Part of the study area is included in or adjacent to natural protected areas under a
conservation legal status. Notably, south of the railway, there are 10 polygons that
constitute the NATURA2000 site “Áreas esteparias de la Mancha Norte,” which are
especially important for the great bustard (Otis tarda) in the Castilla-La Mancha
region. Approximately 60% of the birds in the region are found here.
Bird Occupation of Railway Surroundings
Spatial patterns of birds around the HSR give broad-scale information of infrastructure impacts on the animal community because the presence and abundance of
bird species along the landscape mirrors their response to it. Thus, it is foreseeable
that habitat destruction and degradation in the HSR vicinity will shape the way
birds use the area (Benítez-López et al. 2010; Torres et al. 2011; Wiaçek et al.
2015). Comparisons of species abundance in close proximity to infrastructure
locations with that in the wider landscape are useful for the assessment of infrastructure impacts (Torres et al. 2016). Ideally, to analyze human impacts, animal
communities should be characterized before infrastructure construction as well as
recurrently afterwards, during the operation phase, in a “before and after”
control-impact design (Torres et al. 2011). However, this approach is frequently
unfeasible and scientific quantification of changes in bird densities around roads has
shown that most effects on birds extend up to 500 m from the infrastructure, with
outlying areas largely free of impacts (Benítez-López et al. 2010).
In this case study, the characterization of bird populations potentially affected by
the HSR line started before the operation phase, but after the line was already built.
Thus, there is no information related to impacts associated with the construction
phase. Nonetheless, control areas 500–1,000 m from the railway give a detailed
picture of bird communities presumed to be negligibly affected by the presence of
the project, and they are informative about local changes in bird communities by
comparison with data obtained in close proximity to the HSR (Wiaçek et al. 2015).
The first censuses were conducted in May of 2010, coinciding with the breeding
season. Afterwards, the monitoring of bird populations took place during the first
three years of operation (2011–2013), with censuses in both winter and spring.
A final year-round monitoring with four seasonal samplings was conducted in
2014–2015. All of these censuses involved two complementary methodologies:
(1) linear transects on foot, and (2) direct counts from a car along dirt paths.
The census of passerine birds and other small-sized species was performed by
walking 1 km line-transects without a defined count bandwidth. Each transect was
walked by a single experienced observer, and all birds identified–visually or
acoustically–were recorded. This method is frequently used in extensive surveys to
estimate abundance, distribution, and patterns of habitat selection by birds (Bibby
et al. 2000). The transects were regularly distributed on both sides of the railway in
two lines parallel to the HSR, one next to the fence to sample the bird community
affected by the railway, and the second (control) at a distance of 500 m from it.
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J.E. Malo et al.
conservation legal status. Notably, south of the railway, there are 10 polygons that
constitute the NATURA2000 site “Áreas esteparias de la Mancha Norte,” which are
especially important for the great bustard (Otis tarda) in the Castilla-La Mancha
region. Approximately 60% of the birds in the region are found here.
Bird Occupation of Railway Surroundings
Spatial patterns of birds around the HSR give broad-scale information of infrastructure impacts on the animal community because the presence and abundance of
bird species along the landscape mirrors their response to it. Thus, it is foreseeable
that habitat destruction and degradation in the HSR vicinity will shape the way
birds use the area (Benítez-López et al. 2010; Torres et al. 2011; Wiaçek et al.
2015). Comparisons of species abundance in close proximity to infrastructure
locations with that in the wider landscape are useful for the assessment of infrastructure impacts (Torres et al. 2016). Ideally, to analyze human impacts, animal
communities should be characterized before infrastructure construction as well as
recurrently afterwards, during the operation phase, in a “before and after”
control-impact design (Torres et al. 2011). However, this approach is frequently
unfeasible and scientific quantification of changes in bird densities around roads has
shown that most effects on birds extend up to 500 m from the infrastructure, with
outlying areas largely free of impacts (Benítez-López et al. 2010).
In this case study, the characterization of bird populations potentially affected by
the HSR line started before the operation phase, but after the line was already built.
Thus, there is no information related to impacts associated with the construction
phase. Nonetheless, control areas 500–1,000 m from the railway give a detailed
picture of bird communities presumed to be negligibly affected by the presence of
the project, and they are informative about local changes in bird communities by
comparison with data obtained in close proximity to the HSR (Wiaçek et al. 2015).
The first censuses were conducted in May of 2010, coinciding with the breeding
season. Afterwards, the monitoring of bird populations took place during the first
three years of operation (2011–2013), with censuses in both winter and spring.
A final year-round monitoring with four seasonal samplings was conducted in
2014–2015. All of these censuses involved two complementary methodologies:
(1) linear transects on foot, and (2) direct counts from a car along dirt paths.
The census of passerine birds and other small-sized species was performed by
walking 1 km line-transects without a defined count bandwidth. Each transect was
walked by a single experienced observer, and all birds identified–visually or
acoustically–were recorded. This method is frequently used in extensive surveys to
estimate abundance, distribution, and patterns of habitat selection by birds (Bibby
et al. 2000). The transects were regularly distributed on both sides of the railway in
two lines parallel to the HSR, one next to the fence to sample the bird community
affected by the railway, and the second (control) at a distance of 500 m from it.
120
J.E. Malo et al.