Monarch Butterfly (Danaus plexippus)
One of North America’s best-known butterflies, the Monarch, has experienced steep declines, largely due to pesticides and the loss of its Milkweed host plants. Eleven of 14 Milkweed species in Canada are used by Monarchs, and the butterflies can be found in any habitat where these plants grow (typically meadows, overgrown agricultural fields and roadsides).
Although NHIC does not track Monarch occurrences in Ontario, data from the Ontario Butterfly Atlas indicate that Monarchs are relatively common in the GTA but occur in slightly lower abundance there than more rural parts of the province, possibly due to lack of habitat. Road casualties of Monarchs have been reported to increase with traffic volume and road width. Developing the DRAP would mean widening roads and introducing vehicle traffic to the landscape.
Red-headed Woodpecker (Melanerpes erythrocephalus)
Red-headed Woodpeckers were once abundant across North America, but today, intensifying agriculture, wildfire mitigation, competition with invasive nest predators and loss of habitat have driven them out of many areas. They depend on open deciduous woodlands, savannas, hedgerows and other semi-wooded landscapes, particularly with an abundance of large dead trees. In Ontario, remnant suitable Red-headed Woodpecker habitat disproportionately occurs in agricultural areas, making this species especially vulnerable to negative impacts caused by development of farmland around the GTA.
Tri-colored Bat (Perimyotis subflavis)
Tri-colored Bats are hibernating bats that have succumbed to White-nose syndrome. While they may also roost in man-made structures, they are more strongly associated with forests and may therefore be more sensitive than the Little Brown Bat to urbanization.
Development pressure adjacent to forests may affect bat populations in unknown ways, and the cumulative effects with white-nose syndrome could spell disaster for the Tri-colored Bat in the Rouge Valley.
Cerulean Warbler (Setophaga cerulea)
Cerulean Warblers reach the northern limit of their breeding range in Southern Ontario, where they are a rare summer inhabitant of deciduous forests, especially those dominated by oaks and hickories. They are area-sensitive but may nest in forest fragments as small as 10 ha.
The southwest corner of the DRAP, near the Rouge Valley and Amos Pond, is known to provide habitat for breeding Cerulean Warblers.
Redside Dace (Clinostomus elongatus)
The Redside Dace is an endangered minnow with a global range restricted to certain tributaries of the lower Great Lakes.
Redside Dace have specific habitat requirements: clear rivers and streams with a sand or gravel bottom less than 10m wide with slow-moving sections, pools and overhanging vegetation, and a temperature of 14-23 degrees Celsius. Because of the intense urban development that has occurred in the GTA, many sections of river no longer meet these requirements and Redside Dace have been pushed upstream to occupy headwater sections that have not experienced disturbance.