studies may contribute to such understanding, including comparisons of wildlife
crossings of railways before and after the building of wildlife passes, in places
with and without such passes (i.e., BACI designs; Corlatti et al. 2009; Soanes
et al. 2013). Novel molecular techniques may also contribute to tackle these
issues, using for instance non-invasive genetics to know which individuals cross
the railways and how railway barriers contribute to spatial genetic structuring
(Riley et al. 2006; Balkenhol and Waits 2009; Clevenger and Sawaya 2010;
Simmons et al. 2010; see also Chap. 4). Modelling approaches may also be
useful to explore the demographic and genetic consequences of barrier effects
induced by railways, and to disentangle barrier from mortality effects (Borda-deÁgua et al. 2011, 2014; Ceia-Hasse et al. 2017).
• Fourth, we need to know if and how mortality and barrier effects translate into
population effects, which in turn can affect the persistence of vulnerable species
around railway corridors (van der Grift 1999; Dorsey et al. 2015). This might be
achieved through population modelling approaches similar to those already used
in road ecology (Taylor and Goldingay 2009; van der Ree et al. 2009; Borda-deÁgua et al. 2014; Ceia-Hasse et al. in review). The development of these models
require careful field studies whereby critical information on fecundity, survival
and dispersal are estimated, which can then be used to estimate the conditions
under which population viability may be affected by railways. Due consideration should also be given to age- and sex-specific demographic parameters, as
huge variation in population responses may occur if mortality affects primarily
non-breeding versus breeding individuals, or males versus females. Molecular
methods may also contribute to understand population responses to railways,
either by helping to estimate population parameters, or to evaluate changes in
effective population sizes in relation to mortality and fragmentation effects
(Balkenhol and Waits 2009).
• Fifth, we need studies on railway ecology focusing on a wide range of species,
which should be representative of life history and behavioural traits potentially
affecting vulnerability to railways. To date, most research has focused on species with high socio-economic profile, like large charismatic mammals, or on
those with limited mobility, like herptiles (van der Grift 1999; Dorsey et al.
2015). Broadening the scope of research is important, because mitigation
measures designed for some species may be inappropriate for others, thus
requiring informed adjustment based on scientifically sound information
(Clevenger and Waltho 2005; Morelli et al. 2014; Vandevelde et al. 2014;
Wiacek et al. 2015; see Chap. 16). To forecast impacts on species with differential traits, pilot field studies and a systematic review of the available evidence
should be carried out to investigate what are the key ecological traits, such as
dispersal ability or generation time, affecting population responses to railways.
• Finally, there are a number of important issues that remain poorly explored,
despite their potential importance to the environmentally-sound management of
railways. For instance, little is known about the consequences of vibration and
noise on biodiversity living adjacent to the railway bed (see Chap.6). Also,
studies are needed on the relative cost-effectiveness of different management
19 What’s Next? Railway Ecology in the 21st Century
315
crossings of railways before and after the building of wildlife passes, in places
with and without such passes (i.e., BACI designs; Corlatti et al. 2009; Soanes
et al. 2013). Novel molecular techniques may also contribute to tackle these
issues, using for instance non-invasive genetics to know which individuals cross
the railways and how railway barriers contribute to spatial genetic structuring
(Riley et al. 2006; Balkenhol and Waits 2009; Clevenger and Sawaya 2010;
Simmons et al. 2010; see also Chap. 4). Modelling approaches may also be
useful to explore the demographic and genetic consequences of barrier effects
induced by railways, and to disentangle barrier from mortality effects (Borda-deÁgua et al. 2011, 2014; Ceia-Hasse et al. 2017).
• Fourth, we need to know if and how mortality and barrier effects translate into
population effects, which in turn can affect the persistence of vulnerable species
around railway corridors (van der Grift 1999; Dorsey et al. 2015). This might be
achieved through population modelling approaches similar to those already used
in road ecology (Taylor and Goldingay 2009; van der Ree et al. 2009; Borda-deÁgua et al. 2014; Ceia-Hasse et al. in review). The development of these models
require careful field studies whereby critical information on fecundity, survival
and dispersal are estimated, which can then be used to estimate the conditions
under which population viability may be affected by railways. Due consideration should also be given to age- and sex-specific demographic parameters, as
huge variation in population responses may occur if mortality affects primarily
non-breeding versus breeding individuals, or males versus females. Molecular
methods may also contribute to understand population responses to railways,
either by helping to estimate population parameters, or to evaluate changes in
effective population sizes in relation to mortality and fragmentation effects
(Balkenhol and Waits 2009).
• Fifth, we need studies on railway ecology focusing on a wide range of species,
which should be representative of life history and behavioural traits potentially
affecting vulnerability to railways. To date, most research has focused on species with high socio-economic profile, like large charismatic mammals, or on
those with limited mobility, like herptiles (van der Grift 1999; Dorsey et al.
2015). Broadening the scope of research is important, because mitigation
measures designed for some species may be inappropriate for others, thus
requiring informed adjustment based on scientifically sound information
(Clevenger and Waltho 2005; Morelli et al. 2014; Vandevelde et al. 2014;
Wiacek et al. 2015; see Chap. 16). To forecast impacts on species with differential traits, pilot field studies and a systematic review of the available evidence
should be carried out to investigate what are the key ecological traits, such as
dispersal ability or generation time, affecting population responses to railways.
• Finally, there are a number of important issues that remain poorly explored,
despite their potential importance to the environmentally-sound management of
railways. For instance, little is known about the consequences of vibration and
noise on biodiversity living adjacent to the railway bed (see Chap.6). Also,
studies are needed on the relative cost-effectiveness of different management
19 What’s Next? Railway Ecology in the 21st Century
315