Contributions to the life history of Sacramento perch, Archoplites interruptus, in Pyramid Lake, Nevada

During a two-year period (1976&ndash;1977), 180 Sacramento perch ( Archoplites interruptus ) were sampled from Pyramid Lake, Nevada, on a monthly basis using several capture methods in all lake areas. Age and growth determinations of these fish were inconsistent with previous research on this species. Sacramento perch are entirely carnivorous, adults feeding primarily on tui chub ( Gila bicolor ). Fish accounted for 6 percent of the diet (by volume) of Sacramento perch less than 300 mm fork length, and 98 percent for those exceeding 300 mm. Amphipods, Odonata, and Chironomidae composed 6.3, 5.7, and 1.8 percent, respectively, of the stomach contents by volume for all sizes combined. Females spawned from June to August when water temperatures approached 20 C, and their gonad weight was about 6 percent of the total body weight. A sample of 20 female perch had a mean fecundity of 84,203 eggs. The mean diameter of mature eggs was 0.88 mm. Sacramento perch almost exclusively inhabit the littoral zone of Pyramid Lake. Activity, as indicated by net catches, was greatest during the warm months of May to October. Monthly catches were significantly correlated with temperature (r = 0.577, P < 0.01). No short-term changes in population abundances were observed during 1976&ndash;1977.     

Aspects of the biology of the flathead chub ( Hybopsis gracilis ) in Montana

Mature flathead chubs ( Hybopsis gracilis ) were present in mid - July and mid - August collections from the Musselshell River, Montana. The estimated numbers of mature eggs present in eight females were 360&ndash;753 per female. The smallest mature female and male collected were 113 and 123 mm in total length, respectively. The male to female sex ratio in collections was about 1:1. Only small differences were detected among the length &ndash; weight relationships of males and females and samples taken from various seasons and localities in Montana. Observations on size groups, fish associates, and habitat characteristics of flathead chubs are presented. &nbsp;&nbsp;&nbsp;     

Growth and development of the western harvest mouse, Reithrodontomys megalotis megalotis

Growth rates, gestation period, litter size, reproductive age, sex ratios, and development were studied on 198 litters of Reithrodontomys megalotis megalotis (Baird). Growth was characterized by several standard skull and body measurements and was partitioned into four phases of 1 &ndash; 3, 4 &ndash; 12, 13 &ndash; 22, and 23 &ndash; 70 days. Growth was best described by measurements of tail length, ear length, and dried eye - lens weight. Reproductive activity began as early as 38 days for females and 59 days for males. The gestation period was 22 days, and the mean litter size was 3.83 (range 1 &ndash; 7). Sex ratio was 53.49 percent males to 46.51 percent females. Reproductive efficiency was 53.53 percent. The development of R. m. megalotis was very similar to that of R. m. dychei. Early breeding, postpartum estrous, year - round breeding, high reproductive efficiency, and a short gestation period contribute to a high reproductive potential in R. m. megalotis. &nbsp;     

Pocket gophers ( Thomomys talpoides ) in successional stages of spruce-fir forest in Idaho

This study examined (1) the relative abundance of the pocket gopher ( Thomomys talpoides ) in four successive stages (1&ndash;10, 11&ndash;39, 40&ndash;79, and 80+ years following disturbance) of spruce-fir forest; (2) the relationship between number of gopher sign (mounds and earth plugs) with gopher density; and (3) a method of sampling pocket gopher populations using a 500 by 4 m strip transect. The number of gopher mounds was significantly correlated with the number of earth plugs. Data were pooled and a categorical log linear analysis used to test for significant differences in pocket gopher sign between the four successive stages. The 1&ndash;10 and the 80+ -year-old sites had significantly more gopher sign than the 11&ndash;39 and the 40&ndash;79 year-old sites. No significant differences were found between the 11&ndash;39 and the 40&ndash;79-year-old sites, or between the 1&ndash;10 and the 80+ -year-old sites. The difference in population densities may be due to understory vegetation differences between the successional stages. There was a significant correlation between amount of gopher sign and gophers caught in each of the study sites. This indicates that counts of pocket gopher sign may be used to estimate pocket gopher density. The strip transect is recommended as the most appropriate method when sampling heterogeneous habitats or when there is cause to suspect gopher populations may be aggregated within the area rather than spaced randomly or regularly.     

