Comparison of Snap Traps and Cages for Trapping Rattus norvegicus in Urban Residential Buildings

Mechanical traps are widely used for urban rat surveillance and management, including the brown rat, Rattus norvegicus (Berkenhout). However, relatively few studies have examined the effects of environment, placement, and trap type on trapping outcomes in residential buildings. In this study, we deployed 50 pairs of snap traps and live cage traps for five nights (500 trap nights) in concrete-covered basements in Brooklyn and dirt-covered crawlspaces in Queens, New York City, USA. Capture success differed by site, with Brooklyn yielding higher overall success (38%) than Queens (13%) (p < 0.001). Capture success in Brooklyn was lower in compactor rooms than in other areas (vertical infrastructure, open-floor travel corridors, and burrow entrances). In Queens, success was similar at different placement areas. The two trap types had similar overall capture success (p = 0.090). Cage traps produced more female-biased samples (90% females), while snap traps yielded more balanced sex ratios (53% females) (p < 0.001). In addition, median body mass distributions also differed, with snap traps capturing heavier rats than cage traps at both sites. These findings demonstrate that both placement and trap design are important considerations for urban rat surveillance and urban rat management.