Wrapping up "Bald Eagle & Other Predators" Week at the Daily Bucket....
The Daily Bucket is a regular feature of the Backyard Science group. It is a place to note any observations you have made of the world around you. Rain, sun, wind...insects, birds, flowers...meteorites, rocks...seasonal changes...all are worthy additions to the bucket. Please let us know what is going on around you in a comment. Include, as close as is comfortable for you, where you are located. Each note is a record that we can refer to in the future as we try to understand the patterns that are quietly unwinding around us.
June 12, 2015
Rialto Beach, PNW
Even on a lovely sunny summer's day there aren't many folks who walk very far from the parking lot of this popular Olympic National Park beach. It starts steep and cobbly but soon transitions into clean hard-packed sand, perfect for beach-walking even at a moderately high tide. We had to dodge waves occasionally sprinting around big driftwood, but walking this great wide wilderness Pacific beach in shirtsleeve weather, slightly misty with salt spray, was heaven.
A mile up the beach Ellen Creek empties local runoff and downed trees into the ocean. Usually we have to clamber across it by way of the logjam since it's too deep to wade. It turns out this summer Ellen Creek is almost a trickle, what with the extremely dry weather recently, but before I discovered that, I spent some time poking around the logjam looking for a crossing. And stumbled across a remarkable feather, resting partly in the creek.
Follow me below the fluff for an analysis of feather ID.
~All photos by me (except for the US Fish&Wildlife Service illustrations). In Lightbox...click to enlarge ~
Who could have left this extraordinary feather?
A feather this huge could only come from a very large bird who dropped it either along the beach, in the waves, or upstream where it washed down to rest on the sand. It hadn't been here long since the high tide waves wash up this far. I took a number of photos and measurements, and using the US Fish and Wildlife Service Feather Atlas narrowed it down to the most likely bird that grew and moulted this feather. It is a primary feather, one of the longest outer wing feathers.
Total length of the feather was 47 cm (actually 18" long, 14" vane, 2.5" widest, 8" to the notch...Mr O's tape measure, which he carries always, is in inches, so = 47 cm, 36 cm, 6.4 cm, 20 cm). Here are the possibilities (click on bird name to link to a larger image).
Of the few large birds who live in this area, I ruled out Osprey both for size and color pattern.
Ruled out Turkey Vulture: this feather was longer than the longest vulture primary.
Ruled out Golden Eagle (extremely rare here anyway) because the feather is not two-toned.
...which leaves Bald Eagle as the only possibility.
Eagles are abundant along this coast and I see them on every beach walk.
There's a snag at the end of Rialto where eagles commonly perch. Here's a pair there, surveying the beach below late in the afternoon.
With the help of the Feather Atlas it becomes possible to narrow it down even further: how old was the eagle that dropped this feather? Young eagles grow into their overall final coloring, although their primary wing feathers will be brown all their life. Bald Eagles are fully mature and ready to breed in their 4th or 5th years, after which you can't tell what age they are.
Compare this juvenile landing in a tree to the adult on the rock.
Looking at the difference between primary feathers, those of juvenile (1st year) eagles are actually longer than those of adults, but the notch starts too low compared to the one I found. An adult eagle primary matching the length of the one on the beach is too wide...not a match.
Therefore, this feather most likely came from a subadult, such as a
3rd year eagle.
Here's what a subadult looks like. This one was bathing in a pasture pond near my house but an eagle like it might have been bathing in Ellen Creek. Even birds who live by the ocean prefer to bathe in fresh water.
Or it might have drifted down from a perch high above. This is a distant view of a popular eagle perch on Rialto Beach not far from Ellen Creek. See the adult eagle way up top the bare snag?
It's a really good sign seeing evidence of active subadult Bald Eagles. There are fewer of them in a population than either juveniles or adults. Many juveniles are hatched and fledge but not many survive their first year to grow into subadults. Most eagles are adults since their lifespan is 20 years or so, with skill and luck. At least one young eagle has survived its first few years and has a home along heavenly Rialto Beach.
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All nature observations welcome in the comments.
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