Population ecology and reproduction of the Mexican mud turtle ( Kinosternon integrum ) in Tonatico Estado De México

Ecological data directly from the field are important in understanding the life history strategies of kinosternid species in the tropics. Herein we summarize the basic population ecology and life history of Kinosternon integrum in the municipality of Tonatico (southeastern Estado de M&eacute;xico, M&eacute;xico). From October 2003 to November 2004, we marked a total of 204 turtles and recaptured 118 of them. Mean population size using the Jolly-Seber model was 197 (95% CI 128&ndash;416) individuals, with a sex ratio of 1:1.7, biased to females. Males were larger than females in carapace length and plastron length. The reproductive season starts in late June and finishes in late October. The smallest female with oviductal eggs was 122 mm in carapace length. Mean clutch size was 4 eggs ( s = 1.77, range 1&ndash;8) and was significantly and positively related to body size. Mean egg length was 30.43 mm ( s = 2.24, range 23.92&ndash;35.96), mean width was 16.35 mm ( s = 1.01, range 12.99&ndash;18.30), and mean weight was 5.14 g ( s = 0.60, range 3.41&ndash;6.57). Mean egg length was significantly and inversely related to clutch size. Relative clutch mass (reproductive effort) was 0.043 ( s = 0.017, range 0.017&ndash;0.071), which is the smallest value reported for the genus Kinosternon. Additionally, there was no evidence of a pelvic restriction on egg size in this population. This is the first study that documents basic population ecology and reproductive characteristics for a single population of the most widespread freshwater turtle in Mexico.     

Body fat, body water, and total caloric value of Uinta ground squirrels

The weight of body water and fat-free dry weight of Uinta ground squirrels ( Spermophilus armatus ) is given as a function of body weight. Body fat is presented as a function of body weight and body length. An equation for calculating the total caloric content of Uinta ground squirrels is given. Fat index (weight of fat/fat-free dry weight) values of juveniles increased from 0.11 to 0.22 from 5 June to 28 July. In male yearlings and adults the fat index increased about 8 to 9 times in the latter half of June and early July. &nbsp;&nbsp;&nbsp;     

The reproductive ecology of the Tahoe sucker, Catostomus tahoensis, in Pyramid Lake, Nevada

The Tahoe sucker spawns in Pyramid Lake from April to August at lake temperatures of 11.7 to 22.7 C. The spawning population is comprised of a large lake spawning group and a numerically smaller river running group. The river running group is smaller in length and was not considered during this study. The sex ratio of sampled suckers significantly favored the females. This is the result of the longer life of females and greater mortality of males during spawning. &nbsp; Pyramid Lake Tahoe suckers reach sexual maturity at two to three years of age; however, those in Lake Tahoe do not mature until four or five years of age. The size at sexual maturity is different in both populations, which suggests that size or rate of growth rather than age determines sexual maturity. &nbsp; The fecundity of Tahoe suckers is positively correlated with fork length, weight, and age. Additional analysis showed that a better correlation occurred between fish size (either length or net weight) and total ovary weight. We believe that fish size is primarily correlated with total reproductive tissue produced and secondarily with fecundity. A comparison of the Pyramid Lake population and the Lake Tahoe population demonstrated that size, not age, is the most important determinant of Tahoe sucker fecundity.     

