One of the birds I have only seen up at Timberline is the Clark's Nutcracker. It's a great bird related to Jays and Crows. In the past, I've only seen a couple during each trip with only so-so views, but on this day there were nutcrackers everywhere. You could see them flying from tree to tree as they collected pine seeds.
At times they would fly out of a tree as if they were fly catching. The one above is definitely in pursuit of something, but it looks more like one of the pine seeds than an insect. I have not found any literature that attributes fly catching to nutcracker's, but they are know to include insects in their diet.
Clark's Nutcrackers are well know for collecting and stashing pine seeds for use during the winter months. They have incrediable memories allowing them to find the seeds in their many hiding places. Some of the seeds that they don't consume end up sprouting and growing into more trees, making nutcracker's one of the primary means that some pine forests spread.
Here is an account of this behavior from Cornell's All About Birds website:
All year round, the staple food of a Clark Nutcracker’s diet is pine seeds, either fresh or stored. The nutcracker uses its long, sharp, sturdy bill to crack open closed, unripe pine cones and remove seeds from the cone scales. It shells seeds by cracking them in its bill or by holding them in its feet and hammering them. Between September and December it stores seeds to eat later, placing 30–150 seeds in the pouch under its tongue and carrying them to a spot nearby or up to 15 miles away. It digs a trench in the soil with its bill and puts a cluster of seeds inside before covering them up again, or it pushes individual seeds into gravelly soil, pumice, or crevices in wood. During the winter and spring, it relocates caches by remembering where they lie in relation to nearby objects like rocks, logs, and trees. Nutcrackers have such good memories that they can relocate seeds more than nine months after caching them, though their accuracy declines after about six months. They don’t recover all the seeds they bury, and it’s estimated that for some high-elevation pines, such as whitebark pine, virtually all the trees you can see on the landscape come from seeds planted by a nutcracker. Nutcrackers use cached seeds to feed both themselves and their young. Clark’s Nutcrackers also opportunistically eat insects and spiders, and small vertebrates such as other birds, ground squirrels, chipmunks, voles, toads, and carrion.
While most of the nutcrackers were above in trees, making getting a full shot of them difficult, I found the one above on the ground near a stream up the mountain from Timberline. I could be totally wrong on this, but I suspect this is a first year bird. For one thing, it was a little tamer than the others, which always makes me suspect a young bird. Also, its face doesn't have much white like adults. Unfortunately I couldn't find much information about year old birds, so please feel free to let me know if I am right or all wet.