Dogs increase recovery of passerine carcasses in dense vegetation

Wildlife managers use carcass searches to assess mortality resulting from b iological (e.g., diseases) and physical (e.g., structure collisions) source s. Carcass searches may occur over large areas and need to be completed rap idly because of scavenging and decomposition. However, small carcasses are often missed when dense vegetation is searched. We placed carcasses of hous e sparrows (Passer domesticus) in dense cover of residual and newly grown v egetation and compared searching efficiency of humans and canines. Dogs rec eived no special training in searching for passerine carcasses. In 36 trial s conducted in 5 X 40-m plots? human searchers found 45% (SD = 19) of the c arcasses compared to 92% (SD=13) for dogs (P=0.005). The ratio of recovered to missed carcasses was approximately 12:1 for dogs and 1:1 for humans. Th e improvement in searching efficiency using dogs was similar (P=0.58) betwe en residual cover (searched in April) and new growth cover (searched in Aug ust). A greater rate of searching efficiency is obtained per unit of time b y using dogs. Greater efficiency improves quantitative and qualitative asse ssments of avian mortality in the field.