Eurasian otter

Eurasian otter

The Eurasian otter (Lutra lutra), also known as the European otter, Eurasian river otter, common otter, and Old World otter, is a semiaquatic mammal native to Eurasia. The most widely distributed member of the otter subfamily (Lutrinae) of the weasel family (Mustelidae), it is found in the waterways and coasts of Europe, many parts of Asia, and parts of northern Africa. The Eurasian otter has a diet mainly of fish, and is strongly territorial. It is endangered in some parts of its range, but is recovering in others..

Description

The Eurasian otter is a typical species of the otter subfamily. Brown above and cream below, these long, slender creatures are well-equipped for their aquatic habits. Their bones show osteosclerosis, increasing their density to reduce buoyancy.[2] This otter differs from the North American river otter by its shorter neck, broader visage, the greater space between the ears and its longer tail.[3] However, the Eurasian otter is the only otter in much of its range, so it is rarely confused for any other animal. Normally, this species is 57 to 95 cm (22.5 to 37.5 in) long, not counting a tail of 35–45 cm (14–17.5 in). The female is shorter than the male.[4] The otter's average body weight is 7 to 12 kg (15 to 26 lb), although occasionally a large old male may reach up to 17 kg (37 lb).[5][6] The record-sized specimen, reported by a reliable source but not verified, weighed over 24 kg (53 lb).[7]

Distribution and habitat

The Eurasian otter is the most widely distributed otter species, its range including parts of Asia and Africa, as well as being spread across Europe, south to Israel. Though currently believed to be extinct in Liechtenstein and Switzerland, they are now very common in Latvia, along the coast of Norway, in the western regions of Spain and Portugal and across Great Britain, especially Shetland, where 12% of the UK breeding population exists.[8] Ireland's otters are geographically widespread and believed to be the most stable population in Europe.[9] In Italy, they can be found in southern parts of the peninsula. The South Korean population is endangered. In India, the species is distributed in the Himalayan foothills, southern Western Ghats and the central Indian landscape.[10]

In general, their varied and adaptable diets mean they may inhabit any unpolluted body of fresh water, including lakes, streams, rivers, canals and ponds, as long as the food supply is adequate. In Andalusia the golf courses became part of their habitat.[11] Eurasian otters may also live along the coast, in salt water, but require regular access to fresh water to clean their fur. When living in the sea, individuals of this species are sometimes referred to as "sea otters", but they should not be confused with the true sea otter, a North Pacific species much more strongly adapted to a marine existence.

The extinct Japanese river otter is usually considered a subspecies.

Diet

The Eurasian otter's diet mainly consists of fish.[12] Fish is their most preferred choice of food in Mediterranean and temperate freshwater habitats.[13] During the winter and in colder environments, though, fish consumption is significantly lower, and the otters use other sources of food, including amphibians,[14][15] crustaceans, insects, birds and sometimes small mammals, including young beavers.[16]

Breeding

Eurasian otters are strongly territorial, living alone for the most part. An individual's territory may vary between about 1 and 40 km (1–25 mi) long, with about 18 km (11 mi) being usual. The length of the territory depends on the density of food available and the width of the water suitable for hunting (it is shorter on coasts, where the available width is much wider, and longer on narrower rivers).The Eurasian otter uses its feces, spraints, to mark its territory and prioritize the use of resources to other group members.[17] The territories are only held against members of the same sex, so those of males and females may overlap.[18] Mating takes place in water. Eurasian otters are nonseasonal breeders (males and females will breed at any time of the year) and it has been found that their mating season is most likely determined simply by the otters' reproductive maturity and physiological state. Female otters become sexually mature between 18 and 24 months old and the average age of first breeding is found to be ​2 1⁄2 years. Gestation for the Eurasian otter is 60–64 days, the litter weighing about 10% of the female body mass. After the gestation period, one to four pups are born, which remain dependent on the mother for about 13 months.[19] The male plays no direct role in parental care, although the territory of a female with her pups is usually entirely within that of the male.[18] Hunting mainly takes place at night, while the day is usually spent in the Eurasian otter's holt (den) – usually a burrow or hollow tree on the riverbank which can sometimes only be entered from underwater. Though long thought to hunt using sight and touch only, evidence is emerging that they may also be able to smell underwater – possibly in a similar manner to the star-nosed mole.[20][21]

