Monday, May 27, 2013

Beasts With Fur - The Mammals of Yellowstone

This is the sixth and final post from Karyn and my recent trip to Yellowstone National Park.

Post 1: Eye to Eye - Sandhill Cranes
Post 2: Bullying the Bully - 3 Coyotes v. 1 Wolf
Post 3: Under the Gaze of the Phantom of the North - Great Gray Owl!
Post 4: Bob!!!! - The Case For and Against Mobbing Behavior
Post 5: Bird Watching in Yellowstone

Most of the above posts are dominated by birds, but the primary intent in travelling to Yellowstone is typically to see the mammals. The Ecosystem in Yellowstone is one of the few places in the lower 48 states that has a predator assemblage that is nearly complete. Last year was our greatest year as far as action goes and this year was one of our lightest, but the animals were still around and showed up occasionally to surprise us. It was still well worth the trip!

As I have mentioned, the Grizzly Bears were all high in the mountains. We would see a number of them, but never up close. The wolves were generally traveling as individuals. In fact, only once on this trip did we get to see two wolves together. However, the best sighting was while we were hiking the Garnett Hill loop. This is one of our favorite trails that passes through a number of different habitat types. About 2 miles in, I saw a flash of black out of the corner of my eye. It had to be a wolf! It had ducked out of sight. I prepared the camera in case it came back into view. Yes!

Wolf 890 Male - "Patch" - of the Junction Butte Pack with GPS collar, Yellowstone National Park.

He provided some great views. Later in the hike we would spook up a Black Bear close to the same place we saw bears last year. This is only about a mile from teh Black Bear regularly spotted at Elk Creek.

Black Bear, Garnett Hill, Yellowstone National Park.
Black Bear, Elk Creek, Yellowstone National Park.

In addition to wolves in the Lamar and on the Garnett Hill hike, we also saw one in the Hayden Valley. After numerous trips to Hayden over the years, this is the first wolf we have seen there.

Lone wolf, Hayden Valley, Yellowstone National Park.

We would see moose nearly every day. One morning in Round Prairie, we saw six moose!

Moose, Confluence Lamar River/Soda Butte Creek, Yellowstone National Park.
Moose above Soda Butte Picnic Area, Yellowstone National Park.

Moving large to small...

Bison, Lamar Valley, Yellowstone National Park.
Bison, Lamar Valley, Yellowstone National Park.
Elk, Lamar River, Yellowstone National Park.
Bighorn Sheep, Specimen Ridge Trail, Yellowstone National Park.
Wet Coyote, Hayden Valley, Yellowstone National Park.
Wet Coyote, Hayden Valley, Yellowstone National Park.
Red Fox, Hell Roaring Creek, Yellowstone National Park.
American Badger, Lamar Valley, Yellowstone National Park.
Uinta Ground Squirrels, Specimen Ridge Trail, Yellowstone National Park.

Granted, this next one is not a mammal, but the dung is mammalian!

Dung Beetle, Slough Creek, Yellowstone National Park.

And, last but not least, that most invasive of all mammals - humans. All watching a dead bison, hoping for some action. If there is any doubt about people's commitment to wolves and wildlife, this is but one example. All of these people spent high dollars for scopes, cameras, and binoculars, then spent even more to travel to this spot. They are interested in all wildlife, but they came for wolves. Charismatic species matter as they provide a conservation umbrella for some of the other species photographed above.

Wolf Watchers, Dorothy's Knoll, Lamar Valley, Yellowstone National Park.

Sunday, May 26, 2013

Birds Watching in Yellowstone

This is the fifth post from Karyn and my recent trip to Yellowstone National Park. One more to go after this one.

Post 1: Eye to Eye - Sandhill Cranes
Post 2: Bullying the Bully - 3 Coyotes v. 1 Wolf
Post 3: Under the Gaze of the Phantom of the North - Great Gray Owl!
Post 4: Bob!!!! - The Case For and Against Mobbing Behavior

Most people travel to Yellowstone in the hopes of seeing mammals. This was true for us as well (blog post later on that). However, the birds usually end up presenting some interesting views. That was particularly true on this trip as the wolves were reasonably scarce and the bears were generally at higher elevations. In addition to the SandHIlls Cranes, Eagles, and Great Gray Owls, all referenced in previous posts, the following birds were spectacular.

Western Meadowlark, Lamar Valley, Yellowstone National Park.
Western Meadowlark, Lamar Valley, Yellowstone National Park.
Osprey, Madison Valley, Yellowstone National Park.
Osprey, Madison Valley, Yellowstone National Park.
Osprey, Madison Valley, Yellowstone National Park.
Osprey, Madison Valley, Yellowstone National Park.
Harlequin Duck, Yellowstone/Lamar Confluence, Yellowstone National Park.
Harlequin Ducks, LeHardy Rapids, Yellowstone National Park.
Harlequin Ducks, LeHardy Rapids, Yellowstone National Park.
Mountain Bluebird, Specimen Ridge Trail, Yellowstone National Park.
Violet-green Swallow, Yellowstone/Lamar Confluence, Yellowstone National Park.
Clark's Nutcracker, Yellowstone National Park.
Barrow's Goldeneye, Trout Lake, Yellowstone National Park.
Ruffed Grouse, Trout Lake, Yellowstone National Park.
Vesper Sparrow, Hell Roaring Creek, Yellowstone National Park.
Dark-eyed Junco, Hell Roaring Creek, Yellowstone National Park.
Chipping Sparrow, Hell Roaring Creek, Yellowstone National Park.
Black-billed Magpie, Slough Creek, Yellowstone National Park.
Common Raven, Hell Roaring Creek, Yellowstone National Park.
Common Raven, Hayden Valley, Yellowstone National Park.
Common Raven, Hayden Valley, Yellowstone National Park.

