Tympanuchus phasianellus

T. cupido and T. phasianellus hybridize sporadically, but occasionally they interbreed extensively on a local level (AOU 1983). Genetically, the three species of tympanuchus are not clearly distinct; evidently morphological and behavioral differentiation have progressed rapidly relative to either mtDNA or allozymes (Ellsworth et al. 1994). Six recognized subspecies in North America (AOU 1957, Aldrich 1963). Seventh subspecies HUEYI (formerly New Mexico) extinct since mid-1950s (Dickerman and Hubbard 1994).

Widespread in western North America but has disappeared from large portions of the historic range, due mainly to habitat loss/degradation resulting from agricultural practices, livestock overgrazing, and habitat succession; these threats remain significant.

RESIDENT: locally from Alaska, and Yukon east to western Quebec, south to eastern Washington, eastern Oregon, southern Idaho, Utah, Colorado, northeastern New Mexico (at least formerly), Nebraska, eastern South Dakota, eastern North Dakota, Minnesota, Wisconsin, northern Michigan; formerly south to southern Oregon, northeastern California, northeastern Nevada, western Kansas, southern Iowa, northern Illinois, and probably northern Texas (AOU 1983, Connelly et al. 1998).

Originally occupied 21 states and 8 provinces; extirpated this century from 7 (AOU 1998, Connelly et al. 1998). Subspecies CAMPESTRIS: range declined greatly this century. Subspecies COLUMBIANUS: significant regional and local declines and extirpations have occurred; its geographic distribution has contracted by an estimated 90% (Aldrich 1963, Miller and Graul 1980). Today the subspecies exists in substantial numbers only in Colorado and Idaho; exists in only remnant populations in Utah, Washington, Wyoming, and Montana; was extirpated but reintroduced in Oregon and Nevada; and is extirpated in California. Federal listing as "threatened" warranted (USFWS 1999). Subspecies HUEYI: extinct from New Mexico.

