Dynamics of a grizzly bear population during a period of industrial resource extraction. III. Natality and rate of increase

1989 ◽  
Vol 67 (8) ◽  
pp. 1865-1868 ◽  
Author(s):  
Bruce N. McLellan
Keyword(s):  
Ursus Arctos ◽  
Detrimental Effect ◽  
Timber Harvest ◽  
Reproductive Rate ◽  
Easy Access ◽  
Resource Extraction ◽  
Grizzly Bear ◽  
Reproductive Parameters ◽  
Rate Of Increase ◽  
Industrial Resource

Reproductive parameters and rate of increase were estimated for a grizzly bear (Ursus arctos) population in southeastern British Columbia during a period of timber harvest and gas exploration, 1979–1987.I hypothesized that these activities would be detrimental to the population and predicted a negative rate of increase. There was an average of 2.26 cubs in 31 litters. The average of nine interbirth intervals was 2.67 years, and the average age at which five females produced their first litter was 6 years. The population's annual reproductive rate calculated by three methods averaged 0.86 cubs per adult female. By iteration of the Lotka equation, the best estimate of the exponential rate of increase was 0.081. Industrial activities did not appear to have a significant detrimental effect on the grizzly bear population in the Flathead Valley during the period of study but the roads built provided easy access for hunters and poachers.

Dynamics of a grizzly bear population during a period of industrial resource extraction. I. Density and age–sex composition

1989 ◽  
Vol 67 (8) ◽  
pp. 1856-1860 ◽  
Author(s):  
Bruce N. McLellan
Keyword(s):  
Outdoor Recreation ◽  
Ursus Arctos ◽  
Timber Harvest ◽  
Resource Extraction ◽  
Grizzly Bear ◽  
Adult Males ◽  
Sex Composition ◽  
Adult Females ◽  
Rate Of Increase ◽  
Industrial Resource

The characteristics of a grizzly bear (Ursus arctos) population in southeastern British Columbia were studied between 1979 and 1986, a period of timber harvest, gas exploration, and outdoor recreation, including grizzly hunting. I investigated the hypothesis that collectively these activities were detrimental to the grizzly population. I predicted a low density of bears compared with other interior populations and (or) a negative rate of increase. The sex ratio of cubs and yearlings captured was 50:50 and they represented 21.5 and 17.5% of the population, respectively. Although more adult males than adult females were captured, I estimated that there were more adult females than males in the population. I used two methods of population estimation and assumed saturation trapping : one method was based on home range characteristics and the other on the proportion of aerial locations in the study area. The average estimated bear density was 6.4/100 km2, which was high for an interior population, and increased from approximately 5.7/100 km2 in 1981 to 8.0/100 km2 in 1986, for an average annual observed rate of increase of r = 0.07.

Dynamics of a grizzly bear population during a period of industrial resource extraction. II. Mortality rates and causes of death

1989 ◽  
Vol 67 (8) ◽  
pp. 1861-1864 ◽  
Author(s):  
Bruce N. McLellan
Keyword(s):  
Outdoor Recreation ◽  
Ursus Arctos ◽  
Survival Rates ◽  
Timber Harvest ◽  
Easy Access ◽  
Resource Extraction ◽  
Grizzly Bears ◽  
Grizzly Bear ◽  
Human Intervention ◽  
Management Actions

The causes and rates of grizzly bear (Ursus arctos) mortality in a radio-marked population in southeastern British Columbia were studied for 9 years during a period of timber harvest, gas exploration, and outdoor recreation, including grizzly hunting. During 110 bear-years of radio tracking 55 radio-collared grizzly bears and their dependent offspring, one bear with a functioning radio collar died from natural causes and eight others from human intervention; in addition, four dependent offspring were thought to have died. Excluding trap-related mortalities, the best estimate for the annual survival rates were as follows: 0.82 for cubs, 0.88 for yearlings, 0.93 for subadults, and 0.93 for adults. Of the eight bears killed by human intervention, two were killed by legal harvest, five by illegal harvest (one of these in a trap), and one was killed in a trap by another bear. No mortalities were directly attributable to industrial activities. Resource extraction industries do contribute to grizzly bear mortality indirectly through the construction of roads, which provide easy access to hunters, poachers, and settlers. Road access planning and postoperational control of vehicles are recommended management actions.

scholarly journals Biotic Potential and Reproductive Parameters of Spodoptera frugiperda (J. E. Smith, 1797) (Lepidoptera: Noctuidae)

