Population dynamics and habitat use of the long-haired rat (Rattus villosissimus) in south-western Queensland

1994 ◽  
Vol 21 (1) ◽  
pp. 1 ◽  
Author(s):  
M Predavec ◽  
CR Dickman
Keyword(s):  
Population Dynamics ◽  
Habitat Use ◽  
Food Availability ◽  
Sand Dune ◽  
Population Decline ◽  
Radio Tracking ◽  
Spatial Activity ◽  
Secondary Role ◽  
Population Numbers

A population of Rattus villosissimus was studied during an 18-month period in a sand-dune habitat in south-western Queensland. The population numbers fluctuated dramatically during this time. Increases in population numbers were due primarily to immigration, with reproduction playing a secondary role. Rain-induced increases in food availability are the most likely stimuli for these increases. The cause of population decline is not clear from this study, but predation and disease may be important factors. Radio-tracking showed that the spatial activity of the animals was concentrated on the sides of the dunes, and around burrows. Temporal activity is influenced by moonlight, with animals remaining in burrows for long periods of time on bright nights.

Population dynamics and environemental changes during natural irruptions of Australian desert rodents.

1994 ◽  
Vol 21 (5) ◽  
pp. 569 ◽  
Author(s):  
M Predavec
Keyword(s):  
Population Dynamics ◽  
Sand Dune ◽  
Temporal Trend ◽  
Time Lag ◽  
High Turnover ◽  
Seed Availability ◽  
Temporal Correlations ◽  
Desert Rodents ◽  
Over Time ◽  
Population Numbers

Populations of Pseudomys hermannsburgensis and Notomys alexis were studied during a 33-month period (January 1991 to September 1993) in a sand-dune habitat in south-western Queensland. Population numbers of both species fluctuated dramatically over time with an approximately 40-fold difference between periods of lowest and highest abundance. Increased numbers were due primarily to an influx of juveniles to the population. A high turnover of individuals in both populations resulted in low rates of recapture. Numbers of both species were correlated positively with an index of rainfall with a time-lag of four months. P. hermannsburgensis showed spatial and temporal correlations with seed availability, whereas N. alexis displayed a strong, but non-significant, temporal trend with seed availability. These data suggest strongly that natural irruptions of Australian desert rodents are triggered by rainfall and possibly rain-induced food availability.

Protected areas and unpaved roads mediate habitat use of the giant anteater in anthropogenic landscapes

2021 ◽  
Author(s):  
Natalia F Versiani ◽  
Larissa L Bailey ◽  
Nielson Pasqualotto ◽  
Thiago F Rodrigues ◽  
Roberta M Paolino ◽  
...  
Keyword(s):  
Habitat Use ◽  
Protected Areas ◽  
Native Species ◽  
Population Decline ◽  
Native Vegetation ◽  
Brazilian Cerrado ◽  
Anthropogenic Landscapes ◽  
Unpaved Roads ◽  
Relative Paucity ◽  
Model Average

Abstract The drastic reduction of the Brazilian Cerrado has transformed this savanna hotspot into vast swaths of commodity-based agriculture fields, mainly soybean, sugarcane, and beef-production pasturelands. The resulting habitat loss and fragmentation are the principal factors underlying population decline of native species inhabiting the Cerrado, particularly those with a high demand for space, low population density, and specialized diet, such as the endangered giant anteater (Myrmecophaga tridactyla). Although the species has been studied in protected areas, we know much less about its ability to endure in disturbed landscapes. Here, we analyzed camera-trapping data to estimate a proxy of habitat use (ψ^; occupancy) and detection probabilities of the giant anteater, identifying environmental covariates influencing these parameters in landscapes with intensive agriculture and commercial forestry. We found this species using about half of the study area (model average ψ^ = 0.51, CI = 0.40–0.62), with two predictors strongly influencing habitat use: protected areas and unpaved roads. In turn, detection probability correlates positively with area of open Cerrado and negatively with area of settlements. The species is more likely to use unpaved roads inside protected areas (ψ^ = 0.90, CI = 0.47–0.75), compared to off road sites in the surrounding areas (ψ^ = 0.19, CI = 0.10–0.34). Our findings indicate that giant anteaters are dependent on nature reserves and native vegetation areas existing on private properties, whose protection is regulated by the Brazilian Native Vegetation Protection Law. Given the relative paucity of state-owned protected areas in the Brazilian Cerrado, increasing the adherence of rural owners to this law is, therefore, key for the conservation of the giant anteater. The intense use of unpaved roads might reflect travelling and/or foraging optimization, a behavioral response that, nevertheless, may compound this species’ susceptibility to suffer mortality from roadkill.

