Sharp-tailed grouse

Sharp-tailed grouse
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Galliformes
Family: Phasianidae
Subfamily: Tetraoninae
Genus: Tympanuchus
Species: T. phasianellus
Binomial name
Tympanuchus phasianellus
(Linnaeus, 1758)
Synonyms
  • Pedioecetes phasianellus

The sharp-tailed grouse (Tympanuchus phasianellus) (previously: Tetrao phasianellus), is a medium-sized prairie grouse. It is also known as the sharptail, and is known as "fire grouse" or "fire bird" by Native American Indians due to their reliance on brush fires to keep their habitat open.

Taxonomy

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. The full scientific name of the sharp-tailed grouse is Tympanuchus phasianellus. Six extant and one extinct subspecies of sharp-tailed grouse have been described:[2]

Description

Close-up of a male sharp-tailed grouse.

Adults have a relatively short tail with the two central (deck) feathers being square-tipped and somewhat longer than their lighter, outer tail feathers giving the bird its distinctive name. The plumage is mottled dark and light browns against a white background, they are lighter on the underparts with a white belly uniformly covered in faint "V"-shaped markings. These markings distinguish sharp-tailed grouse from lesser and greater prairie chickens which are heavily barred on their underparts(Connelly et al. 1998). Adult males have a yellow comb over their eyes and a violet display patch on their neck. This display patch is another distinguishing characteristic from prairie chickens as male prairie chickens have yellow or orange colored air sacs(Connelly et al. 1998). The female is smaller than the male and can be distinguished by the regular horizontal markings across the deck feathers as opposed to the irregular markings on the males deck feathers which run parallel to the feather shaft. Females also tend to have less obvious combs. Males weigh an average of 33.5 oz (951 g) and females average 29 oz (815 g).

Distribution

Sharp-tailed grouse historically occupied eight Canadian provinces and 21 U.S. states pre-European settlement (Johnsgard 2002). They ranged from as far north as Alaska, south to California and New Mexico, and east to Quebec, Canada (Johnsgard 2002). Following European settlement the sharp-tailed grouse has been extirpated from California, Kansas, Illinois, Iowa, Nevada, and New Mexico, (Johnsgard 1973; Connelly et al. 1998).

Behavior

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.

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 defined as an assembly area where animals carry on display and courtship behavior (Merriam-Webster Dictionary 2010). During the spring, male sharp-tailed grouse attend these leks from March through July with peak attendance in late April, early May (Conelly et al. 1998). These dates do fluctuate from year to year based on the weather. Johnsgard (2002) observed weather delayed lekking of up to two weeks by sharp-tailed grouse in North Dakota. The males display on the lek by stamping their feet rapidly, about 20 times per second, and rattle their tail feathers while turning in circles or dancing forward. Purple neck sacs are inflated and deflated during display. The males use "cooing" calls also to attract and compete for females (Sisson 1969; Bergerud and Gratson 1988; Conelly et al. 1998). The females select the most dominant one or two males in the center of the lek, copulate, and then leave to nest and raise the young in solitary from the male. Occasionally a low-rank male may disguise himself as a female and walk to where the dominant male is and fight him.

Habitat selection

The sharp-tailed grouse is found throughout different prairie ecosystems in North America. They inhabit ecosystems from the pine savannahs of the eastern upper Midwest to the short grass, mid grass, and shrub steppe prairies of the Great Plains and Rocky Mountain West (Aldrich 1963; Johnsgard 1973; Johnsgard 2002). 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 (Johnsgard 1973; Kohn 1976; Swenson 1985; Roersma 2001; Goddard et al. 2009). The major habitats used by sharp-tailed grouse, recorded in the literature, are savannah style prairie with grasses dominant and shrub patches mixed throughout, with minimal patches of trees (Hammerstrom 1963; Robel 1972; Moyles 1981; Johnsgard 2002; Goddard et al. 2009). In fact, Hammerstrom (1963) states the taller the woody vegetation, the less of it there should be in the habitat. The savannah style habitat is mostly preferred during the summer and brood rearing months through autumn. This general habitat is used during all four seasons for different features. Habitat selection and usage vary by season with; lekking, nesting, brood rearing, and winter habitat selected and utilized differently.

