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Providing evidence to improve practice

Individual study: Demographic connectivity for ursid populations at wildlife crossing structures in Banff National Park

Published source details

Sawaya M.A., Clevenger A.P. & Kalinowski S.T. (2013) Demographic connectivity for ursid populations at wildlife crossing structures in Banff National Park. Conservation Biology, 27, 721-730


This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.

Install overpasses over roads/railways Terrestrial Mammal Conservation

A replicated study in 2006–2008 of two overpasses over a highway in a Natural Park in Alberta, Canada (Sawaya et al. 2013) found that American black bears Ursus americanus and grizzly bears Ursus arctos used the overpasses. Over three years, a total of eight passages of American black bears (by one individual at each overpass) and 210 of grizzly bears (by 10 individuals at each overpass) were detected. Bear crossings were monitored at two overpasses (dimensions not stated) in Bow Valley, Banff National Park. Overpasses were built in the 1980s and 1990s, and cost >US$2 million each to construct. Bear tracks were counted in May–October 2006, April–October 2007 and April–October 2008 using track pads comprising 1.5–2 m of sandy loam. Track pads were checked every two days and the species, direction of travel, and number of animals was recorded. Individuals were identified by DNA analysis of hairs caught on barbed wires on overpasses.

(Summarised by Ricardo Rocha)

Install barrier fencing and underpasses along roads Terrestrial Mammal Conservation

A study in 2006–2008 of 18 wildlife crossings under a highway, along with roadside fencing, in a national park in Alberta, Canada (Sawaya et al. 2013) found that American black bears Ursus americanus and grizzly bears Ursus arctos used underpasses. Over three years, 218 crossings of American black bears and 153 of grizzly bears were detected. These were through 13 culverts (black bear: 44 crossings; grizzly bear: 36) and five open-span underpasses (black bear: 174 crossings; grizzly bear: 117). Bear crossings were monitored at 20 of 25 wildlife crossing structures in Bow Valley, Banff National Park, including 18 culverts and underpasses. Fencing (2.4 m high) was installed alongside the road. Bear tracks were counted in May–October 2006, April–October 2007 and April–October 2008 on track pads, comprising 1.5–2 m of sandy loam, spanning the width of the wildlife crossing. Track pads were checked every two days and the species, direction of travel, and number of animals was recorded.

(Summarised by Ricardo Rocha )