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Advisor(s)
Abstract(s)
Many studies have evaluated bird mortality in relation to roads and other
human structures, but little is known about the potential impacts of railways. In
particular, it is uncertain whether railways are an important mortality source when
crossing wetlands heavily used by aquatic birds. Here we analyze bird collisions in
a railway that crosses the Nature Reserve of the Sado Estuary (Portugal) over an
annual cycle, documenting bird mortality and the flight behaviour of aquatic birds
in relation to a bowstring bridge. During monthly surveys conducted on 16.3 km of
railway, we found 5.8 dead birds/km/10 survey days in the section crossing wetland
habitats (6.3 km), while <0.5 dead birds/km/10 survey days were found in two
sections crossing only forested habitats. Most birds recorded were small songbirds
(Passeriformes), while there was only a small number of aquatic birds (common
moorhen, mallard, flamingo, great cormorant, gulls) and other non-passerines
associated with wetlands (white stork). During nearly 400 h of observations, we 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
Description
L. Borda-de-Água et al. (eds.), Railway Ecology, chapter 7, p. 103-115
Keywords
anthropogenic mortality aquatic birds collision risk environmental impact wetlands wildlife mortality
Pedagogical Context
Citation
Publisher
Springer