Keywords Barrier effect Á Connectivity Á Habitat fragmentation Á Permeability Á
Wildlife pass
Introduction
We know today that linear infrastructures are one of the largest threats to biodiversity worldwide, including habitat loss and fragmentation (Forman et al. 2003;
Benítez-López et al. 2010; van der Ree et al. 2015). As mentioned in the introductory chapter, most of what we know regarding this comes from studies on roads
however, as some of these impacts are shared by roads and railways, many of the
management tools developed for the former can be applied to the latter.
Nevertheless, new approaches are needed in some cases, because some impacts are
railway-specific (Dorsey et al. 2015).
This chapter provides some conceptual insight into, and summarizes in a single
document, what is known about barrier effects caused by railways on wildlife populations, which is considered by some to be one of the greatest ecological impacts of
these infrastructures (Iuell et al. 2003; Rodríguez et al. 2008). This review is organized
as follows: We begin by identifying the factors contributing to railway barrier effects
and we then describe the approaches used to study these effects, and the effectiveness of
the measures implemented to mitigate them. Finally, we suggest management guidelines for railway companies, and present a protocol to minimize these barrier effects.
We searched the ISI Web of Science and Zoological Record databases for railway
ecology studies. For all searches, our search terms were combinations of the following
words: barrier effect, collision, fragmentation, habitat loss, impact, permeability,
radio-tracking, railroad, railway, train, underpass, wildlife pass. We looked for publications in English, Spanish, Portuguese, and French. We also searched Google Scholar™
for additional studies not published in peer-reviewed journals (gray literature) but citing
peer-reviewed papers, such as Ph.D. dissertations, reports, or conference papers.
Barrier Effects
The various sources of railway barrier effects are closely related, and sometimes it is
not easy to clearly separate them. For instance, noisy traffic can cause both habitat
loss (if wildlife refuses to use the area adjacent to the railway right-of-way), and it
can create a behavioral barrier if this noise implies a perceived risk. We identified
four broad types of impacts causing barrier effects.
Physical and Behavioral Barriers
Barriers can be physical, when a species cannot trespass the railway, or behavioral,
when the species may be physically able to cross the barrier but does not do so
because of unfavorable ambient conditions or perceived risk.
44
R. Barrientos and L. Borda-de-Água
Wildlife pass
Introduction
We know today that linear infrastructures are one of the largest threats to biodiversity worldwide, including habitat loss and fragmentation (Forman et al. 2003;
Benítez-López et al. 2010; van der Ree et al. 2015). As mentioned in the introductory chapter, most of what we know regarding this comes from studies on roads
however, as some of these impacts are shared by roads and railways, many of the
management tools developed for the former can be applied to the latter.
Nevertheless, new approaches are needed in some cases, because some impacts are
railway-specific (Dorsey et al. 2015).
This chapter provides some conceptual insight into, and summarizes in a single
document, what is known about barrier effects caused by railways on wildlife populations, which is considered by some to be one of the greatest ecological impacts of
these infrastructures (Iuell et al. 2003; Rodríguez et al. 2008). This review is organized
as follows: We begin by identifying the factors contributing to railway barrier effects
and we then describe the approaches used to study these effects, and the effectiveness of
the measures implemented to mitigate them. Finally, we suggest management guidelines for railway companies, and present a protocol to minimize these barrier effects.
We searched the ISI Web of Science and Zoological Record databases for railway
ecology studies. For all searches, our search terms were combinations of the following
words: barrier effect, collision, fragmentation, habitat loss, impact, permeability,
radio-tracking, railroad, railway, train, underpass, wildlife pass. We looked for publications in English, Spanish, Portuguese, and French. We also searched Google Scholar™
for additional studies not published in peer-reviewed journals (gray literature) but citing
peer-reviewed papers, such as Ph.D. dissertations, reports, or conference papers.
Barrier Effects
The various sources of railway barrier effects are closely related, and sometimes it is
not easy to clearly separate them. For instance, noisy traffic can cause both habitat
loss (if wildlife refuses to use the area adjacent to the railway right-of-way), and it
can create a behavioral barrier if this noise implies a perceived risk. We identified
four broad types of impacts causing barrier effects.
Physical and Behavioral Barriers
Barriers can be physical, when a species cannot trespass the railway, or behavioral,
when the species may be physically able to cross the barrier but does not do so
because of unfavorable ambient conditions or perceived risk.
44
R. Barrientos and L. Borda-de-Água