2019 ◽  
Vol 11 (13) ◽  
pp. 240 ◽  
Author(s):  
Débora G. Montezano ◽  
Alexandre Specht ◽  
Daniel R. Sosa-Gómez ◽  
Vânia F. Roque-Specht ◽  
Juaci V. Malaquias ◽  
...  
Keyword(s):  
Spodoptera Frugiperda ◽  
Reproductive Rate ◽  
Intrinsic Rate Of Increase ◽  
Reproductive Parameters ◽  
Crop Species ◽  
Net Reproductive Rate ◽  
Biotic Potential ◽  
Rate Of Increase ◽  
The Mean ◽  
Lepidoptera Noctuidae

The fall armyworm, Spodoptera frugiperda (J. E. Smith, 1797) (Lepidoptera: Noctuidae), a native to the Americas and recently reported in Africa, Germany, the Netherlands and India, is a significant pest of many crop species. Although a widespread and important pest, information on its biology and development are incomplete and require detailed study. In this study, the biotic potential and reproductive parameters of S. frugiperda were evaluated under controlled conditions (25±1 °C, 70±10% RH and 14 hour photophase). The longevity, pre-, post- and oviposition periods, fecundity, and fertility of 30 pairs were evaluated. The longevity of females (10.87 days) was not significantly different from that of males (10.90 days). The mean durations of the pre-, post- and oviposition periods were 2.63, 0.53 and 7.70 days, respectively. The mean fecundity was 2,370.66 eggs per female and mean fertility was 2,309.03 larvae per female. On average, a female copulated 1.6 times. The biotic potential of S. frugiperda was estimated at 2.086 × 1029 individuals/female/year. The net reproductive rate (Ro) was 1,079.73 times per generation and the mean generation time (T) was 32.00 days. The intrinsic rate of increase (rm) was 0.22, with a finite rate of increase (λ) of 1.24 per day. This study evaluates and describes the biological parameters of S. frugiperda with special emphasis on its biotic potential and reproductive parameters. This information will improve the development of integrated pest management (IPM) and insect resistance management (IRM) for this species.

scholarly journals Biotic potential and reproductive parameters of Spodoptera cosmioides (Walker) (Lepidoptera: Noctuidae) in the laboratory

2019 ◽  
Vol 79 (3) ◽  
pp. 488-494 ◽  
Author(s):  
A. Specht ◽  
V. F. Roque-Specht
Keyword(s):  
Intrinsic Rate ◽  
Reproductive Rate ◽  
Intrinsic Rate Of Increase ◽  
Reproductive Parameters ◽  
Finite Rate ◽  
Net Reproductive Rate ◽  
Biotic Potential ◽  
Rate Of Increase ◽  
The Mean ◽  
Lepidoptera Noctuidae

Abstract In this study we evaluate the biotic potential and reproductive parameters of Spodoptera cosmioides (Walker, 1858) under controlled conditions (25 ± 1 °C, 70 ± 10% RH and 14 hour photophase). Females, on average, (14.433 days) did not live significantly longer than their male counterparts (13.100 days). The mean durations of the pre-oviposition, oviposition and post-oviposition periods were 2.767, 10.600 and 1.067 days, respectively. The mean fecundity of females was 5,073.533 eggs and the mean fertility was 5,021.027 larvae. On average, females copulated 1.167 times. Fecundity was positively correlated with the number of copulations (r = 0.583, P <0.001). The number of copulations, however, was negatively correlated whit the duration of the pre-oviposition (r = -0.560, P = 0.007) and oviposition (r = -0.479, P = 0.048) periods, and overall longevity (r = -0.512, P = 0.031). The biotic potential was estimated at 6.547 x 1021 individuals/female/year. The net reproductive rate (Ro) was 2,193.722 times per generation and the mean generation time (T) was 46.407 days. The intrinsic rate of increase (rm) was 0.166, with a finite rate of increase (λ) of 1.180, per week.

scholarly journals Trend of the Yellowstone Grizzly Bear Population

2010 ◽  
Vol 2010 ◽  
pp. 1-5 ◽  
Author(s):  
L. L. Eberhardt ◽  
J. M. Breiwick
Keyword(s):  
Confidence Intervals ◽  
Current Literature ◽  
Ursus Arctos ◽  
Exponential Model ◽  
Grizzly Bear ◽  
Rate Of Increase ◽  
Lower Limits ◽  
Index Of Abundance