Lekking habitat

The lek, or dancing ground is, usually made up of short, relatively flat native vegetation (Manske and Barker 1987; Hanowski et al. 2000). Other habitat types utilized for leks are cultivated lands, recent burns, mowed sites, grazed hill tops, and wet meadows (Ammann 1957; Kobriger 1965; and Johnsgard 1973; Johnsgard 2002). Manske and Barker (1987) reported sun sedge (Carex inops), needle and thread grass (Hesperostipa comata), and blue grama (Bouteloua gracilis) on lekking grounds in the Sheyenne National Grassland in North Dakota. The males also select for upland or midland habitat type on the tops of ridges or hills (Manske and Barker 1987). Leks surrounded by high residual vegetation were observed by Kirsch et al. (1973). They noticed lek distribution was influenced by the amount of tall residual vegetation adjacent to the lek. Lek sites eventually became abandoned if vegetation structure was allowed to get too high. The invasion of woody vegetation and trees into lekking arenas also caused displaying males to abandon leks (Moyles 1981; Swenson 1985). Moyles (1981) observed an inverse relationship of lek attendance by males with an increase in quaking aspen (Populus tremuloides) within 0.8 km of arenas in the Alberta parklands. Berger and Baydack (1992) also observed a similar trend in aspen encroachment where 50% (7 of 14) of leks were abandoned when aspen coverage increased to over 56 percent of the total area within 1 km of the lek. Males select hilltops, ridges, or any place with a good field of view for leks. So they can see the surrounding displaying males, approaching females to the dancing ground, and predators (Sisson 1969; Manske and Barker1987; Johnsgard 2002).

Nesting habitat

Nesting cover is one of the most important habitat types needed by sharp-tailed grouse hens. Nesting habitat varies widely among the different subspecies of sharp-tailed grouse (Roersma 2001). Hamerstrom Jr. (1939) found the majority of prairie sharp-tailed grouse (T.p.campestris) nests occupyied dense brush and woods at marsh edges. Gieson and Connelly (1993) reported that Colombian sharp-tailed grouse (T.p.columbianus) selected for dense shrub stands with taller, denser shrubs located at the nest site. Plains sharp-tailed grouse (T.p.jamesii) selected nest sites with dense residual vegetation and a shrubby component (Kirby and Grosz 1995;Roersma 2001). However, nest sites are usually characterized by dense tall residual vegetation (last year’s growth) with the presence of woody vegetation either at the nest site or nearby (Manske and Barker 1987; Prose et al. 2002). 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 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 (Hamerstrom 1963; Kohn 1976; Manske and Barker 1987; Roersma 2001; Goddard et al. 2009). This could explain why sharp-tailed grouse nest in or close to shrub communities. The shrub component in brooding habitat provides good canopy protection from direct sunlight and avian predators (Roesmra 2001; Goddard 2009). Hamerstrom (1963) and Goddard et al. (2009) both observed the greatest number of sharp-tailed grouse broods present in open, rather than wooded landscapes. Both hypothesized this use of open landscape was due to an abundance of insects for the chicks and green herbaceous cover for the hen to feed on. Habitat usage by sharp-tailed grouse broods is a function of time of day, available habitat, and weather (Ammann 1957; Kohn 1976). Brood habitats are made up of many complex habitat types. Broods may utilize shrubby areas or oak grassland savannah type habitats (Hamerstrom 1963). Broods utilize these types of habitats for cover, while remaining close to prime foraging habitats in the form of shorter vegetation with a mixture of native vegetation.

