The sharp-tailed grouse (Tympanuchus phasianellus), also known as the sharptail or fire grouse, is a medium-sized prairie grouse. One of three species in the genus Tympanuchus, the sharp-tailed grouse is found throughout Alaska, much of Northern and Western Canada, and parts of the Western and Midwestern United States. The sharp-tailed grouse is the provincial bird of the Canadian province of Saskatchewan.

Taxonomy

In 1750 the English naturalist George Edwards included an illustration and a description of the sharp-tailed grouse in the third volume of his A Natural History of Uncommon Birds. He used the English name "The Long-tailed Grous from Hudson's-Bay". Edwards based his hand-coloured etching on a preserved specimen that had been brought to London from Hudson Bay by James Isham. When in 1758 the Swedish naturalist Carl Linnaeus updated his Systema Naturae for the tenth edition, he placed the sharp-tailed grouse with other grouse in the genus Tetrao. Linnaeus included a brief description, coined the binomial name Tetrao phasianellus and cited Edwards' work. The sharp-tailed grouse is now placed in the genus Tympanuchus that was introduced in 1841 by the German zoologist Constantin Wilhelm Lambert Gloger for the greater prairie chicken. The genus name combines the Ancient Greek tumpanon meaning "kettle-drum" with ēkheō meaning "to sound". The specific epithet phasianellus is a diminutive of the Latin phasianus meaning "pheasant".

The greater prairie chicken, lesser prairie chicken, and sharp-tailed grouse make up the genus Tympanuchus, a genus of grouse found only in North America. Six extant and one extinct subspecies of sharp-tailed grouse are recognised:

  • Length: 15.0–19.0 in (38.1–48.3 cm)
  • Weight: 21.0–31.0 oz (596–880 g)
  • Wingspan: 24.4–25.6 in (62–65 cm)

Distribution

Sharp-tailed grouse historically occupied eight Canadian provinces and 21 U.S. states pre-European settlement. They ranged from as far north as Alaska, south to California and New Mexico, and east to Quebec, Canada.

Behavior

thumb|Sharp-tailed grouse nest with eggs

Feeding

These birds forage on the ground in summer, in trees in winter. They eat seeds, buds, berries, forbs, and leaves, also insects, especially grasshoppers, in summer. Specific species of grasshopper the sharp-tailed grouse is known to feed on are Melanoplus dawsoni and Pseudochorthippus curtipennis.

thumb|left|A male performing its mating display

Breeding

The sharp-tailed grouse is a lekking bird species. These birds display in open areas known as leks with other males, anywhere from a single male to upwards of 20 will occupy one lek (averaging 8–12). A lek is an assembly area where animals carry on display and courtship behavior. During the spring, male sharp-tailed grouse attend these leks from March through July with peak attendance in late April, early May. Selection of specific habitat characteristics and vegetation communities is variable among the different subspecies of sharp-tailed grouse. Selection of these specific habitats depends on the quality of habitat available to grouse. Other habitat types utilized for leks are cultivated lands, recent burns, mowed sites, grazed hill tops, and wet meadows. Goddard et al. (2009) state that the use of shrub dominated habitats has not been documented by many other researchers. Goddard et al. (2009) found that sharp-tailed grouse hens in Alberta, Canada selected more for shrub steppe habitats in their first nest attempts because of increased concealment provided by the shrubs than the residual grass earlier in the breeding season. Roersma (2001) also found that grouse in southern Alberta selected taller, woody vegetation compared to all other habitats assessed, and grouse used this area in greater proportions to available woody habitat. These findings contradict Prose et al. (2002), who states that residual vegetation is critical to sharp-tailed grouse nest success due to the early seasonal nesting nature of the grouse.

Brood habitat

Sharp-tailed grouse are a precocial species, meaning that they hatch with their eyes open, are self-reliant, and do not require the mother to feed them. Shortly after hatching, the chicks and mother leave the nest site in search of cover and food. Brood rearing habitats of sharp-tailed grouse have many characteristics including: shrubby vegetation for concealment, short vegetation nearby for feeding, and high amounts of forbs present. The type of habitat fragmentation varies from ecological succession, as shrub/grassland areas transition into forested areas. Fire suppression, tree plantings, limiting logging practices, and an increase of invasive woody species have also led to habitat fragmentation. The largest contributor to habitat fragmentation has been the agriculture industry.

The Homestead Act 1862 opened up great expanses of virgin prairie in the west to early settlers. By 1905 about 41 million hectares of the west had been homesteaded. Much of this land was in semi-arid rangelands with sub-marginal precipitation to support crop production. Cattle can be an important tool to manage habitat structure for sharp-tailed grouse when managed properly (Evens 1968). The habitat of sharp-tailed grouse was severely affected by early settlers before cattle grazers understood the impact to the environment from overgrazing.