Environmental site characteristics and incidence of chokecherry black knot in Utah

Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 st1\:*{behavior:url(#ieooui) } /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Black knot disease of chokecherries, induced by Dibotryon morbosum (Schw.) Th. & Syd., is widely distributed in Utah. The incidence of black knot was measured by determining the ratio of total black knot gall length to total stem length of plants and then expressing that value as a percentage of diseased stems in the sample plot. The environmental site factors measured were elevation, exposure, slope, soil pH, soil depth, distance to surface water, plant moisture stress, and associated vegetation. Numerical values were determined for each of these variables at each of 18 randomly located plots. Correlation coefficients for plant moisture stress and soil temperature were &ndash;.439 (p = .065) and &ndash;.440 (p = .055). Multiple regression analyses using plant moisture stress and soil temperature gave a regression coefficient of &ndash;.641 (p = .05). As plant moisture stress and soil temperature decreased, incidence of black knot increased. &nbsp;&nbsp;     

Life history of the Lahontan cutthroat trout, Salmo clarki henshawi, in Pyramid Lake, Nevada

Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 st1\:*{behavior:url(#ieooui) } /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} The Pyramid Lake Lahontan cutthroat trout ( Salmo clarki henshawi ) population was sampled on a monthly basis from November 1975 through December 1977. A subsample of 676 trout, stratified by fish size and lake habitat, provided biological data. The entire population is presently derived from hatchery production, stocked at lengths of approximately 75 to 300 mm. Peak annulus formation occurs in March and April, followed by the period of maximum growth. Scale patterns illustrate a variable growing season. Maximum growth in length is in the first three years of life; after that males begin to grow faster than females. Males attained a greater age in our sample; i.e., the oldest male was seven years old compared to six years for females. The Pyramid Lake Lahontan cutthroat trout exhibit nearly isometric growth. The legal sport fishery removed 380 mm); other decimating factors are poorly understood. No evidence of the following diseases or pathogens was found in the Pyramid Lake population, presuming a carrier incidence of 2 percent at the 95 percent confidence level: infectious pancreatic necrosis, infectious hematopoietic necrosis, viral hemorrhagic septicema, bacterial kidney disease, enteric redmouth, furunculosis, whirling disease, blood fluke; however, 7 of 235 (&asymp;3 percent) adults sampled at the Marble Bluff fishway were positive for furunculosis. Small trout feed primarily on zooplankton and benthic invertebrates; cutthroat trout >300 mm are piscivorous, feeding almost exclusively on tui chub ( Gila bicolor ). The spawning migration of Pyramid Lake cutthroat trout to the Marble Bluff egg taking facility in spring 1976 and 1977 peaked in April and May. Females mature at three or four years (352&ndash;484 mm), and males mature at two or three years (299&ndash;445 mm). Mean diameter of mature eggs is 4.51 mm; both ovum size and fecundity are a function of fish size. Fecundity ranges from 1241 to 7963 eggs, with a mean of 3815. Lahontan cutthroat trout comprise     

Observations on the reproduction and embryology of the Lahontan tui chub, Gila bicolor, in Walker Lake, Nevada

Various aspects of the reproduction and embryology of Walker Lake Lahontan tui chub, Gila bicolor , were investigated during the spring&ndash;summer period of 1976, 1977, and 1981. Tui chub were found to spawn in littoral regions of the lake beginning in late May or early June. Early in the season male chub substantially outnumbered females over the spawning grounds, with a normal 1:1 sex ratio gradually approached as the season progressed. The developmental period between fertilization to hatch-out was shortened by increases in water temperature. Selected stages of embryonic development are described from egg fertilization through post-hatch.     

Growth of Dipodomys ordii (Rodentia: Heteromyidae)

Growth rates were determined for laboratory - reared Dipodomys ordii pallidus Durrant & Setzer. Instantaneous growth rates were used to express increase of body weight, total length, tail length, ear length and hind foot length as rates between times of measurements and the instantaneous percentage of maximum size. Data were analyzed for growth periods of 1 &ndash; 3, 4 &ndash; 15, 16 &ndash; 29 and 30 &ndash; 70 days. All five parameters provided significant correlations of growth with age during all growth periods. Even though all of the growth parameters correlate with age, these parameters cannot be reliably used to predict age.     

