Do Common Swifts (Apus apus) know their partner’s behaviour patterns?

During the period when they are feeding their young, the pair of Swifts who nest in a wooden box outside my living room window, usually turn left (to the West) when they leave the nest box, pass over a small open area, and then fly straight away over the houses, or else turn slightly to the left again. They always do this to a set pattern, except in the late evenings, a short time before remaining in the nest box for the night, and then they may fly within the colony territory.

On June 30th, 2002 at 11 a.m. I was standing on my balcony, and observed one parent leaving the next box and turning left, although not passing over the open space, but instead remaining there for a second or two, and then commencing a circular flight to the left. This would bring it back to my house after a few more seconds, but out of my sight, because the house was behind me. Eventually the bird came into sight over my right shoulder again. At this moment the second parent left the nest box and together they disappeared in their usual manner. The sky was empty at this time, because all the Swifts which did not have a nesting site were away for two days due to strong winds, and the other breeding individuals were hunting, so I have no doubt that the Swift I described flying in a circle was the same individual.

This observation stands alone, and is so far unique. It could well be a coincidence. But as we do not have much knowledge about Swifts' social life, let alone their communication systems, it is I think well worth documenting. Previous observations have also showed some interesting behaviour, such as both parents returning earlier to the nest the night before the egg-laying and the night before the chicks opening their eyes (Tigges 2000).

Did the two parent Swifts communicate with each other? Did the first parent know that the second one was going to fly out as well? Did they want to fly together? Every accurate observation, however small, will build us a better picture of Swifts' life.

Reference

Tigges, Ulrich (2000): On the breeding phenology of the Common Swift (Apus apus) - the last

diurnal return to the nest with reference to environmental and social factors, APUSlife    2340, ISSN 1438-2261 (http://commonswift.org/APUSlife.html)

© APUSlife 2003, No. 2885

ISSN 1438-2261