Population dynamics of Newfoundland beaver

1977 ◽  
Vol 55 (9) ◽  
pp. 1480-1492 ◽  
Author(s):  
Arthur T. Bergerud ◽  
Donald R. Miller
Keyword(s):  
Population Dynamics ◽  
Mortality Rate ◽  
Litter Size ◽  
Food Resources ◽  
Territorial Behaviour ◽  
Population Densities ◽  
Adult Females ◽  
Annual Mortality

The demography of beaver was studied in Newfoundland from 1956 to 1965. Population densities were low and seldom exceeded one colony per 2.6 km2 (1 mi2). About 80% of the adult females were fertile and the number of young per litter averaged 2.7. The annual mortality rate of beavers was about 30% in southeastern Newfoundland. A more detailed study was made of a population living in a 39-km2 (15-mi2) study area. This population had 20, 23, and 24 active colonies, 1958–1960. In 1961 it declined to 18 colonies. We removed the beavers in 1962. The replacement colonies, resulting initially from ingress, were 7 in 1962, 12 in 1963, 17 in 1964, and 15 in 1965. When the population was high in 1958–1960, the fertility of females was high (78%) but the litter size in 1960 appeared to be less than elsewhere. When the population declined in 1960–1961, productivity declined and some animals may have starved over winter. It was concluded that territorial behaviour spaces colonies, dispersing the population within the limits dictated by the availability of water and food resources. However, such a system did not prevent overutilization of food resources and decline of the population from reduced reproduction and increased mortality.

Paddlefish Management, Propagation, and Conservation in the 21st Century

2009 ◽  
Keyword(s):  
Growth Rate ◽  
Population Dynamics ◽  
Mortality Rate ◽  
Population Density ◽  
21St Century ◽  
High Growth ◽  
High Growth Rate ◽  
Demographic Groups ◽  
Annual Mortality ◽  
Remnant Population

<em>Abstract</em>.—Paddlefish <em>Polyodon spathula </em>vanished from areas of the upper Tombigbee River basin in Mississippi and Alabama during the 1950s, long before channelization and damming associated with construction of the Tennessee-Tombigbee Waterway (TTW) were completed in 1984. This study was undertaken to assess distribution and population dynamics of any remaining stock. Paddlefish were not captured in upstream impoundments, but an unexploited remnant population was located in the downstream impoundment: Demopolis Lake, Alabama. Paddlefish in Demopolis Lake were characterized by a population density of 2.6 fish/ha, high growth rate relative to more northern populations, and natural annual mortality rate (<em>A </em>= 0.406) similar to other southern populations. Two wintering habitats (cutoff bendways) were heavily utilized by paddlefish. Large males primarily inhabited the more lotic bendway while females and small males were more common in the more lentic bendway, indicating differential importance of habitats among demographic groups. The restricted distribution of TTW paddlefish and demographic differences between habitats suggest that areas heavily utilized by paddlefish should be protected from further degradation. Sedimentation has resulted in reductions of bendway depth and reduced connectivity of backwaters, reducing availability of suitable paddlefish habitat. Restoring connectivity of bendways through dredging could reverse this trend and provide other benefits to fisheries.

Porcupine (Erethizon dorsatum) demography in central Massachusetts

1996 ◽  
Vol 74 (3) ◽  
pp. 480-484 ◽  
Author(s):  
Mary B. Hale ◽  
Todd K. Fuller
Keyword(s):  
Population Dynamics ◽  
Rate Of Change ◽  
Demographic Parameters ◽  
Adult Males ◽  
Erethizon Dorsatum ◽  
Annual Survival ◽  
Adult Females ◽  
Survival And Reproduction ◽  
Pregnancy Status ◽  
Annual Mortality

From 1991 to 1993 we radio-collared and monitored 50 porcupines (Erethizon dorsatum) in central Massachusetts to obtain estimates of survival and reproduction, and applied these estimates to a model of porcupine population dynamics to estimate the annual rate of change (λ). The annual survival rate for all adult (> 1 year old) porcupines was 0.67 ± 0.07 (mean ± SE). Survival was higher, but not significantly so (P = 0.22), for adult females (0.74 ± 0.08) than for adult males (0.56 ± 0.12). Adult porcupines died of starvation (annual mortality rate 0.08), injuries (0.05), interactions with humans (0.04), and disease (0.05) but not predation. Annual survival of juveniles (< 1 year old) ranged from at least 0.37 in 1992 to at most 0.39 in 1993. Minimum birth rates of radio-collared females > 2 years old, determined by sightings of young near females, lactation, and pregnancy status as determined by ultrasound, were 0.64 in 1992 and 0.62 in 1993. Incorporation of maximum and minimum values of demographic parameters from this study and from the literature into population models indicated a decreasing porcupine population.