Home range of the western jumping mouse, Zapus princeps, in the Colorado Rocky Mountains

Western jumping mice, Zapus princeps, were live - trapped during the summer of 1975 in an aspen forest in the Front Range of the Colorado Rocky Mountains. Home range sizes were calculated using the exclusive boundary strip method, and it was discovered that males had larger home ranges (298 &ndash; 3315 m 2 , x = 1743 m 2 ) than females (680 &ndash; 1275 m 2 , x = 1041 m 2 ). Mean range length was 96.5 m for males and 78.5 m for females. Spatial relationships showed that females tended to be more territorial than males, based on the females' higher percentage of exclusive home ranges, greater distance between centers of activity, and more uniform spacing.     

Life history of the cui-ui, Chasmistes cujus Cope, in Pyramid Lake, Nevada: a review

The cui - ui, Chasmistes cujus Cope, a member of the sucker family and endemic to Pyramid Lake, Nevada, is listed as endangered by the U.S. Fish and Wildlife Service. Cui - ui was once a major source of sustenance for native Americans, who have inhabited the Lahontan region for at least 11,000 years. The Northern Paiutes developed sophisticated fishing technology to harvest this resource. The original distribution of cui - ui was the ancient Lake Lahontan complex, but as a result of climatic changes it was restricted to the Pyramid &ndash; Winnemucca &ndash; Truckee system by the turn of the 20th century. Transbasin water diversions (1905 to present) have resulted in further restrictions of habitat. The species is now limited to Pyramid Lake and the lower Truckee River. Reproduction is from hatcheries as well as limited natural reproduction. Females produce more than 40,000 2 - mm eggs per year. The normal development is described from the unfertilized egg through 912 hours post - hatching, when the fry are actively feeding and approaching adult body form. The unusual feature of adult cui - ui morphology is the relatively large ventro - terminal mouth, with thin and obscurely papillose lips. Cui - ui grow slowly and may live 18 years or possibly much longer; females generally live longer and attain a greater size than males. The highest adult mortality probably occurs during spawning runs. At this time they are vulnerable to predation, stress, and sometimes environmental degradation. The highest larval mortality probably occurs from predation when they are planted or migrate into the lake. The trophic ecology of the species is poorly understood, but they are known to ingest algae and zooplankton. Spawning behavior is documented. At present, natural reproduction is probably still the limiting factor for the cui - ui population. Cui - ui composed less than one percent of the total fish in Pyramid Lake during 1975&ndash;1977. During 1982 the largest cui - ui spawning run (13,000) in recent years occurred. The activity of cui - ui in the lake closely resembles that of the Tahoe sucker being most active during the spawning season each spring. Cui - ui inhabit the inshore - benthic zone and the pelagic waters of Pyramid Lake ( &nbsp;&nbsp;&nbsp;     

Growth and reproduction of the flannelmouth sucker, Catostomus latipinnis, in the Upper Colorado River Basin, 1975-76

Growth rates estimated using the scale annuli of flannelmouth sucker, Catostomus latipinnis , did not differ between fish collected from the Gunnison and Colorado rivers, and the Green and Yampa rivers. However, body condition and fecundity were significantly greater in the former population. Age of first maturity for male and female fish from all rivers was IV; and most fish were mature by age VII. The smallest mature female collected was 405 mm, and the smallest mature male was 391 mm total length. Fecundity ranged from 4,000 ova in fish 450 mm long to 40,000 ova in a 500-mm fish: mean ovum diameter was 2.39 mm. Ripe male flannelmouth suckers were collected from early April through June; ripe females were collected from both study areas during May and early June. &nbsp;&nbsp;&nbsp;     

