scholarly journals Post-calving photo-census of the Rivière George caribou herd in July 1993

Rangifer ◽  
1996 ◽  
Vol 16 (4) ◽  
pp. 319 ◽  
Author(s):  
J. Russell ◽  
S. Couturier ◽  
L.G. Sopuck ◽  
K. Ovaska
Keyword(s):  
Population Size ◽  
Total Population ◽  
Radio Telemetry ◽  
Accurate Estimate ◽  
Primary Objective ◽  
Total Size ◽  
Index Method ◽  
Total Population Size ◽  
Photographic Survey

A photographie census of the Rivière George caribou herd in Quebec and Labrador was conducted between 4-23 July 1993 during the post-calving period. The primary objective of the study was to obtain an accurate estimate of the current size of the herd to permit the monitoring of population trends and effective management of the herd. The census procedure consisted of (1) use of satellite and conventional radio-telemetry to locate and photograph post-calving aggregations during the period of optimal aggregation, (2) determination of the minimum population size by direct counts from photographs, and (3) estimation of the total population size using the Petersen Index method. This method allowed extrapolation of the data to caribou that were either not photographed or that were not aggregated at the time of the census. The minimum count indicates that the Rivière George caribou herd consisted of at least 358 460 adults (older than calves) at the time of the census. This count underestimates the total population size but is useful because it is virtually free of error. The total size of the Rivière George herd in July 1993 was estimated to be 540 040 adults within 90% confidence limits of + 12.8%. Comparisons with previous estimates indicate that the size of the herd continues to be large, but that its growth has probably ceased. This study demonstrates that a photographic survey of post-calving aggregations is an effective method to census the Rivière George herd and possibly other large migratory caribou herds that are monitored by telemetry.

Bionomics of Dytiscus alaskanus J. Balfour-Browne (Coleoptera: Dytiscidae) in a central Alberta lake

1985 ◽  
Vol 63 (6) ◽  
pp. 1316-1323 ◽  
Author(s):  
R. B. Aiken ◽  
C. W. Wilkinson
Keyword(s):  
Life History ◽  
Life Cycle ◽  
North America ◽  
Population Growth ◽  
Population Size ◽  
Total Population ◽  
Eutrophic Lake ◽  
North Central ◽  
Total Population Size

There are few studies of life history and population growth of large dytiscid beetles in North America. We sampled populations of Dytiscus alaskanus in a eutrophic lake in north central Alberta weekly in the summers of 1982 and 1983. Like many other temperate zone dytiscids, D. alaskanus has a univoltine life cycle. Dytiscus alaskanus prefers the area at the limit of emergent vegetation in the lake and is most often associated with shoreline vegetation of cattail and sedge. Populations of adult D. alaskanus are at a peak in the late spring and decline throughout the summer. Mark–recapture experiments allowed determination of total population size and monitoring of movement patterns in the lake. Data are discussed with reference to the relatively short summer with which these beetles must cope.

The ecology and conservation of the Aldabran brush warbler Nesillas aldabranus

1979 ◽  
Vol 286 (1011) ◽  
pp. 211-224 ◽  
Keyword(s):  
Population Size ◽  
Small Area ◽  
Total Population ◽  
Accurate Estimate ◽  
Vegetation Community ◽  
Total Population Size ◽  
Conservation Measures

The Aldabran brush warbler, Nesillas aldabranus , is one of the world’s rarest birds. Studies conducted over the course of 2 years indicate that its distribution is probably restricted to one small area of Aldabra Atoll. Within this area it inhabits only one vegetation community, dense ‘mixed scrub’, and even within this it is very patchily distributed. Only five separate individuals were definitely identified during the study, but these included two pairs which held contiguous territories. Aspects of the ecology and behaviour of the species are described. The extremely rough and densely vegetated habitat in which the brush warblers live prohibits an accurate estimate of total population size, but it is probably below 25 individuals. Possible conservation measures are discussed in the light of the information collected.

scholarly journals Assessing population size of the Chestnut-Capped Foliage-Gleaner

2012 ◽  
Vol 52 (24) ◽  
pp. 281-290
Author(s):  
Luciene Faria ◽  
Lucas A. Carrara ◽  
Frederico I. Garcia ◽  
Marcos Rodrigues
Keyword(s):  
Population Size ◽  
Geographic Distribution ◽  
Total Population ◽  
Conservation Status ◽  
Population Decline ◽  
Primary Objective ◽  
Habitat Destruction ◽  
Population Fluctuations ◽  
Total Population Size ◽  
Iucn Criteria

