Dry Drainage Culvert Use and Design Considerations for Small- and Medium-Sized Mammal Movement Across a Major Transportation Corridor

Drainage culverts are ubiquitous features in road and rail corridors. Yet practically nothing is known about the effectiveness of culverts for increasing road permeability and habitat connectivity for small- and medium-sized mammals. The authors quantified mammal use of dry drainage culverts to cross a major transportation corridor. The authors used a null model to evaluate whether culverts serve all species equally or whether some culverts limit habitat connectivity across roads in species-specific ways. The authors also modeled species response to structural, landscape, and road-related attributes and identified which are most important in explaining animal passage rates and culvert effectiveness. Species performance ratios (i.e., observed passage frequency / expected passage frequency) were evaluated for eight small- and medium-sized mammal taxa to 24 culverts along the Trans-Canada highway in Banff National Park, Alberta. Observed passage frequencies were collected from three winter months of culvert monitoring. Carnivores (weasels Mustela sp., martens Martes americana) used more culverts and used them more frequently than small mammals (hares Lepus americanus, red squirrels Tamiasciurus hudsonicus, mice, shrews Sorex sp.). Small mammals were most prevalent on transects outside the culverts. The null model showed that species responded to culverts differently. The authors found that passage use was positively correlated with traffic density, road width, road clearance and culvert length. All species except coyotes ( Canis latrans) and shrews preferred small culverts with low openness ratios. Weasels and shrews preferred culverts with cover nearby. The authors results indicate that drainage culverts can mitigate harmful effects of a high-speed motorway. To maximize road permeability for small fauna, the authors recommend frequently spaced culverts (150-300 m) of varying sizes situated in close proximity to shrub or tree cover.


  • English

Media Info

  • Media Type: Digital/other
  • Features: Figures; References; Tables;
  • Pagination: 17p

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Filing Info

  • Accession Number: 01588247
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Jan 28 2016 9:01AM