There are lots of great resources online about the South Hills Crossbill, and I don't intend to repeat all that information here. Briefly, the crossbill evolved from a fascinating ecological situation where the symbiotic relationship that keeps cones easy to access in the presence of squirrels breaks down in these isolated squirrel-free mountains, resulting in an evolutionary arms race between well-defended Lodgepole Pines and specially adapted crossbill bills. The original paper is a great reference, but summaries are also available here and here, for example. Rather than reiterate the details of ecology and identification that have been published better elsewhere, I will provide here the story of my search, in hopes that it will help others find this cool bird.
|Beyond the Diamondfield Jack Campground, the road was not plowed, but we could still walk it. Snowshoes would have been helpful. A local told us that the road is usually plowed beyond this point.|
When we visited (in late November), the road was plowed to Diamondfield Jack Campground but not beyond. Despite the plowing, I was glad to have snow chains for the tires, but a four-wheel-drive vehicle would have probably been fine without them. We had crossbills several times between the ski area and the Diamondfield Jack Campground, always perched in the top of Lodgepole Pine or flying over, calling in flight.
|If you're looking for South Hills Crossbills, you're looking for this: their preferred habitat, Lodgepole Pine.|
|Fortunately, my audio recordings confirmed that several other crossbills we saw and heard were indeed South Hills Crossbills, a lifer subspecies that will potentially be a lifer species some day!|