| Falcon versus Grouse: Flight Adaptations of a Predator and Its Prey | PENNYCUICK, CJ | 1994 |
KeywordsNo keywords available AbstractSeveral falcons were trained to fly along a 500 m course to a lure. The air speeds of the more consistent performers averaged about 1.5 times their calculated minimum power speeds, and occasionally reached 2.1 times the minimum power speed. Wing beat frequencies of all the falcons were above those estimated from earlier field observations, and the same was true of wild Sage Grouse Centrocercus urophasianus, a regular falconer's quarry in the study area. Measurements of grouse killed by falcons showed that their wings were short, with broad slotted tips, whereas the falcons' wings were longer in relation to their body mass, and tapered. The short wings of grouse result in fast flight, high power requirements, and reduced capacity for aerobic flight. Calculations indicated that the grouse should fly faster than the falcons, and had the large amount of flight muscle needed to do so, but that the falcons would be capable of prolonged aerobic flight, whereas the grouse probably would not. We surmise that Sage Grouse cannot fly continuously without incurring an oxygen debt, and are therefore not long-distance migrants. although this limitation is partly due to their large size, and would not apply to smaller galliform birds such as ptarmigan Lagopus spp. The wing action seen in video recordings of the falcons was not consistent with the maintenance of constant circulation. We call it ''chase mode'' because it appears to be associated with a high level of muscular exertion, without special regard to fuel economy. It shows features in common with the ''bounding'' flight of passerines. AuthorsPENNYCUICK, CJ; FULLER, MR; OAR, JJ; KIRKPATRICK, SJ Year Published1994 PublicationJournal of Avian Biology LocationsDOI10.2307/3677292 |
| VEGETATIONAL COVER AND PREDATION OF SAGE GROUSE NESTS IN OREGON | GREGG, MA | 1994 |
KeywordsCentrocercus urophasianus, habitat, nesting, Oregon, predation, reproduction, sage grouse,selection AbstractBecause of long-term declines in sage grouse (Centrocercus urophasianus) abundance and productivity in Oregon, we investigated the relationship between vegetational cover and nesting by sage grouse in 2 study areas. Medium height (40-80 cm) shrub cover was greater (P < 0.001) at nonpredated (xBAR = 41%, n = 18) and predated (xBAR = 29%, n = 106) nests than in areas immediately surrounding nests (xBAR = 15 and 10%, n = 18 and 106, nonpredated and predated, respectively) or random locations (xBAR = 8%, n = 499). Tall (> 18 cm), residual grass cover was greater (P < 0.001) at nonpredated nests (xBAR = 18%) than in areas surrounding nonpredated nests (xBAR = 6%) or random locations (xBAR = 3%). There was no difference (P > 0.05) in grass cover among predated nests, nest areas, and random sites. However, nonpredated nests had greater (P < 0.001) cover of tall, residual grasses (xBAR = 18%) and medium height shrubs (xBAR = 41%) than predated nests (xBAR = 5 and 29% for grasses and shrubs, respectively). Removal of tall grass cover and medium height shrub cover may negatively influence sage grouse productivity. AuthorsGREGG, MA; CRAWFORD, JA; DRUT, MS; DELONG, AK Year Published1994 PublicationJournal of Wildlife Management LocationsDOI10.2307/3809563 |
| Pre-Laying Nutrition of Sage Grouse Hens in Oregon | BARNETT, JK | 1994 |
KeywordsNo keywords available AbstractDiet, dietary selection, and nutritional composition of the foods of sage grouse (Centrocercus urophasianus) hens were determined during the pre-laying period in southeastern Oregon in 1990 and 1991. We collected 42 female sage grouse during a 5-week period preceding incubation (4 March-8 April). Sagebrush (Artemisia spp.) was the most common among 21 foods consumed but forbs composed 18 to 50% of the diet by weight. Desert-parsley (Lomatium spp.), hawksbeard (Crepis spp.), long-leaf phlox (Phlox longifolia Nutt.), everlasting (Antennaria spp.), mountain-dandelion (Agoseris spp.), clover (Trifolium spp.), Pursh's milk-vetch (Astragalus purshii Dougl.), buckwheat (Eriogonum spp.), and obscure milk-vetch (A. obscurus) were the primary (greater-than-or-equal-to 1% of the diet by weight) forbs consumed. Forbs were used selectively over sagebrush in both low and big sagebrush cover types. All forbs were higher in crude protein and phosphorus and many were higher in calcium than sagebrush. Consumption of forbs increased nutrient content of the composite diet. Substantially fewer forbs were present in the diet in 1991 than in 1990, which coincided with reduced sage grouse productivity on the study area. These results suggest that consumption of forbs during the pre-laying period may effect reproductive success by improving nutritional status of hens. AuthorsBARNETT, JK; CRAWFORD, JA Year Published1994 PublicationJournal of Range Management LocationsDOI10.2307/4002817 |
