Date: 3/25/20 7:37 am
From: Nick Bolgiano <nickbolgiano...>
Subject: vulture-eagle interactions at Tussey Mt HW
Zoey noted yesterday how turkey vultures frequently give away the presence
of eagles. If we don't see the eagle when this happens, it is only because
we fail to spot it. We look for vultures as much as for eagles. Turkey
vultures are deathly afraid of golden eagles. One time, I saw a golden
eagle make a pass at one and get very close, only for the vulture to fold
up, drop-shift, and evade.

Zoey, being a true vulture aficionado, was quick to learn how this works,
which happens way more in the spring than in the fall. One reason for this
is that there are many more vultures around during spring golden eagle
migration and the second is that the give-away seems to be more common when
eagles are moving slowly, as they commonly do in the spring when thermals
are more active. The fall golden eagle migration is concentrated
roughly two months after the fall equinox, eagles are much more reliant on
ridge updrafts, and tend to move steadily through. The spring golden eagle
migration occurs near the spring equinox, the sunlight is much stronger,
and eagles are able to use thermals to a much greater extent, making spring
migration much more challenging as far as spotting the birds. That is why
our vulture help is much appreciated. A flapping vulture often conveys a
sense of eagle distance.

Attached is a picture of a vulture party preceding an eagle sighting.
Also, two pictures of soaring golden eagles, by far the easiest time to
identify and age them. Instant ID is from the long tail and relatively
small head and how the trailing edge of the wing pinches in at the body, a
tip I learned from Dave Brandes many years ago. Bald eagle wings pinch in
only slightly and their head and tails are about equal in length, for they
have a longer head and a shorter tail.

Over a spring season, these scenes occur many times.

Nick Bolgiano

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