and whether it could be compensated by the use of the other saltpans or other places
outside the study area.
We applied an experimental design that provides a spatial and temporal context
to integrate the evaluation of potential impacts of railways and other line infrastructures on wetlands. Our approach surpasses the usual estimators of mortality due
to the effect of barrier and evaluates the effects on the spatial and temporal distribution, survival and behaviour. This decision was made due to the nature of this
railway and the mitigation measures that were decided a priori to decrease the
probability of negative impacts over the aquatic birds that uses the area crossed by
this infrastructure. Indeed, the construction of a viaduct over the most critical areas
was a decision that decreased land reclamation on the saltpans. On the other hand,
this railway was meant from the start to be used for commercial purposes, transporting containers from the harbor to the main national line. The expected traffic
and speed of the trains was thus limited and conditioned to specific daily periods,
thus decreasing the barrier effect of this infrastructure and, hopefully, lowered the
expected mortality due to collisions with the trains. In fact, during the study period,
only two casualties were reported: a common Sandpiper (Actitis hypoleucos) and an
unidentified gull.
The main guidelines described in this book pertaining to future studies in railway
ecology seem mostly designed to terrestrial environments (and species) and long
stretches of continuous railway beds. This study dealt (albeit in a preliminary way)
with some of them, namely by (1) studying species with different ecological traits
(even if belonging to the same taxonomic group), (2) using an experimental analysis, which includes comparison between a control phase with the period of construction and after, (3) studying the effect of habitat fragmentation (in this case, how
the birds responded to the loss/degradation of the impacted saltpans both in the
breeding season and in winter, and (4) a preliminary study of the population persistence in the area after the railway construction.
In our view, the most interesting feature of the present study is the integration of
several spatial scales, from the macroscale of other case studies (see Chaps. 7 and
11) to the microscale of the habitat. This option was imposed by the nature of the
problem itself and allowed us to go beyond the usual evaluation of mortality of
adult birds due to collisions (Chap. 7) or the general patterns of disturbance and
habitat loss (Chap. 11), and changed the focus of analysis to the impact of disturbance (both on the breeding and wintering birds) and chick mortality at smaller
scales (habitat), a feature that is seldom attempted. We have developed a conceptual
methodology where the rationale is hypothesis-based and uses a
Before-After-Control-Impact comparative approach (as advised in the guidelines of
Chap. 19). We think that it can be easily extended to the same or other aquatic bird
species and habitats affected by railways in the wetland areas, enabling a multi-scale
habitat analysis that can be combined with the usual broad scope procedures.
Although the method has the potential to be improved and refined, we feel that it
represents an add-on to the arsenal of methods of analysis in future studies of
railway ecology, as those proposed in Chap. 19.
212
T. Múrias et al.
outside the study area.
We applied an experimental design that provides a spatial and temporal context
to integrate the evaluation of potential impacts of railways and other line infrastructures on wetlands. Our approach surpasses the usual estimators of mortality due
to the effect of barrier and evaluates the effects on the spatial and temporal distribution, survival and behaviour. This decision was made due to the nature of this
railway and the mitigation measures that were decided a priori to decrease the
probability of negative impacts over the aquatic birds that uses the area crossed by
this infrastructure. Indeed, the construction of a viaduct over the most critical areas
was a decision that decreased land reclamation on the saltpans. On the other hand,
this railway was meant from the start to be used for commercial purposes, transporting containers from the harbor to the main national line. The expected traffic
and speed of the trains was thus limited and conditioned to specific daily periods,
thus decreasing the barrier effect of this infrastructure and, hopefully, lowered the
expected mortality due to collisions with the trains. In fact, during the study period,
only two casualties were reported: a common Sandpiper (Actitis hypoleucos) and an
unidentified gull.
The main guidelines described in this book pertaining to future studies in railway
ecology seem mostly designed to terrestrial environments (and species) and long
stretches of continuous railway beds. This study dealt (albeit in a preliminary way)
with some of them, namely by (1) studying species with different ecological traits
(even if belonging to the same taxonomic group), (2) using an experimental analysis, which includes comparison between a control phase with the period of construction and after, (3) studying the effect of habitat fragmentation (in this case, how
the birds responded to the loss/degradation of the impacted saltpans both in the
breeding season and in winter, and (4) a preliminary study of the population persistence in the area after the railway construction.
In our view, the most interesting feature of the present study is the integration of
several spatial scales, from the macroscale of other case studies (see Chaps. 7 and
11) to the microscale of the habitat. This option was imposed by the nature of the
problem itself and allowed us to go beyond the usual evaluation of mortality of
adult birds due to collisions (Chap. 7) or the general patterns of disturbance and
habitat loss (Chap. 11), and changed the focus of analysis to the impact of disturbance (both on the breeding and wintering birds) and chick mortality at smaller
scales (habitat), a feature that is seldom attempted. We have developed a conceptual
methodology where the rationale is hypothesis-based and uses a
Before-After-Control-Impact comparative approach (as advised in the guidelines of
Chap. 19). We think that it can be easily extended to the same or other aquatic bird
species and habitats affected by railways in the wetland areas, enabling a multi-scale
habitat analysis that can be combined with the usual broad scope procedures.
Although the method has the potential to be improved and refined, we feel that it
represents an add-on to the arsenal of methods of analysis in future studies of
railway ecology, as those proposed in Chap. 19.
212
T. Múrias et al.