Sharp-shinned Hawk
If birds have suddenly disappeared from your feeders for a period of time, it could be because a Sharp-shinned Hawk has been present in your backyard. This Hawk will make quick, low flights over bird feeders to scare up birds to capture in flight. Songbirds make up about 90% of their diet.
According to the All About Birds website:
Sharp-shinned Hawks are “pursuit hunters”, often surprising their prey on the wing by bursting out from a hidden perch with a rush of speed. They are versatile: small birds may be taken in the air or on the ground; they may pounce from perches as little as 3 feet above the ground to catch rodents; and they catch some insects on the wing. Sharp-shins make great use of cover and stealth to get close to their prey, surprising it at close range rather than diving from great heights. They are agile and acrobatic fliers, navigating dense woods at high speeds by using their long tail as a rudder. In open areas they sometimes fly very low, hugging ground contours to remain hidden to prey until the last moment.
Often times when a Sharp-shin is in the vicinity, feeder birds will freeze in position hoping the Hawk does not detect them.
More on Sharp-shinned Hawks or “Sharpies” as they are nicknamed:
The Bird that Feeds on Feeder Birds
Every winter I usually have a Cooper’s or Sharp-shinned Hawk preying off the birds congregating at my feeders. This winter I have a Sharp-shin actively hunting my feeders. Both of these species swoop in at a high rate of speed, surprising the feeder birds, barely giving them time to fly off or head into surrounding evergreens to seek c…
We don't have these birds in the UK, but we have sparrowhawks who I believe exhibit similar behaviour.
That picture of a white-breasted nuthatch is beautiful!