I have often noticed an unusual sound that Robins sometimes make: a very high-pitched, down-slurred whistle. They always seem to be sitting very still when they do this, and as I recall, it is always when the weather is at least calm, if not warm or sunny. Why do they do that? A few days ago, while I was walking home from work, I noticed that there were dozens of Robins perched in trees along the street. They all were whistling, almost whining, "seeee", and all were sitting motionless. There are many differing and (sometimes) conflicting interpretations, but no certain explanation. Just another of the mysteries that surround us as we go through our daily routines, reminding us to "keep our ears open and our eyes peeled."