Can anyone explain this behaviour: Around 4:30 in the afternoon yesteray I was skiing through young conifers separating our country yard from the fallow field next to it when I came upon a redtail perched on a dead branch about a foot above the snow. it was maybe 4 feet from me. We stared at each other for a couple of minutes before I left. I returned to take pictures. It did not take flight and let me wander around while I murmured to it. Later I returned with my husband at which point it was resting with it's head tucked in between it's wings. We chatted about it's behaviour concerned for it's health, wondered if there was sufficient food available, if perhaps it was old and dying. It barely moved though it's neck ruffled slightly. This morning it is gone.