Thursday, May 23, 2013

Bob!!!! - The Case For and Against Mobbing Behavior

This is the fourth post from Karyn and my recent trip to Yellowstone National Park. A few more to come so check back!

Post 1: Eye to Eye - Sandhill Cranes
Post 2: Bullying the Bully - 3 Coyotes v. 1 Wolf
Post 3: Under the Gaze of the Phantom of the North - Great Gray Owl!

Upon our arrival in the Lamar Valley, we observed a bison carcass in the middle of the valley. This bison appeared to have died of natural causes as the carcass was largely intact. A bison carcass has the potential to be the center of the wildlife action for many days. As a result, we spent a lot of time watching and waiting for the big predators to come in. The wolves, one at a time, eventually arrived. The bears were all spotted up high and not on the valley floor. The carcass was visited regularly by a local coyote pack, Bald Eagles, Common Ravens, and Black-billed Magpies. The Bald Eagles had a nest in the valley which we could also observe - with two nestlings!

Bald Eagle, Lamar Valley, Yellowstone National Park.
Bald Eagle in nest with 2 nestlings, Lamar Valley, Yellowstone National Park.

The bison carcass provided a great opportunity for our national bird / national animal to exhibit its style by sticking its head in the butt of the bison. Since no large predators had yet found the carcass, most of the meat remained locked inside the tough hide. Only bears and wolves have the ability to "open" the carcass. Until they arrived, only the butt was available to the birds and coyotes. Aren't we impressed!

Two Bald Eagles on Bison Carcass, Lamar Valley, Yellowstone National Park.
Two Bald Eagles on Bison Carcass, Lamar Valley, Yellowstone National Park.

This brings us to the topic of mobbing behavior. Many small birds are known to mob larger birds, particularly predators. This may seem illogical, but in most cases the smaller birds are quicker to respond and can easily stay outside of the reach of the predator. Theory suggests that it is better to know where the danger is than to just know that there is danger. This is why birds fly toward alarm calls instead of away. Also, in many cases, the smaller birds can chase off the larger birds. The same theory as my previous post of three coyotes attacking a lone wolf.

While waiting in the Lamar Valley for the predators to arrive at the carcass, the local Bald Eagle took a pass by the carcass. This pass caused over 30 Common Ravens to rise from the carcass and begin mobbing the eagle. The birds swarmed around the eagle, tagging it in flight. The ravens essentially forced the eagle to the ground. Just as the eagle hit the ground, the ravens began landing as well. One landed a bit too close. In an instant, the eagle was on the raven. "Cousin Bob" was done for. The ravens screeched in horror and a few attacked the eagle grabbing his / her wing and tail. This continued until the eagle began plucking the raven. With feathers flying, apparently the remaining ravens determined that "Cousin Bob" wouldn't be returning to the clan. They gave up the fight and returned to the bison carcass.

Bald Eagle eating Common Raven, Lamar Valley, Yellowstone National Park.

After plucking the raven the eagle tried to take flight with the prize. It was not to be. An eagle weighs about 9.5 pounds, while a raven weights 2.6 pounds. This was just too much. The eagle began consuming the raven and then tried again to fly. No luck - still the same weight, just transferred into his stomach. The eagle crapped twice, but this was still not enough. He ate some more and tried again. This time he landed in a small ravine. A water-logged raven wasn't much better. He had to abandon what was left of "Cousin Bob"...

I was asked by some friends as to why the eagle would eat the raven with a full bison carcass available. There are a couple of possible reasons. First, attacking the mob seems like a great way to decrease the mobbing behavior. Second, and possibly more important, is that many raptor species require a diverse diet to survive especially as nestlings. For example, the bird I study, the Northern Goshawk, cannot survive on mammals alone or birds alone. Delivering a raven to the nest would be a great compliment to the Uinta Ground Squirrels that the eagles had been feeding their young.

Now to the question of mobbing behavior. Did the eagle decrease mobbing behavior by killing one of the mobbing birds? In my opinion it's a mixed result. The eagle clearly selected against the mobbing behavior by killing one of the mobbers. However, the "average" raven is now different as a result of this bird being taken out of the population. The "average" raven is likely faster (assuming the slowest bird was removed) and will likely keep a larger distance during mobbing (assuming the closest bird was removed). This is just a single animal, but provides great insight into the basic mechanics of evolution by natural selection. Each animal removed from a population changes the "average" for the population. If the slowest and closest are consistently removed, the population attributes can change fairly quickly.

This is one reason I find wildlife watching and field work so fascinating. It is not always about what you go there to see, but what you see while you are there.

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.