Bats are the only mammals that can fly. They are found all over the world except the polar regions. All 16 species of bats found in Latvia feed only on insects and are active at night. Bats navigate using ultrasound. In flight, they emit short ultrasonic calls of only a few milliseconds in the range of 20–60 kHz, which echo off both obstacles and food objects. In winter, when insects do not fly, some species of bats migrate south, while others hibernate in caves, cellars and attics.
The Eurasian squirrel or red squirrel (Sciurus vulgaris) can be found in forests, gardens and parks in Latvia. This small rodent with tufts of hair in its ears has a reddish-brown fur in summer and greyish in winter. Most of its life is spent in trees, so the long, bushy tail is used as a rudder during jumps. The squirrel feeds mainly on tree seeds, buds, berries and insects. In autumn, they prepare food reserves for the winter under stumps, tree roots and hollows. Mushrooms are pinned to the branches and dried. The squirrel also gnaws the horns and bones of animals found in the forest, it can also catch small birds. Like other rodents, a squirrel’s incisors grow throughout its life.
The European roller is a gorgeous, rare bird of the Coracias genus in Latvia. In the middle of the last century, several thousand European rollers nested near us, but currently these birds are rare and protected throughout the Baltics. The European roller is not related to the crow family and its plumage is blue rather than green. Only the tail feathers are greenish-blue. The bird is called a crow most likely for its loud, gruff voice. The European rollers nest in cavities made by woodpeckers. By placing suitable bird cages, the population of the European rollers can be increased. These birds feed mainly on large insects caught on the ground or in flight.
The Eurasian hoopoe is a rather rare bird that can be unmistakably recognised by its song (pu-pu-pu-pu). It is one of the most magnificent birds of Latvia with a fan-shaped crest of feathers on its head. The Eurasian hoopoe is a useful bird because it feeds on various insects and their larvae, especially earthworms. Eurasian hoopoes nest in large tree cavities and cocklofts, but can be attracted to gardens by making suitable bird cages. The bird cage’s entrance should be at the bottom of the cage. The Eurasian hoopoe protects the nest from enemies in a special way – the female and the young release a liquid that smells like old meat, which repels potential intruders.
The common starling has a characteristic melodious song. The bird is also able to imitate the sounds and various noises made by other birds. These birds are omnivores. During the nesting season, it feeds only on insects, spiders, earthworms, but during other times it also eats grains, fruits and food waste. The nest is made by the male from dry grass, branches, animal wool and feathers. In it, he often weaves strong-smelling plants to repel bird parasites. The male attracts the attention of the female by loud singing. The female lays 4 or 5 pale blue eggs in the nest. Parents continue to feed the young for another 1–2 weeks after leaving the nest. In the autumn and winter, common starlings usually stay in flocks. A flying flock often rapidly changes shape.
In Latvia, the blue tit is a bird that is often found in populated areas, parks, gardens, forests and reeds. Male and female blue tits look alike. Young birds are brighter than adult birds. Nests are made in tree cavities or bird cages from grass, moss, animal wool and feathers. Sometimes the female carves a cavity in the tree herself. It breeds twice a year on average. The white-spotted eggs hatch into 9–11 young birds, which are fed by both parents. Birds feed mainly on insects, but also eat seeds and fruits. In winter, these birds are frequent visitors to bird feeders.
The house sparrow (Passer domesticus) is a small, brownish-grey bird that can be found almost anywhere in the world. This species is widespread in Latvia. The male house sparrow has a dark brown back and shoulders, a brown and black top of the head and a black or greyish band around the eyes and the base of the beak, whereas the females are grey-brown with dark stripes on the back and light eyebrows. Sparrows stay in flocks, spend the night in dense bushes, nest in cocklofts and attics, cavities and birdcages, where they breed up to four times a year. Sparrows are omnivores, but their young are only fed insects.
A living tree grows one layer of wood each year because the tree grows rapidly in the spring and summer but barely increases in thickness in the autumn and winter. The age of a tree can be accurately determined by growth rings. The width, density, and chemical composition of annual rings can reveal a lot about the climate at a given time, as well as forest fires and other changes that occur during tree growth. Dendrochronologists have discovered many interesting historical facts up to 12,500 years ago while studying ancient wooden products, which can then be used by archaeologists, art historians and specialists in other fields.
The hermit beetle (Osmoderma eremita)
The hermit beetle (Osmoderma eremita) is a beetle whose larvae feed for 3–4 years on the decayed wood in the cavities of oaks, lindens, maples, horse chestnuts and other broad-leaved trees. The laws of Latvia and the EU require that hermit beetle deposits be protected by creating micro-reserves in areas where the species is found.
The variable chafer (Gnorimus variabilis)
The variable chafer (Gnorimus variabilis) is even rarer than the hermit beetle. This beetle is listed in category 1 of the Red Data Book of Latvia, and micro-reserves are also required to protect this species.
The large pine weevil (Hylobius abietis)
The large pine weevil (Hylobius abietis) has tentacles at the tip of the weevil rather than at the base. Adult beetles live for 1–4 years and gnaw on the bark and buds of conifers, while larvae gnaw on the roots of dying and felled conifers, creating long and fairly wide passageways.
The common pine shoot beetle (Tomicus piniperda)
The common pine shoot beetle (Tomicus piniperda) is one of the most common pine pests in Northern Europe, primarily damaging pines but also threatening spruce and larch. The most damaging are the adult beetles that eat the young pine shoots. Larvae develop in passages under the bark of trees.
The common cockchafer (Melolontha melolontha)
The common cockchafer (Melolontha melolontha) is a brownish-black beetle that can grow to be 3.5 cm long. The beetles emerge in late May or early June and live for 4–6 weeks, feeding on the leaves of various deciduous trees. The larvae develop in the soil for 3–4 years and gnaw on tree roots.
The forest cockchafer (Melolontha hyppocastani)
The forest cockchafer (Melolontha hyppocastani) is a beetle that can grow to be 2.5 cm long. Although this species is less common, it can cause damage to pine plantations. Unlike the common cockchafer, the back of its body is more blunt and hairy. The development cycle of the beetle lasts 4–5 years.
Bristly beard lichen (Usnea hirta)
Bristly beard lichen (Usnea hirta) is one of the lichens that does not tolerate polluted air. This beard lichen is one of the more common beard lichen species in Europe. Its thallus is like a small (up to 5 cm long), greenish-grey tuft of beard that hangs from tree trunks to branches. It can be most commonly found on the trunks of pines. In dry weather, the lichen is hard and rough, but becomes very soft when it rains. The thick filaments of the lichen thallus are covered by approximately 1 cm long, tiny hair-like formations or fibrils. When the lichen filaments are separated, a white core created by the fungus’ hyphae is visible.