Anthropogenic contribution to the acoustic environment of Mexican spotted owls in the Gila National Forest, New Mexico Available to Purchase

We monitored the acoustic environment of Mexican Spotted Owls using an array of Larson‐Davis (LD) sound level meters (SLMs) from 2000 to 2005. Thirty‐nine LD‐820 and LD‐824 SLMs were deployed in a distributed array across a 20 km×24 km area, collecting two‐second time interval data as continuously as possible mid‐April to July. Although the study was designed to monitor low‐flying military jets, SLMs collected over 350,000 hr of usable environmental noise data. The data were summarized by time, average level, and on an energy basis. The most important identifiable sources differed depending on metric. On a time basis, the ambient was the greatest contributor, followed by biotic sources and thunder. Regional jets were unexpectedly important, accounting for 2% of the total, far more than military jets. However, military jets and thunder accounted for most of the exposure to high amplitude noise (proportion of 2‐s samples with LAeq \? 60 dBA). In terms of cumulative sound exposure, thunder was the greatest contributor, followed by ambient noise and military jets. The sources most likely to impact owls will depend on the critical features of noise from their perspective; identifying these features is the focus of future analysis [Work supported by U.S. Air Force ACC/CEVP]