Temporal range: Early Pliocene to recent
|Male sage grouse |
|Subfamily:|| Tetraoninae |
Tetraonidae Vigors, 1825
Grouse // are a group of birds from the order Galliformes, in the family Phasianidae. Grouse are frequently assigned to the subfamily Tetraoninae (sometimes Tetraonidae), a classification supported by mitochondrial DNA sequence studies, and applied by the American Ornithologists' Union, ITIS, and others. Grouse inhabit temperate and subarctic regions of the Northern Hemisphere, from pine forests to moorland and mountainside, from 83°N (rock ptarmigan in northern Greenland) to 28°N (Attwater's prairie chicken in Texas).
Grouse are heavily built like other Galliformes, such as chickens. They range in length from 31 to 95 cm (12 to 37 in), and in weight from 0.3 to 6.5 kg (0.66 to 14.33 lb). Males are larger than females—twice as heavy in the western capercaillie, the largest member of the family. Grouse have feathered nostrils. Their legs covered in feathers down to the toes, and in winter the toes, too, have feathers or small scales on the sides, an adaptation for walking on snow and burrowing into it for shelter. Unlike other Galliformes, they have no spurs.
These birds feed mainly on vegetation—buds, catkins, leaves, and twigs—which typically accounts for over 95% of adults' food by weight. Thus, their diets vary greatly with the seasons. Hatchlings eat mostly insects and other invertebrates, gradually reducing their proportion of animal food to adult levels. Several of the forest-living species are notable for eating large quantities of conifer needles, which most other vertebrates refuse. To digest vegetable food, grouse have big crops and gizzards, eat grit to break up food, and have long intestines with well-developed caeca in which symbiotic bacteria digest cellulose.
Forest species flock only in autumn and winter, though individuals tolerate each other when they meet. Prairie species are more social, and tundra species (ptarmigans, Lagopus ) are the most social, forming flocks of up to 100 in winter. All grouse spend most of their time on the ground, though when alarmed, they may take off in a flurry and go into a long glide.
Most species stay within their breeding range all year, but make short seasonal movements; many individuals of the ptarmigan (called rock ptarmigan in the US) and willow grouse (called willow ptarmigan in the US) migrate hundreds of kilometers.
In all but one species (the willow ptarmigan), males are polygamous. Many species have elaborate courtship displays on the ground at dawn and dusk, which in some are given in leks. The displays feature males' brightly colored combs and in some species, brightly colored inflatable sacs on the sides of their necks. The males display their plumage, give vocalizations that vary widely between species, and may engage in other activities, such as drumming or fluttering their wings, rattling their tails, and making display flights. Occasionally, males fight.
The nest is a shallow depression or scrape on the ground—often in cover—with a scanty lining of plant material. The female lays one clutch, but may replace it if the eggs are lost. She begins to lay about a week after mating and lays one egg every day or two; the clutch comprises five to 12 eggs. The eggs have the shape of hen's eggs and are pale yellow, sparsely spotted with brown. On laying the second-last or last egg, the female starts 21 to 28 days of incubation. Chicks hatch in dense, yellow-brown down and leave the nest immediately. They soon develop feathers and can fly shortly before they are two weeks old. The female (and the male in the willow grouse) stays with them and protects them until their first autumn, when they reach their mature weights (except in the male capercaillies). They are sexually mature the following spring, but often do not mate until later years.
Grouse make up a considerable part of the vertebrate biomass in the Arctic and Subarctic. Their numbers may fall sharply in years of bad weather or high predator populations—significant grouse populations are a major food source for lynx, foxes, martens, and birds of prey. However, because of their large clutches, they can recover quickly.
The three tundra species have maintained their former numbers. The prairie and forest species have declined greatly because of habitat loss, though popular game birds such as the red grouse and the ruffed grouse have benefited from habitat management. Most grouse species are listed by the IUCN as "least concern" or "near threatened", but the greater and lesser prairie chicken are listed as "vulnerable" and the Gunnison grouse is listed as "endangered". Some subspecies, such as Attwater's prairie chicken and the Cantabrian capercaillie, and some national and regional populations are also in danger.
The phenotypic difference between males and females is called sexual dimorphism.Male grouse tend to be larger than female grouse, which seems to hold true across all the species of grouse, with some difference within each species in terms of how drastic the size difference is. The hypothesis with the most supporting evidence for the evolution of sexual dimorphism in grouse is sexual selection. Sexual selection favors large males; stronger selection for larger size in males leads to greater size dimorphism. Female size will increase correspondingly as male size increases, and this is due to heredity (but not to the extent of the male size). This is because females that are smaller will still be able to reproduce without a substantial disadvantage, but this is not the case with males. The largest among the male grouse (commonly dubbed 'Biggrouse') attract the greatest numbers of females during their mating seasons,
Male grouse display lekking behavior, which is when many males come together in one area and put on displays to attract females.Females selectively choose among the males present for traits they find more appealing. Male grouse exhibit two types: typical lekking and exploded lekking. In typical lekking, males display in small areas, and in exploded lekking, displays are done in areas that do not have many resources for females. Male grouse can also compete with one another for access to female grouse through territoriality, in which a male defends a territory which has resources that females need, like food and nest sites. These differences in male behavior in mating systems account for the evolution of body size in grouse. Males of territorial species were smaller than those of exploded lekking species, and males of typical lekking species were the largest overall. The male birds that exhibit lekking behavior, and have to compete with other males for females to choose them, have higher sexual size dimorphism. This supports the hypothesis of sexual selection affecting male body size and also gives an explanation for why some species of grouse have a more drastic difference between male and female body size than others.
