Ecological profile of a Nigerian Sahelian wetland: toward integrated vertebrate pest damage management

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Virginia Tech


Interactions among the components of a Sahelian wetland and the ecologic-economic significance of the wetland are described as they relate to vertebrate pest damage. Ongoing hydro-ecological changes, started by periodic meteorological droughts and sustained by the effects of large-scale hydro-agricultural schemes, are described along with their impacts on wildlife habitats and other valuable wetland resources.

People in most communities in the wetland reported crop depredation by vertebrate wildlife. Traditional controls of pests are still practiced, but most are ineffective or time consuming. About 64% of the communities consider acoustic scaring techniques to be the most effective methods of vertebrate pest control. Depredation intensity is exacerbated by: 1) large-scale and year-round cultivation of cereal monocultures; 2) diminishing wetland habitats which concentrates wildlife and farms in a small area, thereby creating ideal conditions for wildlife-crop interactions; and 3) poor husbandry. Yield loss estimates due to vertebrates for major wetland crops were appraised as follows: 15.6-19.9% for rice; 10.6-15.6% for millet; 7.6-14.9% for sorghum; and 25.8-30.2% for cowpea.

About 28 vertebrate species were considered to be contributing to the agriculture-wildlife conflict. Quelea guelea and rodents (mainly Avicanthis niloticus, and Mastomys natalensis) were the most important pests. Waterfowl depredation was uncommon, but locally severe wherever it occurred. Philomachus pugnax, perceived by many local farmers as a serious pest of rice, was observed not to be a significant pest in the wetland.

Experimental investigations of the susceptibility of local rice varieties to granivorous passerines found yarkaushe to be the most resistant. Loss of grain cereals appeared to vary locally with places closest to avian haunts suffering higher losses. The nearness of farms to fallow plots and the flooding status (in the case of rice fields) were also important determinants of depredation intensity. I propose managing the agriculture-wildlife conflict by using the strategy of integrated vertebrate pest damage management (IVPDM), an approach which emphasizes shifting attention from controlling the pest species per se to cost effective changing of the damage they cause using several techniques simultaneously. The following techniques are recommended as potential components of the proposed IVPDM system: 1) improving husbandry practices; 2) manipulating the environment; 3) using audile and visual scaring devices; and 4) using limited amounts of rodenticides.