in numbers in the area (European serin, common linnet), while others that avoid the
railway increased their abundance (Eurasian skylark, spotless starling, rock dove).
Bird Use of Railway Structures
Bird species behavior is an important factor in determining whether the HSR has a
positive or negative impact on proximal population density. The mortality of birds
depends on the extent to which they are exposed to the risk of being over-run while
flying, or being electrocuted by the HSR poles or catenary. In contrast, the provision of
new elements in the landscape (e.g., poles, bridges, embankments) may facilitate the
presence and/or breeding of some species (Tryjanowski et al. 2013; Morelli et al. 2014).
It is therefore interesting to elucidate how birds use track environs, because that use may
be beneficial, such as for nesting, or detrimental, such as by producing a mortality risk. In
a sense, the above-mentioned changes in the bird community may correspond to landscape scale impacts, al-though some impacts of the railway are associated with much
more specific processes that take place on the infrastructure itself (Mainwaring 2015).
Data in this section were obtained from fixed observation stations and made
seasonally between the autumn of 2014 and the summer of 2015. The sampling unit
in this case was 10-min observations of all birds that make any use of a 120 m
section of the HSR from the position of the observer. This distance corresponds to
two spans between catenary poles, elements that aide in systematic data collection
and define a distance that allows the identification of species of almost all observed
individual birds. For each observed bird, the infrastructure elements used, and the
time spent in them, were noted. Recorded elements were powerlines (catenary,
power line and all other supporting wires), built structures (passages and bridges),
ballast (stone and gravel track bed), catenary poles, fences, and embankments.
Sampling station locations were selected with the premise of concentrating on
high embankments where birds have access to all the typical HSR elements and
directly face the need to determine at what height to cross the railway (see below).
In the Villarrubia de Santiago area, 26–28 sampling stations were distributed over
approximately 3360 m. In the Santa Cruz de la Zarza area, 20 stations were distributed over 2400 m. Data from both sections were clumped together for the
presentation of results. The infrastructure use by birds (nesting, rest, power, etc.) is
expressed as: (1) the number of birds and (2) the time of use per kilometer of HSR
during 1 h of observation (birds km
−1 h
−1 ).
In total, 936 birds, belonging to 30 species, were observed with an average of
81.8 birds and 404 min of use per kilometer of HSR observed for 1 h (Table 8.2).
The most common species observed in the vicinity of the HSR were the spotless
starling, common linnet, rock dove, house sparrow, rock sparrow, crested lark, and
common magpie (all >5 birds km
−1 h
−1
). No protected species was found using the
sampled elements of the infrastructure.
The structures used most were embankments (24 species in total; 26.4 birds
km
−1 h
−1 ) and powerlines (12 species; 25.2 birds km
−1 h
−1 ), although the
numerical importance of the latter is due to frequent perching by the most abundant
species—the spotless starling. In this species, 94.3% of the observations were on
these elements. In order of importance, following embankments and powerlines, are
8 Cross-scale Changes in Bird Behavior Around …
123
railway increased their abundance (Eurasian skylark, spotless starling, rock dove).
Bird Use of Railway Structures
Bird species behavior is an important factor in determining whether the HSR has a
positive or negative impact on proximal population density. The mortality of birds
depends on the extent to which they are exposed to the risk of being over-run while
flying, or being electrocuted by the HSR poles or catenary. In contrast, the provision of
new elements in the landscape (e.g., poles, bridges, embankments) may facilitate the
presence and/or breeding of some species (Tryjanowski et al. 2013; Morelli et al. 2014).
It is therefore interesting to elucidate how birds use track environs, because that use may
be beneficial, such as for nesting, or detrimental, such as by producing a mortality risk. In
a sense, the above-mentioned changes in the bird community may correspond to landscape scale impacts, al-though some impacts of the railway are associated with much
more specific processes that take place on the infrastructure itself (Mainwaring 2015).
Data in this section were obtained from fixed observation stations and made
seasonally between the autumn of 2014 and the summer of 2015. The sampling unit
in this case was 10-min observations of all birds that make any use of a 120 m
section of the HSR from the position of the observer. This distance corresponds to
two spans between catenary poles, elements that aide in systematic data collection
and define a distance that allows the identification of species of almost all observed
individual birds. For each observed bird, the infrastructure elements used, and the
time spent in them, were noted. Recorded elements were powerlines (catenary,
power line and all other supporting wires), built structures (passages and bridges),
ballast (stone and gravel track bed), catenary poles, fences, and embankments.
Sampling station locations were selected with the premise of concentrating on
high embankments where birds have access to all the typical HSR elements and
directly face the need to determine at what height to cross the railway (see below).
In the Villarrubia de Santiago area, 26–28 sampling stations were distributed over
approximately 3360 m. In the Santa Cruz de la Zarza area, 20 stations were distributed over 2400 m. Data from both sections were clumped together for the
presentation of results. The infrastructure use by birds (nesting, rest, power, etc.) is
expressed as: (1) the number of birds and (2) the time of use per kilometer of HSR
during 1 h of observation (birds km
−1 h
−1 ).
In total, 936 birds, belonging to 30 species, were observed with an average of
81.8 birds and 404 min of use per kilometer of HSR observed for 1 h (Table 8.2).
The most common species observed in the vicinity of the HSR were the spotless
starling, common linnet, rock dove, house sparrow, rock sparrow, crested lark, and
common magpie (all >5 birds km
−1 h
−1
). No protected species was found using the
sampled elements of the infrastructure.
The structures used most were embankments (24 species in total; 26.4 birds
km
−1 h
−1 ) and powerlines (12 species; 25.2 birds km
−1 h
−1 ), although the
numerical importance of the latter is due to frequent perching by the most abundant
species—the spotless starling. In this species, 94.3% of the observations were on
these elements. In order of importance, following embankments and powerlines, are
8 Cross-scale Changes in Bird Behavior Around …
123