Winter habitat

Winter habitat usage by sharp-tailed grouse seems to shift toward denser cover for thermal insulation. Hammerstrom and Hammerstrom (1951) noticed that grouse use thicker edge type habitat more than the open ground during the winter in Michigan and Wisconsin. Hammerstrom and Hammerstrom (1951) also noted that birds, when found in open habitat, were no more than a few hundred meters from thicker cover. These birds were usually utilizing grain fields. Swenson (1985) observed the same trend in Montana. Hamerstrom and Hammerstrom (1951) declared that use of forested habitat by sharp-tailed grouse vary by location, noting that sharp-tailed grouse in more semi-arid and arid areas utilize brush less frequently in winter. However, Hammerstrom and Hammerstrom (1951) did report that sharp-tailed grouse in Washington and California were observed using edge type habitats more frequently during winter months. Manske and Barker (1987) noticed a similar trend in winter habitat usage in North Dakota, noting that sharp-tailed grouse in small flocks joined together to form larger packs in severe weather. These packs move from open prairie, to shelterbelts, and adjacent croplands with standing corn and sunflowers. Habitat usage in winter varies greatly as a function of snow depth (Swenson 1985). As snow depth increases, habitat selection shifts from cropland and prairie to shelterbelts and woody vegetation. One habitat change seen by Hamerstrom and Hamerstrom (1951), was grouse would select large snow banks to burrow into, to keep warm during cold nights. The use of burrows was also noted by Gratson (1988).

Habitat fragmentation

Habitat fragmentation has been one of factors driving the decline of all subspecies of sharp-tailed grouse across its entire range throughout North America (Silvy and Hagen 2004). 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 (Olsen 1997). Much of this land was in semi-arid rangelands with sub-marginal precipitation to support crop production (Olsen 1997). The plowing of this land represented a permanent change in the nature of the land. Another contributor to habitat fragmentation for grouse is unmonitored and excessive cattle grazing (Kirsch et al. 1973; Giesen and Connelly 1993; Kirby and Grosz 1995; Reece et al. 2001; Sidle 2005). Cattle can be an important tool to manage habitat structure for sharp-tailed grouse when managed properly (Evens 1968; Kirby and Grosz 1995; Sidle 2005). 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 (Olsen 1997). The United States government bought up much of this land through the Land Utilization Program, with management eventually controlled by the United States Forest service and the Bureau of Land Management (Wooten 1965; Olsen 1997). During the drought years of the 1930s, these agencies re-vegetated some of these areas with non-native highly competitive vegetation such as smooth brome (Bromus inermis) and crested wheatgrass (Agropyron cristatum) (USDA- US Forest service 2001). 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 pre-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 x 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 recently 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 1x1 meter cover board at a height of 1 meter, 4 meters away. These digital photographs were uploaded to Adobe Acrobat and digitized to the 1x1 meter backdrop (Limb et al. 2007). 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 1m and a distance of 4m 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 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, Sheyenne National Grasslands, Cedar River National Grassland, and Grand River National Grassland, all found in the Dakota Prairie National Grasslands in North and South Dakota(Forest Service, Northern Region (USDA).2001) . The Robel pole is a non-destructive method for inventorying vegetative biomass (Robel 1970; Benkobi et al. 2000). 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 (Prose 1987). 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 tree encroachment (Manzer and Hannon 2005).

In art

John James Audubon illustrates the "Sharp-tailed Grous(sic)- Tetrao phasianellus" as Plate 382 in Birds of America, published London, 1827–38. The original watercolour by Audubon, from which this print was engraved by Robert Havell in 1837, shows the two grouse separated. However, the constraints of Audubon's wish have the birds illustrated life-size and the maximum page size forced Havell to overlap the birds in the final print. The original watercolour is owned by the New York History Society.

Provincial bird

The sharp-tailed grouse is the provincial bird of Saskatchewan.

Status and conservation

These birds are declining in numbers and range due to habitat loss, but overall they are not considered a threatened species.
Tympanuchus phasianellus call
Bird call of the Sharp-tailed Grouse (Tympanuchus phasianellus)
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Notes

  1. ↑ BirdLife International (2012). "Tympanuchus phasianellus". IUCN Red List of Threatened Species. Version 2013.2. International Union for Conservation of Nature. Retrieved 26 November 2013.
  2. ↑ Hoffman et al. (2007), p. 15.

References

External links

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