Red-tailed Hawks are rather like governmental spy agencies: They like to watch, but they do not appreciate it when they are, themselves, monitored.
The hawks frequently watch from utility poles or trees alongside a roadway, apparently waiting for road-kill. They remain unconcerned if the traffic speeds by below, but if they notice that someone is watching them, even from afar with a scope, they often retreat.
While I am sympathetic to these hawks and do avoid stressing them, it is ironic that they want us to ignore them while simultaneously perching on man-made structures so as to watch our roads. By way of contrast, an eagle or owl would just ignore a passing human.
A minor perquisite of this hawk skittishness is that as a hawk leaves, flight shots are possible. Below are three different flying hawks taken over a period of a three weeks.
A Red-tailed Hawk flew off as I watched from the roadside. The reddish tail is obvious.
Another Red-tailed Hawk lifted off from a distant utility pole and then proceeded to hunt from aloft. This was the first time I had seen a hawk deploy its alulae while trying to hover over prey.
This Red-tailed Hawk flew from a roadside lamp standard. That its tail has yet to turn red reveals it to be a juvenile.