recorded 27,000 movements of aquatic birds across the Sado bridge, particularly in
autumn and winter. However, only <1% of movements were within the area of
collision risk with trains, while about 91% were above the collision risk area, and
8% were below the bridge. Overall, our case study suggests that bird collisions may
be far more numerous in railways crossing wetland habitats than elsewhere,
although the risk to aquatic birds may be relatively low. Information from additional study systems would be required to evaluate whether our conclusions apply
to other wetlands and railway lines.
Keywords Anthropogenic mortality Á Aquatic birds Á Collision risk Á
Environmental impact Á Wetlands Á Wildlife mortality
Introduction
Collision with human structures and vehicles is an important source of wild bird
mortality, killing hundreds of millions of birds each year (Loss et al. 2015).
Although the population-level consequences of such mortality are poorly known
(but see, e.g., Carrete et al. 2009; Borda-de-Água et al. 2014), it is generally
recognized under the precautionary principle that efforts should be made to reduce the
number of birds killed each year as much as possible (Loss et al. 2015). Information is
thus needed on the bird species most vulnerable to collisions, and on the environmental and species-specific factors affecting such vulnerability (Barrios and
Rodríguez 2004; Santos et al. 2016), which are essential for developing management
guidelines aimed at reducing collision risk (Barrientos et al. 2011; May et al. 2015).
To collect baseline information for mitigating impacts, bird collision risk has
been the subject of intensive research over the past two decades (Loss et al. 2015),
with many studies documenting bird mortality and its correlates in relation to roads
(Santos et al. 2016), wind farms (Barrios and Rodríguez 2004; Drewitt and
Langston 2006), power lines (Barrientos et al. 2011, 2012), and buildings (Loss
et al. 2015). Surprisingly, however, very few studies have analyzed bird collision in
relation to railways, although these linear infrastructures extend over tens of
thousands of kilometers across the world (see Chap. 2). Railways present a number
of risks to birds from potential collisions with circulating trains, but there are also
risks regarding collision with catenary wires, electrocution, and barotrauma by the
train movement (Dorsey et al. 2015, and see Chap. 2). The few studies addressing
these problems reported that birds can account for over 50% of the vertebrates
killed in railways (SCV 1996; van der Grift and Kuijsters 1998), and that collisions
may often involve species of conservation concern such as owls and birds of prey
(Peña and Llama 1997; SCV 1996; Schaub et al. 2010). For some of these species,
railway-related mortality may represent a considerable proportion of the overall
mortality (van der Grift and Kuijsters 1998; Schaub et al. 2010), and thus may be a
risk worth considering when designing or managing railways. However, the few
studies conducted so far have covered just a very limited range of species and
environmental conditions, making it difficult to draw generalizations (see Chap. 2).
104
C. Godinho et al.
autumn and winter. However, only <1% of movements were within the area of
collision risk with trains, while about 91% were above the collision risk area, and
8% were below the bridge. Overall, our case study suggests that bird collisions may
be far more numerous in railways crossing wetland habitats than elsewhere,
although the risk to aquatic birds may be relatively low. Information from additional study systems would be required to evaluate whether our conclusions apply
to other wetlands and railway lines.
Keywords Anthropogenic mortality Á Aquatic birds Á Collision risk Á
Environmental impact Á Wetlands Á Wildlife mortality
Introduction
Collision with human structures and vehicles is an important source of wild bird
mortality, killing hundreds of millions of birds each year (Loss et al. 2015).
Although the population-level consequences of such mortality are poorly known
(but see, e.g., Carrete et al. 2009; Borda-de-Água et al. 2014), it is generally
recognized under the precautionary principle that efforts should be made to reduce the
number of birds killed each year as much as possible (Loss et al. 2015). Information is
thus needed on the bird species most vulnerable to collisions, and on the environmental and species-specific factors affecting such vulnerability (Barrios and
Rodríguez 2004; Santos et al. 2016), which are essential for developing management
guidelines aimed at reducing collision risk (Barrientos et al. 2011; May et al. 2015).
To collect baseline information for mitigating impacts, bird collision risk has
been the subject of intensive research over the past two decades (Loss et al. 2015),
with many studies documenting bird mortality and its correlates in relation to roads
(Santos et al. 2016), wind farms (Barrios and Rodríguez 2004; Drewitt and
Langston 2006), power lines (Barrientos et al. 2011, 2012), and buildings (Loss
et al. 2015). Surprisingly, however, very few studies have analyzed bird collision in
relation to railways, although these linear infrastructures extend over tens of
thousands of kilometers across the world (see Chap. 2). Railways present a number
of risks to birds from potential collisions with circulating trains, but there are also
risks regarding collision with catenary wires, electrocution, and barotrauma by the
train movement (Dorsey et al. 2015, and see Chap. 2). The few studies addressing
these problems reported that birds can account for over 50% of the vertebrates
killed in railways (SCV 1996; van der Grift and Kuijsters 1998), and that collisions
may often involve species of conservation concern such as owls and birds of prey
(Peña and Llama 1997; SCV 1996; Schaub et al. 2010). For some of these species,
railway-related mortality may represent a considerable proportion of the overall
mortality (van der Grift and Kuijsters 1998; Schaub et al. 2010), and thus may be a
risk worth considering when designing or managing railways. However, the few
studies conducted so far have covered just a very limited range of species and
environmental conditions, making it difficult to draw generalizations (see Chap. 2).
104
C. Godinho et al.