Rat spatial distribution pattern and its relation to pod damage in a cocoa-coconut planting system

K. A. Kamarudin and C. H. Lee

Abstract

The spatial distribution pattern of rats and cocoa pod damage In a cocoa-coconut planting system was studied in two 30-ha fields for 20 months. Assessments of rat numbers, visitation patterns, pod damage and incidence of trees attacked were undertaken in a rectangular grid with 10 x 10 cocoa trees as co-ordinates in each field. The total number of animals caught and marked in the two fields were 215 and 307 respectively A majority of the animals were caught on the jorquettes. The estimated intra-population dispersion had K values of 3.9 and 8 .7 respectively. Not all co-ordinates were visited, and the visitation pattern studied showed animals to aggregate. Based on animals caught on four or more occasions, equal number of males and females showed clumped distribution. A few animals exhibited random movement, of which most were males. No animals showed hyperdispersion. Damaged pods were scattered and unevenly distributed in the two areas. The K values for both fields were 1.16 and 2.05 respectively, indicating clumped damage. The incidence of trees attacked also showed low to moderate clumping with K values of 2.f16 and 3.06. Slight correlation was observed between visitation pattern and pod damage.

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