footprints, track signs, feeding signs) found along the railway track. For point data,
the kernel density is a nonparametric method of estimating the probability density
function of a random variable that calculates the density of point features around
each output raster cell with a smoothly curved surface fitted over each point.
Estimates were based on the Silverman (1986) quartic kernel function. The output
cell size and search radius were taken as for the “susceptibility map.”
To understand temporal patterns of elephant casualties, we used nonparametric
statistical tests to determine whether the number of accidents changed between
before gauge conversion (1974–2002) and after it (2004–2015). We also evaluated
temporal patterns in accidents according to season of the year and time of day for
records after gauge conversion. For analysis, accidents were aggregated within the
three seasons described above, and in two daily periods, i.e., day (06:00–18:00) vs
night (18:00–06:00).
Results
Elephant Distribution
During the three seasonal field surveys for elephants, we found 589 indirect signs
during the dry season, 599 signs during the maize cultivation/harvest season, and
1,124 signs during the paddy cultivation/harvest season along the 150 km stretch of
the railway track. Overall, most signs were found in the Siliguri–Bagarkote
(Mahananda–Monpong stretch) sector in the western region (8.0 signs/km), followed by the Hasimara–Alipurduar (Buxa Tiger Reserve West) sector in the eastern
region (6.0 signs/km) (Table 10.1).
Elephant Fatalities
Eighty–nine (89) elephant deaths were reported from 61 accidents over a 41-year
period (1974–2015), with a marked increase over time (Fig. 10.1) in the number of
Table 10.1 Number of elephant signs (see text for list) recorded in different sectors along the
railway track in northern West Bengal (Siliguri Junction–Alipurduar Junction; see Fig. 10.7 for
locations of stations)
From (sector station)
To (sector station)
Distance (km)
Signs/km
Siliguri Junction
Bagrakote
33
7.7
Bagrakote
Chalsa
22
0.8
Chalsa
Dalgaon
46
4.4
Dalgaon
Hasimara
25
3.5
Hasimara
Alipurduar Junction
35
5.9
162
M. Roy and R. Sukumar
the kernel density is a nonparametric method of estimating the probability density
function of a random variable that calculates the density of point features around
each output raster cell with a smoothly curved surface fitted over each point.
Estimates were based on the Silverman (1986) quartic kernel function. The output
cell size and search radius were taken as for the “susceptibility map.”
To understand temporal patterns of elephant casualties, we used nonparametric
statistical tests to determine whether the number of accidents changed between
before gauge conversion (1974–2002) and after it (2004–2015). We also evaluated
temporal patterns in accidents according to season of the year and time of day for
records after gauge conversion. For analysis, accidents were aggregated within the
three seasons described above, and in two daily periods, i.e., day (06:00–18:00) vs
night (18:00–06:00).
Results
Elephant Distribution
During the three seasonal field surveys for elephants, we found 589 indirect signs
during the dry season, 599 signs during the maize cultivation/harvest season, and
1,124 signs during the paddy cultivation/harvest season along the 150 km stretch of
the railway track. Overall, most signs were found in the Siliguri–Bagarkote
(Mahananda–Monpong stretch) sector in the western region (8.0 signs/km), followed by the Hasimara–Alipurduar (Buxa Tiger Reserve West) sector in the eastern
region (6.0 signs/km) (Table 10.1).
Elephant Fatalities
Eighty–nine (89) elephant deaths were reported from 61 accidents over a 41-year
period (1974–2015), with a marked increase over time (Fig. 10.1) in the number of
Table 10.1 Number of elephant signs (see text for list) recorded in different sectors along the
railway track in northern West Bengal (Siliguri Junction–Alipurduar Junction; see Fig. 10.7 for
locations of stations)
From (sector station)
To (sector station)
Distance (km)
Signs/km
Siliguri Junction
Bagrakote
33
7.7
Bagrakote
Chalsa
22
0.8
Chalsa
Dalgaon
46
4.4
Dalgaon
Hasimara
25
3.5
Hasimara
Alipurduar Junction
35
5.9
162
M. Roy and R. Sukumar