Assessment of Chukar and Gray Partridge Populations - Idaho Power

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Hells Canyon Chukar and Gray Partridge Report, Ratti and Giudice 18reported a range of 49-86%. However, survival and reproductive success of gray partridgeequipped with radio transmitters should be interpreted with caution because effects of handlingand radio tagging may be complex, e.g., a function of physical condition at time of capture, radiotag design, and interactions mediated by environmental factors such as weather and predatorabundance (Bro et al. 1999). Likewise, mortality estimates derived from seasonal changes indensity may be biased if movements violate the closed-population assumption.4.5. Habitat4.5.1. General4.5.1.1. Chukar. Most descriptions of chukar habitat include only generalphysiographic characteristics, e.g., cheatgrass (Bromus tectorum)-sagebrush (Artemisia spp.)vegetative type, steep topography, rock outcroppings, talus slopes, and arid climate (seeChristensen 1996). The most detailed description was probably given by Galbreath andMoreland (1953), who specified optimum chukar habitat contained about 50% sage-cheatgrassbunchgrass;45% talus slopes, rock outcroppings, and cliffs and bluffs; and 5% brushy creekbottoms and swales. Lindbloom (1998) reported that chukars used rock and shrub cover typesmore than expected and grass/forb areas less than expected during both spring and summer (P
Hells Canyon Chukar and Gray Partridge Report, Ratti and Giudice 19cover (e.g., fencerows, farmsteads, roadside and railroad right-of-ways, waterways, idle grass,brush and timber, pasture, and hay) was preferred during late spring, summer, and fall. Plowedstubble was preferred and winter wheat was generally avoided during winter (Mendel 1979). Insummer, birds generally used grasslands and grain fields, but also used roadsides andshelterbelts. In winter, crop stubble (especially cereal grains) and woody cover were preferred(Carroll 1993). During severe winter weather with deep snow (>10 cm), woody cover nearfarmsteads may be important (Weigand 1980, Schulz 1980, Carroll 1993), although Smith et al.(1982) reported that birds in South Dakota shifted from use of row corps to pastures in a winterof deep snow (56 cm). Habitat use by gray partridge inhabiting canyons and mountainous areas,including Hells Canyon, has not been studied.4.5.2. Nesting4.5.2.1. Chukar. Limited research has been conducted on nest-sitecharacteristics (Lindbloom 1998), probably because chukar nests are difficult to find (Galbreathand Moreland 1953). Nests usually are widely scattered and well concealed, but often arelocated within 183-366 m of a water source (Galbreath and Moreland 1953, Harper et al. 1958).In Nevada, Christensen (1970) found 3 inactive nests, 1 under sagebrush at base of hill and 2hidden among rocks and brush. Harper et al. (1958) found 16 nests in California and concludedthat nesting was not limited to any specific cover type. In contrast, Galbreath and Moreland(1953) reported nest preference for south-facing slopes in Washington. Mackie and Buechner(1963) found 24 nests in Washington, but did not describe nest distribution among cover types.In Idaho, Lindbloom (1998) found 23 nests (10 renests) of radiotagged females. Covertypes used by nesting chukars included grass/forbs (48%), rocks (43%) and shrubs (9%).Average slope and elevation was 58% (standard error [SE] = 2) and 905 m (SE = 22),respectively. Eighty-seven percent of nests were on south-facing slopes (30% southeast, 57%southwest). Rock outcrops were the most prevalent (57%) structure at nest sites, followed bygrass-forbs (26%) and low shrubs (17%). Chukar nests were well concealed, with visualobstruction of 3.9 decimeters (SE = 0.5) and overhead canopy averaging 63% (SE = 9).Lindbloom (1998) concluded that nest placement of chukars was not affected by presence ofyellow-star thistle (but see Brood-rearing, below) and nest-site quality probably was not limitingthe chukar population inhabiting canyon grasslands along the Salmon River.In Oregon, Walter (2000) found 17 nests of radiotagged females and 6 incidental nests.Cover types used for nesting included bunchgrass (42%), rock (38%), shrub (8%), and annualgrass (8%). Fifty-seven percent of nests were concealed by vegetation (bluebunch wheatgrass[35%], basin wildrye [13%], or broom snakeweed [9%]) and 43% were located in or under rocks.Most nests were found on relatively steep (19.4° ± 3.3° [ x ± SE]) south-facing slopes.4.5.2.2. Gray Partridge. No information on gray partridge nests in Hells Canyonor other canyon grasslands is available. Data from other habitats report gray partridge use idlecover (pastures, fence rows, roadsides, and shelterbelts) and hay fields for nesting (see review byCarroll 1989). Nest-site selection by gray partridge in Europe occurs mainly in linear andpermanent cover (Potts 1986). In Great Britain, gray partridge will also use cereal grains fornesting, although mainly for renesting (Carroll 1993). In North America, older studies showedgreater use of hay fields than in Great Britain. However, in more recent studies, the trend is
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Assessment of Chukar and Gray Partridge Populations - Idaho Power

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