Conservation

The Eurasian otter declined across its range in the second half of the 20th century[22] primarily due to pollution from pesticides such as organochlorine and polychlorinated biphenyls. Other threats included habitat loss and hunting, both legal and illegal.[23] Eurasian otter populations are now recovering in many parts of Europe. In the United Kingdom, the number of sites with an otter presence increased by 55% between 1994 and 2002.[citation needed] In August, 2011, the Environment Agency announced that otters had returned to every county in England since vanishing from every county except the West Country and parts of Northern England.[24] Recovery is partly due to a ban on the most harmful pesticides that has been in place across Europe since 1979,[25] partly to improvements in water quality leading to increases in prey populations, and partly to direct legal protection under the European Union Habitats Directive[26] and national legislation in several European countries.[27][28][29] In Hong Kong, it is a protected species under Wild Animals Protection Ordinance Cap 170. It is listed as Near Threatened by the IUCN Red List.[1]

In Asia, it is listed as endangered in Pakistan, India, Bangladesh, Myanmar and Thailand, and critically endangered in Mongolia.[1]

Most species that are victims of population decline or a loss of habitat tend to eventually lose their genetic difference due to inbreeding from small populations. A study conducted in 2001, examined whether or not the populations of Eurasian otters suffered from a lack of genetic variability. In the study, they examined teeth of otter skulls at the Zoological Museum, Copenhagen and the Natural History Museum, Aarhus. The samples were collected between 1883 and 1963 in Denmark (Funen, Zealand, and Jutland). The study examined the tissue on the teeth of the skulls and determined the genetic variability based on DNA analysis. In conclusion, the study discovered that despite the population declines, the Eurasian otter was not a victim of declining genetic variability.[30]

The decline in population of native freshwater fishes, which is the preferred food of Eurasian otters, in the rivers of Iberia, along with the expansion of exotic fish species like centrarchids could potentially put Eurasian otters at risk for extinction.

Common Uk Lizard (Viviparous lizard)

Common Uk Lizards Common Uk Lizards

The viviparous lizard, Zootoca vivipara (formerly Lacerta vivipara), is a Eurasian lizard. It lives farther north than any other species of non-marine reptile, and most populations are viviparous (giving birth to live young), rather than laying eggs as most other lizards do. It is the only species in the monotypic genus Zootoca.[3] Both "Zootoca" and "vivipara" mean "live birth," in Greek and Latin respectively. It was called Lacerta vivipara until the genus Lacerta was split into nine genera in 2007 by Arnold, Arribas & Carranza.[4]

Zootoca vivipara can be seen in a variety of different colours. Female Zootoca vivipara undergo colour polymorphism more commonly than males. A female lizard's display differs in ventral colouration, ranging from pale yellow to bright orange and a mixed colouration. There have been many hypothesis for the genetic cause of this polymorphic colouration. These hypothesis test for colouration due to thermoregulation, predator avoidance, and social cues, specifically sexual reproduction. Through an experiment conducted by Vercken et al., colour polymorphism in viviparous lizard is caused by social cues, rather than the other hypotheses. More specifically, the ventral colouration that is seen in female lizards is associated with patterns of sexual reproduction and sex allocation.[5]

Identification

The length of the body is less than 12 cm (5 in) (excluding the tail). The tail is up to twice as long as the body, although it is often partially or wholly lost. The limbs are short, and the head is rather round. Males have more slender bodies than females. The neck and the tail are thick. The collar and other scales seem jagged.

The colour and patterning of this species is variable. The main colour is typically medium brown, but it can be also grey, olive brown or black. Females may have dark stripes on their flanks and down the middle of their backs. Sometimes females also have light-coloured stripes, or dark and light spots along the sides of their backs. Most males and some females have dark spots in their undersides. Males have brightly coloured undersides – typically yellow or orange, but more rarely red. Females have paler, whitish underparts. The throat is white, sometimes blue.

Range

The viviparous lizard is widely distributed throughout Europe and Asia. Its range extends to the north of the Arctic Circle. It ranges from Ireland to Hokkaido and Sakhalin. It is absent from most of the Mediterranean area, although it occurs in northern Spain, Northern Italy, Serbia, North Macedonia and Bulgaria. It is also absent from the area surrounding the Black Sea.

