Mallee fowl

The mallee fowl is an extraordinary bird that lives in semi-arid parts of southern Australia, notably the mallee scrublands (composed of dwarf eucalypts) from which it takes its name. Although this bird is not particularly noteworthy in appearance, its breeding behaviour makes it remarkable.

The mallee fowl belongs to the megapode group of birds, most of which are forest dwellers and are characterised by building mounds for their nests. However, the mallee fowl has adapted to living in more open environments.

Appearance

The mallee fowl (Leipoa ocellata) is a large bird, some 60 centimetres (24 inches) in length. The head and neck are greyish, with a black crest. The wings are barred and the upperparts are also heavily barred with black, brown, white and grey markings. The underparts are a more uniform grey with a dark line running down the chest. Males and females are similar in appearance.

Behaviour

The mallee fowl is not a great flyer, preferring to spend most of its time on the ground and only flapping with some effort into trees and bushes to roost.

It spends the day foraging for fruits, vegetation and insects.

Breeding

The breeding season is from September to April. The birds build a large mound – up to four feet high and 14 feet across – that consists of vegetable matter that is then covered in soil. As the vegetation rots it creates heat, and this is used to incubate the eggs. A hole is made in the top of the mound, in which the hen bird lays between 15 and 24 eggs at 6-day intervals. The male bird then assumes responsibility for temperature control, either covering the eggs or exposing them to the air. He tests the temperature with his mouth lining and tongue, ensuring that the eggs never vary more than one degree from the ideal level, which is 33 Celsius (91 Fahrenheit).

The process is a long one, taking as much as eight months from the initial laying to the final hatching. No other bird species is known to be able to achieve such a degree of thermal engineering, although not every egg produces a live chick and the failure rate can be as high as 50%.

On hatching, the chicks dig their own way out of the mound and are then completely on their own, getting no support from their parents. They fledge at about one week.

The mallee fowl has clearly evolved in a way that works, although the contrast between intense care for the eggs and none for the chicks may strike one as bizarre. The main threat to the mallee fowl comes from habitat destruction.

© John Welford

Slavonian grebe

The slavonian grebe (Podiceps auritus) is an eye-catching bird, especially in its breeding plumage, but it is more likely to be seen in coastal waters around parts of the British Isles during the winter months. Even then, it is not a common bird, being seen in much greater numbers in Iceland, Scandinavia, Russia and North America. A few pairs breed each year on remote freshwater lochs in the Scottish Highlands, the first such pair having been recorded in 1908.

At around 13 inches (33 cms) in length, the slavovian grebe is about the size of a moorhen. It has a long neck, flat crown and short bill. 

The summer plumage comprises black cheek feathers, chestnut on the neck and flanks, and a dark back. The most striking feature is the prominent yellow tuft, resembling a horn, on either side of the head.

In winter, the Slavonian grebe is a black and white bird, dark above and light below, with a black crown and white cheeks, throat and breast. The plumage – both in summer and winter – is similar as between males and females. 

The slavonian grebe is mostly silent, although during courtship it utters a guttural trill. 

They feed on water insects, larvae and small fish. They will dive for food or take it by skimming the surface.

After wintering on coastal waters, Slavonian grebes return to their breeding grounds in March or early April, having already formed pairs. They have an elaborate courtship ritual in which both birds rear up and face each other, shaking their heads. They will also dive at the same time, come back to the surface carrying water-weed in their bills, then dash side-by-side for up to 10 metres.

The nest is built from water-weed, floating on the surface, but anchored to the lake bottom by plants that grow from there. The nest will be in a sheltered position, possibly under tree branches or overhanging rocks. 

Four or five eggs are laid, to be incubated by both birds, with the chicks hatching after three to four weeks. The chicks are able to swim soon after hatching but will also ride on their parents’ backs. They are able to dive after about ten days, but will rely on being fed by their parents until they are almost ready to fledge, which will be at about two months old. 

The Slavonian grebe is a protected species in the United Kingdom, with every effort made to keep the breeding sites secret as protection against egg collectors.

© John Welford

Eurasian roller

The Eurasian roller (Coracias garrulus) is notable for the proportion of its life that it spends migrating between its breeding grounds in Europe (central and southern) and Asia and its winter quarters in southern Africa.

Appearance

About 12 inches in length, the Eurasian roller has the general shape of a jay but is more highly coloured. The breast is bright blue, the wings are a darker blue, and the back is bright chestnut.

The bird has a harsh and discordant call.

Habitat

The Eurasian roller prefers open countryside that contains mature trees. It can also be seen in forest margins, old orchards and large clearings.

