Closure violation in DNA-based mark-recapture estimation of grizzly bear populations

2001 ◽  
Vol 79 (4) ◽  
pp. 642-651 ◽  
Author(s):  
John Boulanger ◽  
Bruce McLellan
Keyword(s):  
Population Model ◽  
Ursus Arctos ◽  
Survival Rates ◽  
Grizzly Bear ◽  
Apparent Survival ◽  
Mark Recapture ◽  
Closed Model ◽  
Closed Population ◽  
The Relationship ◽  
Grid Based

We use methods in the program MARK to explore the effects of closure violation when DNA-based mark–recapture methods are used to estimate grizzly bear (Ursus arctos) populations. Our approach involves the use of Pradel models in MARK to explore the relationship between recruitment, apparent survival rates, recapture rates, and distance between mean bear-capture locations and the edge of the sampling grid. If the population is demographically closed, it can be assumed that apparent survival estimates the fidelity of bears to the grid area and recruitment estimates rates of addition of bears to the grid area. A core bear population is defined from the Pradel analysis and is used to approximate the grid-based population size. The Huggins closed-population model in MARK is used to provide robust superpopulation estimates by explicitly modeling the relationship between capture probability and distance of bear-capture location from the grid edge. Data from a grizzly bear DNA-based mark–recapture inventory conducted in British Columbia is used to illustrate this method. The results of the Pradel analysis suggest that bears with mean capture locations within 10 km of the grid edge exhibit reduced fidelity rates and higher addition rates. Using the population of bears captured more than 10 km from the grid edge, a core-extrapolated estimate is derived, which is substantially lower than naïve CAPTURE superpopulation estimates. The Huggins model superpopulation estimate displays superior precision compared with CAPTURE model estimates. Our results illustrate the danger of naïve interpretation of closed-model estimates. This method allows further inferences to be made concerning the spatial causes of closure violation, and the degree of bias caused by closure violation to be explored.

scholarly journals Age-specific survival in an English Twite population.

2021 ◽  
Author(s):  
Ismini Gkourtsouli-Antoniadou ◽  
Steven R. Ewing ◽  
George Hudson ◽  
Michael A. Pearson ◽  
Julia Schroeder ◽  
...  
Keyword(s):  
Habitat Degradation ◽  
Survival Rates ◽  
Bird Species ◽  
Small Population ◽  
Juvenile Survival ◽  
Apparent Survival ◽  
Mark Recapture ◽  
The Uk ◽  
Rule Out

Like many bird species associated with agricultural habitats in the UK, the Twite Linaria flavirostris has undergone severe declines over recent decades due to habitat degradation, with populations in England, Wales and Ireland now restricted to a few small pockets. However, the demographic drivers of these declines are still largely unresolved. We estimated the survival of Twite from a small population at the southernmost edge of the English range in Derbyshire using capture-mark-recapture data from 2016–2019. Annual apparent survival for juveniles (0.14–0.34) was lower than for adults (0.29–0.56) and less than that of other Cardueline finches. Our results suggest that low juvenile survival may be one demographic driver underpinning the recent decline of the Derbyshire Twite population, although we also cannot rule out the possibility that differences in emigration of juveniles and adults from the population also contribute to the observed age-specific apparent survival rates.

Estimating population growth of grizzly bears from the Flathead River drainage using computer simulations of reproduction and survival rates

1996 ◽  
Vol 74 (8) ◽  
pp. 1409-1416 ◽  
Author(s):  
Frederick W. Hovey ◽  
Bruce N. McLellan
Keyword(s):  
Ursus Arctos ◽  
Survival Rates ◽  
Population Increase ◽  
Grizzly Bears ◽  
Grizzly Bear ◽  
Reproduction Rate ◽  
River Drainage ◽  
The North ◽  
Flathead River ◽  
Subadult Female

Using survival and reproduction data obtained from radio-tracking 23 adult female, 24 subadult female, 49 yearling, and 44 cub grizzly bears (Ursus arctos) in the Flathead River drainage of British Columbia and Montana, we estimated the finite rate of population increase [Formula: see text] from 1979 to 1994 at 1.085 ± 0.026, with ≈95% confidence limits of 1.032–1.136. Estimated annual survival rates were 0.946 ± 0.026 for adult females, 0.931 ± 0.038 for subadult females, 0.944 ± 0.039 for yearlings, and 0.867 ± 0.050 for cubs (rates for cubs and yearlings represented both sexes). The estimated annual reproduction rate and age at first parturition were 0.422 ± 0.042 female cubs per female and 6.44 ± 0.45 years, respectively. We found that uncertainty in [Formula: see text] was mostly attributable to uncertainty in survival rates (76.7%), with subadult (47.5%) and adult (21.9%) survival contributing the largest portions. These results indicated that to reduce uncertainty in [Formula: see text], further research on grizzly bears in our study area should focus on improving estimates of adult and subadult female survivorship. Other demographic variables are not as important in estimating the grizzly bear population trend in the North Fork of the Flathead River drainage.

