On Sunday, Rykert and I were driving along the Iowa River in Coralville heading to a local establishment to watch the Saints game (let's just pass right over that subject). As we were driving, I noticed lots of Bald Eagles flying over the River. I was impressed, and decided that I wanted to get a closer look. Despite the fact that the high temperature was a balmy 18 degrees F, we packed up Nola and headed to the local dog park crossing the Iowa River by foot.
We crossed the bridge.
While the water just below the dam is full of Canada Geese and Mallard Ducks,
but the real show is higher...
I don't recall seeing Bald Eagles when I was growing up. Of course, I lived in town rather than near a river/lake, and I grew up during a period where the Bald Eagle was still on the endangered list. I'm thus smitten when their migratory patterns bring some of them through Iowa City/ Coralville each winter. Unfortunately, my camera just can't get a decent picture.
So here's what I've learned about their perching behaviors, which perfectly describes the locations where you can find them here in Iowa City:
- Bald eagles generally roost together in large mature trees surrounded by a buffer of smaller trees. (see my picture below)
- Roosts are chosen by the eagles to provide protection from the weather and avoid disturbances, but are also close to a source of food.
- Daytime perches are usually within 60 yards of the water’s edge.
- Large cottonwoods tend to be used most frequently, although the eagles will choose smaller trees that are closer to the water. (Which explains why I once saw one over 3 feet tall on a small, ornamental tree next to Dairy Queen once.)
As you can see I attempted to take some pictures, but my non-telephoto lens didn't provide the greatest shots.
From the IC Dog Park there is a nest that is clearly visible, and it is gigantic from a distance so I have no guess of how large it actually is, but my research indicates that nests can be as large as 7 feet across and 12 feet deep.
Some more Bald Eagle factoids:
- Bald Eagles don't get their characteristic white head and tail markings until they are 4 or 5 years old. This explains why I believed the trees were full of Bald and Golden Eagles. In fact, they were just juvenile and adult Bald Eagles perching together.
- Bald Eagles will almost always be seen near water as the primary component of their diet is fish, but they also eat some water fowl and carrion (road kill).
- During the winter months, Bald Eagles primary goals are to consume as much food as possible and to expend as little energy as possible. Therefore, when watching the Eagles it is imperative that humans not unnecessarily disturb them. I was, in fact, wise in not tracking through the snow to the spot under their perching tree. Humans should try to stay at least 100 yards away.
- Eagles mate for life. If one of a pair dies or if the pair is unable to reproduce, then they may take other mates. They return to nests year after year.
- Eagles tend to feed in the morning hours, before 9 am.
- And my favorite...Eagles stick together but not for social reasons. Eagles are actually kleptoparasitistic, in that they steal food from each other or other birds to either conserve energy that would be required to obtain the food or because the bird lacks the skills to obtain the food independently. In my observations, kleptoparasistism can also be seen in corporate culture.
With the last little factoid in mind, I work Rykert up early on Monday morning, and we headed back to the River to see if the Eagles were a bit more active. And they were.
Again, pictures were ineffective in capturing how cool and enormous these birds are...
It was a very cold adventure, but it was interesting. Nola, on the other hand, was unaffected by the cold, and wished she could get down in the water and get after some of those ducks...
