Estimating low-density snowshoe hare populations using fecal pellet counts

2002 ◽  
Vol 80 (4) ◽  
pp. 771-781 ◽  
Author(s):  
Dennis L Murray ◽  
James D Roth ◽  
Ethan Ellsworth ◽  
Aaron J Wirsing ◽  
Todd D Steury
Keyword(s):  
Fecal Pellet ◽  
Nonlinear Models ◽  
Robust Estimator ◽  
Snowshoe Hare ◽  
Low Density ◽  
Intensive Study ◽  
Pellet Counts ◽  
Pellet Density ◽  
Study Sites ◽  
Northern Idaho

Snowshoe hare (Lepus americanus) populations found at high densities can be estimated using fecal pellet densities on rectangular plots, but this method has yet to be evaluated for low-density populations. We further tested the use of fecal pellet plots for estimating hare populations by correlating pellet densities with estimated hare numbers on 12 intensive study areas in Idaho; pellet counts from extensive transects (n = 615) across northern Idaho enabled rectangular plots (0.155 m2) to be compared with paired small (0.155 m2) and large (1 m2) circular plots (metre-circle plots). Metre-circle plots had higher pellet prevalence, lower sample variance, and lower estimates of pellet density than the other plot types. Transects comprising circular plots required less establishment time, and observer training reduced the pellet-count bias attributable to plot shape. The number of hares occupying intensive study sites was correlated with pellet density on all plot types, but rectangular plots provided a slightly closer linear fit to hare numbers than did metre-circle plots. The relationship between pellet density and hare number may have been curvilinear rather than linear, but linear and nonlinear models provided similar numerical estimates over much of the range of pellet densities. These results indicate that pellet counts are a robust estimator of hare numbers in low-density populations, and that metre-circle plots represent an improvement over standard rectangular plots in terms of unbiased pellet counts, sacrificing little predictive power. We recommend using pellet counts in metre-circle plots for estimating populations of snowshoe hares in their southern distribution.

scholarly journals Estimation of snowshoe hare population density from turd transects

1987 ◽  
Vol 65 (3) ◽  
pp. 565-567 ◽  
Author(s):  
Charles J. Krebs ◽  
B. Scott Gilbert ◽  
S. Boutin ◽  
R. Boonstra
Keyword(s):  
Population Density ◽  
Fecal Pellet ◽  
Accurate Method ◽  
Yukon Territory ◽  
Lepus Americanus ◽  
Snowshoe Hare ◽  
Model Average ◽  
Pellet Counts ◽  
Hare Population ◽  
Kluane Lake

We counted the number of snowshoe hare (Lepus americanus) fecal pellets on 50 quadrats of 0.155 m2 on each of six areas near Kluane Lake, Yukon Territory, once a year from 1977 to 1983. On four of these areas we livetrapped hares once a month and estimated population density from the Jolly–Seber model. Average hare density for the year was linearly related to fecal pellet counts (r = 0.94) over the range 0–10 hares/ha. Mean turd counts also are related to the variance of these counts by Taylor's power law with exponent 1.30, indicating a clumped pattern in turd deposition. Fecal pellet counts provide a quick and accurate method for snowshoe hare censuses on an extensive scale.

Effects of precommercial thinning on snowshoe hare habitat use during winter in low-elevation montane forests

2005 ◽  
Vol 35 (1) ◽  
pp. 206-210 ◽  
Author(s):  
David E Ausband ◽  
G Ross Baty
Keyword(s):  
Habitat Use ◽  
Fecal Pellet ◽  
Lepus Americanus ◽  
Snowshoe Hare ◽  
Precommercial Thinning ◽  
Treatment Type ◽  
Northwestern Montana ◽  
Before And After ◽  
Pellet Counts ◽  
Mature Stands

We assessed snowshoe hare (Lepus americanus L.) habitat use during winter on two precommercial thinning treatments in sapling stands in northwestern Montana, USA. One treatment type retained 0.2-ha patches of unthinned saplings, representing 8% of the total stand area, and the second retained 0.8-ha patches of unthinned saplings, representing 35% of the stand area. Snowshoe hare habitat use was also estimated within a nearby control sapling stand and mature conifer stands. We used snow tracking and fecal pellet counts to estimate use before and after thinning treatments were applied. Although we did not find a conclusive trend in hare use of sapling stands after thinning, use within the control stand and adjacent mature stands suggested there was considerable movement of hares to nearby untreated stands after thinning. Hares used retention patches regardless of size, even though large retention patches were four times larger than small retention patches. Because hares demonstrated an affinity for dense patches of residual forest, any retention of untreated saplings may be beneficial for hares during winter when applying precommercial thinning treatments in areas where stand sizes are relatively small (10–14 ha), and the resulting thinned matrix is less harsh than in larger thinned stands. Use within thinned portions of the stand and unthinned remnant blocks suggests that over the winter hares may also benefit from a connectivity of dense cover.

