2012

Forest animals change fur coats

Latvia is located in the boreal climate zone with considerable temperature fluctuations in all seasons. To adapt to these changes, forest animals change their fur coats.

Animals change fur twice a year – in autumn and spring. When winter approaches, they change both awn hairs and undercoats. Undercoats are particularly thick, mostly ensuring body warmth insulation. Awn hairs in turn protect undercoats from mechanical and water impacts. Animals begin changing fur in early autumn (October) and conclude around November. Mammals usually have different fur colours in winter and summer. For example, roe deer and red deer replace fawn-coloured summer fur with grey-brown fur. Wild boars, elk and predators do not change fur colour throughout the seasons, but grow thick undercoats during winter.

When winter sets in, some mammals not only grow warm fur coats, but also change their colours. For example, white hares and weasels are bright white in winter. White hares have black ear tips, weasels – tail tips. Such changes are adaptation to the region’s blanket of snow. These animals live in open biotopes – bushy meadows and swamps, where they can be easily noticed by their natural enemies – predatory mammals, hawks, owls and eagles. During snowless winters, they become particularly noticeable and endangered. Due to the fact that their white fur is genetically inherited and a result of evolutionary processes, the change happens each year, regardless of snow presence, and climate changes can affect the existence of certain species in the long run.

Birds also change feathers. However, their actions, with some exceptions, are not adaptation to seasonal climate changes. Birds change feathers in a gradual manner, usually once a year. Worn-out feathers are replaced with new ones. Some species, for example, geese and cranes, lose their ability to fly when casting aside their old feathers (in summer). Therefore these birds choose tranquil and barely accessible watery areas and swamps with suitable food options. Such areas are of great importance, to be protected. During the mating period in spring, the males of several bird species are brighter than during the nesting period. Male wild ducks have colourful green heads and necks and chestnut breasts. In summer, when they replace their old feathers, they become brownish and do not differ much from their females. Some bird species have different feathers when it comes to young and adult birds. For example, young swans are grey-brown, while adult swans, regardless of season, are bright white. Willow ptarmigans are the only birds in Latvia that adapt to winter conditions. In winter, they are snow-white, in spring and summer – brownish. Willow ptarmigans are on the brink of extinction in Latvia, due to their habitats retreating north due to shorter winter periods and snow accumulation caused by global climate changes.

Uģis Bergmanis

JSC “Latvia’s State Forests”

Environmental Expert