Yellowstone's grizzlies (Ursus arctos) have been studied for more than 40 years. Radiotelemetry has been used to obtain estimates of the rate of increase of the population, with results reported by Schwartz et al. (2006). Counts of females with cubs-of-the-year “unduplicated” also provide an index of abundance and are the primary subject of this report. An exponential model was fitted ton=24such counts, using nonlinear leastsquares. Estimates of the rate of increase,r, were about 0.053. 95% confidence intervals, were obtained by several different methods, and all had lower limits substantially above zero, indicating that the population has been increasing steadily, in contrast to the results of Schwartz et al. (2006), which could not exclude a decreasing population. The grizzly data have been repeatedly mis-used in current literature for reasons explained here.

Population trend of the Yellowstone grizzly bear as estimated from reproductive and survival rates

1994 ◽  
Vol 72 (2) ◽  
pp. 360-363 ◽  
Author(s):  
L. L. Eberhardt ◽  
B. M. Blanchard ◽  
R. R. Knight
Keyword(s):  
Ursus Arctos ◽  
Survival Rates ◽  
Population Trend ◽  
Point Estimate ◽  
Parameter Estimates ◽  
Grizzly Bear ◽  
Population Parameter ◽  
Ursus Arctos Horribilis ◽  
Rate Of Increase ◽  
Reproductive Rates

The trend of the Yellowstone grizzly bear (Ursus arctos horribilis) population was estimated using reproductive rates calculated from 22 individual females and survival rates from 400 female bear-years. The point estimate of the rate of increase was 4.6%, with 95% confidence limits of 0 and 9%. Caution in interpreting this result is advised because of possible biases in the population parameter estimates. The main prospects for improving present knowledge of the population trend appear to be further study of possible biases in the parameter estimates, and the continued use of radiotelemetry to increase the number of samples on which the estimates are based.

Comparative performance and digestive physiology of Diaphania indica (Lepidoptera: Crambidae) on Trichosanthes anguina (Cucurbitaceae) cultivars

2020 ◽  
Vol 110 (6) ◽  
pp. 756-766 ◽  
Author(s):  
Rahul Debnath ◽  
Syed Husne Mobarak ◽  
Paroma Mitra ◽  
Anandamay Barik
Keyword(s):  
Development Time ◽  
Adult Emergence ◽  
Reproductive Rate ◽  
Intrinsic Rate Of Increase ◽  
Food Utilization ◽  
Comparative Performance ◽  
Net Reproductive Rate ◽  
Diaphania Indica ◽  
Rate Of Increase ◽  
Proteolytic Activities

AbstractDiaphania indica (Saunders) (Lepidoptera: Crambidae) is an important phytophagous pest of Trichosanthes anguina L. in India. We studied life table parameters by age-stage, two-sex, amylolytic and proteolytic activities, and food utilization parameters of D. indica on the leaves of three T. anguina cultivars (Baruipur Long, Polo No. 1 and MNSR-1). Further, nutrients (total carbohydrates, proteins, lipids, amino acids and nitrogen) and antinutrients (total phenols, flavonols and tannins) in leaves were determined. The development time (egg to adult emergence) was the shortest on MNSR-1 (19.79 d) and the longest on Polo No. 1 (25.72 d). Fecundity was the highest and lowest on MNSR-1 (259 eggs) and Polo No. 1 (151.22 eggs), respectively. The lowest intrinsic rate of increase (rm) and net reproductive rate (R0) of D. indica on Polo No. 1 were 0.1112 d−1 and 27.22 offspring individual−1, respectively. The mean generation time (T) was the shortest on MNSR-1 (23.99 days) and the longest on Polo No. 1 (29.70 d). The larvae of D. indica fed with MNSR-1 had the highest level of amylolytic and proteolytic activities, and the lowest activities were in the larvae fed with Polo No. 1. The fifth-instar larvae fed with Polo No. 1 had the lowest consumption index and growth rate. The higher larval development time and lower fecundity of D. indica on Polo No. 1 were due to the lower level of nutrients and a higher level of antinutrients than other cultivars. Our results concluded that Polo No. 1 cultivar could be suggested for cultivation.

