Population dynamics of, and habitat use by, Austrlian native rodents in wet sclerophyll forest, Tasmania II. Pseudomys higginsi (Rodentia : Muridae)

1995 ◽  
Vol 22 (6) ◽  
pp. 661 ◽  
Author(s):  
V Monamy
Keyword(s):  
Population Dynamics ◽  
Habitat Use ◽  
Interspecific Competition ◽  
Demographic Data ◽  
Local Population ◽  
Ground Cover ◽  
Rodent Species ◽  
Low Density ◽  
Sclerophyll Forest ◽  
Age Cohort

A local population of Tasmanian long-tailed mice, Pseudomys higginsi, occupying an area of wet sclerophyll forest at low density was studied for 13 months using mark-recapture techniques. Individuals in the trappable population were readily recaught (29 individuals caught 183 times). Demographic data are presented for a single age cohort born in 1989 (21 individuals trapped 126 times) and surviving until the end of the trapping programme (April 1990). Habitat use was investigated by comparing data from individuals active within four contiguous areas of forest displaying structural and floristic heterogeneity. Trap-revealed habitat use indicated that P. higginsi was completely absent from areas of thickest ground cover where densities of the sympatric murid, Rams lutreolus velutinus, were highest. Conversely, captures of P. higginsi were highest in areas of boulder scree where captures of R. 1. velutinus were lower than expected. Relative numbers of individuals active in each macrohabitat group are examined and a role for interspecific competition between these rodent species is inferred.

Population dynamics of, and habitat use by, Austrlian native rodents in wet sclerophyll forest, Tasmania I. Rattus lutreolus velutinus (Rodentia : Muridae)

1995 ◽  
Vol 22 (6) ◽  
pp. 647 ◽  
Author(s):  
V Monamy
Keyword(s):  
Habitat Use ◽  
Structural Variation ◽  
Local Population ◽  
Ground Cover ◽  
Population Data ◽  
Female Rats ◽  
Heterogeneous Habitat ◽  
Sclerophyll Forest ◽  
Capture History ◽  
Trapping Grid

A local population of velvet-furred rats, Rattus lutreolus velutinus, was studied for 15 months in wet sclerophyll forest in south-eastem Tasmania using mark-recapture techniques. Individuals in the trappable population were readily caught with 90% of captures being recaptures (73 individuals caught 706 times). During winter and the summer breeding season, all individuals had an equal likelihood of recapture, irrespective of sex, age, season or previous capture history. Habitat use was investigated by analysing floristic and structural variation within a 4-ha trapping grid using TWINSPAN. Four heterogeneous habitat groups were defined and population data are compared among these groups. Areas of densest ground cover were preferred by R. 1. velutinus; open areas were avoided. Throughout the study, female rats were captured in the areas with most cover to 50 cm in height; during winter, males were caught in areas of the trapping grid with more sparse ground cover, in lower numbers than females. At the onset of breeding in summer, numerous males were captured in the areas of thickest ground cover occupied by females. These data are discussed in relation to social spacing, habitat utilisation and female choice.

scholarly journals Demographic effects of interacting species: exploring stable coexistence under increased climatic variability in a semiarid shrub community

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ana I. García-Cervigón ◽  
Pedro F. Quintana-Ascencio ◽  
Adrián Escudero ◽  
Merari E. Ferrer-Cervantes ◽  
Ana M. Sánchez ◽  
...  
Keyword(s):  
Population Dynamics ◽  
Species Coexistence ◽  
Climatic Factors ◽  
Demographic Data ◽  
Climatic Variability ◽  
Biotic Interactions ◽  
Vital Rates ◽  
Climatic Fluctuations ◽  
Demographic Models ◽  
Shrub Community

AbstractPopulation persistence is strongly determined by climatic variability. Changes in the patterns of climatic events linked to global warming may alter population dynamics, but their effects may be strongly modulated by biotic interactions. Plant populations interact with each other in such a way that responses to climate of a single population may impact the dynamics of the whole community. In this study, we assess how climate variability affects persistence and coexistence of two dominant plant species in a semiarid shrub community on gypsum soils. We use 9 years of demographic data to parameterize demographic models and to simulate population dynamics under different climatic and ecological scenarios. We observe that populations of both coexisting species may respond to common climatic fluctuations both similarly and in idiosyncratic ways, depending on the yearly combination of climatic factors. Biotic interactions (both within and among species) modulate some of their vital rates, but their effects on population dynamics highly depend on climatic fluctuations. Our results indicate that increased levels of climatic variability may alter interspecific relationships. These alterations might potentially affect species coexistence, disrupting competitive hierarchies and ultimately leading to abrupt changes in community composition.