Influence of rainfall on population dynamics and survival of a threatened rodent (Pseudomys novaehollandiae) under a drying climate in coastal woodlands of south-eastern Australia

2017 ◽  
Vol 65 (1) ◽  
pp. 60 ◽  
Author(s):  
Mandy Lock ◽  
Barbara A. Wilson
Keyword(s):  
Population Dynamics ◽  
Population Decline ◽  
Resource Depletion ◽  
Mammal Species ◽  
Eastern Australia ◽  
Apparent Decrease ◽  
Mediterranean Systems ◽  
Precipitous Decline ◽  
Breeding Seasons ◽  
Successional Vegetation

In Mediterranean systems, such as south-east Australia, predictions of climate change including lower rainfall and extended drought, threaten vulnerable mammal species. We investigated the relationship between rainfall and population dynamics for a native rodent at risk of extinction, the New Holland mouse (Pseudomys novaehollandiae). In the eastern Otways, the species was significantly influenced by rainfall, exhibiting a population irruption (15–20 individuals ha–1) following six years of above-average rainfall and a precipitous decline to site extinction during subsequent drought. The decline was predominantly related to loss of adults before and during breeding seasons, together with an apparent decrease in juvenile survival. Population abundance was positively correlated with a rainfall lag of 0–9 months. We propose that the response of this omnivore to high rainfall was mediated through increased productivity and that rainfall decline resulted in resource depletion and population decline. Under a drying climate the direct impacts of rainfall decline will continue. However management of other threats may increase the species’ resilience. Burning to provide optimal successional vegetation, protection of refugia, and predator control are priorities. However, burning should be avoided during drought, as the likelihood of local extinctions is substantial.

Food supplementation and abundance estimation in the white-footed mouse

2006 ◽  
Vol 84 (8) ◽  
pp. 1210-1215 ◽  
Author(s):  
Pei-Jen L. Shaner
Keyword(s):  
Population Dynamics ◽  
Food Availability ◽  
Robust Design ◽  
Meta Analysis ◽  
Design Model ◽  
Food Supplementation ◽  
Abundance Estimates ◽  
Abundance Indices ◽  
Consumer Population ◽  
White Footed Mouse

Food availability often drives consumer population dynamics. However, food availability may also influence capture probability, which if not accounted for may create bias in estimating consumer abundance and confound the effects of food availability on consumer population dynamics. This study compared two commonly used abundance indices (minimum number alive (MNA) and number of animals captured per night per grid) with an abundance estimator based on robust design model as applied to the white-footed mouse ( Peromyscus leucopus (Rafinesque, 1818)) in food supplementation experiments. MNA consistently generated abundance estimates similar to the robust design model, regardless of food supplementation. The number of animals captured per night per grid, however, consistently generated lower abundance estimates compared with MNA and the robust design model. Nevertheless, the correlations between abundance estimates from MNA, number of animals captured, and robust design model were not influenced by food supplementation. This study demonstrated that food supplementation is not likely to create bias among these different measures of abundance. Therefore, there is a great potential for conducting meta-analysis of food supplementation effect on consumer population dynamics (particularly in small mammals) across studies using different abundance indices and estimators.

scholarly journals Separating the effects of climate, bycatch, predation and harvesting on tītī (Ardenna grisea) population dynamics in New Zealand: A model-based assessment

PLoS ONE ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. e0243794
Author(s):  
Sam McKechnie ◽  
David Fletcher ◽  
Jamie Newman ◽  
Corey Bragg ◽  
Peter W. Dillingham ◽  
...  
Keyword(s):  
Population Dynamics ◽  
New Zealand ◽  
Southern Oscillation ◽  
Population Decline ◽  
Management Strategies ◽  
Model Averaging ◽  
Adult Survival ◽  
Enso Events ◽  
Introduced Predators ◽  
Best Fitting

A suite of factors may have contributed to declines in the tītī (sooty shearwater; Ardenna grisea) population in the New Zealand region since at least the 1960s. Recent estimation of the magnitude of most sources of non-natural mortality has presented the opportunity to quantitatively assess the relative importance of these factors. We fit a range of population dynamics models to a time-series of relative abundance data from 1976 until 2005, with the various sources of mortality being modelled at the appropriate part of the life-cycle. We present estimates of effects obtained from the best-fitting model and using model averaging. The best-fitting models explained much of the variation in the abundance index when survival and fecundity were linked to the Southern Oscillation Index, with strong decreases in adult survival, juvenile survival and fecundity being related to El Niño-Southern Oscillation (ENSO) events. Predation by introduced animals, harvesting by humans, and bycatch in fisheries also appear to have contributed to the population decline. It is envisioned that the best-fitting models will form the basis for quantitative assessments of competing management strategies. Our analysis suggests that sustainability of the New Zealand tītī population will be most influenced by climate, in particular by how climate change will affect the frequency and intensity of ENSO events in the future. Removal of the effects of both depredation by introduced predators and harvesting by humans is likely to have fewer benefits for the population than alleviating climate effects.

