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Observing swifts in flight

While it’s wonderful to be able to observe every move of swifts in their nest boxes with cameras, big mysteries remain about the behaviour of swifts in the sky. Each year I manage to put together more pieces of the puzzle of some flight behaviour, or rather speculate about it a bit more, because unless we can identify the sex of the birds involved it is impossible to know for sure what is happening.

I have names for many different pieces of flight behaviour that I observe. Although it is popular to talk of waves of swifts according to the timing and order of their arrival, this is simplistic. There is so much overlap and variation within each age wave of swifts. The swift season in the UK can be broken down into many swift sub seasons, some only lasting days. My diaries have helped me to build up a picture of what to expect almost on a daily basis. But you then have to add in the weather. This can totally dictate the activity from day to day.

One commonly observed piece of flight behaviour is the V display, as I call it. A swift holds its wings deliberately in a V shape above its back, recalling displays from nightjars. It is a very brief display as the performing swift loses height rapidly. The tail is sometimes closed, sometimes fanned and the bird can be banking at the time. The V displaying swift is usually if not always being tailed by another. It is beautiful, if brief, display to watch and one might jump to the conclusion that it is involved in pair bonding or mating. Wrong, because on numerous occasions I have observed swifts perform the V display when their partner is incubating eggs. Given these pairs are committed why would they be displaying to others?

How do I know that these displaying birds are from a committed pair? I only know by extremely careful observation. I have to track a breeding bird leaving the nest box and keep my eyes fixed upon it while it performs certain aspects of flight behaviour.

Today the weather has been very windy and dull with occasional light rain. Yet the swifts have been very active with lots of fast low level passes, V displays and some prospecting by a new swift or two. While I wonder about what the flight behaviour might mean I never become obsessed by trying to understand it.  But I am obsessed with watching it because the visual spectacle never ceases to give me joy and thus inspires me to sketch and write; each wingbeat, each powered glide, each V, etched on my mind forever.

Swift returning to roost 9.24pm
Sketches of swift V display

All images and text copyright Jonathan Pomroy 2022

3 thoughts on “Observing swifts in flight”

  1. It is wonderful to read your descriptions and observations – and then go and look for our Swifts!

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