scholarly journals Coccolith dissolution within copepod guts affects fecal pellet density and sinking rate

2018 ◽  
Vol 8 (1) ◽  
Author(s):  
Meredith M. White ◽  
Jesica D. Waller ◽  
Laura C. Lubelczyk ◽  
David T. Drapeau ◽  
Bruce C. Bowler ◽  
...  
Keyword(s):  
Fecal Pellet ◽  
Sinking Rate ◽  
Pellet Density

scholarly journals Growth of Crassostrea gasar cultured in marine and estuary environments in Brazilian waters

2013 ◽  
Vol 48 (8) ◽  
pp. 975-982 ◽  
Author(s):  
Gustavo Ruschel Lopes ◽  
Carlos Henrique Araujo de Miranda Gomes ◽  
Cláudio Rudolfo Tureck ◽  
Claudio Manuel Rodrigues de Melo
Keyword(s):  
Weight Gain ◽  
Nonlinear Models ◽  
Size Class ◽  
Von Bertalanffy ◽  
Southern Brazil ◽  
Growth Data ◽  
Shell Size ◽  
Shell Weight ◽  
Data Set ◽  
Study Sites

The objective of this work was to evaluate the growth of the mangrove oyster Crassostrea gasar cultured in marine and estuarine environments. Oysters were cultured for 11 months in a longline system in two study sites - São Francisco do Sul and Florianópolis -, in the state of Santa Catarina, Southern Brazil. Water chlorophyll-α concentration, temperature, and salinity were measured weekly. The oysters were measured monthly (shell size and weight gain) to assess growth. At the end of the culture period, the average wet flesh weight, dry flesh weight, and shell weight were determined, as well as the distribution of oysters per size class. Six nonlinear models (logistic, exponential, Gompertz, Brody, Richards, and Von Bertalanffy) were adjusted to the oyster growth data set. Final mean shell sizes were higher in São Francisco do Sul than in Florianópolis. In addition, oysters cultured in São Francisco do Sul were more uniformly distributed in the four size classes than those cultured in Florianópolis. The highest average values of wet flesh weight and shell weight were observed in São Francisco do Sul, whereas dry flesh weight did not differ between the sites. The estuary environment is more promising for the cultivation of oysters.

Ultrasonic-Vibration-Assisted Pelleting of Cellulosic Biomass: Effects of Moisture Content

2010 ◽  
Author(s):  
Xiaoxu Song ◽  
Meng Zhang ◽  
Z. J. Pei ◽  
Timothy Deines
Keyword(s):  
Experimental Study ◽  
Moisture Content ◽  
Ultrasonic Vibration ◽  
Transportation Cost ◽  
Cost Effective ◽  
Cellulosic Biomass ◽  
Low Density ◽  
High Transportation Cost ◽  
Biomass Materials ◽  
Pellet Density

Cellulosic biomass is an important source for making biofuels. However, there are several barriers to cost-effective manufacturing of biofuels using cellulosic biomass. One such barrier is related to the high transportation cost due to the low density of cellulosic biomass. Pelleting of cellulosic biomass is one way to increase its density. This paper reports an experimental study on ultrasonic vibration-assisted pelleting of cellulosic biomass. The study was focused on the effects of moisture content (MC) on pellet density of three kinds of cellulosic biomass (wheat straw, switchgrass, and sorghum). The experimental results show that sorghum has the highest density with three levels of MC among these biomass materials. The highest density was found with sorghum of 20% MC.

Comparison of capture–recapture estimators of snowshoe hare populations

1994 ◽  
Vol 72 (10) ◽  
pp. 1800-1807 ◽  
Author(s):  
John Boulanger ◽  
Charles J. Krebs
Keyword(s):  
Population Size ◽  
Yukon Territory ◽  
Robust Estimator ◽  
Snowshoe Hare ◽  
Lake Area ◽  
Island Populations ◽  
Snowshoe Hares ◽  
Population Size Estimates ◽  
Size Population ◽  
Capture Recapture

We used two island populations of snowshoe hares (Lepus americanus) in the Kluane Lake area of the Yukon Territory of Canada to evaluate capture – recapture estimators. These islands were intensively sampled, allowing us to enumerate the actual population size. Population size estimates were calculated using the programs CAPTURE and JOLLY, and estimators were compared for bias characteristics. Results from both islands suggest that the CAPTURE heterogeneity models Mh (jackknife), Mh (Chao), and Mth (time – heterogeneity) and the Jolly – Seber model were approximately unbiased. All other CAPTURE models displayed a negative bias. The CAPTURE model selection routine picked estimation models of different biases for each trapping period, an undesirable result. We conclude that it is best to use one robust estimator such as the Mh (jackknife) with snowshoe hare data.