| TECHNICAL NOTE - DIETS AND FOOD SELECTION OF SAGE GROUSE CHICKS IN OREGON | DRUT, MS | 1994 |
KeywordsCentrocercus urophasianus, diets, food, Oregon, sage grouse, selection AbstractDiets and food selection by sage grouse (Centrocercus urophasianus) chicks were determined during 1989 and 1990 on 2 areas that differed in long-term grouse productivity. Chicks consumed the same foods in similar frequencies and exhibited similar dietary selection on the areas, but relative dry mass differed. Forbs and invertebrates composed 80% of the dietary mass on the area with higher grouse productivity, whereas chicks on the other area consumed primarily (65%) sagebrush (Artemisia spp. L.). AuthorsDRUT, MS; PYLE, WH; CRAWFORD, JA Year Published1994 PublicationJournal of Range Management LocationsDOI10.2307/4002848 |
| NESTING AND SUMMER HABITAT USE BY TRANSLOCATED SAGE GROUSE (CENTROCERCUS-UROPHASIANUS) IN CENTRAL IDAHO | MUSIL, DD | 1994 |
NESTING AND SUMMER HABITAT USE BY TRANSLOCATED SAGE GROUSE (CENTROCERCUS-UROPHASIANUS) IN CENTRAL IDAHOKeywordsNo keywords available AbstractWe translocated 196 Sage Grouse (Centrocercus urophasianus) into Sawtooth Valley, Idaho, during March-April 1986-87 to augment a small resident population. Forty-four grouse equipped with radio transmitters were monitored through spring and summer. Nest sites (n = 6) had greater (P = .032) horizontal cover than did independent random plots (n = 7). During summer, grouse used sites (n = 50) with taller live and dead shrub heights, greater shrub canopy cover, and more ground litter (P < .009) than were found on dependent random plots (n = 50) 50-300 m from use sites. Distance to edge and mountain big sagebrush (Artemisia tridentata vaseyana) density best separated use sites from independent random plots in logistic regression analysis and correctly classified 64% of the use sites and 78% of the independent random plots. Sage Grouse used sites that had narrower frequency distributions for many variables than did independently plots (P < .04), suggesting selection for uniform habitat. AuthorsMUSIL, DD; REESE, KP; CONNELLY, JW Year Published1994 PublicationGreat Basin Naturalist Locations |
| THE INFLUENCE OF SEASON, TEMPERATURE, AND ABSORPTIVE STATE ON SAGE GROUSE METABOLISM | SHERFY, MH | 1994 |
THE INFLUENCE OF SEASON, TEMPERATURE, AND ABSORPTIVE STATE ON SAGE GROUSE METABOLISMKeywordsNo keywords available AbstractWe used indirect respiration calorimetry to measure the metabolism of six adult sage grouse (Centrocercus urophasianus) during winter, spring, and summer. During winter the metabolic rate of fed birds was higher (P < 0.05) than that of fasted birds. The standard metabolic rate (SMR) of females (0.692 mL O-2.g(-1).h(-1)) was higher than of males (0.583 mL O-2.g(-1).h(-1)) in winter; in both sexes SMR was higher in winter than in summer. Females' SMR was lower (P = 0.0001) in spring than in winter. Lower critical temperatures of both males and females were substantially lower in winter (-0.6 degrees C, -4.8 degrees C) than in summer (14.9 degrees C, 14.8 degrees C). Although seasonally elevated, the SMR of sage grouse in winter is low in comparison with that of other galliforms with northern distributions. Thermoregulation during a winter night at -10 degrees C would result in minimal (<5%) expenditure of endogenous reserves by either sex. Thermoregulation and SMR in winter are more energetically costly to female sage grouse than to males, and may necessitate increased behavioral thermoregulation by females. Seasonal change in SMR differs between the sexes, and is probably influenced by the energetic demands of the breeding season. AuthorsSHERFY, MH; PEKINS, PJ Year Published1994 PublicationCanadian Journal of Zoology-Revue Canadienne De Zoologie Locations |
| BROOD HABITAT USE BY SAGE GROUSE IN OREGON | DRUT, MS | 1994 |