HABITAT: Historic conversion of native habitat to private cultivation is cited as a major contributor to declines (Buss and Dziedzic 1955, Kessler and Bosch 1982). Natural succession of grasslands and shrublands to forests, accelerated or expanded geographically by artificial fire regimes, have influenced habitat quality and populations in several regions. Habitat and distribution is constrained in regions where fire suppression has reduced early and mid-successional vegetation communities. Encroachment of aspen into prairie habitat has reduced the number of leks in southwestern Manitoba (Berger and Baydack 1992). Some types of prairie and shrub-steppe habitats protected from fire are readily colonized by evergreens which degrade habitat quality. Various evergreen trees (PINUS spp., PSEUDOTSUGA MENSEZII, JUNIPERUS spp.), and fewer deciduous species (QUERCUS spp., BETULA spp.) aggressively compete with shrubs, grasses and forbs, and dominate sites contributing to increased avian predation. At the landscape level these vegetation changes fragment and isolate habitats and populations (Berg 1990, Manley and Wood 1990, Dickson 1993). GRAZING: Over-grazing by domestic livestock is the activity most frequently attributed to causing declines, especially where it degrades habitat by reducing residual cover necessary for nesting, brood rearing, and predator evasion (Kessler and Bosch 1982). Kessler and Bosch (1982) surveyed biologists who manage both COLUMBIANUS and JAMESI and found that grazing intensity and subsequent effects on residual cover were overwhelmingly identified as the major conflict in conserving the taxon. HUNTING: Because they display on traditional lek sites during the fall hunting season, may be especially vulnerable to excessive harvest, particularly if the population is low and in fragmented habitats (Klott 1993). Annual harvest rates in Idaho range from approximately 10-30 percent (approximately 6,500 birds) of the total population during the hunting season. Harvest rates in Colorado are not reliable, but are likely less than 10 percent of the total estimated population. Harvest rates in British Columbia may approach 50 percent in some years (Ritcey 1995, USFWS 1999). Range-wide, current harvest estimates vary from 4-56 percent, and at lower population levels may negatively impact some populations (Connelly et al. 1998). However, for relatively large, stable populations hunting is not likely to have an additive effect over natural mortality (Braun et al. 1994). HUMAN DISTURBANCE: At leks, males are tolerant of a variety of disturbances but are displaced by human presence. Females are more susceptible to various types of disturbance than males. Disturbance of leks appears to limit reproductive opportunities and may result in regional population declines (Baydack and Hein 1987). BIOCIDES: Ritcey (1993) relates anecdotal reports of mortalities caused by insecticides and surface application of Compound 1080, a rodenticide. Malathion and dieldrin can also be lethal (McEwen and Brown 1966). The USFWS Contaminant Hazard Review (CHR) series cites possible impacts from zinc phosphide grain bait and toxaphene (Eisler 1995). Others have suggested population declines precipitated by insecticides, causing both direct mortalities and the loss of critical insect food resources (Bown 1980). Herbicide treatments may further fragment native vegetation communities critical as feeding, nesting, and wintering habitat. Reduced herbicide use is recommended to increase plant and insect diversity on margins of agricultural lands (J. W. Connelly, pers. comm.). PREDATION: Local changes in habitat, such as forest encroachment, power pole and fence arrays, and other structures may favor avian predators by providing cover and platforms from which to more effectively hunt. Similarly, decreased availability of nesting or escape cover, or increased travel distance to forage resources, may create less-optimal habitats and increase vulnerability to many sources of predation (Dickson 1993; J. W. Connelly, pers. comm.; A. Sands, pers. comm.). As a ground nester and feeder, adults and young are commonly depredated by various animals. Newly introduced, expanding, subsidized or feral predators such as red fox (VULPES VULPES), raccoon (PROCYON LOTOR), coyote (CANIS LATRANS), plus various mustelids, felines, rodents, corvids, and several larger raptors, have been observed as predators of nests and adults (see Connelly et al. (1998) for a summary of predation). Avian predators have taken significant proportions of radio-marked birds, though this may be an artifact of instrumentation (Gratson 1982, Marks and Marks 1988, Deeble 2000). INBREEDING: The fragmented and isolated nature of many populations is a concern for the species in portions of its range. The deleterious effects of inbreeding and the changes in gene frequencies may pose long-term threats to small, isolated populations, and a reduction in fitness. In the Greater Prairie-Chicken (TYMPANUCHUS CUPIDO PINNATUS), reductions in population size and fitness have been observed concurrent with reductions in genetic diversity; fitness, in the form of restored egg viability, was increased by translocations of individuals from large genetically diverse populations (Westemeier et al. 1998). Several aspects of life history and reproductive behavior predispose the taxon to small effective population size. Annual survival of adult males as determined from lek attendance ranges from 24-47 percent (Brown 1966, Robel et al. 1972, Cope 1992). Polygynous lek breeding system has small proportion of males do the majority of mating (Weddell 1992). This breeding regime skews the sex ratio by limiting the number of males contributing during any breeding season to the gene pool, and reduces effective population size. Naturally occurring impacts and human influences may pose additional threats to these isolated populations. Such events may include drought, fire, inclement weather, accidents, cultivation practices, and hunting (Hart et al. 1950, Rogers 1969, WDFW 1995, Mitchell 1995). Subspecies COLUMBIANUS: unlikely that any one factor has caused observed declines. Starkey and Schnoes (1976) hypothesize that hunting and overgrazing caused historic declines, followed by habitat changes resulting from fire suppression, continued overgrazing, and cultivation. Current loss and degradation of habitat is due to any one or a combination of factors including crop production, livestock grazing, rural and suburban development, dam construction, biocides, fire, drought, recreation and other factors (Hart et al. 1950, Buss and Dziedzic 1955, WDFW 1995, McDonald and Reese 1998, USFWS 1999). If Conservation Reserve Program (CRP) lands important to some populations are put back into crop production, adverse impacts to at least the COLUMBIANUS subspecies will likely occur (USFWS 1999). Subspecies CAMPESTRIS: decline due to vegetation succession, improperly placed conifer plantations, intensive agricultural development, cutting and spraying CRP lands (Hamerstrom and Hamerstrom 1961, Berg 1990).