The Awakening of the Brown Bear

15 March 2022

With its distinctive appearance and impressive size, the brown bear (Ursus arctos) is unmistakable: there are no other species like it in Iberia that we might confuse it with. Our bears, which live in the Cantabrian Mountains and the Pyrenees, measure between one and two-and-a-half metres and can weigh up to 250 kilos.

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Oso cantábrico comiendo frutos del pudio.

Cantabrian brown bear eating the fruit of the Alpine buckthorn. Photo: Fundación Oso Pardo

Their North American cousin, the grizzly bear, which scientists have christened with the descriptive name Ursus arctos horribilis, is twice their weight and size, reaching up to 700 kilos in mass and four metres in height.

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Ejemplar de grizzly en el campo

Grizzly bear in the countryside

Much less carnivorous than wolves, brown bears eat a fruit-based diet, especially in autumn, when wild fruits, berries, and shoots of shrubs are plentiful: heather, broom, juniper, hawthorn, etc. Moreover, in spring and summer, they catch all kinds of prey: ants, worms, beetles, and all sorts of reptiles, amphibians, and fish.

These bears have a great ability to coexist with the rural population and rarely come into conflict with shepherds and cattle-raisers. Attacks on livestock do happen, of course, but they are few and far between, and damages are duly compensated by the government. Brown bears do not represent competition for hunters, either, as they are more scavengers than predators.

Something else altogether is the conflicts that stem from these giant animals’ taste for honey and ripe fruit, especially cherries. Their appetite for these foods makes it necessary to protect beehives with electric fences, close off the perimeter of fruit groves, and also implement other protective measures. Beekeepers and farmers do receive subsidies for these measures, though, as well as for any damage the bears may cause.

When winter arrives, the majority of Iberian bears (some choose to remain active) disappear from the mountains, withdrawing to the shelter of a cave. There, their vital signs will slow down and they will sleep while consuming their reserve of accumulated fats, drifting into a dozy slumber. They do not fall into a deep sleep completely, however, as they tend to come out of the caves to go on winter walks, enabling us to follow their tracks.

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Oso alrededor de un roble

Bear in an oak tree. Photo: Fundación Oso Pardo

Bear tracks on the snow are very clear. In them, you can make out the sole of the paw perfectly, similar to the sole of a bare human foot, with five digits, pads, and claws. The front paws are much smaller than the back ones. Some of the other usual signs of bear activity are scratches on tree trunks, fur stuck in tree bark or barbed wire, and trails marked with their excrement to mark territory.

Nevertheless, the experts who follow the evolution of the species have been warning for years that, in the Cantabrian Mountains and Pyrenees, these bears have been hibernating less and less. One of the main causes of this change in behaviour could be the alteration of the natural rhythm of the seasons brought about by climate change.

In any case, the start of the bears’ hibernation depends on meteorological factors, food availability, and individual characteristics. In general, males remain active for longer and come out of the caves first, while pregnant females are first to go in and last to leave. These females emerge accompanied by their cubs, having gone through an eight-month gestation period and given birth inside the cave in the first weeks of January.

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Oso cantábrica con crías.

Cantabrian brown bear with cubs. Photo: Fundación Oso Pardo

Hibernation is a dormant state in which the bears’ cardiac rhythm decreases from 50 beats per minute to barely 10, their respiratory rhythm drops by half, and their body temperature falls by five degrees. During this period, the bears stop eating, drinking, defecating, and urinating. They maintain the most functional vital signs thanks to the energy provided by stored fat.

Now, however, this biological standstill is about to reach its conclusion. Around this time in March, just before the imminent arrival of spring, the males wake up and, having lost nearly one-third of their body mass, they abandon their shelter to feed on everything their surroundings (often still snow-covered) offer them, to quickly regain energy.

The females will do the same within a few weeks, by early April, along with their cubs, whom they must protect from attacks by males. This is particularly true in areas where populations are growing and the competition for females is fiercer. There is a tendency towards infanticide, which the males use to try to get the females to go back on heat.

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Oso cantábrica con crías.

Cantabrian brown bear accompanied by her cubs. Photo: Fundación Oso Pardo

After falling to levels that led to fears they might go extinct, and thanks to the work carried out through conservation programmes and the joint work of government authorities and conservation entities (particularly the Fundación Oso Pardo (Brown Bar Foundation)), the Iberian Peninsula’s brown bear population has managed to recover and now totals over 400 bears, with 350 in the Cantabrian Mountains and 60 in the Pyrenees.

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