Early survival of Punjab urial

2008 ◽  
Vol 86 (5) ◽  
pp. 394-399 ◽  
Author(s):  
Ghulam Ali Awan ◽  
Marco Festa-Bianchet ◽  
Jean-Michel Gaillard
Keyword(s):  
Population Growth ◽  
Litter Size ◽  
Protected Area ◽  
Adult Survival ◽  
Apparent Survival ◽  
Mark Recapture ◽  
Sex Effect ◽  
Salt Range ◽  
Early Survival ◽  
The Relationship

There is almost no information on age-specific survival of Asiatic ungulates based on mark–recapture studies. Survival of marked Punjab urial ( Ovis vignei punjabiensis Lydekker, 1913) aged 0–2 years was studied in the Salt Range, Pakistan, in 2001–2005. Male lambs were heavier than females at birth. The relationship between litter size and birth mass varied among years, with a tendency for twins to be lighter than singletons. Birth mass had a positive but nonsignificant relation with survival to 1 year. Neither sex nor litter size affected survival to 1 year, which averaged 55% (95% CI = 41%–68%). There was no sex effect on survival of yearlings, which averaged 88% (95% CI = 4%–100%). Although survival of lambs and yearlings was similar to that reported for other ungulates, apparent survival of 2- and 3-year-olds was very low at only 47%, possibly because of emigration. Early survival in this protected area is adequate to allow population growth, but more data are required on adult survival.

scholarly journals A new approach to the “apparent survival” problem: estimating true survival rates from mark–recapture studies

Ecology ◽  
2012 ◽  
Vol 93 (7) ◽  
pp. 1509-1516 ◽  
Author(s):  
James J. Gilroy ◽  
Thomas Virzi ◽  
Rebecca L. Boulton ◽  
Julie L. Lockwood
Keyword(s):  
Survival Rates ◽  
Apparent Survival ◽  
Mark Recapture ◽  
New Approach

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.

Survival and nesting success of the Pacific Eider (Somateria mollissima v-nigrum) near Bathurst Inlet, Nunavut

2010 ◽  
Vol 88 (6) ◽  
pp. 511-519 ◽  
Author(s):  
A. K. Hoover ◽  
D. L. Dickson ◽  
K. W. Dufour
Keyword(s):  
Ursus Arctos ◽  
Grizzly Bear ◽  
Somateria Mollissima ◽  
Apparent Survival ◽  
Ice Breakup ◽  
Ursus Arctos Horribilis ◽  
The Pacific ◽  
Mammalian Predators ◽  
Ice Conditions ◽  
Marked Decline

We used resighting data from 242 individually marked females to estimate apparent survival of Pacific Eiders ( Somateria mollissima v-nigrum Bonaparte, 1855) at a nesting colony in central arctic Canada from 2001 to 2007. In addition, we used data from nest searches conducted on islands at a freshwater lake and an adjacent marine environment to estimate annual breeding success. Annual survival rate estimates ranged from 0.84 ± 0.04 (mean ± SE) to 0.86 ± 0.05. Mayfield estimates of nest success ranged from 48.8% to 68.1% at the freshwater colony, and from 13.9% to 43.5% at the marine nesting colonies. The overwhelming cause of nest failure at both nesting areas was predation by grizzly bear ( Ursus arctos horribilis Ord, 1815), arctic fox ( Vulpes lagopus (L., 1758)), and wolverine ( Gulo gulo (L., 1758)). The majority of nests were initiated prior to ocean ice breakup in mid-July, thus mammalian predators had access to the islands well into incubation. Our results suggest that during the period from 2001 to 2007, the population of Pacific Eiders was likely not in decline. Therefore, the marked decline observed for eiders migrating past Point Barrow, Alaska, from 1976 to 1996 was more likely attributable to a stochastic event, such as unfavourable ice conditions, than to a chronic factor.

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.

scholarly journals Apparent Survival Rates of Western Sandpiper (Calidris Mauri) Wintering in Northwest Baja California, Mexico

The Auk ◽  
2003 ◽  
Vol 120 (1) ◽  
pp. 55-61 ◽  
Author(s):  
Guillermo Fernández ◽  
Horacio de la Cueva ◽  
Nils Warnock ◽  
David B. Lank
Keyword(s):  
Hierarchical Modeling ◽  
Survival Rates ◽  
Average Quality ◽  
Apparent Survival ◽  
Calidris Mauri ◽  
Local Survival ◽  
Western Sandpiper ◽  
Western Sandpipers ◽  
Best Fit ◽  
Effect Of Age

AbstractTo estimate annual apparent local survival, we collected capture–resighting data on 256 individually marked male Western Sandpipers (Calidris mauri) wintering at Estero de Punta Banda, Mexico, between 1994–1997. A hierarchical modeling approach was used to address the effect of age class and year on survivorship rates. The best-fit model included a constant apparent survival probability (ϕ = 0.489; 95% CI = 0.410–0.569), but several models fit nearly as well, and averaging among the top five, to account for model uncertainty, suggested that adults had somewhat higher values than juveniles (ϕ = 0.490 ± 0.051 vs. 0.450 ± 0.067). Detection probability was substantially higher for adults than for juveniles (p = 0.741 vs. p = 0.537). Those apparent survival estimates are low compared with those from other studies of Western Sandpipers at breeding and other nonbreeding locations, and substantially lower than the true survivorship rates expected for small sandpipers in general. We interpret these results as indicating that this site is of below average quality for nonbreeding male Western Sandpipers.

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.

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