Weaver news

PAPER: Estimating Bird Damage to Rice

2012-04-15 (206)

de Mey Y, Demont M, Diagne M. 2012. Estimating Bird Damage to Rice in Africa: Evidence from the Senegal River Valley. Journal of Agricultural Economics 63:175–200.

Abstract. Granivorous birds, mainly the Red-billed Quelea, have subsisted on cereal crops in Africa for centuries and have caused substantial damage. There is, however, limited recent evidence on their impact. We propose an indirect method to estimate bird-inflicted crop losses by fitting a production function with a damage abatement component and pest intensity slope dummies on a panel database of rice farmers in the Senegal River Valley. This allows us to estimate both bird damage and marginal productivity of bird control at different levels of bird pressure. Annual bird damage is found to average around 13.2% of the potential rice production during the wet seasons of 2003–2007, which translates into an average annual economic loss of 4.7 billion FCFA (€7.1 million). Our results are consistent with farmers’ perceived bird-inflicted crop losses, averaging 15.2%. More alarmingly, we observe declining marginal productivities of bird control under increasing bird pressure. Farmers indicate that at high bird pressure, the efficacy of traditional bird scaring methods is inadequate, which suggests that predictive (monitoring), preventive (population control) and protective (insurance) measures against massive invasions are more urgent than improving the average efficacy of curative measures (pest control). These findings are especially relevant to farmers and policy-makers who are currently struggling to implement an ambitious food self-sufficiency programme in Senegal.

Bird species that cause damage to cereal crops in West Africa include several weaver species, the most important species being the Spur-winged Goose Plectropterus gambensis, Knob-billed Goose Sarkidiornis melanota, Village Weaver Ploceus cucullatus, Black-headed Weaver Ploceus melanocephalus, Red-billed Quelea Quelea quelea, Red-headed Quelea Quelea erythrops and Golden Sparrow Passer luteus.

Photo: male Red-billed Quelea.

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