Measuring crop damage and yield loss is labor
intensive and complicated by the ability of rice to
compensate for rodent damage up to tillering (Buckle
and Rowe, 1981; Islam and Hossain, 2003). Damage is
measured usually only once after tillering, often in the
2 weeks prior to harvest (Buckle et al., 1985; Fieldler,
1986). When rice is mature and nutritious, to obtain
sufficient food rats need to cut only 1–2 tillers instead
of numerous tillers at booting. That only 16% of the
cumulative damage was recorded just prior to harvest
suggests that a 6.5 times multiplier of damage in the
week prior to harvest would provide a simple index for
estimating rat damage during the reproductive stage of
lowland irrigated rice.