A grizzly bear from the Middle Wisconsin of Woodbridge, Ontario

1976 ◽  
Vol 13 (2) ◽  
pp. 341-347 ◽  
Author(s):  
Charles S. Churcher ◽  
Alan V. Morgan
Keyword(s):  
Ursus Arctos ◽  
Grizzly Bears ◽  
Grizzly Bear ◽  
Bone Fragment ◽  
Mammuthus Primigenius ◽  
Ursus Arctos Horribilis ◽  
Before And After ◽  
Lake Simcoe ◽  
Left Humerus ◽  
Woolly Mammoth

The distal end of the left humerus of a grizzly bear, Ursus arctos, has been recovered from above the Early Wisconsin Sunnybrook Till at Woodbridge, Ontario, from the same horizon that previously has yielded remains of the woolly mammoth, Mammuthus primigenius. The age of these specimens is estimated at 40 000–50 000 years BP, within the mid-Wisconsin, Port Talbot Interstadial. The only other recognized Canadian record of a grizzly bear east of Manitoba is from a gravel sequence at Barrie, near Lake Simcoe, Ontario, dated from a bone fragment to 11 700 ± 250 years BP. A specimen recovered in Toronto in 1913 from an Early Wisconsin horizon is also considered to represent the grizzly. Bears of the grizzly type, Ursus arctos-horribilis were present in Ontario before and after the Early and Late Wisconsin ice advances.

scholarly journals Gray Wolves, Canis lupus, Killed by Cougars, Puma concolor, and a Grizzly Bear, Ursus arctos, in Montana, Alberta, and Wyoming

2008 ◽  
Vol 122 (1) ◽  
pp. 76 ◽  
Author(s):  
Michael D. Jimenez ◽  
Valpa J. Asher ◽  
Carita Bergman ◽  
Edward E. Bangs ◽  
Susannah P. Woodruff
Keyword(s):  
United States ◽  
Canis Lupus ◽  
Ursus Arctos ◽  
Puma Concolor ◽  
Western United States ◽  
Grizzly Bear ◽  
Grey Wolf ◽  
Gray Wolves ◽  
Large Predators

Four cases where large predators caused Grey Wolf (Canis lupus) mortality are recorded. We describe two incidents of Cougars (Puma concolar) killing Wolves in Montana and one incident of a Cougar killing a Wolf in Alberta. We report the first recorded incident of a Grizzly Bear (Ursus arctos) killing a Wolf in the western United States.

scholarly journals Effects of imidacloprid and thiamethoxam on the development and reproduction of the soybean aphid Aphis glycines

PLoS ONE ◽  
2021 ◽  
Vol 16 (9) ◽  
pp. e0250311
Author(s):  
Aonan Zhang ◽  
Lin Zhu ◽  
Zhenghao Shi ◽  
Tianying Liu ◽  
Lanlan Han ◽  
...  
Keyword(s):  
Treatment Group ◽  
Reproductive Rate ◽  
Soybean Aphid ◽  
Aphis Glycines ◽  
Intrinsic Rate Of Increase ◽  
Control Group ◽  
Net Reproductive Rate ◽  
Treatment Groups ◽  
Rate Of Increase ◽  
The Mean

The soybean aphid Aphis glycines Matsumura (Hemiptera: Aphididae) is a primary pest of soybeans and poses a serious threat to soybean production. Our studies were conducted to understand the effects of different concentrations of insecticides (imidacloprid and thiamethoxam) on A. glycines and provided critical information for its effective management. Here, we found that the mean generation time and adult and total pre-nymphiposition periods of the LC50 imidacloprid- and thiamethoxam-treatment groups were significantly longer than those of the control group, although the adult pre-nymphiposition period in LC30 imidacloprid and thiamethoxam treatment groups was significantly shorter than that of the control group. Additionally, the mean fecundity per female adult, net reproductive rate, intrinsic rate of increase, and finite rate of increase of the LC30 imidacloprid-treatment group were significantly lower than those of the control group and higher than those of the LC50 imidacloprid-treatment group (P < 0.05). Moreover, both insecticides exerted stress effects on A. glycines, and specimens treated with the two insecticides at the LC50 showed a significant decrease in their growth rates relative to those treated with the insecticides at LC30. These results provide a reference for exploring the effects of imidacloprid and thiamethoxam on A. glycines population dynamics in the field and offer insight to agricultural producers on the potential of low-lethal concentrations of insecticides to stimulate insect reproduction during insecticide application.

Sign in / Sign up

Export Citation Format

Share Document