Meta-analysis of survey data to assess trends of prairie butterflies in Minnesota, USA during 1979–2005

摘要: During 1993–1996, two teams (Schlicht, Swengels) surveyed the same Minnesota prairies, but without any coordination of sites, routes, methods, dates, and results between teams. In 27 instances, both site in year 30 June 18 July. For most frequently recorded species, abundance indices (individuals/h per site) significantly covaried for 11 (61%) including 2/3 prairie specialists tested. No species correlated negatively, 17/18 had positive correlations, preponderance correlations was significant. Swengel hour (two surveyors; unlimited-width transect) averaged 2.42 times Schlicht (one surveyor; fixed-width transect). These demonstrate that transect surveys by different at sites not routes produce similar rankings among sites. This approach to population monitoring (transect during season covers specialist once, necessarily with fixed recording all seen) might also be appropriate other regions high habitat loss low human density. Abundance from seven spanning 1979–2005 were calculated evaluating trends. five analyzable 25/30 trend tests a negative direction, highly significant skewing (P < 0.0001). By contrast, “common” (most non-specialist) an even distribution While adjacent similarly timed decline thresholds (last when higher rate or individual vs. first subsequent lower zero) within these synchronized counties. All analyzed this study preserves managed primarily fire. ecosystem (or vegetative) reserve selection has been validated studies effective capturing populations associated butterflies, butterfly declines after designation will likely continue unless management includes specific consideration species’ required resources tolerances.