Wednesday, May 22, 2013

Under the Gaze of the Phantom of the North - Great Gray Owl!

This is the third post from Karyn and my recent trip to Yellowstone National Park. Many more to come!

Post 1: Eye to Eye - Sandhill Cranes
Post 2: Bullying the Bully - 3 Coyotes v. 1 Wolf

Over the years we have made many friends with the wildlife watchers who visit the park the same time of year that we do. It is always interesting to arrive and see who else is around. Our friends Paul, Mark, and Carol all left the week before we arrived, but our good friends Jim and Joellyn were there. We had missed them last year so it was great to spend time with them. Jim and Joellyn volunteer as part of the wolf project and have a deep knowledge of the history of the wolf reintroduction in the park and the current state of the wolf packs. We spent hours with them at "Dorothy's Knoll" waiting for the wolves and bears to find the bison carcass laying in the center of the Lamar Valley (apparently died of natural causes).

We were camping just outside the northeast entrance of the park near Cooke City. Jim and Joellyn were staying in Cooke City. Each morning upon meeting up in the Lamar Valley we would compare notes on what we have seen on the drive in. This almost always included Moose and Bison, but occasionally included more exotic species. One morning Jim mentioned that they had seen a Great Gray Owl! Wow, we were 15 minutes ahead of them and had seen nothing. I pressed him for details. What does a raptor biologist do with information about the location of a rare raptor (rare for the area) during breeding season? Go look for a nest!

Great Gray Owl Global Range Map. From Wikipedia.

That evening Jim and Joellyn observed the bird again on their way back to Cooke City. Amazing. We passed slowly through the areas, but didn't see anything (except Moose). The next day Jim marked the location on a log with some Black tape. The pressure was on. I now had to find the nest. My reputation as a Raptor Biologist depended on it.

Jim's marker.

Searching for a nest sounds easy, but it is actually fairly hard. Mistletoe, a parasitic plant, grows in dense balls in trees. These look like a nest and are everywhere. Furthermore, I knew little of the type of nests that Great Gray Owls prefer. I knew they did not build their own nest as no owl builds a nest. That means it uses a Northern Goshawk nest, a Raven's nest, or some other structure. As we left the highway, Karyn suggested that we go left, but I had my sights on the right.

Karyn's vote.

We searched to the right, zigging and zagging every 50 meters out to a distance of 200 meters. We crossed the road and continued there. A carcass... a Robin... plucked by a bird... But probably not our bird. Maybe a Cooper's Hawk.

Plucked American Robin.

We decided to take a pass though the route that Karyn originally suggested. As I led out, within 5 minutes, I saw a large Mistletoe ball. Wait! There were tail feathers extending over the side! We found it! All I could see were the horizontal tail feathers. We re-positioned ourselves to get a better view.

Great Gray Owl nest in Mistletoe ball, Yellowstone National Park.
Great Gray Owl nest in Mistletoe ball, Yellowstone National Park.
Great Gray Owl nest in Mistletoe ball, Yellowstone National Park.
Great Gray Owl feather.

We kept our distance and kept quiet. Raptor nests early in the season are particularly vulnerable to disturbance. No matter how habituated a raptor may be to humans, disturbance still has an impact on reproductive success (Strasser 2010). We noted the lack of fecal material on the nest rim indicating that the eggs had not hatched or if they had, were less than 5 days old. The owl's posture indicated that they had not yet hatched. My first Great Gray Owl nest!

Since Jim had gone to such work to mark the location, I wanted to take him to see the nest. This provided a great opportunity to share my knowledge of owls with him.

Raptor Rob (left), Jim (right), Great Gray Owl nest in the distance.
Scoping the nest!

I asked Jim to take another look in three weeks to let me know how many nestlings hatch.

1 comment:

Ronnie Howard said...

how far from the road is this nest. we will be there next weekend. We live near Jackson and love great gray owls but have never seen a nest. We respect wildlife and would not disturb them

Thanks Ronnie Howard