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One of my favourite birds to watch and to photograph is the Kestrel (Falco Tinnunculus), poetically referred to as the ‘Windhover’, for obvious reasons. They are widespread in Britain and can be seen in many different habitats. When driving along motorways or dual carriageways it is not unusual to see them hovering over the verges looking for prey. When doing so, they can keep their heads virtually motionless relative to the ground.

Their usual prey is small mammals, particularly voles, mice, and shrews, although they sometimes take small birds and invertebrates. An ability to see ultra violet light means they are able to detect streaks of urine, left behind by their unfortunate mammalian prey, which fluoresce at these frequencies. So, when they are hovering above the ground, this isn’t necessarily an aimless vigil, they may be looking at a ‘map’ of possible locations.

Recently, on the edge of one of the local moors, I found what I think may be a small family group of three (or perhaps more) Kestrels (see photograph). When hunting, they prefer to face into the prevailing breeze, as it rises up a hillside, to assist their hover. From there they scan the heather and grasses. They often start high in the sky before dropping down to a lower position, perhaps to get a better view of potential prey or preparing to swoop. On some occasions this is followed by a swift descent to the ground – more often they move fifty yards or so and repeat the process.

Although Kestrel numbers are relatively good, they have been in decline. Consequently, the RSPB have placed them on their Amber list of Birds of Conservation Concern. Investigative studies have found them to be breeding successfully, leading to the conclusion that access to nest sites and/or post-fledging survival are the issues. Availability of prey may be a factor. However, related to this, the effect of rodenticides is an additional worry that is being investigated. These are seen as important tools for farmers – but as they have become more powerful so the potential ‘knock-on’ effects for predators of rodents are greater.

I was surprised to read that a threat can also come in the form of another predator - the Goshawk. Kestrels can be targeted by Goshawks as prey and, according to one study, this can have a very significant impact on local populations. I suppose the typical hunting method of Kestrels – the ‘Windhover’ - makes them particularly vulnerable to attack.

By Steve Westerman