Sexual size dimorphism can manifest itself differently between grouse and other birds. In some cases, the female is dominant over the male in breeding behavior, which can result in females that are larger than the males.
Grouse are game, and hunters kill millions each year for food, sport, and other uses. In the United Kingdom, this takes the form of driven grouse shooting. The male black grouse's tail feathers are a traditional ornament for hats in areas such as Scotland and the Alps. Folk dances from the Alps to the North American prairies imitate the displays of lekking males.
|Falcipennis – spruce grouse|
|Dendragapus – blue grouse|
|Lagopus – ptarmigans|
|Tetrao – capercaillies|
|Lyrurus – black grouse|
|Tetrastes – hazel grouse|
|Bonasa – ruffed grouse|
|Centrocercus – sage grouse|
|Tympanuchus – prairie grouse|
Sexual selection is a mode of natural selection in which members of one biological sex choose mates of the other sex to mate with, and compete with members of the same sex for access to members of the opposite sex. These two forms of selection mean that some individuals have better reproductive success than others within a population, for example because they are more attractive or prefer more attractive partners to produce offspring. For instance, in the breeding season, sexual selection in frogs occurs with the males first gathering at the water's edge and making their mating calls: croaking. The females then arrive and choose the males with the deepest croaks and best territories. In general, males benefit from frequent mating and monopolizing access to a group of fertile females. Females can have a limited number of offspring and maximize the return on the energy they invest in reproduction.
Peafowl is a common name for three bird species in the genera Pavo and Afropavo of the family Phasianidae, the pheasants and their allies. Male peafowl are referred to as peacocks, and female peafowl as peahens, though peafowl of either sex are often referred to colloquially as "peacocks".
Galliformes is an order of heavy-bodied ground-feeding birds that includes turkey, grouse, chicken, New World quail and Old World quail, ptarmigan, partridge, pheasant, guineafowl, francolin, junglefowl, peafowl (peacock), and the Cracidae. The name derives from "gallus", Latin for "cock" or "rooster". Common names are gamefowl or gamebirds, landfowl, gallinaceous birds, or galliforms. "Wildfowl" or just "fowl" are also often used for the Galliformes, but usually these terms also refer to waterfowl (Anseriformes), and occasionally to other commonly hunted birds. This group has about 290 species, one or more of which are found in essentially every part of the world's continents. They are rarer on islands, and in contrast to the closely related waterfowl, are essentially absent from oceanic islands—unless introduced there by humans. Several species have been domesticated during their long and extensive relationships with humans.
Sexual dimorphism is the condition where the two sexes of the same species exhibit different characteristics beyond the differences in their sexual organs. The condition occurs in many animals and some plants. Differences may include secondary sex characteristics, size, weight, colour, markings, and may also include behavioral and cognitive differences. These differences may be subtle or exaggerated, and may be subjected to sexual selection and natural selection. The opposite of dimorphism is monomorphism.
Waders or shorebirds are birds of the order Charadriiformes commonly found along shorelines and mudflats that wade in order to forage for food in the mud or sand. The term "wader" is used in much of the world, while "shorebird" is used in North America, where "wader" may be used instead to refer to long-legged wading birds such as storks and herons.
The Phasianidae are a family of heavy, ground-living birds, which includes pheasants, partridges, junglefowl, chickens, turkeys, Old World quail, and peafowl. The family includes many of the most popular gamebirds. The family is a large one, and is occasionally broken up into two subfamilies, the Phasianinae and the Perdicinae. Sometimes, additional families and birds are treated as part of this family. For example, the American Ornithologists' Union includes the Tetraonidae (grouse), Numididae (guineafowl), and Meleagrididae (turkeys) as subfamilies in Phasianidae.
A lek is an aggregation of male animals gathered to engage in competitive displays and courtship rituals, known as lekking, to entice visiting females which are surveying prospective partners to mate with. A lek can also indicate an available plot of space able to be utilized by displaying males to defend their own share of territory and/or mates. Leks are commonly formed before or during the breeding season. A lekking species is characterised by male displays, strong female mate choice, and the conferring of indirect benefits to males. Although most prevalent among birds such as black grouse, lekking is also found in crustaceans, fish, amphibians, reptiles, mammals, and insects including paper wasps.
