The spatial distribution and seasonal change of food plants are considered to be
important factors determining the movement patterns of ungulates (Mueller and Fagan
2008). Therefore, environmental unpredictability at the landscape level affects
movement patterns of animals through seasonal and interannual changes in food
availability. Mongolian gazelles in the eastern steppe of Mongolia have nomadic
movements that are more irregular than those of other ungulate species, such as caribou
(Rangifer tarandus granti) in Alaska, which exhibit regular seasonal migration, or the
guanaco (Lama guanicoe) in Argentina and moose (Alces alces) in the northeastern
United States, both of which move shorter distances with more predictable movements
(Mueller et al. 2011). Therefore, in order to conserve nomadic animals, like Mongolian
gazelles, that live in unpredictable environments, the maintenance of good environmental conditions and access to vast areas are essential, especially during those periods
when conditions become unsuitable in much of their ranges.
Effects of the Ulaanbaatar–Beijing Railway on Wild
Ungulates
Barrier Effect of the Existing Railway
The barrier effect of the Ulaanbaatar–Beijing Railway on the movements of wild
ungulates in Mongolia has been apparent since the beginning of satellite tracking of
these animals. We first conducted satellite tracking of Mongolian gazelles in 2002 (Ito
et al. 2005, 2006). In October 2002, two female gazelles were captured on the southwestern side of the railway and collared with a satellite transmitter. The distance
between the site of capture and the railway was about 7 km. Although both gazelles
were captured at exactly the same place, their movements after release were different
(Fig. 14.3). This is a small sample size, but it is representative of the movements of more
individuals because at the time when the animals were captured, the gazelles were part
of a herd with several hundred animals. The different movements of the two gazelles
also indicate loose relations among gazelle individuals. Sometimes Mongolian gazelles
form large herds, whereas other times they separate into relatively small groups. Such
uncoordinated movement patterns were also reported in a comparative study of the
Mongolian gazelle, caribou, guanaco, and moose (Mueller et al. 2011).
The two gazelles captured near the railway moved along it for a year, but never
crossed it (Ito et al. 2005). They moved closer to the railway during winter
(October–March) than during summer (April–September), and the nearest distances
of the two gazelles to the railway were 0.3 and 1.8 km, respectively (Fig. 14.3).
These results suggest that the railway is a barrier for gazelle movements mainly
because of the fences along the rails. Some wildlife crossing locations exist along
the railway (Fig. 14.4), but our data suggest that these crossings are ineffective,
probably due to their limited number and their lack of suitable natural features that
could reduce the natural wariness of the gazelles.
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important factors determining the movement patterns of ungulates (Mueller and Fagan
2008). Therefore, environmental unpredictability at the landscape level affects
movement patterns of animals through seasonal and interannual changes in food
availability. Mongolian gazelles in the eastern steppe of Mongolia have nomadic
movements that are more irregular than those of other ungulate species, such as caribou
(Rangifer tarandus granti) in Alaska, which exhibit regular seasonal migration, or the
guanaco (Lama guanicoe) in Argentina and moose (Alces alces) in the northeastern
United States, both of which move shorter distances with more predictable movements
(Mueller et al. 2011). Therefore, in order to conserve nomadic animals, like Mongolian
gazelles, that live in unpredictable environments, the maintenance of good environmental conditions and access to vast areas are essential, especially during those periods
when conditions become unsuitable in much of their ranges.
Effects of the Ulaanbaatar–Beijing Railway on Wild
Ungulates
Barrier Effect of the Existing Railway
The barrier effect of the Ulaanbaatar–Beijing Railway on the movements of wild
ungulates in Mongolia has been apparent since the beginning of satellite tracking of
these animals. We first conducted satellite tracking of Mongolian gazelles in 2002 (Ito
et al. 2005, 2006). In October 2002, two female gazelles were captured on the southwestern side of the railway and collared with a satellite transmitter. The distance
between the site of capture and the railway was about 7 km. Although both gazelles
were captured at exactly the same place, their movements after release were different
(Fig. 14.3). This is a small sample size, but it is representative of the movements of more
individuals because at the time when the animals were captured, the gazelles were part
of a herd with several hundred animals. The different movements of the two gazelles
also indicate loose relations among gazelle individuals. Sometimes Mongolian gazelles
form large herds, whereas other times they separate into relatively small groups. Such
uncoordinated movement patterns were also reported in a comparative study of the
Mongolian gazelle, caribou, guanaco, and moose (Mueller et al. 2011).
The two gazelles captured near the railway moved along it for a year, but never
crossed it (Ito et al. 2005). They moved closer to the railway during winter
(October–March) than during summer (April–September), and the nearest distances
of the two gazelles to the railway were 0.3 and 1.8 km, respectively (Fig. 14.3).
These results suggest that the railway is a barrier for gazelle movements mainly
because of the fences along the rails. Some wildlife crossing locations exist along
the railway (Fig. 14.4), but our data suggest that these crossings are ineffective,
probably due to their limited number and their lack of suitable natural features that
could reduce the natural wariness of the gazelles.
234
T.Y. Ito et al.