A Technique for Estimating the Numbers of Eastern Gray Kangaroos, Macropus-Giganteus, Grazing a Given Area of Pasture

1986 ◽  
Vol 13 (3) ◽  
pp. 335 ◽  
Author(s):  
RJ Perry ◽  
ML Braysher
Keyword(s):  
Decay Rate ◽  
Relative Density ◽  
Nature Reserve ◽  
Faecal Pellet ◽  
Absolute Number ◽  
Pellet Group ◽  
Potential Error ◽  
Grey Kangaroo ◽  
Pellet Counts ◽  
Pellet Density

This paper outlines a technique for estimating, by means of faecal pellet counts, the absolute number of eastern grey kangaroos, Macropus giganteus, grazing on a given area in the A.C.T. Absolute numbers were obtained by comparing relative density of pellets on the area to be assessed, with pellet density in the grey kangaroo enclosure at Tidbinbilla Nature Reserve, which has a known area and a known kangaroo population. The decay rate of pellets in three different areas did not vary significantly. The average number of pellets per pellet group was similar in all three areas, but during drought kangaroos tended to drop fewer pellets per group. However, the potential error caused by this can be avoided if the control and test areas are assessed at the same time. The problem of defining a group is eliminated by counting individual pellets rather than groups.

scholarly journals Demography and spatial activity of fire salamanders, Salamandra salamandra (Linnaeus, 1758), in two contrasting habitats in the Vienna Woods

Herpetozoa ◽  
2021 ◽  
Vol 34 ◽  
pp. 23-34
Author(s):  
Stephan Burgstaller ◽  
Christoph Leeb ◽  
Max Ringler ◽  
Günter Gollmann
Keyword(s):  
Population Dynamics ◽  
Beech Forest ◽  
Amphibian Conservation ◽  
Low Density ◽  
Apparent Survival ◽  
Capture Recapture ◽  
Salamandra Salamandra ◽  
Contrasting Habitats ◽  
Study Sites ◽  
Two Populations

Understanding population dynamics is vital in amphibian conservation. To compare demography and movements, we conducted a capture-recapture study over three spring seasons in two populations of Salamandra salamandra in the Vienna Woods. The study sites differ in topography, vegetation, and the type of breeding waters. Population density in a beech forest traversed by a stream was more than twice as high as in an oak-hornbeam forest with temporary pools. Movement distances were on average higher at the latter site whereas home range estimates were similar for both sites. The sexes did not differ significantly in the observed movement patterns at either site. Annual apparent survival was mostly high (~0.85), but the estimate for females from the low-density site was lower (~0.60), indicating a higher rate of emigration or mortality.

An Experimental Comparison of Two Pelleting Methods for Cellulosic Ethanol Manufacturing

2011 ◽  
Author(s):  
Qi Zhang ◽  
Pengfei Zhang ◽  
Z. J. Pei ◽  
Jonathan Wilson ◽  
Leland McKinney ◽  
...  
Keyword(s):  
Cellulosic Ethanol ◽  
Cellulosic Biomass ◽  
Experimental Comparison ◽  
Low Density ◽  
Manufacturing Costs ◽  
Transportation Fuels ◽  
Pellet Density ◽  
Energy Consumptions ◽  
Preliminary Research ◽  
And Storage

Ethanol produced from cellulosic biomass is an alternative to petroleum-based transportation fuels. However, manufacturing costs of cellulosic ethanol are too high to be competitive. Low density of cellulosic feedstocks increases their handling and transportation costs, contributing to high overall costs of cellulosic ethanol manufacturing. Pelleting can increase density of cellulosic feedstocks, reduce transportation and storage costs, and make cellulosic ethanol production more competitive. UV-A (ultrasonic vibration-assisted) pelleting is a new pelleting method (available only in lab scale now). Preliminary research showed that UV-A pelleting could significantly increase pellet density and pellet durability but it has never been compared with other pelleting methods (e.g., using an extruder, a briquetting press or a ring-die pelleting). The objectives of this research are to compare UV-A pelleting with ring-die pelleting in terms of pellet density, pellet durability, energy consumptions of pelleting. The results will be useful to find a better pelleting method for cellulosic ethanol manufacturing.

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