Status and distribution of the Fish Creek Springs tui chub, Gila bicolor euchila

The Fish Creek Springs tui chub, Gila bicolor euchila , is present in large numbers throughout its native habitat in spite of extensive man-caused habitat disturbance. This subspecies occurs further downstream in Fish Creek than previously reported. &nbsp;     

Monitoring Idaho fescue grasslands in the Big Horn Mountains, Wyoming, with a modified Robel pole

The reliability of monitoring visual obstruction and estimating standing herbage with a modified Robel pole was examined for high-elevation meadows in sedimentary soils on the Bighorn National Forest, Wyoming. Our objectives were to (1) test a modified pole graduated with 1.27-cm (0.5-inch) bands for estimating standing herbage based on linear regression of visual obstruction readings (VORs) on standing herbage, (2) validate the derived regression, (3) provide sample size estimates, and (4) develop guidelines for monitoring mountain grasslands. Each transect had 20 visual obstruction stations spaced 10 meters apart with 4 visual obstruction readings at each station. At 4 stations, vegetation within a 0.25-m 2 area was clipped at ground level. VORs and clipped standing herbage were averaged by transect for analysis. Visual obstruction reliably predicted average standing herbage (dry weights) for mountain meadows ( r 2 = 0.81, s x&macr; = 382 kg &sdot; ha &ndash;1 ). Standing herbage ranged from 387 kg &sdot; ha &ndash;1 to 3930 kg &sdot; ha &ndash;1 , with a mean of 1742 kg &sdot; ha &ndash;1 . A validation data set of 13 transects sampled across the range of variation in standing crop showed that 85% of transects fell within the 90% prediction limits. We recommend a minimum of 4 transects for monitoring key areas or small areas up to 259 ha (640 acres) when managers need to consider differences in VOR bands and address multiple objectives. Cluster analyses (ISODATA) applied to the pole readings resulted in 4 visual obstruction categories: short, short-intermediate, tall-intermediate, and tall. This tool provides a simple, reliable, and cost-effective (time-saving) alternative to clipping vegetation and obtaining dry weights for monitoring. Mention of a proprietary product does not constitute a guarantee or warranty of the product by USDA or the authors and does not imply its approval to the exclusion of other products that also may be suitable.     

High rates of photosynthesis in the desert shrub Chrysothamnus nauseosus ssp. albicaulis

&nbsp; Basic aspects of photosynthesis were investigated in white rubber rabbitbrush ( Chrysothamnus nauseosus (Pallas) Britt. ssp. albicaulis ), a common C 3 deciduous shrub native to arid regions of the western U.S. Under favorable field conditions, net photosynthesis (P n ) ranged from 36 to 73 mgCO 2 &middot; dm &ndash; 2 &middot; hr &ndash; 1 , which is relatively high for a woody species. The leaves from the actively growing flowering shoots exhibited higher P n than those on the vegetative shoots. P n also varied according to the age of the leaves and the location of the plants. P n did not light saturate even at quantum flux densities (QFD) equivalent to full sunlight. The light compensation point was relatively high (ca 100 &mu; mol &middot; m &ndash; 2 &middot; S &ndash; 1 ), perhaps due to the presence of a tomentose vestiture on the leaf surface. At high QFD's, the stomatal conductance was high (ca 520 mmol &middot; m &ndash; 2 &middot; s &ndash; 1 ) for a woody species. RUBP - carboxylase content of the leaves ranged from 20 to 22 mg per gram F.W., which is similar to that found in most C 3 crop species. These results suggest that rabbitbrush is able to maintain high rates of P n , at least under nonstressed conditions. &nbsp;&nbsp;&nbsp; &nbsp;     

