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Today on Animal Fact Files we’re discussing capercaillies. This grouse’s common name comes from a gaelic word meaning “bird of the woods,” or “old man of the woods,” or “horse of the woods!” Different sources say different meanings, so I'm just going to give you all of them to cover our bases. There are two capercaillie species, the western species and the black-billed species. The western capercaillie has a broader range throughout the palearctic across Europe and Asia. The black-billed capercaillie is confined to eastern Russia and northern Mongolia and China. In some parts of its range, the western capercaillie has actually faced extinction with one prominent example being Scotland. Although it was reintroduced to this country with birds from other parts of their range, they're once again on the decline.

Capercaillies need pine forests to survive. They rely on pine needles during winter as their main source of food. These birds prefer undisturbed forests, but, unfortunately, few of these remain throughout human inhabited parts of their range. Capercaillies tolerate pine plantations, but when other primary forest is available they prefer that. Although they need vegetation along the ground for hiding and nesting, they also utilize open spaces, especially during the breeding season when males gather to display for females. These birds also roost in trees.

The capercaillie is the largest living grouse. Males reach about the size of a turkey. They're 3 feet, 91 centimeters, long and weigh up to 11 pounds, 5 kilograms. Females are half that weight and reach around 2 feet, 61 centimeters, long at max size. The two sexes can be told apart visually because capercaillies are sexually dimorphic. Males have black and dark brown feathers speckled with white, a glossy green chest and throat, red fleshy skin over the eyes, and a cream to yellow beak. Females are brown and speckled which helps them blend in with their surroundings. They do all the chick rearing, so they need to be more cryptic. The black grouse looks similar to a capercaillie male, and was even once placed in the same genus, but it has since been reclassified.

Males capercaillies gather in lekking grounds. Although these birds aren't migratory, they may travel to a specific spot to put in their elaborate displays. Some lek sites are known for their reuse by capercaillies over subsequent years. Each male capercaillie has his own lek spot which he defends from other males. They sometimes fight one another to gain dominance and the best site for attracting females, although these matches are rarely fatal. They boys gesture with their head thrown back and tail fully fanned out. Probably the most noticeable aspect of their mating display are their calls. Here's an example: (clicks and pops)

Females choose the dominant male and leave shortly after mating to lay their eggs and raise their young on their own. A capercaillie nest is typically in the ground, and the eggs are laid over the course of a week or two. She'll lay anywhere from 5 to 16 eggs, each one day at a time, and won't start incubating the clutch until they're all laid. Because the 25 day incubation starts at the same time for all the eggs in the nest, they also all hatch at the same time! Capercaillie chicks leave their nest shortly after hatching and begin foraging.

Young capercaillies eat bugs, specifically insect larvae such as caterpillars. This important food source becomes less available during wet summers, which makes it more difficult for the chicks to reach adulthood. When they reach 2 to 3 months old, they're able to fly. The lifespan of capercaillies isn't fully studied, however most reports suggest they live less than a decade in the wild. Apart from low insect yield years, these birds also face habitat loss and run-ins with fences. Their predators include pine martens, badgers, foxes, lynxes, and other carnivorous predators.

Although they face many types of threats, capercaillies aren't pushovers. Females will feign an injury to distract a predator away from her brood. Males are also known to aggressively defend their range with documentation of them going after dogs, sheep, deer, and even humans they feel have ventured too close. Of course, capercaillies are pretty exclusively plant eaters once they reach adulthood. During the winter they eat pine needles and unopened pine cones. During the summer their diet expands to include newly formed buds, berries, leaves, and moss.

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