Searching for "tree blobs", "whitewash", and "pellets" is the usual way to find owls.
We found this one by asking the park ranger where the owls were.* He spotted this one for us, using the traditional technique of scanning the tree branches for a blob shape. And when you raise your binoculars the blob becomes an owl, in this case a long-eared owl.
* There is an old joke amongst physics students (my bachelors degree is in physics) that has to do with using a barometer to determine the height of a building. The expected answer is to take a reading at the base of the building and then one on the roof and use the difference to calculate the height. The clever answer is to find the building superintendent and offer him a nice barometer if he'll tell you the height.
I had expected long-eared owls to be here, as I had seen two a couple of weeks before. My friend Laura had yet to see long-eareds, so it was easy to talk her into joining me for a return visit, even with the forecast for sub-freezing temperatures (I do not think it broke 20〫F all day).
I was glad we met up with him in the parking lot, as his finding the first owl took all the pressure off me to find Laura an owl (a multi-hour drive in freezing weather to come up empty would not have been fun). Having spotted us an owl he, after we thanked him, headed off down the trail, no doubt further ranger business calling.
Laura and I continued to explore the area, as he had mentioned that there had been five long-eared owls spotted in the grove. He also noted that the birds had been moving form tree to tree (I don't know if this is because so many people wander about or because there was just so much good habit). We found plenty of pellets, and in several spots Laura found the feather remains of several large birds (canada geese?).
And while she was examining feathers of one of those presumed geese I found a massive number pellets beneath the tree shown above. Can you see them? There are at least three owls in this image. (Click on the image to bigafy it. Answer below*.)
Yep, that's what makes owling so difficult. (But we did spot four of the five reported owls. Not bad at all.)
I backed off from under the tree, both to avoid disturbing the owls too much, and to get better camera angles (having a 100-400 mm lens with a 2x doubler allows for a lot of backing off). And I shot this image (and a bunch more). Unfortunately there was no really clear line of sight and this was the best I could do.
Despite the cold, despite the long drive, despite listening to country music (!), despite the snow storm on the ride home, Laura and I had a great time wandering in the woods and spotting the owls (and enjoying the wood burning stove in the nature center!).
Etiquette in the birding world holds that the location of owl roosts is not shared outside of one's trusted birding buddies, so as not to disturb the birds too much. But some places become so well known, because they are easily accessible (these owls were with yards of the parking lot) or because the owls return year after year, that they become "well known secret places". Like this one.
* There is one owl in the center of the image, this is the easiest one to see. Directly to the right and mostly hidden behind a branch is the second owl. The third one is directly above the first. Not much help is it?