Effects of crop sequence and rainfall on population dynamics of Fusarium solani f.sp. phaseoli in soil

1992 ◽  
Vol 70 (10) ◽  
pp. 2005-2008 ◽  
Author(s):  
Robert Hall ◽  
Lana Gay Phillips
Keyword(s):  
Population Dynamics ◽  
Phaseolus Vulgaris ◽  
Population Density ◽  
Fusarium Solani ◽  
Population Densities ◽  
Total Rainfall ◽  
Colony Forming Units ◽  
Bean Crop ◽  
Previous Summer ◽  
Crop Sequence

Evidence is presented that population dynamics of Fusarium solani f.sp. phaseoli in soil depend on the effects of crop sequence and rainfall on parasitic activities of the pathogen. In a rotation trial started in 1978 and conducted over 14 years, population densities (colony-forming units/g) of the fungus in soil remained below 50 in treatments (fallow, repeated corn, repeated soybean) where the preferred host plant (common bean, Phaseolus vulgaris) was not grown. Where bean was grown every 3rd year or every year, population densities reached 475 and 660, respectively, by 1984. Thereafter, population densities of the fungus fluctuated widely from year to year in both rotation and repeated bean treatments. In the rotation treatment, peaks in population density of the pathogen coincided with the years of bean production. In repeated bean plots between 1985 and 1991, population density of the fungus in June was significantly correlated (r = 0.77, p = 0.04) with total rainfall received during the previous summer (June–August). It is postulated that higher rainfall during the growing season of the bean crop stimulated root growth and root infection, leading to the accumulation of higher levels of potential inoculum in infected tissue and the release of higher levels of inoculum into the soil by the following June. Key words: Fusarium solani f.sp. phaseoli, bean, Phaseolus vulgaris, rainfall, crop rotation.

Abstract P261: Intensive Systolic Blood Pressure Lowering Will Prevent Over 100,000 Deaths Annually

Hypertension ◽  
2016 ◽  
Vol 68 (suppl_1) ◽  
Author(s):  
Holly Kramer ◽  
Adam Bress ◽  
Srinivasan Beddhu ◽  
Paul Muntner ◽  
Richard S Cooper
Keyword(s):  
Blood Pressure ◽  
Mortality Rate ◽  
Systolic Blood Pressure ◽  
Mortality Rates ◽  
Mortality Data ◽  
Blood Pressure Lowering ◽  
Cvd Risk ◽  
Pressure Lowering ◽  
Annual Mortality ◽  
The U.S

Background: The Systolic Blood Pressure Intervention Trial (SPRINT) trial randomized 9,361 adults aged ≥50 years at high cardiovascular disease (CVD) risk without diabetes or stroke to intensive systolic blood pressure (SBP) lowering (≤120 mmHg) or standard SBP lowering (≤140 mmHg). After a median follow up of 3.26 years, all-cause mortality was 27% (95% CI 40%, 10%) lower with intensive SBP lowering. We estimated the potential number of prevented deaths with intensive SBP lowering in the U.S. population meeting SPRINT criteria. Methods: SPRINT eligibility criteria were applied to the National Health and Nutrition Examination Survey 1999-2006, a representative survey of the U.S. population, linked with the mortality data through December 2011. Eligibility included (1) age ≥50 years with (2) SBP 130-180 mmHg depending on number of antihypertensive classes being taken, and (3) presence of ≥1 CVD risk conditions (history of coronary heart disease, estimated glomerular filtration rate (eGFR) 20 to 59 ml/min/1.73 m 2 , 10-year Framingham risk score ≥15%, or age ≥75 years). Adults with diabetes, stroke history, >1 g/day proteinuria, heart failure, on dialysis, or eGFR<20 ml/min/1.73m 2 were excluded. Annual mortality rates for adults meeting SPRINT criteria were calculated using Kaplan-Meier methods and the expected reduction in mortality rates with intensive SBP lowering in SPRINT was used to determine the number of potential deaths prevented. Analyses accounted for the complex survey design. Results: An estimated 18.1 million U.S. adults met SPRINT criteria with 7.4 million taking blood pressure lowering medications. The mean age was 68.6 years and 83.2% and 7.4% were non-Hispanic white and non-Hispanic black, respectively. The annual mortality rate was 2.2% (95% CI 1.9%, 2.5%) and intensive SBP lowering was projected to prevent 107,453 deaths per year (95% CI 45,374 to 139,490). Among adults with SBP ≥145 mmHg, the annual mortality rate was 2.5% (95% CI 2.1%, 3.0%) and intensive SBP lowering was projected to prevent 60,908 deaths per year (95% CI 26, 455 to 76, 792). Conclusions: We project intensive SBP lowering could prevent over 100,000 deaths per year of intensive treatment.

