This is the time of year when swifts and swallows are most busy. As a generalisation, swifts fly high and faster, swallows lower, slower, and are more manoeuvrable. This is very obvious at The Cavern. First thing in the morning – first light on sunny days – both the White-rumped Swifts and Greater Striped Swallows circle low over the front lawn. Then, as the temperature rises, the swifts disappear upwards, only returning at intervals to bring food to their nestlings. This is in response to insect prey also moving up on air currents warmed by the ground.
That’s on sunny days. If it’s raining the morning circus stays low as long as the ground remains cold. This is a great chance to see the absolute difference in wing shape between swifts and swallows. Swifts have a perfect curved scimitar; swallows have a slight “break” in the middle of the wing which is very obvious when they make a sharp turn.
This is also a rare chance to get a close look at the swifts. There are in fact three species of small dark swifts with white rumps. All could occur here. The White-rumped Swift – note capitals, it means that this is the full correct name for a unique species – has a curved white rump patch and a deeply forked tail. The other white-rumped swifts – lower case = any swift with a white rump – have square patches and much less forked tail.