Economic Valuation of Rice Crop Damage by Red-billed Quelea and Other Granivorous Birds on a Rural Irrigation Scheme in Western Kenya

Aims: The study aimed at estimating economic losses incurred by farmers from damage of rice crop by graniviorous pest birds and assessing the implication of this for sustainable food security.

Study Design: Line transect bird sampling with spatial and temporal replications; bird feeding rate determination; per-season and per annum economic valuation of rice damage
Place and Duration of Study: Ahero Rice Irrigation Scheme in western Kenya from November 2011 to February 2012.
Methodology: To estimate economic losses of rice we first estimated graniviorous bird density from two census periods from whence we estimated seasonal and annual quantities of rice loss calculated from the birds’ feeding rates. We then valued economic damage as a factor of the crop loss and prevailing rice producer market price and finally estimated net economic loss by subtracting the cost of hiring labour to scare birds from damaging mature crop. Period of bird damage was restricted to the period between crop-maturity to harvest.
Results: Estimated annual loss was 407 tonnes or 7.7% of potential yield for the whole irrigation scheme excluding bird scaring costs. This was equivalent to Ksh. 40.7 million annually at 1 USD=87 Ksh. representing a 31.1% loss of net income. Inclusive of bird scaring costs, annual losses were Ksh. 20,763/ha equivalent to 39.5% of net income. Estimated annual rice damage due to Q. quelea was more than that due to the other granivorous birds combined (215 compared to 192 tonnes).
Conclusion: This loss magnitude considerably undermines efforts to reduce rural poverty and attain sustainable food security. In addition to the crop-guarding method, reducing losses from damage by the pest birds requires integration of several measures that have proved successful elsewhere, adoption of improved farming technologies and planting recently developed higher- yielding rice varieties.