Competition between the non-native amphipod Caprella mutica and two native species of caprellids Pseudoprotella phasma and Caprella linearis

2009 ◽  
Vol 89 (6) ◽  
pp. 1125-1132 ◽  
Author(s):  
Richard Shucksmith ◽  
Elizabeth J. Cook ◽  
David J. Hughes ◽  
Michael T. Burrows
Keyword(s):  
Interspecific Competition ◽  
Direct Contact ◽  
Native Species ◽  
Low Density ◽  
Artificial Habitat ◽  
Resident Species ◽  
Invasion Dynamics ◽  
Aggressive Interactions ◽  
Resource Space ◽  
Caprella Mutica

Competition plays an important role in invasion dynamics. According to Elton's biodiversity and invasibility hypothesis, non-native species must be competitively superior to the resident species in order to successfully invade. An invader that is ecologically similar to a native species may cause intense interspecific competition as they both require the same resource. Furthermore, an increase in the density of an invading competitor may enhance the intensity of the competitive interaction, however, this may be reduced if the inferior competitor has a refuge that reduces the amount of time it is in direct contact with the superior competitor. In laboratory-based competition experiments between the non-native caprellid Caprella mutica and two ecologically similar native caprellids Caprella linearis and Pseudoprotella phasma, C. mutica successfully displaced both species from homogeneous artificial habitat patches after 48 hours. Patches that contained a refuge reduced the number of C. linearis being displaced but only when C. mutica was at a low density. Potentially aggressive interactions between C. mutica and the native C. linearis may have caused C. linearis to be displaced from the patches and could have caused significantly higher mortality of C. linearis compared to the controls. This is the first study to show that the non-native C. mutica has the ability to displace ecologically similar native species when the resource space is limited and when the density of C. mutica was significantly (10 times) lower than the density of C. linearis.

scholarly journals Breeding transients in capture–recapture modeling and their consequences for local population dynamics

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Daniel Oro ◽  
Daniel F. Doak
Keyword(s):  
Growth Rate ◽  
Population Dynamics ◽  
Population Growth ◽  
Population Growth Rate ◽  
Local Population ◽  
Environmental Stochasticity ◽  
Adult Survival ◽  
Local Survival ◽  
First Reproduction ◽  
Capture Recapture

Abstract Standard procedures for capture–mark–recapture modelling (CMR) for the study of animal demography include running goodness-of-fit tests on a general starting model. A frequent reason for poor model fit is heterogeneity in local survival among individuals captured for the first time and those already captured or seen on previous occasions. This deviation is technically termed a transience effect. In specific cases, simple, uni-state CMR modeling showing transients may allow researchers to assess the role of these transients on population dynamics. Transient individuals nearly always have a lower local survival probability, which may appear for a number of reasons. In most cases, transients arise due to permanent dispersal, higher mortality, or a combination of both. In the case of higher mortality, transients may be symptomatic of a cost of first reproduction. A few studies working at large spatial scales actually show that transients more often correspond to survival costs of first reproduction rather than to permanent dispersal, bolstering the interpretation of transience as a measure of costs of reproduction, since initial detections are often associated with first breeding attempts. Regardless of their cause, the loss of transients from a local population should lower population growth rate. We review almost 1000 papers using CMR modeling and find that almost 40% of studies fitting the searching criteria (N = 115) detected transients. Nevertheless, few researchers have considered the ecological or evolutionary meaning of the transient phenomenon. Only three studies from the reviewed papers considered transients to be a cost of first reproduction. We also analyze a long-term individual monitoring dataset (1988–2012) on a long-lived bird to quantify transients, and we use a life table response experiment (LTRE) to measure the consequences of transients at a population level. As expected, population growth rate decreased when the environment became harsher while the proportion of transients increased. LTRE analysis showed that population growth can be substantially affected by changes in traits that are variable under environmental stochasticity and deterministic perturbations, such as recruitment, fecundity of experienced individuals, and transient probabilities. This occurred even though sensitivities and elasticities of these parameters were much lower than those for adult survival. The proportion of transients also increased with the strength of density-dependence. These results have implications for ecological and evolutionary studies and may stimulate other researchers to explore the ecological processes behind the occurrence of transients in capture–recapture studies. In population models, the inclusion of a specific state for transients may help to make more reliable predictions for endangered and harvested species.

Modelling climate influences on population dynamics and diurnal time budget of the Shelduck (Tadorna tadorna) wintering in Ramsar wetlands of Algeria

2019 ◽  
Vol 12 (3) ◽  
pp. 77-95 ◽  
Author(s):  
Adel Bezzalla ◽  
Moussa Houhamdi ◽  
Mohamed Cherif Maazi ◽  
Haroun Chenchouni
Keyword(s):  
Population Dynamics ◽  
Habitat Use ◽  
Generalized Linear Models ◽  
Linear Models ◽  
Time Budget ◽  
Climate Variables ◽  
Conspecific Density ◽  
Lack Of Information ◽  
International Importance ◽  
Important Bird Area

Several North African wetlands are classified as wetlands of international importance (Ramsar sites and Important Bird Area) because thousands of Shelducks ( Tadorna tadorna) winter in these habitats. However, Shelduck’s patterns of habitat use in these protected wetlands during the wintering season are still hindered by lack of information in arid and semi-arid regions regarding population dynamics and the effects of climate variables. This ornithological survey aims to study population dynamics and temporal patterns of diurnal activities of the Shelduck at two Ramsar and Important Bird Area sites (Chott Tinsilt and Sebkhet Ezzemoul) with respect to the effect of climatic parameters of the habitat in order to deepen our understanding of wintering strategies and habitat use. Populations were weekly censused from 06:00 to 19:00 during the entire wintering season (September 2015–May 2016). Diurnal behavioural activities were monitored at the same rate, and then the variation of time budget was tested using generalized linear model to determine the effects of climate variables and conspecific density dependence. The Shelduck was observed at both sites from the end of November and remained there until the total desiccation of both lakes in early May. Trends of Shelduck’s population dynamics differed between the two sites. Generalized linear models revealed the significant effects of temperature, wind speed and number of snowy days on population dynamics. Feeding was the main diurnal activity of the Shelduck at both sites with 80.2% of time budget at Chott Tinsilt (mainly feeding at lake shores) and 82% at Sebkhet Ezzemoul (mainly feeding in water). The generalized linear models showed that the variation of time budget allocated to different diurnal activities was not density-dependent, but rather it was negatively affected by the increase of air temperature. Significant effects of the interaction between population size and some climatic variables were found and discussed. During the whole wintering season, Chott Tinsilt and Sebkhet Ezzemoul play an important ecological role since they offer a wide-ranging diurnal forging habitat and a shelter for thousands of this waterfowl.

An Experimental Field Study to Examine Whether Capillaria Hepatica (Nematoda) Can Limit House Mouse Populations in Eastern Australia.

1995 ◽  
Vol 22 (1) ◽  
pp. 31 ◽  
Author(s):  
GR Singleton ◽  
GR Singleton ◽  
LK Chambers ◽  
LK Chambers ◽  
DM Spratt ◽  
...  
Keyword(s):  
Population Dynamics ◽  
Host Population ◽  
Rapid Decline ◽  
Low Density ◽  
Noticeable Effect ◽  
Mouse Population ◽  
Apparent Lack ◽  
Capillaria Hepatica ◽  
Experimental Field ◽  
Eastern Australia

