Overpasses and underpasses: Effectiveness of crossing structures for migratory ungulates

Simpson, Nova; Stewart, Kelley M.; Schroeder, Cody; Cox, Mike; Huebner, Kari K.; Wasley, Tony

doi:10.1002/jwmg.21132

Cited by 56 publications

(48 citation statements)

References 33 publications

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“…Nonetheless, they were used by more species and had higher crossing rates of wild animals than underpasses, among which most have larger functional space for animals. Overpasses proved to be especially suitable for wild ungulates, which corresponds to studies in North America showing that the mule deer (Odocoileus hemionus) and the pronghorn (Antilocapra Americana) have greater passage rates at overpasses than underpasses (Sawyer et al 2016;Simpson et al 2016).…”

Section: Discussionmentioning

confidence: 59%

Mammal use of wildlife crossing structures along a new motorway in an area recently recolonized by wolves

Mysłajek

Olkowska²,

Wronka-Tomulewicz³

et al. 2020

Eur J Wildl Res

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Wildlife crossing structures (WCSs) enhance connectivity between habitats of wild animals fragmented by fenced motorways, but factors affecting their use by targeted species remain understudied, particularly in areas recently recolonized by large carnivores. We investigated the use of WCS—6 overpasses (width 30-45m), 5 large underpasses (width 33–114 m) and 4 small underpasses (width 15–19 m)—located along the A4 motorway in the Lower Silesian Forest (western Poland), a large forest tract recently recolonised by wolves (Canis lupus). Identifying and counting tracks of mammals left on sand-beds as well as individuals recorded by camera traps were used to determine species diversity, number and activity patterns of mammals on WCS, and to reveal seasonal and temporal changes of WCS use over 3 years of study (2010–2013). WCSs were mostly used by wild species (51.5%), followed by humans (34.8%), livestock and pets (13.7%). Among wild species, ungulates were the most common (77.4% of crossings), while lagomorphs and carnivores were recorded less often (15% and 7.6% of crossings, respectively). The number of species and crossings of wild mammals, especially wild ungulates and wolves, was substantially higher on overpasses (mean effective number of species (Hill numbers): 0D = 7.8, 1D = 4.1 and 2D = 3.3) than on underpasses (0D = 6.3, 1D = 2.9 and 2D = 2.3) and was not affected by distance between WCS and human settlements or WCS width. There was a higher diversity of wild species and more crossings under large extended bridges than on smaller underpasses. The number of species and number of crossings of wild mammals, domestic animals and people increased from 2010 to 2013. There was a significant difference in activity patterns, with almost all wild species being nocturnal, in contrast to people and dogs. There was no relationship between crossing time and rates of wild carnivores and potential prey. We conclude that overpasses, even with steep entrance slopes (25–26.5%) or integrated with moderately used gravel roads, maintain movement of wild terrestrial mammals much better than underpasses, and the presence of wolves does not hamper the movement of other wild species. As there are significant temporal changes in use of WCS by mammals, we recommend monitoring WCS in all seasons for at least 3 years as a minimum standard for the post-investment assessment of WCS utilization by animals.

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Section: Discussionmentioning

confidence: 59%

Mammal use of wildlife crossing structures along a new motorway in an area recently recolonized by wolves

Mysłajek

Olkowska²,

Wronka-Tomulewicz³

et al. 2020

Eur J Wildl Res

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“…The size of a passage affects its usage by various animal species that show selectivity in this aspect, especially large animals (van Bohemen 1998, Gloyne andClevenger 2001, Ford et al 2017). The passages for animals significantly reduce the effect of fragmentation of habitats, improve the communication between populations, and limit wildlife activity within the road lane (Simpson et al 2016). Also, road fencing or a combination of fencing and crossing structures reduce the risk of animal-vehicle collisions (Ascensão et al 2014, Huijser et al 2016, Rytwinski et al 2016.…”

Section: Introductionmentioning

confidence: 99%

Use of underpasses by animals on a fenced expressway in a suburban area in western Poland

