Bighorn Basin site, mid-May 2012.
The same Bighorn Basin site, mid-May 2011.
Wow! We finally got a break last week from the hot, dry spring weather with two days of rain, and today we have temps in the 30s and snow. What a difference a week makes. This was shaping up to be the warmest, driest spring in decades. Sometimes people forget to make the distinction between long-term climate change and day-to-day, season-to-season, and year-to-year weather fluctuations. Both are important to patterns of vegetation and animal behavior, but exert their influence on different time and geographic scales. Just to document year-to-year variation, I shoot photographs of several sites in our Golden Eagle study area in the Bighorn Basin on or about the same dates each year. Comparing my photographs of this May 16 with last year’s May 16 at one site shows how much drier we have been this year. It will be interesting to see how this recent wet spell changes things.
Golden Eagles are well into the nesting season, with the first eggs hatching in late April. Our citizen scientists, the Golden Eagle Posse, have been monitoring several selected nests since the first of May. Here are some excerpts from their weekly narrative reports thus far:
From Anne Hay and Richard Gruber, 01 May: We arrived at 1:00 P.M. to find an adult sitting on the nest. 5-minutes later the other parent arrived, but only stayed for about 4-minutes, then flew to the top of the ridge. The female then stood up, and fed on an unknown food source for a short time. We saw no signs of a chick, so we ask ourselves, “brooding, or incubating?” The female then spent most of her time lying down, with some feeding from this position. At 2:27 the female stood up and stretched. “We have a chick,” I exclaimed. A little head popped up, looking quite white in the sunshine. Mom left briefly, returning with pine boughs to add to the nest. She fed the chick for a couple of minutes, then continued to brood. At 3:01 the male arrived with what looked like a talon full of dry grass. The female looked as though she was calling out the entire time he was present, as we could see her mouth moving up and down, however, with wind gusting to 30 mph toward the nest, we could not hear her.
This curious youngster is ready for some food! C.R. Preston photo.
And here is a report from Richard Brady and Sharyl McDowell, 07 and 10 May: last week we reported two chicks on nest… Today only one at a time. Scanned rocks/cliff bottom etc. No baby eagle apparent. Chick appears to be 5-15 day old. Very white down. Moving around inside the nest, did not see second parent eagle. An eagle soared over the nest for a while, but there was no calling, it did not come in to perch and mom eagle did not leave the nest. Could have been an eagle from the airport nest out for some exercise. 5/10: Arrived at nest site in a 10~20 mph wind. Ascertained an adult eagle was sitting in the nest site. Absolutely no activity during our observation period. She at times did turn her head from left to right. No sighting of second eagle. The large antelope we have observed each time was present again but he also soon disappeared, seeking shelter from the wind. The other times we have visited this nest, we have seen and heard any number of smaller birds flying and calling. Today we did not observe or hear any of this activity. Conclusion: Birds don’t like to try to move around in the wind either.
Just a sampling of prey remains from one golden eagle nest last year. C.R. Preston photo.
This is an excerpt from last week’s report from Bud and Dale Schrickling: During the first observation period we were able to verify that there was a single chick in the nest. We witnessed a parent return to the nest and feed the chick. Our optics prevent aging the chick at this time due to the distance we are away from the nest. The second observation period was cut a little short due to bad weather. We intended to return later, but both were not well for a couple days.
And, finally, here is a note from Sammi Bray from 22 May: Arrived at nest at 1430, it was windy as crap so I did not stay due to poor observation conditions (could not even hold binoculars still; wind estimated at 30-40mph). No data sheet for this observation. Greenery was visible on nest, but no adults or chicks could be seen. There is no place to get a good line of sight into this nest that is not extremely far away.
Well, some days are better than others. Hang in there Sammi!!
Our 2012 undergraduate intern from the University of Wyoming, Nathan Horton, is taking advantage of today’s nasty weather to stay in our lab and begin sorting through some of last year’s Golden Eagle prey remains we collected at the end of the nesting season, after youngsters fledged. You’ll be hearing from Nathan in subsequent postings, and much more from our Posse as the eagle nesting season progresses. Stay tuned!