Bar-tailed Godwits: migration & survival

 The Bar-tailed godwit (Limosa lapponica) is a large wader. The migration of its subspecies Limosa lapponica baueri across the Pacific Ocean from Alaska to New Zealand is the longest known non-stop flight of any bird, and also the longest journey without pausing to feed by any animal. The round-trip migration for this subspecies is over 29,000 km (18,020 mi).

Appearance

The Bar-tailed godwit is a relatively short-legged species of godwit. The adult has blue-grey legs and a long, tapering, slightly upturned bi-colored bill: pink at the base and black towards the tip. The neck, breast, and belly are unbroken brick red in breeding plumage, and dark brown above. Females’ breeding plumage is much duller than males, with a chestnut to cinnamon belly. Breeding plumage is not fully apparent until the third year, and there are three distinguishable age classes; during their first migration north immature males are noticeably paler in colour than more mature males. Non-breeding birds seen in the Southern Hemisphere are plain grey-brown with darker feather centres, giving them a striped look, and are whitish underneath. Juveniles are similar to non-breeding adults but more buff overall with streaked plumages on flanks and breast.

Distribution

Geography

Bar-tailed godwits breed in Scandinavia, northern Asia, and Alaska and migrate to coastal East and South Asia, Australia, Africa, northwestern Europe, and New Zealand. Their breeding grounds include open tundra, mudflats, marshy and swampy areas, river valleys, lakes, and bogs. The winter habitats are usually located along muddy coastlines, estuaries, shallow bays and lagoons.

Habits and Lifestyle

Bar-tailed godwits are social but extremely wary birds. They congregate in flocks but when feeding during the day they may disperse individually or in small groups. Bar-tailed godwits forage by probing in mudflats or marshes using their long sensitive bills. They may also find insects by sight in short vegetation. When birds are alarmed they produce high-pitched “kik” or “kiv-ik”. During courtship displays and on nesting grounds their calls sound as “a-wik, a-wik, a-wik” and a “ku-wew, ku-wew”.

Diet and Nutrition

Bar-tailed godwits are carnivores and eat mainly insects, crustaceans, and mollusks. They may also feed on parts of aquatic plants, seeds, and berries occasionally.

Mating Habits

Bar-tailed godwits are monogamous which means that one male mates with only one female. They breed between May and June performing courtship displays in which the male circles high above the nest site and calls loudly. The nest is a shallow cup in moss sometimes lined with vegetation. The female lays 2 to 4 which are incubated about 20-22 days. Both parents share incubation of the eggs and care for the young. The chicks are precocial (fully-developed; they hatch with their eyes open and are able to follow their parents to nearby marshy areas to find their own food. The young fledge and become independent from their parents when they are 1 month old reach reproductive maturity at 2 years of age.

Population

Population threats

Major threats to Bar-tailed godwits include habitat loss due to residential and commercial development, expansion of the agriculture and mining, climate change and serve weather as well as hunting in some areas of their range. They also suffer from pollution, human disturbance, and outbreaks of infectious diseases.

Weasel

 The Weasel (Mustela nivalis) is the smallest member of the Mustelid family and Britains smallest carnivore.

Common weasels are found in central and western Europe and the Mediterranean region (but not the Mediterranean islands). Weasels also inhabit North Africa, Asia and North America, and were introduced to New Zealand.

Weasels are widespread and common throughout England, Scotland and Wales but absent from Ireland, the Isle of Man and most smaller islands. Like the stoat, it is still persecuted by gamekeepers. Weasels look very similar to Stoats, the only noticeable difference being, that unlike stoats, weasels do not have a black tip to the tail.

Stoats

Both weasels and stoats have a very similar diet and enjoy similar habitats and ranges around Britain, yet they tend to stay out of each others way if possible. Male and Female stoats and weasels are referred to as a dog and a bitch respectively. The young are called kittens or kits. Collective nouns for a group of weasels include boogle, gang, pack and confusion.