In the southern parts of its distribution range, the species lives at high elevations, occurring as high as 3,000 metres (9,800 ft) above sea level in the Alps. In these areas, the viviparous lizard lives in damp locations, often near water, including meadows, swamps, rice fields, by brooks and in damp forests. In the northern part of the range, the species is also found in lowlands, where it occurs in drier environments, including open woodland, meadows, moorland, heathland, fens, dunes, rocks, roadsides, hedgerows and gardens. It lives mainly on the ground, although it may climb onto rocks, logs and low-growing vegetation.

Behaviour

The viviparous lizard feeds on invertebrates, mostly small insects and spiders. It shakes larger prey in its jaws before chewing it and swallowing it whole. In early spring, late autumn, and cool summer days, it basks in the sun to reach its optimum body temperature, which is about 30 °C (86 °F).

These lizards mate in April or May. Males take females in their jaws before mating – if the female is not interested, she will bite the male fiercely. The offspring develops inside the female for about three months.

The name of the species is derived from its ability to give birth to live young, an adaptation to a cool climate, but some southern populations are oviparous (egg-laying). The three to ten young (or eggs) are usually produced in July. The blackish young measure about 3 cm (1.2 in), and when first born are surrounded by egg membrane, from which they break free after about a day. Males reach sexual maturity at the age of two years, females at the age of three years. Individuals from viviparous and oviparous populations may be hybridised, but with significant embryonic malformation.[6] Viviparous Z. vivipara do develop placentae to facilitate pregnancy but there is no substantial transport of nutrients as seen in some other species of viviparous reptiles (e.g. the southern grass skink).

Due to the cool climate, in northern regions, viviparous lizards begin hibernation in September or October, underground or in log piles. Hibernation ends about mid-February. Further south, the species is active throughout the year.

Colour polymorphism

The colour polymorphism of female Zootoca vivipara has not been thoroughly studied in past years, regardless of the extensive research done on the species itself.[7] Female lizards exhibit three types of body colouration within a population: yellow, orange, and mixture of the two. These discrete traits are inherited maternally and exist throughout the individual's lifetime.[7] The organism's colour morphs are determined by their genotype as well as their environment.

The frequency of multiple morphs occurring in a population varies with the level of population density and frequency-dependent environments.[7] These factors cause the lizards to vary in terms of their fitness (clutch size, sex ratio, hatching success).[7] In lower density populations, colour polymorphism is more prevalent.[5] This is because viviparous lizards thrive in environments where intraspecific competition is low.[8] Increased competition among individuals results in lower survival rates of lizards. Additionally, female lizards disperse through habitats based on the frequency of colour types that are already present in the population.[8] Their reproductive abilities vary according to this frequency-dependent environment. The number of offspring that they produce correlates with the colour morph: yellow females produce the fewest offspring, while orange females produce more than yellow, but fewer than mixed females, which produce the most offspring.[5] The amount of offspring produced varies in regards to colour frequencies in the population; for example, if yellow females have higher density within the population, the clutch size for orange lizards is usually lower.[5]

Orange females are more sensitive to intraspecific and colour-specific competition.[5] They have smaller clutch sizes when the density of the population is high, or when the number of yellow females in the population is high. This could be due to their need to conserve energy for survival and reproductive events.[5] Their colour morph remains in the population due to the trade-off between the size of offspring and the clutch size. Offspring born in smaller clutches are often larger and thus have a higher survival likelihood.[5] Natural selection will favor individuals with larger size because of their advantage in physical competition with others. Yellow females have larger clutch sizes early in their life, but their hatch success decreases as the female ages.[5] Their reproductive viability decreases, resulting in fewer offspring throughout their lifetime. Yellow morphs remain in the population due to their large clutch size, which causes an increased frequency of those females.[5] Selection favors the yellow morph because of the ability to produce large clutch sizes, which increases the female's fitness. In mixed-coloured females, reproductive success is less sensitive to competition and frequency-dependent environments.[5] Since these lizards show a mixture of yellow and orange colouration, they adopt benefits from both of the morphs. As a result, they can maintain high reproductive success and hatching success with large clutch sizes.[5] Their colour morph remains in the population due to its high fitness, which selection will favor.

All three colours have evolutionary advantages in different ways. While yellow females have higher fitness due to their large clutch sizes, orange females enjoy high fitness due to their large body size and increase competitive advantages. Mixed females exhibit both of these advantages.

Cockchafer Beetles (Maybugs)

Cockchafer Beetle / Maybug Cockchafer Beetle / Maybug taking flight

The cockchafer, colloquially called Maybug[1][a] or doodlebug,[3] is the name given to any of the European beetles of the genus Melolontha, in the family Scarabaeidae.