Ważna¹,

Kaźmierczak²,

Cichocki³

et al. 2020

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Expressways act as barriers to animals that block free movement in their habitats, especially when the roads are continuously fenced to prevent collisions between animals and vehicles. Various types of animal passages have been repeatedly studied in terms of their utility, albeit rather less frequently in the suburban environment. We conducted our research in a section of the fenced expressway S3 connecting two closely located cities in western Poland (Lubuskie province). Over the course of one year, we monitored four underpasses intended for small- and medium-sized animals using tracks. The underpasses were inspected weekly. Animal traces most frequently found belonged to roe deer Capreolus capreolus (20.9%), red fox Vulpes vulpes (15.1%), wild boar Sus scrofa (14%), and domestic dog Canis l. familiaris (12.4%). Surprisingly, the results of our study indicate that underpasses for small and medium mammals are also used by ungulate mammals. The use of the underpasses varied seasonally, being the highest in spring (37.9%) and the lowest in winter (10.4%). Moreover, seasonal differences in the use of passages were related to particular species/groups of animal species. We found that 22% of animals that entered the passage did not completely traverse it. People accounted for 17.1% of all stated traces in the underpasses. Stagnant water in the underpasses reduced the number of predatory mammals and wild boars using the underpasses but did not affect the activity of roe deer. These studies indicate that animal underpasses located in suburban areas are used by many species of animals despite the activity of humans and domesticated mammals.

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“…To date, it is unknown if guanacos utilize these structures effectively. This should be a topic of future research, particularly since evidence suggests that ungulates tend to demonstrate a preference for utilizing overpasses rather than underpasses ( Simpson et al, 2016 ). Overall, our results suggest that the coastal populations may be functionally isolated, a situation that would endanger their long-term persistence.…”

Section: Discussionmentioning

confidence: 99%

Landscape connectivity among remnant populations of guanaco (Lama guanicoe Müller, 1776) in an arid region of Chile impacted by global change

Espinosa

Gouin

Squeo

et al. 2018

PeerJ

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Connectivity between populations plays a key role in the long-term persistence of species in fragmented habitats. This is of particular concern for biodiversity preservation in drylands, since water limited landscapes are typically characterized by little suitable habitat cover, high habitat fragmentation, harsh matrices, and are being rapidly degraded at a global scale. In this study, we modelled landscape connectivity between 11 guanaco Lama guanicoe populations in Chile’s arid Norte Chico, a region that supports the last remnant coastal populations of this emblematic herbivore indigenous to South America. We produced a habitat suitability model to derive a regional surface resistance map, and used circuit theory to map functional connectivity, investigate the relative isolation between populations, and identify those that contribute most to the patch connectivity network. Predicted suitable habitat for L. guanicoe represented about 25% of the study region (i.e., 29,173 km2) and was heterogeneously distributed along a continuous stretch along the Andes, and discontinuous patches along the coast. As a result, we found that high connectivity current flows in the mid and high Andes formed a wide, continuous connectivity corridor, enabling connectivity between all high Andean populations. Coastal populations, in contrast, were more isolated. These groups demonstrate no inter-population connectivity between themselves, only with higher altitude populations, and for two of them, animal movement was linked to the effectiveness of wildlife crossings along the Pan-American highway. Our results indicate that functional connectivity is an issue of concern for L. guanicoe in Chile’s Norte Chico, implying that future conservation and management plans should emphasize strategies aimed at conserving functional connectivity between coastal and Andean populations, as well as the protection of habitat patches likely to act as stepping stones within the connectivity network.

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Overpasses and underpasses: Effectiveness of crossing structures for migratory ungulates

Cited by 56 publications

References 33 publications

Mammal use of wildlife crossing structures along a new motorway in an area recently recolonized by wolves

Mammal use of wildlife crossing structures along a new motorway in an area recently recolonized by wolves

Use of underpasses by animals on a fenced expressway in a suburban area in western Poland

Landscape connectivity among remnant populations of guanaco (Lama guanicoe Müller, 1776) in an arid region of Chile impacted by global change

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