Elements that promote highway crossing structure use by small mammals in Banff National Park

Published source details McDonald W. & St.Clair C.C. (2004) Elements that promote highway crossing structure use by small mammals in Banff National Park. Journal of Applied Ecology, 41, 82-93.
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This study is summarised as evidence for the following.

	Action	Category
	Install overpasses over roads/railways Action Link
	Install barrier fencing and underpasses along roads Action Link

Install overpasses over roads/railways

A replicated study in 1999–2000 in Alberta, Canada (McDonald & St Clair 2004) found that deer mice Peromyscus maniculatus, but not red-backed voles Clethrionomys gapperi or meadow voles Microtus pennsylvanicus, crossed wildlife overpasses. Forty percent of deer mice translocated across roads crossed back over when released alongside overpasses, but no voles did. More animals successfully returned through overpasses (and underpasses) with 100% vegetation cover at entrances (55–100% of animals) compared to those with 50% cover (20–76% of animals) or no cover (0–66% of animals). Those animals that crossed did so in 1–4 days. Two sparsely vegetated wildlife overpasses (75–79 m long, 15 m wide) were used. Territorial mice and voles were caught using Longworth live traps (166 caught in total), ear-tagged, coated with fluorescent powder, translocated across the road, released 2 m from overpasses (or underpasses) and followed as they returned. The amount of ground cover 2 m inside and outside entrances was manipulated to 100%, 50% and no cover, using spruce branches. Traps at original capture sites were monitored for four days after translocation. Animals that did not return were returned by hand. Monitoring was undertaken in July–October 1999 and 2000.

(Summarised by: Rebecca K. Smith)
Install barrier fencing and underpasses along roads

A study in 1999–2000 in Alberta, Canada (McDonald & St Clair 2004) found that small culverts, in areas with roadside barrier fencing, were used by mice and voles more than were larger underpasses. More translocated animals returned to their capture location through 0.3-m-diameter culverts (deer mice Peromyscus maniculatus: 100% returned; red-backed voles Clethrionomys gapperi: 86%; meadow voles Microtus pennsylvanicus: 58%) than through 3-m-wide underpasses (69, 49, 10% respectively). More animals successfully returned through underpasses (and overpasses) with 100% vegetation cover at entrances (55–100% of animals returned) compared to those with 50% (20–76%) or no cover (0–66%). Animals crossed within 1–4 days. Nine vegetated soft-bottomed, unvegetated arch-shaped underpasses (64–73 m long) and nine metal drainage culverts with grass cover (63–72 m long) were studied. Crossings were linked to roadside fencing that limited movements of large animals. Territorial mice and voles were captured using Longworth live traps (166 caught), ear-tagged, coated with fluorescent powder, taken across the road, released at standardized distances from crossings (20, 40, 60 m) and followed as they returned. Vegetation cover 2 m inside and outside entrances was varied using spruce branches to 100%, 50% and no cover. Traps at original capture sites were monitored for four days after translocation. Monitoring was undertaken in July–October 1999 and 2000.

(Summarised by: Rebecca K. Smith)