Thursday, April 18, 2013

Peregrine Survey

Young falcons at Aggie's Bluff in 2012
According to the weather forecast, 4/16/13 was the only sunny day this week. Time for a peregrine survey! Dave Kester and I set off at 6:30 AM for the Lansing Power plant cliff, where we quickly located two adult falcons.  One was sitting on a cliff nest box that we mounted several years ago to attract falcons away from a ledge that provided poor shelter and was accessible to raccoon. The ledge nest site failed to produce young, but the nest box has proven productive. Nine young have fledged from this site since 2009.

We were very pleased to find an adult female falcon on Guider’s Bluff just south of the town of Lansing, IA.  We heard one bird wailing, indicating that there was probably a second falcon on site.

We did not find any falcons on Aggie's Bluff, two miles upstream of the Lansing, IA bridge.  We decided to head upstream and return to this cliff later in the day.
We found two adult falcons at the Shellhorn cliff just south of Brownsville, MN.
We did not stop for long at the new V cliff south of Homer, MN, since I had confirmed two falcons defending the site on my last river survey.  I remember hovering over this cliff ten or more years ago in a Bell Jet Ranger helicopter and thinking that someday this cliff could attract falcons, since it looks much more falcon-friendly from the air than from the ground.
Dan Berger at Homer Bluff. Dan documented
the extirpation of the Peregrine from the Mississippi
in the 1950s. He is still banding birds today. 
We were very excited to find two falcons defending the Homer/P4 cliff that has not attracted nesting falcons for a few years.  We observed one falcon fly and land in a tree very close to the eyrie location.
We have falcons at Red Wing Grain, but needed to confirm whether we also had them at Diamond Bluff, in Diamond Bluff Wisconsin. We were pleased to find two adult falcons defending this cliff, but we don't know whether they are using a nestbox or a pothole. This cliff will need some observation. We mounted this nest box over 20 years ago, and we are very pleased with how it has held up.

We saw falcons at West Bluff and Maiden Rock, staying at Maiden long enough to confirm one falcon protesting a vulture flying to close to the eyrie. All appears well at this location!

There were no falcons at Twin Bluff in Nelson Wisconsin. This is our third visit to this cliff without finding falcons, although we found two adults on our first survey. A mystery.
We found one falcon on the cliff face at Maassen's bluff, and our friends who live down below indicate that all is well.  The pair is using an eyrie we improved by adding 80 pounds of pea-gravel to improve nest drainage.

I observed one falcon at Castle Rock on 4/9/13, during driving rain.  On this visit, we observed two adult falcons. However, the adult female left the cliff and flew out of sight, heading directly north. She did not return. The adult male set off in the direction of the Bay State Milling plant in Winona, MN, where our nestbox camera has confirmed four eggs.  If I recall correctly, every time we have falcons at Bay State Milling we do not have nesting falcons at the nearby Castle Rock cliff.
We passed by the Homer/P4 cliff again and made our way downstream to a new cliff.  The light was very poor, since we had to look into the setting sun, but we did spot one falcon perched on a limb near the cliff top. We raced back up to the Homer (P4) cliff hoping to confirm falcons were not just bouncing back and forth between the two cliffs.  We were pleased to find two adult falcons on site.
 By this time it was getting late in the afternoon, and we wanted to return to Aggie’s Bluff to see if a second visit would lead to finding a falcon. Despite the poor lighting conditions, we were pleased to find one falcon perched on the cliff face.
We returned home at 6PM, pleased to finding so many falcons defending Mississippi cliffs.  It was not that many years ago that some thought we would never have the peregrine back on these historic cliffs. It is wonderful to see them back 30 years after my first captive bred falcon was released in the river valley.
Bob Anderson