Rock ptarmigan

Name and taxonomy

The scientific name of the rock ptarmigan is Lagopus muta. Lagopus joins the Greek words for a hare and a foot. It probably describes the feathered legs, which look like a hare's feet. The species name means mute, and it points at the plain croaking song of the male. Writers spelt it mutus for many years, because they took the genus name for a masculine one. The Greek root is feminine, so muta is the correct form.

The English word ptarmigan comes from the Gaelic tarmachan, which means croaker. Somebody added the silent p in the belief that the word was Greek. The change probably came from the Greek word for a wing.

Ornithologists accept 23 subspecies. They run from the Scottish form to the birds of Honshu in Japan. Separate forms hold Iceland, Svalbard, the Alps, the Pyrenees and many Aleutian islands. The number of named forms suggests how broken up the range has become.

Evolution and relatives

The genus Lagopus holds four species. The other three include the willow ptarmigan and the white-tailed ptarmigan. As with the rock ptarmigan, they all turn pale or white for the winter. The rock ptarmigan runs about ten percent smaller than its willow relative. It also carries a slimmer bill.

The two birds separate by ground as well as by size. The willow ptarmigan stays below the tree line in scrub. The rock ptarmigan takes the higher and barer slopes. A winter male rock ptarmigan shows a black line from bill to eye, which the willow bird lacks. During the last ice age the species covered far more of continental Europe. The groups in the Alps, the Pyrenees and Japan are probably what that colder range left behind.

Appearance

An adult measures 34 to 36 cm from bill to tail. The tail alone is about 8 cm long. The wingspan runs 54 to 60 cm, and weight runs 0.44 to 0.64 kg. The bird looks like a small grouse or a short pheasant.

Winter plumage is pure white apart from the black outer tail feathers and the dark eye line. In spring the feathers moult to grey and brown. A breeding male is greyish above with white wings and white underparts. Females carry coarser brown and black barring than males. A female on summer tundra is very hard to see.

The male has a scarlet comb above each eye. He also has a black streak that runs from the bill to the eye. Some females show that streak and some do not. Males hold their white plumage later into spring than females. Every ptarmigan has feathered feet that work as snowshoes and add insulation.

Habitat and range

The rock ptarmigan breeds on rocky mountainsides and open tundra. The range crosses Arctic and subarctic Eurasia and North America, and takes in Greenland. It runs from Norway and Sweden east to the Siberian Far East. Isolated groups live in Scotland, the Pyrenees, the Alps, Bulgaria, the Urals, the Pamirs and the Altai. In Japan the bird holds only the Japanese Alps and Mount Haku.

Good ground is dry and open, with rock outcrops, bare ridges and patches of dwarf willow and birch. In winter the birds drop to brushy slopes near the timberline, where plants push through the snow. Males stay on the higher open ground and females look for more cover. Chicks favour hollows and ridges without thick scrub, so they can slip behind a rise. The species is recorded in 32 countries on GBIF.

The bird bred in the Lake District fells of England until the early 1800s. It held on a little longer in the Southern Uplands of Scotland. Today the only British birds are in the Scottish Highlands. People have released the species in New Zealand, South Georgia, Kerguelen and the Crozet Islands. Attempts in the Faroe Islands and Ireland came to nothing.

Diet and feeding

Adult rock ptarmigans eat almost nothing but plants. The exact food changes a great deal from one region to another. In Alaska the winter staple is buds and catkins of aspen, dwarf birch and willow. Spring birds move on to crowberry and lingonberry shrubs. Early summer brings the widest choice: willow leaves, plus Dryas and locoweed leaves and flowers. Berries, bistort seeds and birch buds carry the birds from late summer into autumn.

Chicks eat insects, larvae, spiders and snails before they turn to greenery. An adult walks and picks quickly, nipping items off with the bill. Birds sometimes follow caribou or musk ox and feed where the herd has scraped the snow away.

Long ceca let the gut ferment poor food and pull more from it. The species stores very little fat, so a winter bird must feed often. Most birds hold no more than 20 grams of fat at any time of year. That reserve covers about 2 days without food. The Svalbard subspecies is the exception and puts on about 100 grams. That store can carry a bird through 10 days of hunger.

Behaviour and social life

The rock ptarmigan lives on the ground and stays in one district all year. Because the ground is remote, the birds meet few people and are often easy to approach. Sexes split up in winter and form single sex flocks. The flocks break up in early spring. Males then take large territories and defend them hard.

Fast chases through the air, with plenty of calling, follow any challenge. Real fights between neighbouring males are rare. A territory holder presses much harder against a young male with no ground of his own.

