Mitigation reduces road mortality of a threatened rattlesnake

Published source details Colley M., Lougheed S.C., Otterbein K. & Litzgus J.D. (2017) Mitigation reduces road mortality of a threatened rattlesnake. Wildlife Research, 44, 48-59.
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This study is summarised as evidence for the following.

	Action	Category
	Use signage to warn motorists about wildlife presence Action Link
	Install tunnels/culverts/underpasses under roads/railways Action Link
	Install barriers and crossing structures along roads/railways Action Link

Use signage to warn motorists about wildlife presence

A replicated, before-and-after study in 2002–2014 on three roads in Ontario, Canada (Colley et al. 2017) found that eastern massasauga rattlesnake Sistrurus catenatus road mortality was reduced after signs for motorists, guide fencing and tunnels were installed. The number of rattlesnakes found, both dead or alive on roads decreased after sign, fence and tunnel installation (dead: 6, alive: 14) compared to before installation (dead: 41, alive: 68) and during installation (dead: 15, alive: 37). In 2007–2013, four signs to encourage motorists to slow down for snakes were installed near known snake road crossing locations (precise installation dates not provided), and three sets of mesh barrier fences were installed (600 m–1 km apart; 600–900 m of fencing on one or both sides of the road). In 2010–2011, within each of the two sets of fencing on both sides of the road, two grate-top tunnels (8.5 m long x 1.2 m wide x 0.5–0.6 m deep) were installed. Eastern massasauga rattlesnakes on the road were surveyed from May to October by car before (2005–2007) and during installation (2008–2012), and by bicycle after installation (2013–2014).

(Summarised by: Katie Sainsbury)
Install tunnels/culverts/underpasses under roads/railways

A replicated, before-and-after study in 2002–2014 on three roads in Ontario, Canada (Colley et al. 2017) found that two snake species showed similar willingness to enter tunnels. Eastern massasauga rattlesnakes Sistrurus catenatus and garter snakes Thamnophis sirtalis showed a similar willingness to enter tunnels (rattlesnakes: 18 of 19 entered; garter snakes: 15 of 16) and to complete crossings to the other side (rattlesnakes: 7 of 19; garter snakes: 5 of 16). In 2010–2011, two grate-top tunnels (8.5 m long x 1.2 m wide x 0.5–0.6 m deep) were installed along a road. In 2014, rattlesnakes and garter snakes were caught opportunistically and placed at tunnel entrances to test willingness to enter and complete tunnel crossings.

(Summarised by: Katie Sainsbury)
Install barriers and crossing structures along roads/railways

A replicated, before-and-after study in 2002–2014 on three roads in Ontario, Canada (Colley et al. 2017) found that eastern massasauga rattlesnake Sistrurus catenatus mortality was reduced after tunnels and guide fencing, along with signs for motorists, were installed. The number of rattlesnakes found dead or alive on roads decreased after tunnel, fence and sign installation (dead: 6, alive: 14) compared to before installation (dead: 41, alive: 68) and during installation (dead: 15, alive: 37). Fourteen of 68 individually-marked (‘PIT tagged’) rattlesnakes were recorded using tunnels. Rattlesnakes and garter snakes Thamnophis sirtalis showed a similar willingness to enter tunnels (rattlesnakes: 18 of 19; garter snakes: 15 of 16) and complete crossings to the other side (rattlesnakes: 7 of 19; garter snakes: 5 of 16). In 2007–2013, three mesh barrier fences 600–900 m long were installed on one or two sides of the road). In 2010–2011, a grate-top tunnel (8.5 m long x 1.2 m wide x 0.5–0.6 m deep) was installed in two of the fenced sections. Four signs to encourage motorists to slow down for snakes were installed near known snake road crossing locations. Rattlesnakes were surveyed on the road in May–October before (2005–2007) and during installation (2008–2012) by car and after installation (2013–2014) by bicycle. Tunnel use was monitored with camera traps and automated PIT tag readers. In 2014, rattlesnakes and garter snakes were caught opportunistically and placed at tunnel entrances to test willingness to enter and complete tunnel crossings.

(Summarised by: Katie Sainsbury)