Behaviour and feeding

The Eurasian roller is a carnivorous bird that feeds on insects, invertebrates, small rodents and even other birds. It feeds by swooping down from a high perch.

Breeding

Eurasian rollers reach their breeding grounds in late April or early May, after which the males perform a courtship display that consists of plunges and aerobatics accompanied by loud calling.

Nests are built in hollow trees or holes in river banks. Up to seven eggs are laid, these being incubated by both parents for 17-20 days.

Migration

At the end of Summer the Eurasian roller begins its journey south, flying around 40 miles a day and taking frequent breaks before reaching East Africa by late October or early November, and South Africa in early December. The return flight is started in February. It is therefore settled in one place for a relatively short time.

© John Welford

Shore lark

The shore lark (Eremophila alpestris) breeds in the high Arctic but moves south in the winter, which is when it can be seen on the east coast of England between October/November and March. Other populations are found in south-east Europe, Asia and North America. 

At 14-17 cm (7 inches) the shore lark is smaller than the skylark. It has a pinkish-brown streaked back, pale underparts, a black and yellow face and a black throat. Adult males have a black band on the forehead that extends to two small “horns” on the crown. Female shore larks have less contrast in their markings but are otherwise similar in appearance. Both sexes are poorly marked in autumn and winter.

Shore larks feed on open ground, such as in salt marshes, shuffling along or making small hops. In summer food consists of insects and seeds, but in winter it is mainly seeds. Preferred insect food is springtails, flies and beetles. Seed food is mainly from sedges, docks, grasses and grains.

Shore larks nest on the ground, in a depression made by the female in the open amongst short vegetation. 2-4 eggs are incubated by the female for 10 or 11 days. When the young birds hatch they are cared for and fed by both parent birds. They leave the nest at 9-12 days but do not fly until 16-18 days. A second brood can be raised.

Numbers of wintering shore larks in Britain have increased in recent years, with the current total somewhere between 200 and 300 individuals. It is a specially protected species in Great Britain.

© John Welford

Snowy owl

The snowy owl (Bubo scandiacus) measures up to 70 centimetres (28 inches) in length with a wingspan of up to 150 centimetres (28 inches). This makes it one of the largest owl species. It is also one of the heaviest, weighing in at up to 6 kilos (13 pounds).

As the name suggests, the plumage is largely white – almost entirely so in adult males but with black specks and spots in females and juveniles. The beak is black and the eyes yellow. The feet have large talons covered in feathers.

Snowy owls entered the popular imagination when J K Rowling introduced one as “Hedwig” in the Harry Potter books. The owl is a messenger in these stories – taking letters and packets between her owner and other members of the magical world – and always has an air of mystery about her. That is not inappropriate, given that snowy owls have long presented questions to naturalists that have only recently been answered.

The problem with the snowy owl is that it is a native of the far north – in Eurasia and North America – but those regions are almost inaccessible during the long winter months when there is extensive snow cover and the sun never rises. It has therefore only been possible to study snowy owls during the summer, so what do they do during the winter? What is their food source? How do they survive?

It is known that snowy owls sometimes migrate southwards in what are known as “irruptions”, when large numbers can appear in winter at latitudes far to the south of their usual range. This coincides with the unavailability of their main food source, namely the lemming, a small mouse-like rodent that regularly goes through huge population fluctuations. When lemmings are plentiful, snowy owls can raise up seven or eight young in a breeding season; however, a poor summer for lemmings can mean that snowy owls do not breed at all.

Snowy owls therefore tend to follow the lemmings, especially in autumn when snow cover in the north makes hunting progressively more difficult. Snowy owls do not exclusively eat lemmings, so other prey is sought when there are no lemmings to be had. This is why some irruptions take snowy owls much further south than lemming territory.

In the winter of 2013/14 there was a particularly notable irruption in North America when large numbers of snowy owls ventured south, some even being seen in Georgia, Florida and Bermuda. This provided a rare opportunity to study snowy owl behaviour by using technology, in the former of tracking devices and transmitters fitted to captured and released birds, to monitor their every move.

One assumption that was soon overturned was that snowy owls, unlike other owl species, were diurnal – i.e. that they hunted during the day rather than the night. Given the choice, snowy owls prefer to hunt under cover of darkness. The reason why they had always been seen hunting in daylight in the high Arctic was that summer in that region is always day time – the sun does not set so there is no night to hunt in.

Another misconception was that irruptions are dictated by hunger and that snowy owls swarm south because of starvation. Observations in 2013 showed that the birds were well fed and also that they were mainly younger specimens. What happens in a good breeding season, with plentiful food to hand, is that many offspring survive and they are not encouraged to hang around by their parents. As winter approaches, the older birds protect their hunting grounds and the younger ones must move elsewhere. A large irruption may therefore be the result of too much food being around, not too little!