Southern birds in Japan and Scotland move only a short way down the hill for winter. Arctic birds travel much further. Birds in Iceland have been found with Greenland minerals in the gizzard, after a 300 km sea crossing. One bird ringed on Disko Island turned up over 1,000 km to the south the next winter. The small group on Franz Josef Land sits out the polar night under seabird cliffs, where the plants are rich.

Communication and senses

The male produces a set of guttural snores and rattles. He aims most of them at other males in the breeding season. Several males may display together on an open lek. The song flight starts with a leap and a burst of fast wingbeats. The bird climbs until it almost stalls, then spreads the tail and glides down. Listeners compare the rasping call to a stick dragged across a picket fence.

On the ground the male fans his tail, stretches his neck and drops his wings. He circles a female and drags one wing along the ground. He raises the red combs at the same time. Comb size tracks the level of testosterone in the blood. A report from 1981 tied that hormone level to aggression towards other males.

Females appear to read the combs when they choose a mate. At Scarpa Lake in Nunavut, males with two mates had larger combs than males with one. The link to size faded after a male's first year, but the link to comb condition held.

Reproduction and life cycle

The female nests on the ground in a shallow scrape. She adds a thin lining of moss, lichen, grass and a few feathers. The site is usually a bare rocky outcrop with almost no plant cover. She normally picks a spot beside a large rock, which gives some cover from above.

A clutch holds 7 to 10 eggs. The female sits alone and the male gives no help. Incubation takes about 21 days. Downy chicks are out of the nest less than a day after they hatch. Their mother guards them, but they find their own food from the start.

Chicks can fly a short way at about 10 days old. They become independent at 10 to 12 weeks. A rock ptarmigan can breed at six months old. A pair commonly rears up to six chicks. That fast turnover means hunting has little effect on total numbers. The oldest ringed wild bird was at least 11.7 years old.

Predators and threats

The bird has few predators, because its ground is high and remote. The gyrfalcon, the golden eagle and the Arctic fox are the main three. Males keep their white plumage later than females in spring. That habit is part of display, and it also costs males heavily to gyrfalcons. Chicks escape by dropping behind a ridge or a hollow.

People hunt the species in Alaska with a shotgun or a snare. Numbers rise and fall on a cycle of about ten years, which is well recorded in Iceland. Iceland closed the season in 2003 and 2004 after a sharp decline. Shooting returned in 2005 on a small number of set days. All trade in Icelandic ptarmigan is now illegal.

Population and conservation

The IUCN lists the rock ptarmigan as Least Concern. The bird is scarce near Arctic settlements but common over huge areas of tundra. Regional lists tell a harder story in the south. Italy and Spain both rate the species as Vulnerable. France and Switzerland rate it as Near Threatened, and Germany calls it extremely rare.

NatureServe ranks the bird S5 in Nunavut and in the Northwest Territories. It ranks it lower, at S3, in Newfoundland and Labrador. Japan protects the species across the whole country. The small alpine groups are probably the ones most at risk, because they cannot move to cooler ground. iNaturalist holds 6,473 observations of the species.

Relationship with humans

The rock ptarmigan is a game bird across much of its range. In the Alaskan interior it gives both food and sport. Hunters take it with a shotgun or catch it in a snare. The meat is dark, and Thomas Bewick recorded a slightly bitter taste like that of a hare. He called the bird the White Grouse in his book of 1797.

Icelandic households roast the bird for Christmas and serve it with a cream sauce and jam. That tradition ran into trouble when stocks fell late in the twentieth century. The country now allows a short season and bans all sale of the meat.

The bird is the territorial bird of Nunavut, where the Inuktitut name is aqiggiq. Newfoundland and Labrador names it the official game bird. Gifu, Nagano and Toyama prefectures in Japan all use the species as their bird. Walkers on Arctic and alpine ground may meet the bird at close range.

In culture and myth

Japanese tradition calls the bird raicho, which means thunder bird. The name suggests an old link between the bird and storms in the high mountains. Japan gives the species legal protection across the country. Three mountain prefectures have taken it as their emblem.

In Nunavut the Inuktitut name aqiggiq atajulik belongs to the territorial bird. The choice appears to tie the new territory to a bird of the open tundra. Newfoundland and Labrador chose it as a game bird instead.

Iceland probably keeps the strongest food tradition around the species. Roast ptarmigan is still the Christmas dish in many houses. Scottish Gaelic gave the world the word tarmachan, the croaker. A false Greek origin then added a silent letter that nobody says.