scholarly journals Hippocampus-dependent emergence of spatial sequence coding in retrosplenial cortex

2018 ◽  
Vol 115 (31) ◽  
pp. 8015-8018 ◽  
Author(s):  
Dun Mao ◽  
Adam R. Neumann ◽  
Jianjun Sun ◽  
Vincent Bonin ◽  
Majid H. Mohajerani ◽  
...  
Keyword(s):  
Population Dynamics ◽  
Spatial Learning ◽  
Calcium Imaging ◽  
Place Cell ◽  
Retrosplenial Cortex ◽  
Population Code ◽  
Spatial Activity ◽  
Cellular Calcium ◽  
Hippocampal Lesions ◽  
Over Time

Retrosplenial cortex (RSC) is involved in visuospatial integration and spatial learning, and RSC neurons exhibit discrete, place cell-like sequential activity that resembles the population code of space in hippocampus. To investigate the origins and population dynamics of this activity, we combined longitudinal cellular calcium imaging of dysgranular RSC neurons in mice with excitotoxic hippocampal lesions. We tracked the emergence and stability of RSC spatial activity over consecutive imaging sessions. Overall, spatial activity in RSC was experience-dependent, emerging gradually over time, but, as seen in the hippocampus, the spatial code changed dynamically across days. Bilateral but not unilateral hippocampal lesions impeded the development of spatial activity in RSC. Thus, the emergence of spatial activity in RSC, a major recipient of hippocampal information, depends critically on an intact hippocampus; the indirect connections between the dysgranular RSC and the hippocampus further indicate that hippocampus may exert such influences polysynaptically within neocortex.

Population Dynamics of Municipalities in Central Russia

2017 ◽  
Vol 2017 (6) ◽  
pp. 97-124
Author(s):  
Irina Kalabikhina ◽  
Denis Mokrensky
Keyword(s):  
Population Dynamics ◽  
Elderly Population ◽  
Population Change ◽  
Population Decline ◽  
The Elderly ◽  
Second Stage ◽  
Central Russia ◽  
Population Concentration ◽  
Population Reduction ◽  
Demographic Policy

In this paper we present the results of the analysis of the population change in nonmetropolitan city municipalities by components and concentration of population in the municipalities were investigated, their typologization was developed in accordance with the contribution of various components to population dynamics. The article discusses the limitations of municipal statistics. The methods of average values, the balance equation, and the measures of population concentration are used. The main conclusions confirm the trends of population decline at the second stage of demographic policy, territorial unevenness and concentration of population in administrative centers and the closest settlements to them. Less than 2% of the municipalities in question demonstrate both natural and migratory growth, and in 70% of municipalities both migration and natural components make a contribution to population reduction. The relatively high proportion of the elderly population was observed in the studied municipalities; crude birth and death rates were worse than the average in the district.

scholarly journals Ready for bed: pre-hibernation movements and habitat use by Fowler’s Toads (Anaxyrus fowleri)

2018 ◽  
Vol 132 (1) ◽  
pp. 46-52
Author(s):  
David M. Green ◽  
Katharine T. Yagi
Keyword(s):  
Habitat Use ◽  
Global Positioning System ◽  
Late Summer ◽  
The Body ◽  
Positioning System ◽  
Radio Tracking ◽  
Water Line ◽  
Global Positioning ◽  
Radio Transmitters ◽  
Early Fall

We used radio-tracking to investigate movement patterns and habitat use of Fowler’s Toads (Anaxyrus fowleri) during late summer and early fall in a relatively undisturbed lakeshore dune and beach habitat at Long Point, Ontario. Small radio transmitters were fitted to 11 adult toads with an external harness made from fine surgical plastic tubing wrapped around the body behind the front limbs. We located radio-tagged toads morning and evening, for a maximum of 9 days, recording their locations using Global Positioning System units. Initially, the toads were located on the upper beach or in the fore-dunes during the day, either dug in under the sand or hiding beneath debris; in the evening, they were generally active on the lower beach close to the water line. After a storm and the onset of cooler autumn weather, the toads tended to move further from the water line. They also curtailed their nightly activity and retreated deeper into the sand. As this sort of behaviour was not observed during the summer, we interpret it as pre-hibernation movement to more stable sites away from the beach where the animals can burrow deeply into the sand to lie dormant during the winter.

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.

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