Dr. Charles R. Preston, Senior and Founding Curator, Draper Natural History Museum, at the Buffalo Bill Center of the West, Wyoming
11 June – Wyoming, Park County, Bighorn Basin, east of Cody: What a beautiful day in the Bighorn Basin! While the Yellowstone Plateau to the west is getting more snow today, this easternmost front of the Greater Yellowstone Ecosystem is partly cloudy, cool (about 51 degrees F at 08:00), and with only a slight breeze from the west. The roads are muddy, though, and I wasn’t able to reach some of the nest areas I wanted to check on this morning.
With all the recent moisture, the sagebrush-steppe is uncharacteristically green, and wildflowers are blooming everywhere. Each year brings a different look, with different blooms, depending much on timing, amount, and type of moisture. Our Draper Museum research assistant, Richard Jones, and I visited a couple of our Golden Eagle nest sites, and saw several subadult, non-nesting eagles in the area.
We also watched a female Northern Harrier feeding on a Uinta Ground Squirrel. We saw no sign of the Burrowing Owls that nested in the Oregon Basin area last year, but saw and heard many Long-billed Curlews. Lots of Pronghorn running around, too – but we didn’t see any new fawns.
We split up around noon, and I drove north in our study area to check on Golden Eagle nest 60A and the Red-tailed Hawk nest in the nearby drainage. The cottonwood ribbons located along these few drainages in this dry landscape provide nesting opportunities for Red-tails and a few Swainson’s Hawks. Occasionally, we find Golden Eagles nesting in these areas, but most of our eagle nests are on sandstone outcrops. Of more than 60 eagle nest sites we’ve identified in our study area, only 3 are in trees – only one of these tree nests is occupied this year. Our research is designed to help us understand the independent and combined effects of various human activities, weather, and prey availability on mortality, breeding success, and productivity of predators like the Golden Eagle, but we’re also interested in gaining a better understanding of why some eagles are more tolerant than other eagles to human disturbance and environmental change…how much of this tolerance is learned and how much is inherited? These questions speak to the heart of our Draper Museum mission – to increase understanding and appreciation of the relationships binding humans and nature in the Greater Yellowstone region.
A huge part of our study depends on a group of volunteer citizen-scientists – our Golden Eagle Posse. These folks contribute in many ways, but one of their most important duties is to monitor selected eagle nests each week from observation posts several hundred meters from their assigned nest. These Posse members record detailed data on preprinted data sheets, but also maintain field journals to document their experiences and observations. Here is a sampling from the summary reports submitted by Posse members during the last couple of weeks:
Sharyl McDowell and Richard Brady recorded these observations on June 6:
Wow – our baby birds are growing up. Large chick has almost all dark body feathers – The V between head and chest is dark – body feathers under the wings are still white. Front of head is white – top and back are a light brown/light gold color. Smaller chick is showing lots more brown feathers – wings and body are mostly brown. V on chest is still white as are the head and body feathers under the wing. I still estimate this chick to be a week younger than the larger sib. I now see how the white wash gets on the edge of the nest and the rocks below. the smaller chick stood – facing the interior of the nest = and squirted fecal matter 2-3 feet – which caused it to land on the from of the next and the rocks below. There’s an explanation for everything!!! 1515 – Parent bird arrived, bringing what I think was a rabbit. She is tearing it apart and feeding the chicks. Large chick seems to receive food morsel and eat it in its entirety – while mother is still feeding the younger chick.
Anne Hay, Richard Gruber, and Don Chaffey recorded these observations on June 10:
We had a busy day at the nest! Both our babies are healthy and well fed. So well fed, that we see no begging behavior at all. Each stands by patiently as the other sibling is fed. The oldest has a lot of brown on it, including its wings, around the neck area, and the sides of its breast. The younger has brown on both its primary and secondary wing feathers. We saw the adults a number of times, with one perching on various locations along a couple of the rock formations for long periods of time. One rabbit was brought to the nest, and based on the size of this rabbit compared to the mother as she dragged it from one side of the nest to the other, and the 15 minute feeding time, we speculate that it was a cottontail, but we do not have definitive proof. The other feeding was both sad and interesting. As I was watching an adult perched along a rock formation, she (he?) turned, then flew to a tree (pine?). As she perched on a branch she looked into the tree, then moved within the branches. A magpie flies at her, and she comes out of the tree with something in her talons, flies to the nest with the magpie making a brief chase, where she does a very brief feeding. This was such a brief feeding, that I suspect that it was a chick from a nest within the tree branches. Maybe a baby magpie? I tried to see if there was a large, roundish style magpie nest in the tree, but from our distance, even with the scope, I could not see a nest within the branches. It is really getting beautiful around our view point, we have a few more wild flowers blooming, and everything is so green.
And Former Wyoming Game Warden Dave Bragonier and his wife Germaine recorded these observations earlier today:
Both chick and parent were present in the nest upon our arrival. Shortly thereafter, and although the wind was howling, we heard what turned out to be eagle chatter between two eagles – the adult on the nest and an adult on the ground on the steep sidehill about 75 meters below the nest. The eagle on the ground had caught a cottontail rabbit, but it was obviously struggling to get the carcass up to the nest and seemed to be begging for help with the effort. The eagle from the nest swooped down, grabbed the dead rabbit, and in increments, managed to get the carcass on a point above the nest, where it soon arrived with the lunch. My belief that this was a single-parent nest was immediately shattered! Where had this other adult been hiding all this time? And, the bird also left toward the east! I’ve been fooled too many times over the years by Mother Nature that I should know better by now but don’t. My latest theory: old experienced mom, – young, dad.
I really look forward each week to hearing from all our Posse teams! We will begin posting video clips in the coming weeks. In the meantime I hope you enjoy the photographs and notes from our ongoing adventure with Golden Eagles in the Greater Yellowstone Ecosystem. Next week, we’ll be taking out a group of youngsters to learn about eagles, the sagebrush-steppe environment, and the process of studying nature through scientific inquiry. This is one of our Discovery Camps organized by the Center’s natural history educator and interpretive specialist, Emily Buckles. Stay tuned for a posting of their experience. In the meantime, get out, explore, learn, and inspire someone to experience nature!
So long, from the Draper Museum of Natural History, Buffalo Bill Historical Center in Cody, Wyoming.