scholarly journals Analysis of mortality from diarrheic diseases in under-five children in Brazilian cities with more than 150,000 inhabitants

2009 ◽  
Vol 25 (5) ◽  
pp. 1093-1102 ◽  
Author(s):  
Juraci Vieira Sergio ◽  
Antônio Carlos Ponce de Leon
Keyword(s):  
Mortality Rate ◽  
Time Trends ◽  
Sharp Decrease ◽  
Mortality Rates ◽  
The North ◽  
Indicator Variables ◽  
Before And After ◽  
Geographic Regions ◽  
Annual Mortality ◽  
Children Under 5

This study analyzes mortality from infectious diarrheic diseases in children under 5 years of age in Brazilian municipalities with more than 150,000 inhabitants, excluding State capitals. The annual mortality rates by municipality from 1990 to 2000 were analyzed using a multilevel model, with years as first level units nested in municipalities as second level units. The dependent variable was the yearly mortality rate by municipality, on the log scale. Polynomial time trends and indicator variables to account for differences in geographic regions were used in the modeling. Time trends were centered on 1995, so they could be modeled differently before and after 1995. From 1990 to 1995 there was a sharp decrease in mortality rates by diarrheic diseases in most Brazilian municipalities, while from 1995 to 2000 the decrease was more heterogeneous. In 1995 the North and Northeast of Brazil had higher mortality rates than the Southeast, and the differences were statistically significant. Most importantly, the study concludes that there was an important difference in the pattern of mortality rate decreases over time, comparing the country's five geographic regions.

THE ACCUMULATIVE EFFECT OF FINNSHEEP BREEDING IN CROSSBREEDING SCHEMES: REPRODUCTIVE PERFORMANCE

1988 ◽  
Vol 68 (1) ◽  
pp. 69-81 ◽  
Author(s):  
MOHAMED H. FAHMY ◽  
JACQUES J. DUFOUR
Keyword(s):  
Body Weight ◽  
Mortality Rate ◽  
Key Words ◽  
Litter Size ◽  
Reproductive Performance ◽  
Conception Rate ◽  
Ovulation Rate ◽  
Genetic Groups ◽  
Linear Regressions ◽  
Size At Birth

Reproductive performance and body weight were studied on 361 ewes, representing Finnsheep (F), DLS (a population of 1/2 Dorset, 1/4 Leicester, 1/4 Suffolk) and seven combinations ranging from 1/8 to 7/8 Finnsheep breeding. Conception rate in yearlings was 61.5% for DLS compared to 89.0% for F with the crosses being intermediate. Conception rate in older ewes was similar in the different genetic groups (avg. 94%). Ovulation rate and litter size at birth of DLS ewes were 1.72 and 1.44 lambs, which was less than half those of F ewes (3.51 and 2.86 lambs, respectively). Both traits increased progressively with an increase in F breeding in crosses and with advances in age. DLS ewes weaned 1.22 lambs compared to 2.03 lambs for F ewes and 1.84 lambs for 4/8 F ewes. The heaviest litters at weaning (31.7 kg) were raised by 4/8 F ewes, followed by 7/8 F (30.8 kg) while those raised by DLS ewes weighed 23.0 kg and F ewes 29.1 kg. Percentage of ova lost per ewe mated averaged 24% and ranged between 18% (DLS and 1/8 F) and 29% (6/8 F). About 3.6% of lambs were born dead and a further 13.8% died before weaning. Preweaning mortality rate was highest in F (22.9%) and lowest in 3/8 F (9.4%). Average kilograms of lambs weaned per ewe exposed was highest in 4/8 F (27.6 kg) followed by F (26.0 kg), whereas that of DLS was the lowest at 18.1 kg. The 4/8 F cross showed 25% heterosis in kg of lambs weaned per ewe exposed and 52.5% increase over DLS. Significant positive linear regressions were calculated for ovulation rate, litter size and preweaning mortality rate on proportion of Finnsheep breeding in crosses. The relation was quadratic for percent ova lost and lamb mortality at weaning. Yearling DLS females weighted 36 kg compared to 44 kg for F yearlings. However, at 5 yr of age DLS ewes weighed 62 kg, 5 kg heavier than F ewes. The heaviest ewes at all ages were the 4/8 F (45 kg at 1 yr, 65 kg at 5 yr). Key words: Reproduction, DLS sheep, Finnsheep, crossbreeding, heterosis, repeatabilities

scholarly journals Interannual variation in the epibenthic megafauna at the shallowest station of the HAUSGARTEN observatory (79° N, 6° E)

