TREND ANALYSIS FOR THE NORTHERN SAW-WHET OWL IN MARYLAND

Abstract

Dunn and Hussell's methodology "Steps for Basic Analysis of Daily Migration Counts using Multiple Regression- was used with thirteen to seventeen years of Maryland banding data to conduct a trend analysis for the Northern Saw-whet Owl (Aegolius acadicus) population. No significant long term population trends were evident using this method with the Maryland data. However, the three stations analyzed showed similar four year cyclical irruption patterns. While the effort values varied between stations, effort did not directly relate to the number of owls netted. The index value (mean number of owls per day in that season after adjustment for variable effort and missing days) was highest at the station with the lowest effort values. The migration window and middle date of migration showed variation based on location- the earliest migration time began at the western most station with the highest elevation.