Once abundant throughout Europe and a major pest in the periodical years of "mass flight", it had been nearly eradicated in the middle of the 20th century through extensive use of pesticides and has even been locally exterminated in many regions. However, since pest control was increasingly regulated in the 1980s, its numbers have started to grow again.

Description

Adults of the common cockchafer reach sizes of 25–30 mm; the forest cockchafer is a little smaller (20–25 mm). The two species can best be distinguished by the form of their tail end: it is long and slender in the common cockchafer, but shorter and knob-shaped at the end in the forest cockchafer. Both have a brown colour.

Male cockchafers have seven "leaves" on their antennae, whereas the females have only six.

The species M. pectoralis looks similar, but its pygidium is rounded. The cockchafer should not be confused with the similar European chafer (Rhizotrogus majalis), which has a completely different life cycle, nor with the June beetles (Phyllophaga spp.), which are native to North America, nor with the summer chafer (or "European June bug", Amphimallon solstitiale), which emerges in June and has a two-year life cycle. (All of these are Scarabaeidae, have white grubs, and are turf pests.)

Life cycle

Adults appear at the end of April or in May and live for about five to seven weeks. After about two weeks, the female begins laying eggs, which she buries about 10 to 20 cm deep in the earth. She may do this several times until she has laid between 60 and 80 eggs. The common cockchafer lays its eggs in fields, whereas the Forest Cockchafer stays in the vicinity of the trees. The preferred food for adults is oak leaves, but they will also feed on conifer needles.

The larvae, known as "white grubs" or "chafer grubs", hatch after four to six weeks. They feed on plant roots, for instance potato roots. The grubs develop in the earth for three to four years, in colder climates even five years, and grow continually to a size of about 4–5 cm, before they pupate in early autumn and develop into an adult cockchafer in six weeks.

The cockchafer overwinters in the earth at depths between 20 and 100 cm. They work their way to the surface only in spring.

Because of their long development time as larvae, cockchafers appear in a cycle of every three or four years; the years vary from region to region. There is a larger cycle of around 30 years superimposed, in which they occur (or rather, used to occur) in unusually high numbers (10,000s).

Pest control and history

Both the grubs and imagos have a voracious appetite and thus have been and sometimes continue to be a major problem in agriculture and forestry. In the pre-industrialized era, the main mechanism to control their numbers was to collect and kill the adult beetles, thereby interrupting the cycle. They were once very abundant: in 1911, more than 20 million individuals were collected in 18 km2 of forest.[1]

Collecting adults was an only moderately successful method. In the Middle Ages, pest control was rare, and people had no effective means to protect their harvest. This gave rise to events that seem bizarre from a modern perspective. In 1320, for instance, cockchafers were brought to court in Avignon and sentenced to withdraw within three days onto a specially designated area, otherwise they would be outlawed. Subsequently, since they failed to comply, they were collected and killed. (Similar animal trials also occurred for many other animals in the Middle Ages.)[4]

In some areas and times, cockchafers were served as food. A 19th-century recipe from France for cockchafer soup reads: "roast one pound of cockchafers without wings and legs in sizzling butter, then cook them in a chicken soup, add some veal liver and serve with chives on a toast". A German newspaper from Fulda from the 1920s tells of students eating sugar-coated cockchafers. Cockchafer larvae can also be fried or cooked over open flames, although they require some preparation by soaking in vinegar in order to purge them of soil in their digestive tracts[5]. A cockchafer stew is referred to in W. G. Sebald's novel The Emigrants.

Only with the modernization of agriculture in the 20th century and the invention of chemical pesticides did it become possible to effectively combat the cockchafer. Combined with the transformation of many pastures into agricultural land, this has resulted in a decrease of the cockchafer to near-extinction in some areas in Europe in the 1970s. Since then, agriculture has generally reduced its use of pesticides. Because of environmental and public health concerns (pesticides may enter the food chain and thus also the human body) many chemical pesticides have been phased out in the European Union and worldwide. In recent years, the cockchafer's numbers have been increasing again, causing damage to over 1,000 km2 of land all over Europe. At present, no chemical pesticides are approved for use against cockchafers, and only biological measures are utilised for control: for instance, pathogenic fungi or nematodes that kill the grubs are applied to the soil.