The Weasel pre-breeding season population is estimated to be 450,000 adults.

WEASEL DESCRIPTION

Weasels vary in length, but generally, male weasels measure around 20 – 22 centimeters long and have a tail length of 6.5 centimeters and female weasels measure around 15 – 18 centimeters long and have a tail length of 4.5 centimeters. The average weasel weighs about 198 grams (7 ounces), however, males usually weigh up to 115 grams and females up to 59 grams.

Weasels bodies and necks are shaped cylindrically, they are long and slender and they have short legs. Their long slender bodies enable them to follow their prey into burrows.

Weasels have light brown fur on their backs and their underparts are creamy/white. The weasel is smaller than the stoat and lacks the small white patches under their chin and throat. In many weasel species, populations living at high latitudes moult to a white coat with black fur at the tip of the tail in winter. Weasels have sharp eyesight and excellent hearing.

WEASEL HABITATS

Weasels have a wide range of habitats from grasslands, sand dunes, lowland forests to upland moors and even towns, anywhere where there is suitable food. Their nests are made of grass and leaves, usually in holes in a wall, or tree stumps.

WEASEL DIET

Weasels feed on small mammals and in former times were considered vermin since some species took poultry from farms, or rabbits from commercial warrens. Certain species of weasel and ferrets, have been reported to perform the mesmerizing weasel ‘war dance’, after fighting other animals, or acquiring food from competing creatures. In folklore at least, this dance is particularly associated with the stoat. Mice and voles make up 60% – 80% of their diet, however, they also eat rats, frogs and birds. Their prey is killed with a sharp bite to the back of the neck. Prey is usually taken on the ground.

Cats, owls, foxes and birds of prey will all try to kill weasels, although a weasel will fight hard to defend itself.

WEASEL BEHAVIOUR

The weasel may travel up to 2.5 kilometers on a hunting expedition. Weasels are good climbers and will often raid birds nests, taking the eggs and young. When ratting, its courage is even greater than the stoats.

Female weasels are considerably smaller than males, however, both are small enough to pursue rats, mice and even field voles in their own tunnels. Weasels are crepuscular, active at twilight (dusk and dawn), and it must consume a quarter to a third of its body weight every day to survive.

Each weasel has a territory of 4 – 8 hectares (1 hectare is equal to 2 football pitches). Male territories are larger than females and they may overlap with one another. The size of the territory depends on the food supply; where there is plenty there is no need to hunt for food far and wide. The individual territories are marked with strong-smelling secretions from the anal scent glands.

Females stay in their territory throughout the year, however, during the mating season, males may travel long distances outside their normal range to find a mate. Weasels do not make themselves any kind of permanent burrow, they usually use the tunnel or burrow of one of the animals they have eaten.

WEASEL REPRODUCTION

Weasels breed between April and August, this is the only time males and females associate with each other. They produce 1 – 2 litters per year which contain 4 – 6 young each. Gestation period is around 5 weeks. The young of the first litter grow very fast, they are weaned at 4 weeks, at which time their eyes open and are able to hunt and kill at 5 – 8 weeks. They often accompany their mother on hunting expeditions.

Young weasels, born early in the year, are capable of breeding themselves during their first summer, unlike other British carnivores which do not breed until their second year.

Stoats and Weasels are quite different in their reproductive habits, this is probably due to the short life that weasels lead, forcing them to produce offspring as quickly as possible. Unlike stoats, weasels have no delayed implantation. Weasels have a life span of up to 2 – 3 years in the wild, up to 10 years in captivity.

WEASEL CONSERVATION STATUS

Neither the stoat or weasel is in any real danger of extinction in the UK, they are however threatened by hunting, habitat loss, poisoning and both often get run over on the country lanes. They do tend to live around farms as the hedgerow habitat and plentiful food supply suits them. This often leads them into conflict with farmers, especially problematic are stoats who are very able at snatching chickens, eggs as well as game birds.