KESTREL (Falco tinnunculus)
The Kestrel is the most common falcon in Switzerland and probably throughout western Europe. It is almost unmistakable in both appearance and behaviour. The adult birds have rich brown wings with dark tips and the tail, which in the male is blue-grey like the head, has a black terminal band which is easily seen.
It is common in most habitats from the agricultural lowlands to the high alps up to about 2,500m. This is the bird that is seen hovering as it looks for prey. Fast direct flight is often followed by a banking turn to face the wind, it then spreads its wings and tail, lowers its head and by using its wings in a humming-bird type of motion stays stationary whilst it searches the ground below for suitable food. In the mountains in an updraught this can be done with no wing movements at all, just letting the upwards movement of air take its weight and hold the bird motionless. This behaviour is also a tribute to the excellent eyesight of birds of prey when you realise that most of its food is small mammals (voles - campagnol) and insects like grasshoppers (sauterelle) and beetles (coléoptère).
Like most birds of prey Kestrels are generally quiet, and calls that I have heard are usually in the vicinity of a nest or when two birds are interacting. The most common call I know is a high pitched "whickering" ki-ki-ki-ki. Here is a bird some distance away sailing across a cliff calling, it was a hot day in August so there is much insect noise and cows bells echoing off the cliff:
This ki-ki-ki call is one of two clear calls I have identified from adult Kestrels. The other is a more rolling whinnowing call. I recently found a pair of Kestrels with 3 young that had just left the nest - I could see the nest on a nearby cliff ledge and although the young were flying with the adults they were still begging for food. I heard the female making this whinnowing call as she first sat and then circled a tall dead tree above me:
In the background you can hear the other bird (the male) answering with the ki-ki-ki call from further down the valley.
Here is the reverse, with the parabola turned on the male and you can hear the whinnowing call from the female in the background:
However my observations that day make me believe that both birds can make both sounds - here is the male as I followed him flying near to the turbine systems of the nearby dam, he first makes the whinnowing call and later (at about 15s) switches to the ki-ki call:
As I said, the three young birds were clearly only very recently out of the nest and the whole family was flying around in a very excited manner. I watched the female land on a large rock, she was immediately approached by a young bird which let out two whistles then, with neck outstretched and wings down in a begging posture proceeded to call at the female in a manner very similar to the whinnowing call used by the adults:
So my conclusions are that even in these family interactions Kestrel vocabulary is somewhat limited. To round off this conclusion here was a completely different group of birds (three in total but too far away for me to identify the sexes) who were seeing off a Black Kite which had been patrolling the cliffs where I assume the Kestrels were nesting - the three of them kept diving at the Kite making these by now familiar sounds: