Population dynamics of island populations of subarctic Clethrionomys rutilus

1981 ◽  
Vol 59 (11) ◽  
pp. 2115-2122 ◽  
Author(s):  
Gordon R. Burns
Keyword(s):  
Population Dynamics ◽  
Breeding Season ◽  
Growth Potential ◽  
Demographic Parameters ◽  
Juvenile Survival ◽  
Island Populations ◽  
Clethrionomys Rutilus ◽  
Green Island ◽  
Mackenzie River

Populations of Clethrionomys rutilus were studied on two islands (Island 2 and Green Island) in the Mackenzie River during the summers of 1976 to 1978. This was done to examine the demographic parameters related to confinement of northern red-backed vole populations on islands.The number of voles on Island 2 in 1977 increased until late June and then remained nearly constant until trapping ceased in late August. On Green Island in 1977 and 1978 and Island 2 in 1978, populations grew all summer and even in August had not reached the densities found during the 1977 high on Island 2. Island 2 in 1977 had an unusually low number of maturing young voles. Higher wounding rates and shorter adjusted range lengths were associated with higher population densities.Although high densities of voles were reached early in the summer of 1977 on Island 2, numbers stopped increasing before the end of the breeding season. Restraint of growth potential was seen in poor maturation of the young and in declining juvenile survival and recruitment of young through summer.

scholarly journals Dealing with many correlated covariates in capture-recapture models

2016 ◽  
Author(s):  
Olivier Gimenez ◽  
Christophe Barbraud
Keyword(s):  
Principal Component Analysis ◽  
Population Dynamics ◽  
Statistical Significance ◽  
Principal Component ◽  
High Dimensionality ◽  
Demographic Parameters ◽  
Statistical Tools ◽  
Capture Recapture ◽  
New Variables ◽  
Standard Software

SummaryCapture-recapture models for estimating demographic parameters allow covariates to be incorporated to better understand population dynamics. However, high-dimensionality and multicollinearity can hamper estimation and inference. Principal component analysis is incorporated within capture-recapture models and used to reduce the number of predictors into uncorrelated synthetic new variables. Principal components are selected by sequentially assessing their statistical significance. We provide an example on seabird survival to illustrate our approach. Our method requires standard statistical tools, which permits an efficient and easy implementation using standard software.

Dynamic modes of exploited limited population: results of modeling and numerical study

2016 ◽  
Vol 11 (1) ◽  
pp. 1-13 ◽  
Author(s):  
Г.П. Неверова ◽  
G.P. Neverova
Keyword(s):  
Population Dynamics ◽  
Density Dependence ◽  
Population Size ◽  
Age Structure ◽  
Birth Rate ◽  
Numerical Study ◽  
Dynamic Regime ◽  
Demographic Parameters ◽  
Current Population

The paper investigates the model of population dynamics with age structure and density dependence of birth rate. We consider two situations: 1) the population develops freely and 2) the population is exploited. It was shown that harvesting leads to the stabilization of the dynamics. There is multiregimism, i.e. different dynamic regimes are possible with the same values of demographic parameters. It is shown that even a single harvesting in the current population size could lead to a change of the observed dynamic regime.

The ecology of the deer mouse Peromyscus maniculatus in a coastal coniferous forest. I. Population dynamics

1974 ◽  
Vol 52 (1) ◽  
pp. 107-118 ◽  
Author(s):  
B. G. Petticrew ◽  
R. M. F. S. Sadleir
Keyword(s):  
Population Dynamics ◽  
Breeding Season ◽  
Deer Mouse ◽  
Coniferous Forest ◽  
Deer Mice ◽  
Population Parameters ◽  
Male Behavior ◽  
Mature Forest ◽  
Live Trapping ◽  
Breeding Seasons

A 3-year live-trapping study of deer mice was carried out on separate 1-hectarc (ha) grids located in a mature forest, a recently logged area, and a young plantation. Despite apparent gross differences in the habitats, populations on the recently logged area were similar in numbers, survival, and recruitment to those in the mature forest. There were greater differences in population parameters between years than between these two areas. Populations of deer mice in the young plantation were lower in numbers and eventually went to extinction in the summer of 1970. This appeared to be due rather to the presence of numerous Microtus oregoni in this area than to the habitat being less suitable for deer mice.On the basis of this and previous studies it is proposed that the numbers of deer mice in a population are regulated as follows. During breeding seasons the numbers of males and juveniles are regulated by agonistic male behavior while the numbers of females may be a function of the length of the breeding season. During non-breeding seasons the changes in numbers of all deer mice are regulated by the length of such seasons.

Sexual maturity, factors affecting the breeding season and breeding in consecutive seasons in populations of overabundant Victorian koalas (Phascolarctos cinereus)

2006 ◽  
Vol 54 (6) ◽  
pp. 385 ◽  
Author(s):  
Natasha McLean ◽  
Kathrine A. Handasyde
Keyword(s):  
Population Dynamics ◽  
Breeding Season ◽  
Sexual Maturity ◽  
Island Population ◽  
Population Parameters ◽  
Free Living ◽  
Phascolarctos Cinereus ◽  
Factors Affecting ◽  
Reproductive Patterns ◽  
South West

It is important to have knowledge of basic population parameters to understand how these vary geographically and temporally and how they contribute to population dynamics. This paper investigates three of these parameters in Victorian koala populations: sexual maturity, aspects of the breeding season, and the continuity of individuals’ breeding. The investigation was carried out in koalas of known-age in two free-living (Redbill Creek on French Island and Brisbane Ranges) and one semi-captive (the Koala Conservation Centre on Phillip Island) population as well as koalas of unknown age in four Victorian populations of overabundant koalas: Mt Eccles and Framlingham in south-west Victoria, French Island in Western Port and Snake Island in south Gippsland. At sexual maturity, female koalas had a mean age (±95% confidence interval) of 24.4 months (23.5–25.3 months), a mean head length of 125 mm (124–127 mm) and a mean body mass of 6.6 kg (6.3–6.8 kg). Only 7.4% of independent females (of unknown age) were carrying young when they weighed less than 6 kg. The breeding season was more restricted in the south-west populations. At Framlingham and Mt Eccles 85% and 91% of births, respectively, occurred between December and March. At Snake and French Islands only 46% and 53% of births, respectively, were recorded in the same period. In the Chlamydia-free population (Red Bill Creek) none of the koalas that were monitored stopped breeding and then resumed breeding in a subsequent season whereas many females from Chlamydia-infected populations (Brisbane Ranges and the Koala Conservation Centre) did so. This variation in reproductive patterns is likely to make an important contribution to the variation in the demography observed in different koala populations.

Effects of predation and rabbit haemorrhagic disease on population dynamics of rabbits (Oryctolagus cuniculus) in North Canterbury, New Zealand

2002 ◽  
Vol 29 (6) ◽  
pp. 627 ◽  
Author(s):  
Ben Reddiex ◽  
Graham J. Hickling ◽  
Grant L. Norbury ◽  
Chris M. Frampton
Keyword(s):  
Population Dynamics ◽  
New Zealand ◽  
Breeding Season ◽  
Predator Control ◽  
Zealand Rabbit ◽  
Rabbit Haemorrhagic Disease ◽  
Low Levels ◽  
Haemorrhagic Disease ◽  
The Impact ◽  
Very High

The impact of predation and rabbit haemorrhagic disease (RHD) on population dynamics of rabbits, and the survival of juvenile rabbits, was investigated between July 1999 and March 2000 in North Canterbury, New Zealand. Rabbit abundance and pre- and post-emergent rabbit mortality were monitored on four sites, two of which were subject to predator control. RHD spread naturally through all sites from late November to early December. Rabbit densities declined on all sites, but after the RHD epidemic, declines were significantly greater where populations of predators had not been controlled. Survival of rabbit nestlings was lower where predators were not controlled. All post-emergent radio-collared rabbits died at sites where predators were not controlled, whereas 18% of those collared at sites where predators were controlled survived to maturity. In contrast to the results from previous studies, rabbits born at the start of the breeding season had very high rates of post-emergent mortality, as they appeared to be susceptible to the RHD virus later in the breeding season. The age at which juvenile rabbits become susceptible to RHD, the timing of RHD epidemics, and the abundance of predators are likely to be important in determining survival of juvenile rabbits. This study demonstrates that predation can reduce rabbit populations to low levels, but only in combination with other factors, in this case RHD.

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