Chestnut-Capped Foliage-Gleaner (Hylocryptus rectirostris) is a Neotropical ovenbird species (Furnariidae) endemic to gallery forests of the Cerrado region of central Brazil. While it is not considered globally threatened, the degree of habitat loss occurring throughout much of its known distribution may warrant its inclusion on red lists beyond just the state of Sao Paulo. The primary objective of this study is to evaluate the conservation status of Chestnut-Capped Foliage-Gleaner according to those criteria adopted by the IUCN. Results of censuses conducted in the Serra do Cipó National Park were used to estimate the entire population size of the Chestnut-Capped Foliage-Gleaner and refine our understanding of its actual geographic distribution. Census results indicate that the species has a population density of 3.8 pairs/100 ha and occupies only a quarter of its preferred habitat in the study area, which is well below the carrying capacity. The total population size estimate, accounting for its entire extent of known occurrence, is just over 54,000 pairs. The geographic distribution and total population size estimated in this study do not indicate that the Chestnut-Capped Foliage-Gleaner should be considered a threatened species according to IUCN criteria. However, it was not possible to evaluate this species’ conservation status based on information concerning population fluctuations over time, another of the IUCN criteria. Nonetheless, the rate of habitat destruction in the Cerrado during the last century has certainly resulted in a population decline of greater than 10%, a factor sufficient enough to warrant its inclusion in the IUCN category of vulnerable.

scholarly journals Carrying Capacity of a Population Diffusing in a Heterogeneous Environment

Mathematics ◽  
2020 ◽  
Vol 8 (1) ◽  
pp. 49 ◽  
Author(s):  
D.L. DeAngelis ◽  
Bo Zhang ◽  
Wei-Ming Ni ◽  
Yuanshi Wang
Keyword(s):  
Population Size ◽  
Carrying Capacity ◽  
Heterogeneous System ◽  
Total Population ◽  
Reaction Diffusion ◽  
Maximum Growth ◽  
Reaction Diffusion Equations ◽  
Logistic Growth ◽  
Chemostat Model ◽  
Total Population Size

The carrying capacity of the environment for a population is one of the key concepts in ecology and it is incorporated in the growth term of reaction-diffusion equations describing populations in space. Analysis of reaction-diffusion models of populations in heterogeneous space have shown that, when the maximum growth rate and carrying capacity in a logistic growth function vary in space, conditions exist for which the total population size at equilibrium (i) exceeds the total population that which would occur in the absence of diffusion and (ii) exceeds that which would occur if the system were homogeneous and the total carrying capacity, computed as the integral over the local carrying capacities, was the same in the heterogeneous and homogeneous cases. We review here work over the past few years that has explained these apparently counter-intuitive results in terms of the way input of energy or another limiting resource (e.g., a nutrient) varies across the system. We report on both mathematical analysis and laboratory experiments confirming that total population size in a heterogeneous system with diffusion can exceed that in the system without diffusion. We further report, however, that when the resource of the population in question is explicitly modeled as a coupled variable, as in a reaction-diffusion chemostat model rather than a model with logistic growth, the total population in the heterogeneous system with diffusion cannot exceed the total population size in the corresponding homogeneous system in which the total carrying capacities are the same.

Estimation of the parameters of a branching process from migrating binomial observations

1998 ◽  
Vol 30 (4) ◽  
pp. 948-967 ◽  
Author(s):  
C. Jacob ◽  
J. Peccoud
Keyword(s):  
Confidence Interval ◽  
Asymptotic Behaviour ◽  
Population Size ◽  
Branching Process ◽  
Total Population ◽  
Initial Population ◽  
Asymptotic Confidence Interval ◽  
Total Population Size ◽  
Initial Population Size ◽  
Watson Process

This paper considers a branching process generated by an offspring distribution F with mean m < ∞ and variance σ2 < ∞ and such that, at each generation n, there is an observed δ-migration, according to a binomial law Bpvn*Nnbef which depends on the total population size Nnbef. The δ-migration is defined as an emigration, an immigration or a null migration, depending on the value of δ, which is assumed constant throughout the different generations. The process with δ-migration is a generation-dependent Galton-Watson process, whereas the observed process is not in general a martingale. Under the assumption that the process with δ-migration is supercritical, we generalize for the observed migrating process the results relative to the Galton-Watson supercritical case that concern the asymptotic behaviour of the process and the estimation of m and σ2, as n → ∞. Moreover, an asymptotic confidence interval of the initial population size is given.

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