The willow ptarmigan is a bird in the grouse subfamily Tetraoninae of the pheasant family Phasianidae. It is also known as the willow grouse and in Ireland and Britain, where it was previously considered to be a separate species, as the red grouse. It is a sedentary species, breeding in birch and other forests and moorlands in northern Europe, the tundra of Scandinavia, Siberia, Alaska and Canada, in particular in the provinces of Newfoundland and Labrador and Quebec. It is the state bird of Alaska. In the summer the birds are largely brown, with dappled plumage, but in the winter they are white with some black feathers in their tails. The species has remained little changed from the bird that roamed the tundra during the Pleistocene. Nesting takes place in the spring when clutches of four to ten eggs are laid in a scrape on the ground. The chicks are precocial and soon leave the nest. While they are young, both parents play a part in caring for them. The chicks eat insects and young plant growth while the adults are completely herbivorous, eating leaves, flowers, buds, seeds and berries during the summer and largely subsisting on the buds and twigs of willow and other dwarf shrubs and trees during the winter.
The rock ptarmigan is a medium-sized gamebird in the grouse family. It is known simply as the ptarmigan in the UK and in Canada, where it is the official bird for the territory of Nunavut, and the official game bird for the province of Newfoundland and Labrador. In Japan, it is known as the raichō (雷鳥), which means "thunder bird". It is the official bird of Gifu, Nagano, and Toyama Prefectures and is a protected species nationwide.
The greater prairie chicken or pinnated grouse, sometimes called a boomer, is a large bird in the grouse family. This North American species was once abundant, but has become extremely rare and extirpated over much of its range due to hunting and habitat loss. Conservation measures are underway to ensure the sustainability of existing small populations. One of the most famous aspects of these creatures is the mating ritual called booming.
The white eared pheasant also known as Bee's pheasant is a species of "eared pheasant" that get its name because its colouration is white and has the prominent ear tufts of the genus, not because it has white ears. The indigenous people of Himalaya call it shagga, meaning snow fowl. This gregarious bird lives in large flocks, foraging on alpine meadows close to or above the snowline throughout the year. C. crossoptilon is found in China, Qinghai, Sichuan, Yunnan, and Tibet, where it tends to inhabit mixed forests and can be found around Buddhist monasteries.
The ruff is a medium-sized wading bird that breeds in marshes and wet meadows across northern Eurasia. This highly gregarious sandpiper is migratory and sometimes forms huge flocks in its winter grounds, which include southern and western Europe, Africa, southern Asia and Australia.
The sharp-tailed grouse is a medium-sized prairie grouse. It is also known as the sharptail or fire grouse
The white-tailed ptarmigan, also known as the snow quail, is the smallest bird in the grouse family. It is a permanent resident of high altitudes on or above the tree line and is native to Alaska and the mountainous parts of Canada and the western United States. It has also been introduced into the Sierra Nevada in California, the Wallowa Mountains in Oregon and the Uinta Mountains in Utah. Its plumage is cryptic and varies at different times of the year. In the summer it is speckled in gray, brown and white whereas in winter it is wholly white. At all times of year the wings, belly and tail are white. The white-tailed ptarmigan has a diet of buds, leaves, flowers and seeds. The nest is a simple depression in the ground in which up to eight eggs are laid. After hatching, the chicks soon leave the nest. At first they eat insects but later move on to an adult diet, their mother using vocalisations to help them find suitable plant food. The population seems to be stable and the IUCN lists this species as being of "Least Concern".
Attwater's prairie chicken is a vulnerable subspecies of the greater prairie chicken that is native to coastal Texas and Louisiana in the United States.
The ghost moth or ghost swift is a moth of the family Hepialidae. It is common throughout Europe, except for in the far south-east.
Monogamous pairing in animals refers to the natural history of mating systems in which species pair bond to raise offspring. This is associated, usually implicitly, with sexual monogamy.
A biological ornament is a characteristic of an animal that appears to serve a decorative function rather than a utilitarian function. Many are secondary sexual characteristics, and others appear on young birds during the period when they are dependent on being fed by their parents. Ornaments are used in displays to attract mates, which may lead to the evolutionary process known as sexual selection. An animal may shake, lengthen, or spread out its ornament in order to get the attention of the opposite sex, which will in turn choose the most attractive one with which to mate. Ornaments are most often observed in males and choosing an extravagantly ornamented male benefits females because the genes that produce the ornament will be passed on to her offspring, increasing their own reproductive fitness. As Ronald Fisher noted, the male offspring will inherit the ornament while the female offspring will inherit the preference for said ornament, which can lead to a positive feedback loop known as a Fisherian runaway. These structures serve as cues to animal sexual behaviour, that is, they are sensory signals that affect mating responses. Therefore, ornamental traits are often selected by mate choice.
Sexual selection in birds concerns how birds have evolved a variety of mating behaviors, with the peacock tail being perhaps the most famous example of sexual selection and the Fisherian runaway. Commonly occurring sexual dimorphisms such as size and color differences are energetically costly attributes that signal competitive breeding situations. Many types of avian sexual selection have been identified; intersexual selection, also known as female choice; and intrasexual competition, where individuals of the more abundant sex compete with each other for the privilege to mate. Sexually selected traits often evolve to become more pronounced in competitive breeding situations until the trait begins to limit the individual's fitness. Conflicts between an individual fitness and signaling adaptations ensure that sexually selected ornaments such as plumage coloration and courtship behavior are “honest” traits. Signals must be costly to ensure that only good-quality individuals can present these exaggerated sexual ornaments and behaviors.
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