A secondary effect of early agriculture during the years of the Dust Bowl and Great Depression in the late 1920s and early 1930s was when homesteaders abandoned the unproductive land. These plants served their purpose by re-vegetating and protecting the soil. But these invaders became great competitors and directly affected native vegetation. In some instances crested wheatgrass and smooth brome have forced out native vegetation, creating monoculture habitats. Monoculture habitats are not favored by sharp-tailed grouse, as they prefer sites with high heterogeneity. Hamerstrom (1939) was quoted as saying "More important than the individual cover plants is the fact that most of the nests of all species were in cover mixtures rather than pure stands."

Habitat assessment

Research conducted before 1950 on sharp-tailed grouse habitat assessment was done visually. Hamerstrom (1939) reported sparse vegetation was seldom selected for nesting due to lack of adequate cover. Habitat generalizations were formed based on the number of individuals found at a given local. These assumptions were if more birds were present at one location and less at another, then the first must be the better habitat. Hamerstrom (1963) observed 119 of 207 (57%) grouse broods frequenting savannah style habitat. He concluded that the savannah style habitat was the habitat needed for best management. As the research on habitat for grouse species matured, so did the techniques used for assessment. Cover boards and Robel poles were developed to measure visual obstruction (VO) and create habitat indices. Cover boards were developed as early as 1938 by Wight (1938) to study white-tailed deer habitat. Wight's (1938) cover board was 6 feet in height, marked and numbered every foot. Visible marks were counted to measure obstruction by plants. Kobriger (1965) developed a 4×4-foot board marked at 3-inch intervals with alternating white and black squares. He placed a camera in the center of the breeding ground at a height of 3 feet. He then placed the cover board 30 feet away taking photographs of the cover board. After compiling all the photographs, they were analyzed with a hand lens to assess the number of squares visible. This number gave him a vegetation index of cover classes. This method has been modified by Limb et al. (2007). Instead of taking photographs 30 feet away like Kobriger (1965), Limb et al. (2007) took photographs of vegetation back-dropped by a 1×1-meter cover board at a height of 1 meter, 4 meters away. These digital photographs were uploaded to Adobe Acrobat and digitized to the 1×1-meter backdrop. Robel et al. (1970) developed a pole to determine height based on correlated vegetation weight. The pole was duly named the Robel pole. Robel et al. (1970) found that VO measurements taken at a height of 1 m and a distance of 4 m from the pole gave a reliable index of the amount of vegetation production at a location. Hamerstrom et al. (1957) were quoted as saying "Height and density of grass were clearly more important to the prairie chickens than species composition" as reported by Robel et al. (1970). This was also believed to be true for the sharp-tailed grouse. These key aspects can now be assessed using the Robel pole, Nudds cover board, and Limb et al. digital photography method effectively and efficiently.

Management

It is apparent that the effects of habitat fragmentation across all habitat types selected by sharp-tailed grouse are impacting this species. The management of sharp-tailed grouse habitat has changed over the years from observational (making sure current habitat is maintained) to a more hands on approach. The management of lekking habitat and winter habitat are not as clearly defined in the literature as nesting and brood rearing habitat assessment and management. The development of the Robel pole and cover boards has become a key tool in habitat assessment providing land managers a means to inventory and study habitat preferences based on vegetation structure and density. The Robel pole has become the more favored of the two methods in recent years for habitat assessment. The United States Forest Service (USFS) uses visual obstruction readings (VOR) to set stocking densities for cattle based on the current years standing residual vegetation . This method is currently conducted on the USFS Little Missouri Grasslands, Cheyenne National Grasslands, Cedar River National Grassland, and Grand River National Grassland, all found in the Dakota Prairie National Grasslands in North and South Dakota. This method was used to create a habitat suitability index based on vegetation visual obstruction (VO), ranging from 0–30.5 cm with a suitability index rating of 0–1.0. Studies of nesting habitat by Prose et al. (2002) in the Nebraska Sandhills found that nesting sharp-tailed grouse selected nest sites with visual obstruction readings (VOR) of more than 4 cm. Similarly, Clawson and Rottella (1998) observed that 58% of nests (432 of 741) in Southwestern Montana were located in sites with an average VOR of 24 cm. The other nests in this study were located in sites with VOR's of 11–18 cm. Reece et al. (2001) observed that sites with a VO of less than 5 cm near possible nesting locations indicated a decline in quality nesting habitat as average VO declined. The use of the Robel pole to assess habitat for sharp-tailed grouse has given managers a target height of vegetation structure to have at the end of the grazing season. This allows managers to set the appropriate stocking rate to best attain a desired vegetation height. As a rule of thumb, the average VOR reading for suitable grouse nesting habitat is 3.5in (8.89 cm). Lekking habitat can be managed by burning, mowing, clear cutting, and grazing across the entire range of the sharp-tailed grouse subspecies. Ammann (1957) found that leks that contained woody vegetation did not exceed 30% of the total lek area. Similarly, Moyles (1989) found a negative correlation with increased in aspen trees (Populus tremuloides) on lekking sites and the number of displaying males present. Trees may provide perches for avian predators but further work needs to be done on the effects of woody plant encroachment.

Status and conservation

These birds are increasing in numbers and are listed as least concern.