Human body-mass index (weight in kg/stature in m²) as a useful proxy to assess the relation between income and wildlife consumption in poor rural societies

There is growing interest in assessing how income influences the consumption of wildlife in poor rural areas of developing nations. The interest stems from the possibility of using income to contribute to the conservation of wildlife. Though promising, efforts have been hampered by the difficulty of obtaining accurate measures of income. We propose using human body-mass index (BMI: weight in kilograms/physical stature in m²), an indicator of short-term nutritional status, as a proxy variable for monetary income to estimate income elasticities of wildlife consumption (income elasticity: percent change in wildlife consumption/one-percent change income). The advantages of BMI over monetary income include a positive association with monetary income, ease of measurement, and absence of zero values. The assessment procedure was tested among Tsimane' Amerindians, a society of foragers and farmers in the Bolivian Amazon. The population over 15 years of age (350 men and 322 women) in 13 villages was surveyed for five consecutive quarters (August 2002-November 2003). Income elasticities of wildlife consumption using BMI as a proxy for income ranged from -0.84 to -1.20. The estimates suggest that wildlife is a food item whose consumption declines with increasing income. Estimates of income elasticity of wildlife consumption using conventional indices of monetary income are negative, but lower and indistinguishable from zero owing to classical measurement errors of monetary income. The use of BMI to estimate income elasticities of wildlife consumption is promising, but requires further validation in different settings.