Seasonality of raiding

There seem to be several considerations for seasonal patterns of crop raiding by elephants. These include the extent of availability of crops, the presence of elephants in habitats near cultivated areas, and possibly the attractiveness of crops in relation to wild forage during a particular season. In the relatively aseasonal tropics, such as in peninsular Malaysia, there may be no consistent seasonal pattern of raiding perennial crops such as oil palm. Raiding may peak at a given location when a particular group of elephants moves into the area, but no pattern may be discerned over the larger region. In regions with a clear seasonality in rainfall patterns as well as in cultivation of annual crops, there is much stronger evidence for seasonality in crop raiding by elephants.

In the Biligirirangans, I found two peaks in raiding frequency—a first minor one corresponding to the cultivation of maize by some farmers during the first wet season, and a major peak following the cultivation of finger millet by most farmers during the second wet season (fig. 8.2). There was a time lag of about 1-2 months between peaks in rainfall and in raiding as elephants awaited the maturing crops that they preferred. This pattern is largely true of most other elephant regions in southern India as well as other parts, such as northern West Bengal, where farmers cultivate two cereal crops in a year. At Sengwa in Zimbabwe also, a peak in raiding is seen during the transition from the wet to the dry season.

Martin Tchamba's study in northern Cameroon clearly brought out the influence of movement pattern of elephants, as opposed to merely rainfall patterns or crop availability, in determining raiding frequency. In the southern part of the study area, there was a clear late wet season peak in raiding frequency that was also quite high (fig. 8.3). In the north, raiding by elephants occurred only during the dry months, but the frequency was much lower than in the south. Raiding in the intermediate zone was more irregular. This raiding pattern was clearly related to the seasonal migration of elephants between Waza and Kalamaloue National Parks in the south and in the north, respectively.

We can also examine the influence of rainfall on crop raiding in terms of their variation from one year to another. During 1982, the crop yields in the Biligirirangans were poor because of a drought in southern India related to El Nino. I observed that elephants raided crops only about half as frequently that year compared to the previous year, when rainfall was normal. Richard Hoare's

Figure 8.2

Monthly per capita frequency of crop raiding by elephants in relation to monthly rainfall in the Biligirirangans in southern India during 1981-1982. (Based on Sukumar 1985, 1989a.)

Figure 8.2

Monthly per capita frequency of crop raiding by elephants in relation to monthly rainfall in the Biligirirangans in southern India during 1981-1982. (Based on Sukumar 1985, 1989a.)

study during 1993-1995 in Zimbabwe's Sebungwe region found only a weak relationship between annual rainfall and raiding frequency in a given year. Raiding was highest during the year with intermediate rainfall and lowest during a drought year.

Thus, a complex interplay of factors seems to decide raiding frequencies. While the seasonal availability and productivity of crops is a major determinant, the movement pattern of elephants and the relative difference in productivity or quality of crops versus wild forage may also influence raiding frequency.

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