Circus aeruginosus

Marsh Harriers have always been part of the avifauna of the UK, but numbers dropped dramatically as the fens and wetlands in the east were drained for agriculture. The population took a further hit in Victorian times, as birds were targeted as predators, by hunters, farmers and landowners at the same time eggs were being collected or destroyed and habitat continues to be lost. By the late 1800s they had become extinct in England and the last pair bred in Ireland in 1917.

Occasional birds, almost certainly originally from the continent, bred in Suffolk and Norfolk, with the core being at Minsmere reserve, but numbers increased in fits and starts up to the 1950s. A resurgence was expected but numbers crashed again and, by 1961 no Marsh Harriers bred in the UK.

This time it is believed that the population crash was caused by the use of organochlorine pesticides, especially in their Scandinavian heartland. They did maintain a toe-hold, with one nest annually at Minsmere until the use of pesticides was banned. Numbers began to climb once again and now, thankfully, these magnificent birds are an integral part of the fens, marshes and reedbeds of Eastern England.

Marsh Harriers are not closely related to the other harrier species found in Britain, but form a group of species which occur across Asia, Indian Ocean islands and Australia.

They are sexually dimorphic in plumage, with adult females a handsome chocolate brown colour with cream heads and forewings, whereas the males have a complex pattern of brown, russet and grey. Juveniles tend to have a female-like plumage. Study of a number of birds of known age, however, has shown that plumage in Marsh Harriers is not straightforward, with some older birds having juvenile-type plumage, and some old females developing male-type plumage!  They are quite large birds, heavier and more sturdy than our other harriers, and have long wings often held in an upward ‘V’ shape, reminiscent of Buzzard or Black Kite which can cause a confusion, especially when encountered away from their usual wetland habitats. However, the low, inconspicuous quartering back and forth over the hunting site is characteristic.

VITAL STATISTICS

Size: Average 52cm, wingspan 122cm. Females (670g) larger than males (540g).

Status. Resident breeding bird. Migrant and passage visitor.

Population size. 400 breeding pairs.

Conservation status: AMBER (recovered from historical decline, but recent population and range declines)

Lifespan: Average lifespan is 6 years, with an adult survival rate of 74% year on year. First year survival is not known, but birds have a 15% chance of reaching their third year, when they will begin breeding. The oldest known wild bird in the world, was 6½ years old (ringing recovery).

Nesting: Invariably, Marsh Harriers nest on the ground in long vegetation. British Marsh Harriers have always nested in reed beds, although in Europe they nest in rank vegetation and even in agricultural crops. Since recolonising, some British harriers are starting to show a wider breeding habitat, with records of crop-breeding and even moorland-breeding. This change of behaviour should offer opportunities for the recovering population. It is common for males to support more than one female. On occasion one male may be paired with three females, although breeding success is often lower as the male is not able to provision all the nests and chicks sufficiently.

Number of eggs: 4-5

Incubation: 31-38 days

Fledging time: 35-40 days

Habitat and Distribution: Marsh Harriers are still very much birds of eastern England, centred on East Anglia and the eastern coast. Small populations also occur in a number of places, most notably Lancashire and Dorset. IN winter, as birds range more widely, they may be encountered anywhere, but are still very rare outside of their core areas. During the breeding season, Marsh Harriers are typically seen in extensive reed beds but a few can be found in other open, well-vegetated habitats. After breeding birds range more widely, and can be found in coastal areas and even quartering fields; in East Anglia, some seem to favour stubble fields in the autumn

Movements: It is almost certain that the recolonising birds originated from Europe, and for many years Marsh Harriers were regarded as migrants, but in fact birds are more likely to remain all year. As birds are three before breeding they spend their first two years ranging widely away from where they were hatched, and this may include leaving the country, through southern Europe and even as far as Africa (several wing-tagged birds have been recorded south of the Sahara). It is likely that some adult individuals leave the country, whilst others show remarkable loyalty to their territorial areas. Birds may appear at winter harrier roosts with Hen Harriers.

Feeding: Marsh Harriers are catholic in their diet but prefer to take their prey from the ground. They will target small mammals, birds, insects, reptiles, frogs and even, on occasion, fish. As with other harrier species, they can exchange food with their mates in mid-air.

Accipiter gentilis

Goshawk are well-known as feisty and difficult falconers’ birds and their scientific name gentilis derives from the fact that traditionally only members of the gentry or nobility were allowed to carry one. Goshawks are the largest of the accipiter/hawk group of birds of prey and are found across much of the northern Hemisphere. In much of their range they are one of the top predators, but share their habitat with other, smaller, accipiters such as Sparrowhawk in the UK and Sharp-shinned and Cooper’s Hawks in North America.

Goshawks are formidable hunters and often seem fearless, with many accounts of them tackling much larger prey than themselves. They are certainly adaptable, but will also actively target perceived threats and competition such as Buzzard, falcons and owls; in fact in Europe Goshawk is the second most frequent cause of predation on owls after Eagle Owl.

Identification of Goshawk can be difficult, and it is a notorious ‘beginner’s bird’, especially with fleeting views or where size is not apparent. Adults should be reasonably obvious, with grey/brown backs, dark caps and cheeks and pale eyestripes with very fine barring on the pale undersides. Young birds are brown above and have dark ‘drop’ marks on the chest, as opposed to young Sparrowhawks which are coarsely barred below, but young female Sparrowhawks in particular are often identified as Goshawk. A large female Sparrowhawk can approach the size, if not the bulk, of a male Goshawk, but female Goshawks are Buzzard-sized.

VITAL STATISTICS

Status. Reintroduced resident breeder.

Population size. 400 pairs.

Conservation status: GREEN (Least concern).

