IUCN / SSC Cat Specialist Group - Digital Cat Library |
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| Osaka, M.; Okamura, M. | |
| Spatiotemporal patterns of endangered species roadkill: Iriomote Cat-Vehicle Collisions | |
| 2012 Bulletin of the Nippon Veterinary and Life Science University (61): 1-9 | |
The aim was to propose techniques for analysis of spatiotemporal patterns of vehicle collisions with an endangered species. We examined Iriomote cat-vehicle collisions from 1978-2008 (n=46) along only a 50-km trunk road in the Iriomote island of Japan. The collisions obeyed a nonhomogeneous Poisson process with mean landa(t) that increased with time t. Hence, the collisions turned out to be increasing steadily. To test for spatial distribution, the road was divided into 500 segments. We assumed a null hypothesis that each collision occurred with the same probability on each of the segments. We generated 1000 samples, each of which consisted of 46 randomly selected segments, and counted clusters of various sizes. We defined a cluster as collisions over or equal 4 (size 4) within 1km. The results were 1.544/sample for size 4, 0.349/ sample for size 5, 0.0054/ sample for size 6, and 0.008/ sample for size 7. The real distribution had 1 cluster of size 4, 2 clusters of size 5 and 2 clusters of size 7 (P<0.001). In the almost all of these clusters, it have already paid for many effort to prevent cat-vehicle collision such as underpasses, elevated segments of the road and zebra zone, our findings suggest that it is reasonable statistically. Because the situation around the cat-vehicle collisions, such as road structure, traffic volume and habitat condition of the cat along the road, has been changed, we think also that it is necessary to examine further analysis using additional data to suggest the measurement against collision effectively. |
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