Sharp-tailed Grouse (Tympanuchus phasianellus) are medium sized, ground-nesting birds that average a length of 43 cm, a 63.5 cm wingcol-sm-, and an average weight of 880 g (Sibley 2000). The coloration is a drab gray-brown mottled with white (Figure 1). Both sexes have horizontal or v-shaped markings on the breast, a slight crest on the head, white spots on the wings, light colored flanks and belly, and feathered legs (Johnson and Knue 1989). Males have purple air sacs on the side of the neck and a yellow comb above the eyes, both of which are only visible during mating season. Wings are short and rounded, used for short bursts of flight followed by gliding. The tail is pale and pointed.
You can also view the training videos for identifying sharp-tailed grouse, their nests, and their predators here.
Sharp-tailed Grouse can be found from Alaska, east to East Central Canada, south through Michigan, Minnesota and Wisconsin, and west to Southern Colorado and Utah (Figure 2). Sharp-tailed Grouse prefer open, fairly treeless areas that contain a mix of dense grasses, forbs, and shrubs. Habitat is chosen based on openness and plant density (Marks 2007).
Nesting habitat of grouse depends on what is available to them. Some studies have suggested that grouse prefer to nest near areas with taller, denser shrubs. This is not a necessity for a successful nest, as many females will select areas with lower shrub cover but a higher level of forbs (Goddard et al. 2009). The extra cover provided by the shrubs or dense forbs is most important during the first 14 days after chicks hatch, which is when offspring survival rates are the lowest due to predation and adverse weather (Goddard and Dawson 2009).
The diet of adult grouse is comprised mainly of plant material, including buds, flowers, and seeds. A small portion of the adult diet consists of insects, including ants, beetles, grasshoppers and crickets (Marks 2007). The only months when grouse do not consistently feed on the ground are the winter months when snow covers these food sources. During these months, grouse will often forage in shrubs and trees.
Sharp-tailed Grouse are among four species of North American grouse that congregate in specific areas, known as leks, to engage in elaborate mating rituals known as 'dancing' (see lek videos). Mating is based on selection of suitable males, who take part in the displays, by females, who do not display but rather observe male displays and choose a mate. The size of a lek is relatively small, ranging from as small as a small house or as large as a baseball diamond. Leks are traditionally used multiple years, although if the habitat is no longer suitable a new lek can be formed elsewhere. A lek is usually found within 1-2 kilometers of denser grass cover, which is necessary for nesting materials and cover (Prose 1987). Leks often have low, sparse vegetation, allowing for clear vision in all directions and adequate space to engage in dancing, as well as vision to help escape and minimize predation. Areas that are often used for leks include rangeland, harvested or low cropland, low ridges and knolls, recent burns, and even abandoned runways (Prose 1987).
Beginning in March, the males gather on the lek in the morning, usually arriving 30 to 60 minutes before sunrise, and at its peak a lek may contain anywhere from 2 to 35 displaying males. Once on the lek, males usually remain there for 2 or 3 hours. This behavior of returning to the lek in the morning takes place on a lesser scale in the fall. The purpose of returning to a lek in the fall is to maintain the hierarchy and structure established in the spring, which can have a substantial impact on male mating success (Tsuji et. al. 1994).
The dancing ritual of the males is highly elaborate and involves both active and relaxed phases. To begin, the male bends forward to the point that its body is nearly parallel with the ground. It spreads its wings and fans them a bit, so they are perpendicular with its body. The tail is held erect and is the only part of the body that is not held parallel to the ground, and the air sacs on the side of the neck are also inflated. This position is held for the duration of the dance (Prose 1987).
The movements involved in the dance are very rapid and precise. The male will either rush forward or rapidly spin in a circle. No matter which the male chooses, while dancing it also rapidly stomps its feet. Additionally, the male moves its central tail feathers so they make a clicking noise, as well as producing hooting, cackling, cooing and gobbling sounds. Often there is more than one male dancing at the same time, and the males involved often start and stop specific movements at the exact same time, almost as if they were doing this on cue. These dancing bouts can last from roughly 30 to 50 seconds (Marks 2007).
Within 1 to 3 days of mating the hen will lay the first egg, with an additional egg being laid every 1 to 2 days. Clutch sizes average 11 to 12 eggs and the incubation period lasts 21 to 25 days, beginning when the last egg is laid. Although the eggs are laid days apart they all hatch at the same time due to incubation not occurring until the last egg is laid, and thus, the precocial (i.e., very well developed young with feathers, eyes open, and ready to leave the nest shortly after hatch) young will hatch within 24 hours of one another and leave the nest (Roersma 2001).
Common nest predators include coyote (Canis latrans), striped skunk (Memphitis memphitis), a variety of ground squirrels, common ravens (Corvus corax), and common predators of grouse include coyote, a variety of hawks, and great horned owl (Bubo virginianus, Schroeder and Baydack 2001). However, our study is examining this very issue and we hope to provide insight on specific rates of different predators in western North Dakota.
Sharp-tailed grouse populations are in decline in areas, but this decline is not considered to be a major concern yet. Many states and provinces that have Sharp-tailed Grouse populations have a hunting season on the bird.
One major factor contributing to the declines noted is habitat loss. Two different factors play into this. First, many acres of grassland are being converted for agriculture. Second, grouse will move away from an area if too much woody vegetation is present. This is especially evident in areas with leks, where males will abandon a lek where even small increases of woody vegetation have occurred (Hanowski et. al. 2000). Furthermore, recent expansion of gas and oil development in western North Dakota may result in fragmentation of the vast grasslands, as well as frequent disturbances such as noise, additional lighting, and dust.