Pitfall traps: A review of methods for estimating arthropod abundance

Pitfall traps are commonly used in diet studies for insectivorous and omnivorous wildlife. Pitfall trap methodologies and designs vary considerably among studies and investigators. Such variation and lack of standardization limits scientists' abilities to compare their results with others. We conducted a literature review to identify the most common methods used by past investigators who placed pitfall traps for the purpose of quantifying indices of arthropod abundances, and used this information to guide our proposal for standardized pitfall trapping methods. We documented the pitfall-trap methods of 257 studies published between January 1994 and March 2016 in 107 scientific journals. Pitfall-trap methods varied greatly across the time period. We found only minor differences in the pitfall-trap methods most commonly used in different vegetation communities (e.g., preservative was used less frequently for pitfall trap studies in grasslands). Studies published in wildlife journals tended to use pitfall traps of larger diameters than studies published in other disciplines; these studies also had worse rates of methodological reporting than those in entomology journals. We did not detect a decline in negligent reporting over time; >= 1 key methodological detail was missing from >50% of studies regardless of the decade published. Published 2018. This article is a U.S. Government work and is in the public domain in the USA.