2012 ◽  
Vol 9 (12) ◽  
pp. 18039-18081 ◽  
Author(s):  
K. S. Meyer ◽  
M. Bergmann ◽  
T. Soltwedel
Keyword(s):  
Population Dynamics ◽  
Deep Sea ◽  
Interannual Variation ◽  
Suspension Feeding ◽  
Fram Strait ◽  
Population Densities ◽  
Camera System ◽  
Sea Floor ◽  
Time Period ◽  
Food Input

Abstract. Epibenthic megafauna play an important role in the deep-sea environment and contribute significantly to benthic biomass, but their population dynamics are still understudied. We used a towed deep-sea camera system to assess the population densities of epibenthic megafauna in 2002, 2007 and 2012 at the shallowest station (HG I, ~ 1300 m) of the deep-sea observatory HAUSGARTEN, in the eastern Fram Strait. Our results indicate that the overall density of megafauna was significantly lower in 2007 than in 2002, but was significantly higher in 2012, resulting in overall greater megafaunal density in 2012. Different species showed different patterns in population density, but the relative proportions of predator/scavengers and suspension-feeding individuals were both higher in 2012. Variations in megafaunal densities and proportions are likely due to variation in food input to the sea floor, which decreased slightly in the years preceding 2007 and was greatly elevated in the years preceding 2012. Both average evenness and diversity increased over the time period studied, which indicates that HG I may be food-limited and subject to bottom-up control. The varying dynamics of different species may have been caused by differential capacities of populations to respond to increased food input through either recruitment or migration.

Population dynamics and production of a brine shrimp, Parartemia zietziana Sayce (Crustacea : Anostraca), in two salt lakes in westren Victoria, Australia

1977 ◽  
Vol 28 (4) ◽  
pp. 417 ◽  
Author(s):  
R Marchant ◽  
WD Williams
Keyword(s):  
Population Dynamics ◽  
Population Density ◽  
Temperature Stress ◽  
Brine Shrimp ◽  
Dry Weight ◽  
Salt Lakes ◽  
Confidence Limits ◽  
Length Frequency ◽  
Population Densities ◽  
The Mean

Quantitative samples of P. zietziana were taken monthly for two years from Pink Lake and Lake Cundare. Shrimps were usually contagiously distributed. To reduce error, samples were stratified resulting in confidence limits of 40-50% for the mean population density. Despite this variability, stable trends emerged, and variation was not so great as to mask significant differences. Length-frequency analyses distinguished cohorts; a regression was established between length and dry weight, enabling growth to be estimated from samples. By combining growth with population densities in Allen curves, production was computed. In Pink Lake and Lake Cundare mean pro- duction was 11.3 and 1.0 g dry weight m-2 year-1 respectively. Generally there were two or three generations per year, but time and extent of recruitment were not predictable. Each generation suffered continuous mortality, the death of young shrimps accounting for most of the production. This mortality remains unexplained; there are no significant predators and salinity and temperature stress would occur only during summer.

scholarly journals Methods for Quantification of the Decline Phenomenon and Determination of the Vulnerability Degree for the Oak Stands in Northwestern Transylvania, Romania

2017 ◽  
Vol 45 (2) ◽  
pp. 623-631
Author(s):  
Vasile ŞIMONCA ◽  
Ioan OROIAN ◽  
Dănuț CHIRA ◽  
Ioan TĂUT
Keyword(s):  
Mortality Rate ◽  
Incipient Stage ◽  
Management Measures ◽  
Slow Development ◽  
Synthetic Index ◽  
Quercus Species ◽  
Fast Development ◽  
Annual Mortality ◽  
Experimental Plots

The decline phenomenon of stands can be defined as the totality of effects that damage the normal vegetation state of trees and stands. There are two types of decline, the acute one, with fast development, and the chronical one, with slow development in space and time. The accurate capture of the phenomenon has direct implications for the forest management measures. A first step in this direction is the analysis of the development type and of its dynamics. Forests which have Quercus species in composition are affected more by this phenomenon. There were identified oak stands presenting decline phenomenon in 9 Forest Districts in Northwestern Transylvania and 22 experimental plots were analyzed. These plots were located in middle aged stands that were affected in different ways. The study was performed during 2013-2015 and focused on crown level assessments of trees, taking into consideration the shape and size, defoliations, percentage of dead or missing slender branches, number of dead thick branches, presence of epicormic branches or dormant buds on the stem, presence of pathogens or pests. These elements were used for calculating some technical indicators of the health and vegetation state: degree of dieback, damage and devitalization, synthetic index damage, annual mortality rate. In 7 out of 22 stands, the overcoming of the incipient stage and beginning of active dieback stage was observed. The strongest correlation occurred between the annual mortality rate and the synthetic index damage.

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