Keywords Shorebirds Á Wetlands Á Saltpans Á Impact Á Railway
Introduction
The assessment of ecological effects on habitats and species of the construction and
posterior operation of railways is still in its infancy when compared with other
human-made infrastructures, like such as roads or powerlines, as largely stressed in
Chap. 1. Although mortality is the most obvious and direct ecological effect of railways (as with other linear structures), the railways may also have indirect
effects-namely as barriers for wildlife (Chap. 4), as vectors for the transport of alien
species (Chap. 5), and as sources of disturbance (Chap. 6). In this book, most examples refer to railways on land or aquatic inland ecosystems (e.g. lakes, rivers), which is
rather logical, since for the most part, railway lines are built overland. However, they
may also impact non-terrestrial habitats (and associated species), when they are built in
or near commercial ports. These are almost invariably located on estuaries, one of the
most sensible ecosystems in terms of functioning and conservation, and critical for the
conservation of many bird species (McLusky and Elliott 2004).
The eventual negative impacts of railways in estuarine systems may be particularly
relevant for shorebirds and related species (Charadriiformes), which are among the
birds of highest conservation concern (International Wader Study Group 2003; van de
Kamp et al. 2004), due to their migratory status, feeding specialization, and, as a
result, dependency on a limited set of areas for breeding, staging, and wintering
(McLusky and Elliott 2004). Most of these species are very dependent on estuarine
habitats and neighboring inland wetlands, as saltmarshes (Prater 1981) and, in
southern Europe, also saltpans (Luís et al. 2002; Masero 2003; Múrias et al. 1997;
Rufino et al. 1984). Therefore, it is important to assess the impacts of railways on this
group of species, thereby allowing the development of adequate mitigation measures.
Portugal is one of the countries in southern Europe that holds international
important wetlands for shorebirds, and where the development of railway networks
to serve harbors can impact on estuarine and other coastal habitats. In these wetlands, saltpans appear to play an important role for shorebird conservation, as they
are used both as refuges for sheltering at high tides, and as foraging habitats,
especially when the mudflats are covered. Therefore, saltpans provide important
sources of supplementary energy for birds, particularly during the demanding
migratory periods and in winter (Dias et al. 2014; Lopes et al. 2005; Múrias et al.
2002; Rufino et al. 1984). Moreover, saltpans provide suitable breeding locations to
populations of some shorebird species, such as Black-winged Stilt Himantopus
himantopus, Kentish plover Charadrius alexandrinus, Redshank Tringa tetanus
and Little tern Sterna albifrons (Fonseca et al. 2005; Jardim 1984; Múrias et al.
1997; Rufino and Araújo 1987). For the Black-winged stilt they even represent the
most important breeding areas in Portugal (Rufino and Neves 1992).
Despite their importance for shorebirds, saltpans in Portugal are fast disappearing due to abandonment or conversion to aquaculture. As a result, only a few
198
T. Múrias et al.
Introduction
The assessment of ecological effects on habitats and species of the construction and
posterior operation of railways is still in its infancy when compared with other
human-made infrastructures, like such as roads or powerlines, as largely stressed in
Chap. 1. Although mortality is the most obvious and direct ecological effect of railways (as with other linear structures), the railways may also have indirect
effects-namely as barriers for wildlife (Chap. 4), as vectors for the transport of alien
species (Chap. 5), and as sources of disturbance (Chap. 6). In this book, most examples refer to railways on land or aquatic inland ecosystems (e.g. lakes, rivers), which is
rather logical, since for the most part, railway lines are built overland. However, they
may also impact non-terrestrial habitats (and associated species), when they are built in
or near commercial ports. These are almost invariably located on estuaries, one of the
most sensible ecosystems in terms of functioning and conservation, and critical for the
conservation of many bird species (McLusky and Elliott 2004).
The eventual negative impacts of railways in estuarine systems may be particularly
relevant for shorebirds and related species (Charadriiformes), which are among the
birds of highest conservation concern (International Wader Study Group 2003; van de
Kamp et al. 2004), due to their migratory status, feeding specialization, and, as a
result, dependency on a limited set of areas for breeding, staging, and wintering
(McLusky and Elliott 2004). Most of these species are very dependent on estuarine
habitats and neighboring inland wetlands, as saltmarshes (Prater 1981) and, in
southern Europe, also saltpans (Luís et al. 2002; Masero 2003; Múrias et al. 1997;
Rufino et al. 1984). Therefore, it is important to assess the impacts of railways on this
group of species, thereby allowing the development of adequate mitigation measures.
Portugal is one of the countries in southern Europe that holds international
important wetlands for shorebirds, and where the development of railway networks
to serve harbors can impact on estuarine and other coastal habitats. In these wetlands, saltpans appear to play an important role for shorebird conservation, as they
are used both as refuges for sheltering at high tides, and as foraging habitats,
especially when the mudflats are covered. Therefore, saltpans provide important
sources of supplementary energy for birds, particularly during the demanding
migratory periods and in winter (Dias et al. 2014; Lopes et al. 2005; Múrias et al.
2002; Rufino et al. 1984). Moreover, saltpans provide suitable breeding locations to
populations of some shorebird species, such as Black-winged Stilt Himantopus
himantopus, Kentish plover Charadrius alexandrinus, Redshank Tringa tetanus
and Little tern Sterna albifrons (Fonseca et al. 2005; Jardim 1984; Múrias et al.
1997; Rufino and Araújo 1987). For the Black-winged stilt they even represent the
most important breeding areas in Portugal (Rufino and Neves 1992).
Despite their importance for shorebirds, saltpans in Portugal are fast disappearing due to abandonment or conversion to aquaculture. As a result, only a few
198
T. Múrias et al.