Grouse

Like many other galliforms, grouse are generally heavily-built birds. The traditional grouse (excluding turkeys) range in length from {{convert|31|to|95|cm|in|frac=2|abbr=on}}, and in weight from {{convert|0.3|to|6.5|kg|lb|frac=4|abbr=on}}. If they are included, wild turkey toms are the largest grouse species, attaining lengths of 130 cm (50 in) and weighing up to 10 kg (22 lb).{{cite web | title=Turkey Description, Habitat, & Facts | website=Encyclopedia Britannica | date=4 May 1999 | url=https://www.britannica.com/animal/turkey-bird | access-date=27 August 2023}} Male grouse are larger than females, and can be twice as heavy in the western capercaillie (the largest of the traditional grouse). Like many other galliforms, males often sport incredibly elaborate ornamentation, such as crests, fan-tails, and inflatable, brightly colored patches of bare skin. Many grouse have feathered nostrils, and some species, such as the ptarmigans, have legs which are entirely covered in feathers; 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 many other galliforms, they typically have no spurs, although turkeys do possess very prominent spurs.{{cite web | title=Turkey Records - The National Wild Turkey Federation | website=- | url=https://www.nwtf.org/the-lifestyle/turkey-records-home | access-date=27 August 2023}}

Grouse 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.

File:Bonasa-umbellus-001edit1.jpg in Canada.]]

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.{{citation needed|date=October 2020}}

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 wild turkey precipitously declined before returning to abundance, even in developed areas.

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.{{citation needed|date=October 2020}}

{{Main|Lek mating}}

Male grouse display lekking behavior, which is when many males come together in one area and put on displays to attract females.{{cite journal |last1=Fiske |first1=Peder| last2=Rintamaki |first2=Pekka |last3=Karvonen |first3=Eevi|title=Mating success in lekking males: a meta-analysis |journal=Behavioral Ecology |date=1998 |volume=9 |issue=4 |pages=328–338 |doi=10.1093/beheco/9.4.328 |doi-access=free}} 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 defending a limited territory, and in exploded lekking, displaying males are covered over an expansive land area and share larger territories. 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 greater sexual dimorphism in size.{{cite journal|last1=Soulsbury|first1=Carl D|last2=Kervinen|first2=Matti|last3=Lebigre|first3=Christophe|title=Sexual size dimorphism and the strength of sexual selection in mammals and birds|journal=Evolutionary Ecology Research|date=2014|volume=16|pages=63–76}} This suggests 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.{{citation needed|date=October 2020}}

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.{{cite journal| last1= Mueller |first1= H. C.|title= The Evolution of Reversed Sexual Dimorphism in Owls: An Empirical Analysis of Possible Selective Factors |journal= The Wilson Bulletin |volume=98|issue=3|pages=387–406}}

File:Enontekiö.vaakuna.svg in the coat of arms of Enontekiö.]]

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.

• Genus †Proagriocharis
• Proagriocharis kimballensisLarry D. Martin; James Tate, Jr. (1970). "A new turkey from the Pliocene of Nebraska"{{refn|group=note|Extinct species, late Miocene and early Pliocene.}}{{refn|group=note|name=melpuc}}
• Genus †Rhegminornis
• Rhegminornis calobatesStorrs L. Olson; John Farrand, Jr. (1974). "Rhegminornis restudies: a tiny Miocene turkey"{{Cite web |title=BioLib: Biological library |url=https://www.biolib.cz/en/taxon/id469956/}}{{refn|group=note|Extinct species, early Miocene.}}{{refn|group=note|name=melpuc}}

{{Reflist|refs=

{{cite journal |author1=Gutiérrez, R. J. |author2=Barrowclough, G. F. |author3=Groth, J. G. |title=A classification of the grouse (Aves: Tetroninae) based on mitochondrial DNA sequences |journal=Wildlife Biology |volume=6 |issue=4 |year=2000 |pages=205–212 |url=http://fwcb.cfans.umn.edu/research/owls/lit%20folder/gutierrez%20et%20al.%202000.pdf |url-status=dead |archive-url=https://web.archive.org/web/20150327211714/http://fwcb.cfans.umn.edu/research/owls/lit%20folder/gutierrez%20et%20al.%202000.pdf |archive-date=2015-03-27 |doi=10.2981/wlb.2000.017 |s2cid=85807603 }}

{{cite web|url=http://checklist.aou.org/taxa/ |title=AOU Checklist of North and Middle American Birds |publisher=American Ornithologists' Union|access-date=2014-03-13}}

{{ITIS|id=553485|taxon=Tetraoninae|access-date=2013-03-13}}

{{cite web|url=http://jboyd.net/Taxo/List2.html#phasianidae|title=Phasianidae: Turkeys, Grouse, Pheasants, Partridges |work=Aves – A taxonomy in flux|author=Boyd, John|access-date=2014-03-13}}

{{cite book | last = Storch | first = Ilse | author2 = Bendell, J. F. | year = 2003 | chapter = Grouse | editor = Perrins, Christopher | editor-link = Chris Perrins | title = The Firefly Encyclopedia of Birds | publisher = Firefly Books | pages = [https://archive.org/details/fireflyencyclope0000unse/page/184 184–187] | isbn = 978-1-55297-777-4 | chapter-url-access = registration | chapter-url = https://archive.org/details/fireflyencyclope0000unse | url = https://archive.org/details/fireflyencyclope0000unse/page/184 }}

{{cite book |editor=Forshaw, Joseph|author= Rands, Michael R.W.|year=1991|title=Encyclopaedia of Animals: Birds|publisher= Merehurst Press|location=London|pages= 91|isbn= 978-1-85391-186-6}}

{{cite journal|last1=Drovetski|first1=S. V.|last2=Rohwer|first2=S.|last3=Mode|first3=N. A.|title=Role of sexual and natural selection in evolution of body size and shape: a phylogenetic study of morphological radiation in grouse|journal=Journal of Evolutionary Biology|date=2006|volume=19|issue=4|pages=1083–1091|doi=10.1111/j.1420-9101.2006.01097.x|pmid=16780509|s2cid=6144117 |doi-access=free}}

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{{Reflist|group=note|1}}

• {{cite book |author=De Juana, E. |year=1994 |chapter=Family Tetraonidae (Grouse) |pages=[https://archive.org/details/handbookofbirdso0001unse/page/376 376–411] |editor1=del Hoyo, J. |editor2=Elliott, A. |editor3=Sargatal, J. |title=Handbook of the Birds of the World, Vol. 2. New World Vultures to Guineafowl |publisher=Lynx Edicions |location=Barcelona |isbn=978-84-87334-15-3 |chapter-url=https://archive.org/details/handbookofbirdso0001unse/page/376 }}
• {{cite web|url=https://theuplandhunter.com/ruffed-grouse-eat-spring-fall-winter/ |title=What Do Grouse Eat? |publisher=The Upland Hunter |date=1 September 2017}}

{{Commons}}

• [http://ibc.lynxeds.com/family/grouse-tetraonidae Grouse videos] on the Internet Bird Collection
• {{cite journal | last1 = Johnsgard | first1 = P. | year = 1982 | title = Etho-Ecological Apects of Hybridization in the Tetraonidae | url = http://digitalcommons.unl.edu/johnsgard/16/ | journal = World Pheasant Association Journal | volume = VII | pages = 42–57 }}
• {{Cite NIE|wstitle=Grouse|short=x}}

{{Phasianidae|state=all}}

{{Birds}}

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Category:Bird common names

Category:Taxa named by William Elford Leach