BROOD HABITAT USE BY SAGE GROUSE IN OREGONKeywordsNo keywords available AbstractHabitat use by Sage Grouse (Centrocercus urophasianus) hens with broods was examined at Jackass Creek and Hart Mountain, Oregon, from 1989 through 1991. Sage Grouse hens initially selected low sagebrush (Artemisia spp.) cover types during early brood-rearing, big sagebrush cover types later in the brood-rearing period, and ultimately concentrated use in and near lakebeds and meadows. Areas used by Sage Grouse broods typically had greater forb frequency than did random sites. Hens at Jackass Creek selected sites with forb cover similar to that generally available to broods at Hart Mountain, but home ranges were larger at Jackass Creek because of lower availability of suitable brood-rearing habitat. Differences in habitat use by broods on the two areas were reflected in dietary differences; at Hart Mountain, chicks primarily ate forbs and insects, whereas at Jackass Creek most of the diet was sagebrush. Larger home ranges, differences in diets, and differences in availability of forb-rich habitats possibly were related to differences in abundance and productivity between areas. AuthorsDRUT, MS; CRAWFORD, JA; GREGG, MA Year Published1994 PublicationGreat Basin Naturalist Locations |
| PREDATION OF ARTIFICIAL SAGE GROUSE NESTS IN TREATED AND UNTREATED SAGEBRUSH | RITCHIE, ME | 1994 |
PREDATION OF ARTIFICIAL SAGE GROUSE NESTS IN TREATED AND UNTREATED SAGEBRUSHKeywordsNo keywords available AbstractWe measured predation on 120 artificial Sage Grouse (Centrarcus urophasianus) nests in montane sagebrush grassland in northern Utah. We examined nests in areas that had been chained and seeded 25 years previously (treated areas) and in areas that were untreated. Predation rates of artificial nests were higher in areas of untreated sagebrush, even though these areas had greater sagebrush cover, taller shrubs, and greater horizontal plant cover. These results differ from those previously hypothesized for treated sagebrush habitat and may reflect a greater abundance of other potential prey species, especially lagomorphs, in untreated areas that attracted greater densities of predators. In addition, over 80% of nests were depredated by mammals, which hunt using olfaction and are less likely than avian predators to be affected by nest cover. We conclude that, after treated sagebrush has recovered to some degree, predation rates of Sage Grouse nests may be lower in treated sagebrush. Consequently, factors other than nest predation (e.g., winter food, thermal cover, insects, perennial forb abundance) may be more important reasons for preserving mature sagebrush stands for Sage Grouse. AuthorsRITCHIE, ME; WOLFE, ML; DANVIR, R Year Published1994 PublicationGreat Basin Naturalist Locations |
| LEK BEHAVIOR IN CAPTIVE SAGE GROUSE CENTROCERCUS-UROPHASIANUS | SPURRIER, MF | 1994 |
LEK BEHAVIOR IN CAPTIVE SAGE GROUSE CENTROCERCUS-UROPHASIANUSKeywordsNo keywords available AbstractNo abstract available AuthorsSPURRIER, MF; BOYCE, MS; MANLY, BFJ Year Published1994 PublicationAnimal Behaviour Locations |
| Influence of wind speed on sage grouse metabolism | SHERFY, MH | 1995 |
KeywordsNo keywords available AbstractWe measured the effect of wind speed on the metabolic rate of six adult sage grouse (Centrocercus urophasianus) with indirect respiration calorimetry at ambient temperatures above, near, and below the lower critical temperature. There was a significant effect (P < 0.05) of temperature on metabolic rate at all wind speeds, and a significant effect (P < 0.05) of wind speed on metabolic rate for temperatures less than or equal to 0 degrees C. Wind speed had a more pronounced effect on metabolism at temperatures below the lower critical temperature for sage grouse. Metabolic rates measured at wind speeds of greater than or equal to 1.5 m/s were significantly higher than those measured at wind speeds < 1.5 m/s. Multiple regression analysis of wind speed (u; m/s) and temperature (T-a; degrees C) on metabolism (MR; mL O-2 . g(-1). h(-1)) yielded the equation MR = 0.0837 (u) - 0.0248 (T-a) + 0.5444. The predicted cost of thermoregulation at conditions of -5 degrees C and u = 1.5 mis was about 1.5 x standard metabolic rate; half the increase was due to wind. Measurements of wind speed in sagebrush (Artemisia spp.) stands indicate that such habitat effectively reduces wind speed to < 1.5 m/s. Microhabitat value should be recognized in the management of sagebrush stands. AuthorsSHERFY, MH; PEKINS, PJ Year Published1995 PublicationCanadian Journal of Zoology LocationsDOI10.1139/z95-088 |