Mycorrhization of ponderosa pine in a second-growth Sierra Nevada forest

Ectomycorrhizal colonization and rooting characteristics were quantified in a mature ponderosa pine ( Pinus ponderosa Dougl. ex Laws.) stand in the western Sierra Nevada. Root length totaled 3835.9 m &middot; m &ndash;2 of forest floor surface area, with 96% consisting of the fine-root fraction. Total root dry weight and volume were 2230.4 g &middot; m &ndash;2 and 5807.4 cm 3 &middot; m &ndash;2 of forest floor area, respectively, with 69% of the former and 75% of the latter accounted for by the coarse fraction. Fine roots were most prevalent in the upper 15 cm of the mineral soil profile, and their abundance declined with increasing depth. Coarse roots were most abundant at a depth of 15&ndash;30 cm. Ectomycorrhizal counts totaled 26,814 &middot; m &ndash;2 of forest floor area, and an overwhelming preponderance was associated with the fine-root fraction. More than three-quarters of mychorrhizae resided in the upper 15 cm of mineral soil, with an overall trend of declining numbers with increasing depth. Roots and mycorrhizae were exceedingly scarce at a depth of 45&ndash;60 cm, and neither was found in the organic soil layer above the mineral profile. A necessary step in understanding the ecophysiological role of mycorrhizae in mature forests is to quantify their abundance in such settings, and the results of this study contribute such information for ponderosa pine.     

Reproductive cycle of the lizard Sceloporus mucronatus with comments on intraspecific geographic variation

Sceloporus mucronatus is a viviparous lizard that inhabits high altitudes in central M&eacute;xico. Lizards from Tecocomulco, Hidalgo, M&eacute;xico, were collected monthly at 2500 m throughout one year. Macro- and microscopic evidence of gonads showed that both sexes reproduce synchronously during the fall. In males, after a short testicular quiescence in December, the recrudescence begins in winter (January) and continues through spring and summer (July), with maximum activity occurring from late summer to early fall (August&ndash;September). Regression takes place simultaneously with copulation during the fall (October&ndash;November). In females, vitellogenesis occurs during summer and fall (August&ndash;November), with ovulation in the fall (November&ndash;December). Gravid females were found throughout the winter, and parturition occurs during spring (May). Litter size was correlated with female snout&ndash;vent length. Female reproductive phenology of viviparous Sceloporus species seems to be highly conservative at different altitudes, but male reproductive phenology shifts between spring&ndash;summer (in populations higher than 2500 m) and summer&ndash;fall (in populations 2500 m or lower), as in the present study. The longer period of testicular recrudescence (January&ndash;July) in the studied population from Tecocomulco suggests plasticity in testicular activity.     

Life history, abundance, and distribution of Moapa dace ( Moapa coriacea )

Moapa dace ( Moapa coriacea ) is a federally listed endangered fish endemic to the spring-fed headwaters of the Muddy River, Clark County, Nevada. Species life history, abundance, and distribution were studied from March 1984 to January 1989. Reproduction, which was observed year-round, peaked in spring and was lowest in fall. It occurred in headwater tributaries of the Muddy River within 150 m of warm water spring discharge in water temperatures ranging from 30 to 32 C. Females matured between 41 and 45 mm in fork length (FL). Egg abundance increased with female size ( r 2 = .93); counts ranged from 60 for a 45-mm-FL female to 772 for one 90-mm FL. The oldest of eight fish, aged by the opercle method, was a 90-mm-FL, 4+-year-old female. Adults are omnivorous but tended toward carnivory; 75% of matter by volume consumed was invertebrates and 25% plants and detritus. Fish size was generally commensurate with flow, the largest fish occurring in the greatest flow. Adults were near bottom, in focal velocities ranging from 0 to 55 cm/s. Juveniles occupied a narrower range of depths and velocities than adults, and larvae occupied slack water. From December 1984 to September 1987, the total adult population ranged from 2600 to 2800. Although these numbers are higher than previously believed for Moapa dace, they are still sufficiently low to warrant its endangered status. The dependency of Moapa dace's different life history stages to various areas and habitat types of the Warm Springs area suggests that all remaining habitat is necessary for their survival.