Relative Importance of Experience and Meteorological Factors in Migratory Performance of Golden Eagles (Aquila chrysaetos)
Abstract
Migratory performance of large soaring raptors primarily is influenced by experience and by weather conditions. We evaluated the relative importance of these factors on the migratory performance by eastern North America migratory Golden Eagles (Aquila chrysaetos). We analyzed GPS data from 65 eagles that spanned three age classes (juvenile, sub-adult, and adult). We defined migratory performance as the distance an eagle travelled at hourly and daily scales and we only considered movements we defined as migratory (>10 km over 1 hour). We paired each GPS point with NCEP/NARR meteorological covariates linked to wind speed and direction, solar radiation and updraft potential. Our results show that on average, Golden Eagles traveled from approximately 10 to 470 km per day and had strong influences of both weather (birds travelled farthest on days when potential for thermal updraft was highest) and experience (there is strong seasonality in migratory movements). Next steps in the analysis include model selection on a set of candidate linear mixed models to evaluate the importance of each of these factors. Then, we will evaluate these models in the context of potential evolutionary pressures the birds face when making migratory movements.
Relative Importance of Experience and Meteorological Factors in Migratory Performance of Golden Eagles (Aquila chrysaetos)
Migratory performance of large soaring raptors primarily is influenced by experience and by weather conditions. We evaluated the relative importance of these factors on the migratory performance by eastern North America migratory Golden Eagles (Aquila chrysaetos). We analyzed GPS data from 65 eagles that spanned three age classes (juvenile, sub-adult, and adult). We defined migratory performance as the distance an eagle travelled at hourly and daily scales and we only considered movements we defined as migratory (>10 km over 1 hour). We paired each GPS point with NCEP/NARR meteorological covariates linked to wind speed and direction, solar radiation and updraft potential. Our results show that on average, Golden Eagles traveled from approximately 10 to 470 km per day and had strong influences of both weather (birds travelled farthest on days when potential for thermal updraft was highest) and experience (there is strong seasonality in migratory movements). Next steps in the analysis include model selection on a set of candidate linear mixed models to evaluate the importance of each of these factors. Then, we will evaluate these models in the context of potential evolutionary pressures the birds face when making migratory movements.