In culture

Children since antiquity have played with cockchafers. In ancient Greece, boys caught the insect, tied a linen thread to its feet and set it free, amusing themselves to watch it fly in spirals. English boys in Victorian times played a very similar game by sticking a pin through one of its wings.[6] Nikola Tesla recalls that as a child he made one of his first "inventions"—an "engine" made by harnessing four cockchafers in this fashion.[7]

Cockchafers appear in the fairy tales Thumbelina by Hans Christian Andersen and Princess Rosette by Madame d'Aulnoy.

The cockchafer is featured in a German children's rhyme similar to the English Ladybird, Ladybird:

Maikäfer flieg...
Dein Vater ist im Krieg
Deine Mutter ist in Pommerland
Pommerland ist abgebrannt
Maikäfer flieg!
Cockchafer fly...
Your father is at war
Your mother is in Pomerania
Pomerania is burned to the ground
Cockchafer fly!

The verse dates back to the Thirty Years' War in the first half of the 17th Century, in which Pomerania was pillaged and suffered heavily. Since World War II, it is associated in Germany also with the closing months of that war, when Soviet troops advanced into eastern Germany.

The cockchafer was the basis for the "fifth trick" in the well-known illustrated German book Max and Moritz, dating from 1865.

Jim Dixon, in Kingsley Amis's comic novel Lucky Jim (1954), repeatedly calls his department head, Professor Welch, an "old cockchafer."

The Italian – specifically Neapolitan – collection of stories Il Pentamerone of Giambattista Basile (in its English translation by Norman M. Penzer from Benedetto Croce's Italian) contains a tale on Day 3, Night 5: "The Cockchafer, Mouse and Grasshopper".

There have been four Royal Navy ships named HMS Cockchafer.

Common Slow Worm (Anguis fragilis)

Common Slow Worm (Anguis fragilis) Common Slow Worm (Anguis fragilis)

Anguis fragilis is a reptile native to Eurasia. It is also called a deaf adder, a slowworm,[2] a blindworm, or regionally, a long-cripple, to distinguish it from the Peloponnese slowworm. These legless lizards are also sometimes called common slowworms. The "blind" in blindworm refers to the lizard's small eyes, similar to a blindsnake (although the slowworm's eyes are functional).

Slowworms are semifossorial[3] (burrowing) lizards, spending much of their time hiding underneath objects. The skin of slowworms is smooth with scales that do not overlap one another. Like many other lizards, they autotomize, meaning that they have the ability to shed their tails to escape predators. While the tail regrows, it does not reach its original length. In the UK, they are common in gardens, and can be encouraged to enter and help remove pest insects by placing black plastic or a piece of tin on the ground. On warm days, one or more slowworms can often be found underneath these heat collectors. One of the biggest causes of mortality in slowworms in suburban areas is the domestic cat, against which it has no defence.

Physical traits

These reptiles are mostly active during the twilight and occasionally bask in the sun, but are more often found hiding beneath rocks and logs. They are carnivorous and, because they feed on slugs and worms, they can often be found in long grass and other damp environments.

The females give birth to live young (ovoviviparous birth). In the days leading up to birth, the female can often be seen basking in the sun on a warm road.

Although these lizards are often mistaken for snakes, a number of features differentiate them. The most important one is that they have small eyes with eyelids that, like other lizards, blink. Unlike snakes, they may also have visible ears. They shed their skin in patches, whereas most snakes shed their skins whole. Slowworms may also shed their tails (autotomy) as a defence mechanism, by breaking one of their tail vertebrae in half. The pattern of a slowworm's ventral scales is also different from that of a snake's.

Size and longevity

Adult slowworms grow to be about 50 cm long, and are known for their exceptionally long lives; the slowworm may be the longest-living lizard, living about 30 years in the wild and up to at least 54 years in captivity (this record is held by a male slowworm that lived at the Copenhagen Zoo from 1892 until 1946, the age when first obtained is unknown).[4][5] The female often has a stripe along the spine and dark sides, while the male may have blue spots dorsally. Juveniles of both sexes are gold with dark brown bellies and sides with a dark stripe along the spine.

Protected status in the UK

In the United Kingdom, the slowworm has been granted protected status, alongside all other native British reptile species. The slowworm has been decreasing in numbers, and under the Wildlife and Countryside Act 1981, to intentionally kill, injure, sell, or advertise to sell them is illegal.[6][7]

Ireland

The slowworm is not native to Ireland, but is believed to have been illegally introduced in the 1970s. It has been sighted only in parts of County Clare, mainly in the Burren region.[8][9][10]