Performance of Ramp and Pitfall Traps for Arthropods and non-Target Vertebrates in Californian Oak Woodland and Chaparral Habitats

Abstract

Abstract. \n Selection of tools for monitoring epigeal arthropods may be limited by site characteristics and the need to reduce risk of vertebrate bycatch. We designed a ramp trap for sampling surface-active arthropod diversity and compared its effectiveness with pitfall traps. Paired transects of ten ramp and ten pitfall traps were laid out in five sites at the Hopland Research and Extension Center in California. We identified and enumerated the ground-dwelling arthropods in the samples, with an emphasis on beetles and spiders, and compared trap types using t-tests and NMDS. There was no significant difference in abundance and diversity between ramp and pitfall traps for beetles or spiders; however, there were significantly more millipedes caught by pitfall traps. The NMDS analysis of beetle assemblages distinguished between trap types; however, differences were not significant for spider assemblages. The ramp traps were more difficult to fabricate and transport because of their complexity and bulk, but they were easier and faster to setup, more resistant to disturbance, and resulted in less vertebrate bycatch. Ramp traps are a useful tool to be used alongside or as an alternative to pitfall traps.