Many aspects of human behaviour impact on ecological systems. For example, farming practices affect biodiversity in agricultural landscapes (Robinson & Sutherland 2002), and fishing, hunting or collecting forest products can affect target and non-target populations (Milner-Gulland & Mace 1998). Ecologists often need information on changes in these behaviours and are therefore increasingly using methods more familiar to social scientists, such as interviews and social surveys (White et al. 2005). However, there is little quantitative information available on the reliability of these methods, which limits their usefulness as a tool for scientific management.

Quantification of local people’s use of wildlife is important in assessing the sustainability of harvests (Jones et al. 2005), or their value to local people (Godoy et al. 2000). In addition, harvester behaviour and off-takes may contain information on stock status (Siren, Hamback & Machoa 2004) and therefore provide cost-effective monitoring. Interviews with harvesters where informants are asked to recall extraction over a period of time are often used to quantify use of wildlife resources (e.g. Sambou et al. 2002; Wynne & Cote 2007), and can generate information with less effort than more intensive methods such as daily interviews (e.g. Jones et al. 2006). However, little is known about the quality of the information reported in interviews with long recall periods and, hence, their reliability as indicators of trends. We know of only one study that formally validates the results of rapid assessment interviews about forest product harvesting with data on true levels of harvesting over a year (Gavin & Anderson 2005).