Spatial Distribution of Collision Risk
There was a strong spatial variation in the number of accidents both before and after
gauge conversion (Fig. 10.5), with many accidents occurring in the same areas and
none in others. The concentrations of accidents matched some areas with high
elephant activity as estimated from the densities of elephant signs (Fig. 10.6), but
there were also areas with large densities of elephant signs but with no or just a few
accidents. However, when we divided the entire railway line surveyed into segments of 2 km each (n = 76) and plotted the elephant signs found (dung, tracks,
foot prints, feeding signs) in each segment with the number of accidents that
occurred, we found a strong correlation (Spearman’s rank correlation r = 0.80,
P
0.001).
During 2004–2015, after gauge conversion, the Buxa Tiger Reserve West
Division region recorded the highest number (29%) of the accidents that took place
(n = 35), followed by the Mahananda Wildlife Sanctuary (26%), the Jalpaiguri
Forest Division (17%), the Jaldapara Wildlife Division (14%), the Kalimpong
Forest Division (9%), and the Gorumara Wildlife Division (6%). When we consider
the number of elephants killed (n = 62), the highest figures were observed in
Jalpaiguri (31%), followed by the Buxa Tiger Reserve West (26%), Gorumara
Wildlife (16%), Mahananda Wildlife Sanctuary (15%), Jaldapara Wildlife Division
(8%), and Kalimpong Division (5%). More elephant groups were involved in
accidents in Gorumara and Jalpaiguri resulting in multiple fatalities per accident.
Discussion
Our study describes the spatial and temporal mortality patterns of elephants due to
collisions with trains along a 150-km stretch of the 161-km railway line between the
Siliguri and Alipurduar Junctions. Collisions occurred throughout the study period
(1974–2015), but they greatly increased after 2004, when a new schedule of trains
began operating, after the line was converted from meter gauge to broad gauge.
Most collisions occurred during the night, and adult male elephants and calves
appeared particularly susceptible to this type of mortality. There was an uneven
distribution of accidents during the annual cycle, with peaks in May–June and
September–October, during the crop cultivation seasons of maize and paddy rice,
respectively. The spatial distribution of accidents was also uneven, occurring
mostly in a few well-defined hotspots. Overall, our study provides useful information to mitigate elephant–train accidents in the Siliguri–Alipurduar railway, and
elsewhere in India.
One reason for the increase that was seen in the frequency of accidents was
probably the increase in the number of circulating trains, from about 10 trains/day
during the pre-conversion period, to estimates of between 17 (Ghosh 2001) and 22–
26/day (Das 2013) during the post-conversion period, thereby increasing the
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M. Roy and R. Sukumar
There was a strong spatial variation in the number of accidents both before and after
gauge conversion (Fig. 10.5), with many accidents occurring in the same areas and
none in others. The concentrations of accidents matched some areas with high
elephant activity as estimated from the densities of elephant signs (Fig. 10.6), but
there were also areas with large densities of elephant signs but with no or just a few
accidents. However, when we divided the entire railway line surveyed into segments of 2 km each (n = 76) and plotted the elephant signs found (dung, tracks,
foot prints, feeding signs) in each segment with the number of accidents that
occurred, we found a strong correlation (Spearman’s rank correlation r = 0.80,
P
0.001).
During 2004–2015, after gauge conversion, the Buxa Tiger Reserve West
Division region recorded the highest number (29%) of the accidents that took place
(n = 35), followed by the Mahananda Wildlife Sanctuary (26%), the Jalpaiguri
Forest Division (17%), the Jaldapara Wildlife Division (14%), the Kalimpong
Forest Division (9%), and the Gorumara Wildlife Division (6%). When we consider
the number of elephants killed (n = 62), the highest figures were observed in
Jalpaiguri (31%), followed by the Buxa Tiger Reserve West (26%), Gorumara
Wildlife (16%), Mahananda Wildlife Sanctuary (15%), Jaldapara Wildlife Division
(8%), and Kalimpong Division (5%). More elephant groups were involved in
accidents in Gorumara and Jalpaiguri resulting in multiple fatalities per accident.
Discussion
Our study describes the spatial and temporal mortality patterns of elephants due to
collisions with trains along a 150-km stretch of the 161-km railway line between the
Siliguri and Alipurduar Junctions. Collisions occurred throughout the study period
(1974–2015), but they greatly increased after 2004, when a new schedule of trains
began operating, after the line was converted from meter gauge to broad gauge.
Most collisions occurred during the night, and adult male elephants and calves
appeared particularly susceptible to this type of mortality. There was an uneven
distribution of accidents during the annual cycle, with peaks in May–June and
September–October, during the crop cultivation seasons of maize and paddy rice,
respectively. The spatial distribution of accidents was also uneven, occurring
mostly in a few well-defined hotspots. Overall, our study provides useful information to mitigate elephant–train accidents in the Siliguri–Alipurduar railway, and
elsewhere in India.
One reason for the increase that was seen in the frequency of accidents was
probably the increase in the number of circulating trains, from about 10 trains/day
during the pre-conversion period, to estimates of between 17 (Ghosh 2001) and 22–
26/day (Das 2013) during the post-conversion period, thereby increasing the
166
M. Roy and R. Sukumar