A replicated experimental field investigation to examine the effect of the nematode parasite Capillaria hepatica on populations of Mus domesticus is described. A 2-year study was conducted at 7 sites with matching farming practices, soil types, topography and habitat heterogeneity on the Darling Downs in south-eastern Queensland, Australia, where mice cause substantial economic, social and environmental problems. A 4 km2 sampling zone was designated on each site and sites were assigned randomly to one of 3 untreated and 4 treated groups. The parasite was released successfully on 3 occasions at 3 markedly different stages of mouse population dynamics. The first release was in winter 1992 into a low-density, non-breeding population. Mice on treated sites had significantly lower survival for 6 months after the release than mice on untreated sites. The parasite had a relatively high impact on survival of young mice (<72 mm long) 2 months after its release. The greatest impact on old mice (>76 mm) occurred a month later. The most pronounced effects of C. hepatica on mouse abundance occurred during the 4 months after its release (June-September). Mice on the untreated sites, however, had poor survival in September, so by October their population abundance was at a level similar to that of the treated populations. Once breeding began in mid-October C. hepatica had no noticeable effect on mouse population dynamics. This was because the parasite (i) had no effect on breeding of mice, (ii) had minimal transmission and (iii) had a diminishing effect on survival after October. The apparent lack of transmission of C. hepatica was probably due to a combination of low population density, the transient nature of the mouse population and predominantly dry weather for 6 months after the release. A second release was made in February 1993 into a breeding, medium-density host population that was rapidly increasing in abundance. Less than 2% of the population was affected during the release so interest focused on transmission rather than the effect of the parasite on the host's demographic machinery. Transmission did occur at a low rate and the parasite persisted for 4.5 months (to June) when it was decided to boost the proportion of mice infected in order to follow its effect on the overwintering population and the demographic effects during the next breeding season. This late release was compromised by synchronous, widespread and rapid decline in mouse densities. Densities fell from greater than 500 ha to less than 1 ha in less than 6 weeks. Two messages emerge from these studies. First, C. hepatica will not limit mouse populations if it is released into a low-density population during a long dry period on the Darling Downs. Second, more information is needed about the factors that influence the survival and transmission of the parasite under field conditions.

Modelling the rate of successful search of red foxes during population control

2019 ◽  
Vol 46 (4) ◽  
pp. 285 ◽  
Author(s):  
Tom A. Porteus ◽  
Jonathan C. Reynolds ◽  
Murdoch K. McAllister
Keyword(s):  
Population Dynamics ◽  
Survey Methods ◽  
Mechanistic Model ◽  
Local Population ◽  
Parallel Applications ◽  
Sources Of Information ◽  
Absolute Abundance ◽  
Red Foxes ◽  
Informative Prior ◽  
Successful Search

Context Relative abundance indices of wildlife can be scaled to give estimates of absolute abundance. Choice of scaling parameter depends on the data available and assumptions made about the relationship between the index and absolute abundance. Predation-mechanics theory suggests that a parameterisation involving the rate of successful search, s, will be useful where the area searched is unknown. An example arises during fox culling on shooting estates in Britain, where detection and cull data from gamekeepers using a spotlight and rifle are available, and can potentially be used to understand the population dynamics of the local population. Aims We aimed to develop an informative prior for s for use within a Bayesian framework to fit a fox population-dynamics model to detection data. Methods We developed a mechanistic model with a rate of successful search parameter for the gamekeeper–fox system. We established a mechanistic prior for s, using Monte Carlo simulation to combine relevant information on its component factors (detection probability, observer field of view and speed of travel). We obtained empirical estimates of s from a distance-sampling study of fox populations using similar survey methods, and used these as data in a Bayesian model to develop a mechanistic–empirical prior. We then applied this informative prior within a state–space model to estimate fox density from fox-detection rate on four estates. Key results The mechanistic–empirical prior for the rate of successful search was lognormally distributed with a median of 2.01 km2 h–1 (CV = 0.56). Underlying assumptions of the parameterisation were met. Local fox-density estimates obtained using informative priors closely reflected regional density. Conclusions A mechanistic understanding of the search process leading to fox detections by gamekeepers, and the use of Bayesian models, allowed the use of diverse sources of information to develop an informative prior for s that was useful in estimating fox density from detection data. Implications Careful use of prior knowledge within a Bayesian modelling framework can reduce uncertainty in population estimates derived from index data, and lead to improved management decisions. The mechanistic approach we have used will have parallel applications in many other contexts.

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