Carp Barrens Trail Study – Phase 2 Report

Consulting ecologist Holly Bickerton carried out Phase 2 of the Carp Barrens Trail Study from July through October. Her focus was on determining the extent of turtle nesting, the presence of species at risk birds and rare/unusual plant species, and the impact of human use on the fragile ecology.

Holly had volunteer help from FCH, from notable Ottawa ecologist Dan Brunton, and from Jakob Mueller of the Ottawa Field Naturalists’ Club (OFNC), who led a herpetology survey.

During three field visits, ten sites (three on the north side and seven on the south side) with disturbed and excavated turtle nests were observed. Nests had been excavated by a predator, possibly raccoons, skunks or black bears.  Five of these nests had been laid in the loose, friable soil of the trail itself, and four others were laid within 15 meters of the trail.  One was located adjacent to off-trail bike tracks.  It is likely that female turtles are drawn to the loose substrate created by repeated bike traffic to lay their eggs.

Below are the main impacts observed during fieldwork in Phase 2:

  • The single largest impact of the trail network is the incursion of human presence into a previously inaccessible and regionally significant, high quality natural area. Cyclists, hikers, dog walkers and naturalists have all been observed using these trails.
  • The trails are getting wider.  Off-trail bike tracks were found throughout the south side.
  • A high number of predated turtle nests along the trail suggest that the loose soil of the trail is functioning as a habitat sink, meaning female turtles may be drawn to nest in these unsafe areas.
  • Five species (one considered regionally significant) of herptiles were found under rocks on or near a trail.  Snakes or their sheltering rocks may be run over by bikes. The rocks on which they depend for shelter and hibernation have been displaced throughout the area for trail or cairn construction.
  • Direct impacts (trampling, compaction, erosion) were observed to populations of nine regionally significant terrestrial plant species, and non-native plants, brought in on shoes and bike treads, continue to be observed in higher concentration along the trail network.
  • Observation of fishers and Black Bear south of Thomas Dolan Parkway demonstrate that the area has a high ecological integrity for wide-ranging mammals, which may be affected by the increased presence of humans and dogs.
  • A poor fen mat was discovered in a wetland located between the two loops of the trail. Poor fens form on relatively acidic substrates where there are few plant nutrients. Poor fens are peat-based systems that are relatively rare in the limestone-rich Ottawa area. The poor fen mat contained three regionally rare species: Filiform Cotton-grass, Bog Buckbean, and Rose Pogonia. Several uncommon species (e.g. Sundew (Drosera rotundifolia), and Leatherleaf (Chamaedaphyne calyculata) were common here. Blanding’s Turtles were also observed in this waterbody.

While it may be possible to mitigate some impacts, the effect of intensifying human presence on the critical habitat of species at risk and on the area’s high ecological integrity cannot.  This issue will be addressed in the Phase 3 report.

Holly’s costs were covered by the City of Ottawa Rural Community Building Grant Program and by a research grant from OFNC.

Background information about the study and its purpose are available at:  Carp Barrens Trail Study.