Community Engagement Assistant, Oliver Davies, explores the ecology and behaviour of two raptors which anyone is – almost – guaranteed to see when visiting Coombe Bissett Down: the buzzard and the kestrel.

Introduction

The end of winter denotes the start of the breeding season for many of Britain’s avian residents. At Coombe Bissett Down, the mixed landscape of woodland and species-rich chalk downland provides plenty of nesting sites for local grassland and farmland birds; however, the nature reserve is also the perfect hunting ground for birds of prey.

Having suffered centuries of persecution and ecological neglect, Britain’s most accomplished hunters are finally progressing towards healthy population sizes. Goshawks, ospreys, marsh harriers, honey buzzards and white-tailed eagles were once wiped out from the UK entirely, but they have all been brought back through a series of reintroduction programs – a process that also responsible for the recovery of red kites.

In this article, I will be detailing the ecology and behaviour of two raptors (order Falconiformes), which anyone is – almost – guaranteed to see when visiting Coombe Bissett Down. As many of Britain’s birds prepare for months of building nests, rearing chicks, and defending territories, the raptors take this to the extreme, exhibiting behaviours worth looking out for as they try to find a mate and settle down for spring.  

Common buzzard (Buteo buteo)

True to its name, the common buzzard is one of the world’s most common raptors. Its population in the British Isles stands at roughly 60,000 pairs, which is a sizable chunk of the 4 million individuals than can be found between Britain and Japan. It is a medium-sized ‘general purpose’ raptor that may not be the most competent hunter, but it is a valuable predator of rabbits and an enthusiastic roadkill scavenger.

The plumage of this broad-chested and stocky raptor can range from dark chocolate to creamy white, but its short neck and splayed tail help distinguish common buzzards from corvids and other birds of prey. On the underside of its wings, the flight feathers have pale roots and dark tips, which can usually be seen when the bird is wheeling on thermals, mewing softly as it scans the land for carrion. Common buzzards often join the rabble of gulls and crows that are searching for earthworms behind a plough, but when conditions aren’t favourable, they will try to hunt small mammals, frogs and snakes by sitting in a tree and waiting.

On fine days in late winter, a female and her potential mate will fly together, calling constantly as they climb upwards. The smaller male will then demonstrate his fitness by ascending even further and repeatedly diving and pulling back above his mate. They may even lock talons and tumble down to the earth together in order to fully establish a long-lasting bond. The pair will then start defending their territory and building a nest, which usually takes two months as they build a new one every season. The female typically lays two or three eggs in mid-April, and both parents will take turns in incubating the eggs over the following 34 days. Around 40 days after hatching, the chicks begin to take their first tentative flights, but they will only start breeding after 3 years – if they can establish their own territories. 

Buzzard, Darin Smith

Kestrel (Falco tinnunculus)

Due to its small size, varied diet, and fast rate of maturation, the kestrel is the only British raptor that has been consistently widespread over the last few centuries. In the British Isles, there are estimated to be 36,800 pairs, and they can be found in almost any open patchwork of countryside. As a small mammal specialist, kestrels are regularly seen hovering at the sides of roads, waiting for prey to be flushed out of the grassy verges.

Kestrels are a rich chestnut-brown with black streaks on their front and back. Both sexes have dark moustacial stripes below their eyes, but the grey head and black-tipped tail distinguishes a male from a female, which is mostly brown and has dense barring on its tail instead. When hovering, a kestrel’s head is completely still and its tail is fanned, and it will progressively drop lower until it is close enough to fold its wings and land on its prey. They feed on voles, mice and shrews (in that order of preference), as well as insects, lizards and earthworms.

In early spring, pairs from the previous year – as females tend to move away in winter – will re-establish themselves in the same territory. Their courtship behaviour can take place right through to summer, and it consists of noisy ‘rocking’ and ‘winnowing’ flights: soaring together at a great height as they tilt from side to side, and flying slowly together whilst rapidly beating their wings. The male then starts to provide food for the female as she gets ready to lay four or five eggs and incubate them for the majority of the following 32 days. The offspring will be ready to fledge when they are four weeks old, but they usually hang around the nest as the parents continue to feed them – sometimes transferring food in mid-air acrobatics. Eventually, the younglings start hunting for themselves and move on to find their own partners and nesting sites within the year.

Images (left to right): Kestrel, Darin Smith; Kestrel hovering, Steve Waterhouse.

In the next blog, I will be exploring three other raptors that are often seen at Coombe Bissett Down, including one species that nests on Salisbury Cathedral.