Lifespan: Average age in the wild is 7 years. Adults have an 83% year-to-year survival. First year survival is not known, but birds have a 40% chance of reaching their second year. The oldest known wild bird was almost 19 years old (ringing recovery).

Nesting: Goshawks build large stick nests high up in a tree, usually a conifer. They are highly secretive whilst nesting, but when displaying on fine days in early spring, high above the trees, they can give their presence away and this is often the best time to see this elusive species.

Number of eggs: 3-4

Incubation: 35-38 days

Fledging time: 35-42 days

Habitat and Distribution: Goshawk share the same short blunt wings, as their smaller cousin, Sparrowhawk, which gives a clue to their woodland habitat. Enabling them to move rapidly and agilely through dense vegetation, Goshawk are supremely adapted to life in wooded areas. The majority birds are found in woodland, and they are prone to disturbance, so tend to be found in remoter areas, they are extremely rare in urban areas and are highly unlikely to be found taking birds in gardens. They are most likely to be encountered in Wales and southern and eastern Scotland, but there are also well-known populations around Dartmoor, New Forest, Thetford Forest, Pennines and Northumberland. It is believed that the population is increasing, but numbers are still too low for it to be monitored by standard bird surveys.

Movements: Throughout their huge world range, Goshawks can be highly migratory, but British Goshawks are invariably sedentary. Occasionally young birds and migrants wander to UK from northern Europe where they may be more migratory in response to varying food availability. It is possible that some of the recent population comes from continental birds.    

Feeding: In the UK most prey taken are birds, with Wood Pigeons and members of the crow family favourites. In some areas, such as North America, mammals may also feature highly and a study in Thetford Forest showed that over 50% of the food fed to chicks in the nest was Grey Squirrel. Food availability is unlikely to be a factor in suppressing numbers of Goshawk which are presently well below expected carrying capacity in UK. They are adaptable and catholic hunters, making use of any opportunities. They invariably hunt by sitting and watching, combined with short, stealthy flights between perches. Once prey is spotted it can be caught in a number of different ways, but Goshawk are even known to hunt by foot on the ground in very dense habitats. Most prey are likely to be taken by surprise, although long, agile chases occasionally occur, especially if the hawk is hungry.

Accipter nisus

Accipter hawks are short-winged birds of prey, perfectly designed for rapid manoeuvring amongst the heavily vegetated areas in woodlands which are their main habitat. Many birds of prey exhibit sexual dimorphism – differing sizes of male and female – the largest difference of all is Sparrowhawk, where females can be 25% larger than the males. It is believed that this ensures both birds can hunt different prey, and not come into conflict over limited prey, especially in winter. Particularly in the early stages of pairing up in the spring, males must be cautious, as they are well within the range of female prey and it is not unknown for males to be taken, although they are more agile than the heavier females.

Although well-known as a visitor to garden bird feeding stations, only 10% of Sparrowhawk hunting flights are successful. They use a variety of hunting techniques, but perhaps the most characteristic one is to fly low on the far side of a hedge or fence, before flipping over the top and surprising the birds on the other side. Some small birds, such as Blue Tit have a specific warning call they give if they spot a Sparrowhawk. Other birds, including other species, can understand this call and also seek cover. The call will also alert us to the near-by presence of a Sparrowhawk!

The colouration, size and even flying style of Sparrowhawks is very similar to that of Cuckoo, and it is believed that Cuckoos have evolved this, as other small birds see them as predators, rising off the nest to ‘mob’ a potential predator and, in the process, revealing the location of their nests which the female Cuckoo will be looking for to lay her eggs in.

Males are blue-grey above with fine orange barring beneath, females are grey-brown and white. Young birds are browner with coarsely barred chests. The only likely confusion species is Goshawk.

VITAL STATISTICS

Size: Average 33cm (male) 37cm (female); wingspan 62cm (male), 74cm (female). Females (260g) much heavier than males (150g).

Status. Resident breeder and passage/winter visitor.

Population size. 33,000 pairs.

Conservation status: GREEN (Least concern).

Lifespan: Typical lifespan of 4 years, with an adult year-to-year survival rate of 69%. First year survival is just 34%. The oldest known wild bird was just over 17 years old (ringing recovery).

Nesting: Sparrowhawks nest in messy stick nests in trees, often deep in forested areas, although they will nest in parks, large gardens and small wooded patches. They are quite shy whilst breeding, but when they have well-grown chicks in the nest, their incessant begging can give the location away.

Number of eggs: 4-5

Incubation: 33 days

Fledging time: 27-31 days

Sparrowhawks are single-brooded and will breed in the year after hatching.

Habitat and Distribution: One of our most frequent and familiar birds of prey, Sparrowhawks are birds of woodland, but they have adapted to life in our mosaic habitats, including gardens, farmland and even urban areas. Sparrowhawks occur over the whole of the UK, although they are scarcer in the north and west. Numbers crashed in the latter part of the 20^th Century, due to pesticides used as seed dressings accumulating in their bodies through eating contaminated prey. This poisoning caused thinned egg shells leading to breakage in the nest. From the 1970s, after these chemicals were banned the population slowly recovered, leading to stability in the 1990s. Numbers have dropped slightly in the last decade.

Movements: Most British Sparrowhawks remain rather sedentary, although young birds can move significant distances in the search for a territory. Birds from northern Europe migrate here for the winter and can often be encountered in the east.   

Feeding: Reliant on small birds, which are often caught in a twisting, agile flight. Despite their name sparrows are not particularly sought, but any small bird is a potential target. In gardens tits are frequent prey, and males will frequently hunt birds up to the size of a Blackbird. Females tend to target larger prey, and commonly tackle Collared Doves and Wood Pigeons. Prey is usually dispatched with their very long toes and talons, but distressingly plucking can often begin before the prey is dead. Larger prey, such as Magpies, is often drowned.