Assessment of Chukar and Gray Partridge Populations - Idaho Power

Hells Canyon Chukar and Gray Partridge Report, Ratti and Giudice 48The only anthropogenic issues that we observed that may be limiting to partridge were(1) the establishment of Brownlee, Oxbow, and Hell Canyon dams (and resulting reservoirs), and(2) livestock grazing. In general, we did not detect, nor do we suspect, any significant impactsfrom inundation of the Snake River (and hydroelectric operations) in Hells Canyon on partridgepopulations or habitat. On 1 occasion we flushed a covey of gray partridge near the river edgeon the Idaho side of Brownlee Reservoir, and this covey crossed the reservoir and landed on theOregon side. These birds seemed to have little difficulty with the long flight, even though it wasa relatively wide section of reservoir (near the wide bend in the river at approximately mile 318).Thus, we feel certain the reservoirs have not completely restricted regional movements and geneflow. This question could easily be examined with a radio telemetry study.Grazing intensity probably has the largest impacts on partridge populations in theCanyon. However, at this time it is not clear what the relationship is between livestock grazingand partridge ecology. It seems likely (from our data) that an inverse relationship exists betweengrazing intensity and gray partridge distribution and density. This relationship is not as apparentwith chukar. We noted high chukar numbers on a few areas that were severely overgrazed;however, chukars were often in very steep and rocky portions of habitats that received littlepressure from nearby livestock. However, our bird observations were during fall and winter.Spring and summer grazing may affect chukar (and gray partridge) reproductive success.General habitat conditions and vegetative composition are also influenced by grazing intensity.Grazing can influence exotic weed species (see Section 4.10.6.1 above) and various grass speciesused by partridge for food, nesting habitat, loafing, and escape habitat. Thus, much additionalresearch will be needed to resolve questions on this potential impact on habitat and populations.Regardless, we strongly suspect a significant negative relationship exits between grazingintensity and partridge ecology, and recommend that grazing be considered with regard topartridge management.6.4. Projected future status of chukar and gray partridge populationsand habitat quality in Hells Canyon.It is difficult to project the future status of any wildlife population, even for species thathave been studied thoroughly. Many factors associated with our changing environment couldeffect partridge populations and habitats. For example, use of pesticides to control weeds andinsects that compete for livestock forage may have significant effects on bird populations (e.g.,reproduction). Few toxicology studies on wild populations have been completed, and chemicalcompounds change frequently (often annually). Other factors such as invasion of exotic weedsor climate warming could significantly change habitat conditions.However, given the above caveat, the projected long-term status of partridge populationsin Hells Canyon appears to be good. This region is very rugged, remote, and difficult to developor use for agriculture. In addition, much of the land is in protected status, being owned and/ormanaged by natural-resource agencies. Hells Canyon is also a popular natural area and isheavily used for outdoor recreation. Thus, there likely exists strong public support for protectionof the natural environment. For the immediate future (5-10 yrs), we are confident that partridgepopulations and habitat will remain in good condition.