by providing logs, stumps and wood mulch generated during the maintenance of the City's urban forest. This partnership allows the City to improve habitat diversity in the Rouge Park and efficiently dispose of logs and wood that might otherwise go to waste in a landfill.

Logs and wood chips provide good hiding and nesting spots for toads, turtles, leopard frogs, mice, meadow voles, rabbits and many other creatures.

Songbirds such as the meadowlark and field sparrow use the log piles to declare their territory, seek a mate or avoid predation. Butterfly larva form their pupa under the logs and bark.

FRW also places wood chips around newly planted trees to:

  • Hold moisture in the soil and moderate soil temperature;
  • Add organic matter and beneficial fungal organisms to the soil;
  • Suppress grass and weed growth and competition for water and rooting space.

As the wood chips decay they enrich the soil with organic matter and, in the longer term, the decaying logs provide habitat for salamanders, worms and insects.

If wood chips piles remain on a site, they attract milk snakes, red-bellied snakes, toads and other creatures because the wood chips generate heat as they decay and thus provide cover and warmth.

Cautionary Note

Extra care must be taken by City staff and FRW to survey incoming logs and wood to avoid the spread of problematic pests such as the Asian longhorn beetle.

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