The use of photographic rates to estimate densities of cryptic mammals: response to Jennelle et al. - Carbone, C; Christie, S; Conforti, K; Coulson, T; Franklin, N; Ginsberg, JR; Griffiths, M; Holden, J; Kinnaird, M; Laidlaw, R; Lynam, A; MacDonald, D; et al. (ANIMAL CONSERVATION, 2002)