A major surprise was the discovery that snowy owls will hunt other birds and not just small mammals. Some were found to prey on ducks and other waterbirds, especially in the Great Lakes region. Those large talons are used to tackle prey that is even larger that the snowy owls themselves, such as snow geese.

The study prompted by the 2013/14 irruption therefore showed the snowy owl to be a highly adaptable bird that is well equipped to survive in changing circumstances. J K Rowling’s choice of the snowy owl as her model for Hedwig – a wise bird who knows what’s what – would seem to have been an inspired one!

© John Welford

Greater scaup

The greater scaup (Aythya marila) is a salt-water duck found in the tundra regions of the Northern Hemisphere. Breeding areas include Alaska, Iceland and northern Europe and Asia. Its wintering areas include the Pacific and Atlantic coasts of North America, the British Isles, the Mediterranean and Black Seas, and coastal China and Japan. It is a gregarious bird, and large rafts of greater scaup can be seen on larger expanses of water.

Greater scaup are 17-20 inches (42-52 cm) long. Males and females are the same size.

The male greater scaup has a black head with a greenish tinge. The neck, breast, upper back and rump are black, with the belly and flanks being white. The upperparts are pale grey with wavy black stripes. The bill is pale blue with a black tip. The irises of the eyes are yellow. The feet and legs are greyish-blue.

The female greater scaup has a white patch at the base of the bill and a whitish spot on the side of the head. The body is mainly brown.

The greater scaup is silent in flight. The male has a soft courtship whistle and the female a growling “krrr” or “karr karr”.

Food is an equal mixture of molluscs and aquatic vegetation. 

The nest comprises a depression in the ground at a site quite close to water. Up to nine eggs are laid, these being incubated by the female for up to 28 days. 

© John Welford

Oilbird

The oilbird (Steatornis caripensis) is a South American bird that has adopted a lifestyle more like that of bats than the average bird species. Flocks of oilbirds spend the day on ledges high up in forest caves and sweep out at dusk to feed.

Distribution and habitat

Oilbirds are found in the forests of northern South America, notably in Venezuela, Colombia and Bolivia. They are also found on the island of Trinidad and in western Guyana.

Populations tend to be local, being dependant on the presence of suitable caves. Although individual birds may fly long distances when foraging, they always return to the same cave and are likely to spend their whole lives in the cave they were born in.

Appearance

Oilbirds are up to 18 inches long with a 3 foot wingspan. The tail is long and wide. The powerful hooked beak has whiskery feathers on each side. The legs are short.

The plumage is a rich brown in colour, with darker bars on the wings and tail. There are conspicuous white spots on the head, wing coverts, and the edges of the tail and flight feathers.

Behaviour

Oilbirds are nocturnal and spend the day in caves that are pitch dark even during daytime. They have therefore developed echolocation, by which is meant the instinctive calculation of distances to obstacles by taking account of the time that the sound of a click-like call echoes back to them. Unlike bats, oilbirds use audible calls for this purpose as opposed to supersonic ones. This method of navigation only applies inside the caves, because oilbirds have excellent night vision and a strong sense of smell which are used to locate food during the hours of darkness in the forest.

Oilbirds feed on the fruit of forest trees, picking these on the wing by wrenching them off with their beaks and swallowing them whole. They rely on a limited number of tree species, notably palms, laurels and those that produce incense. The latter are preferred for feeding to their chicks, which renders the bodies of young birds particularly “oily”, hence the name.

The preferred fruits contain a single seed that is regurgitated intact once the highly nutritious pericarp has been digested. This helps the trees to reproduce in other parts of the forest, but many seeds end up on cave floors where they germinate but soon wither for lack of light.

Breeding

Oilbirds pair up and mate for life, roosting at their nests throughout the year, whether or not they are breeding. An oilbird nest is a mound made from semi-digested fruit pulp. The nest continues to grow as new material is added but will eventually fall from its ledge and have to be rebuilt.

A clutch of up to four eggs is laid over a period of two or more weeks, with several days elapsing between the laying of each egg. Incubation begins as each egg is laid and may take up to 34 days. The chicks therefore hatch at intervals and grow very slowly, being fed entirely on fruit.

A chick at 70 days old may weigh more than a parent bird but then lose weight as the adult plumage grows. The interval from first egg-laying to the fledging of the last chick can be as much as six months.

Conservation

Early Western explorers discovered that oilbird chicks were an excellent source of oil for lamps and cooking once their carcasses were boiled down, and this led to the species coming under severe threat.

However, the oilbird is now a protected species in much of its range, with the main threat coming from deforestation.

© John Welford