Date: 4/9/17 5:42 am From: Nick Bolgiano <nickbolgiano...> Subject: picture example of golden eagle heading north
Attached are pictures from March 29 at Tussey Mt of a golden eagle soaring higher and higher and eventually leaving the ridge to head straight north. At some point, all leave the ridges during spring migration and head N.
Biologist Trish Miller has explained how golden eagles employ three kinds of lift: updrafts off a ridge, thermals, and the third being to get up very high and utilize thermals for lift and wind (usually tailwind or crosswind) for push. They can use this third way to travel many miles cross country without depending upon ridges. I think that they use this third method more in spring than in fall, because fall migration is typically 1-2 months past the fall equinox and the sun's rays are comparatively weak, but spring migration is around the spring equinox and the sun's rays are much stronger.
What is interesting about this particular eagle is that it was using this third way while flying into a 10-mph N headwind. Flying this way into a headwind isn't the common case, but I've seen it with eagles, red-tails, and turkey vultures.