Areas Of Dense Cover Research Articles

Movements and habitat use of painted button-quail, Turnix varius, in tropical savanna of northern Queensland

Despite painted button-quail, Turnix varius, being one of Australia’s most common and widespread button-quail, knowledge of the species’ habitat use and movements is poor, and largely based on incidental observations. We GPS tracked eight painted button-quail individuals near Mareeba in northern Queensland during both dry (May to June 2020) and wet (January to February 2021) seasons. We found no evidence of nomadic or migratory movements; individuals occupied small home ranges (1.38–10.3 ha) and the species was present year-round. Differences in home-range size were detected between sexes and between seasons, likely reflecting the species’ polyandrous mating system. In both wet and dry seasons, painted button-quail occupied open savanna with a groundcover of native perennial tussock grasses. The home ranges of all tracked birds were associated mostly with ridges and slopes, although some use of alluvial flats was observed. The presence of perennial tussock grasses was consistent across the areas used by tracked individuals. In contrast to anecdotal reports, painted button-quail utilised areas with open groundcover (as low as 5% groundcover vegetation) as well as areas of dense cover (95% groundcover vegetation). Given that this is the first GPS-based movement study of any button-quail species, our findings provide potentially important insights into the daily and annual movements of this cryptic genus.

Predicting Variation in Microhabitat Utilization of Terrestrial Salamanders

Understanding patterns of microhabitat use among terrestrial salamanders is important for predicting their responses to natural and anthropogenic disturbances. The dependence of terrestrial salamanders on cutaneous respiration limits their spatial distribution to moist, humid areas. Although many studies have shown negative effects of canopy removal on terrestrial salamander abundance, some have shown potential ameliorating effects of retaining coarse woody debris (CWD) as moist refugia (critical resources in the landscape). Because cover objects like CWD retain moisture longer than fine debris, terrestrial salamanders are often more locally abundant in areas of dense cover. Temporally variable environmental conditions could affect microhabitat quality and influence the fine-scale spatial distributions of salamanders. Spatial and temporal variability in microhabitat use greatly influence individual detectability, which is always a challenge for terrestrial salamanders. We conducted repeated area-constrained surveys to examine variation in salamander microhabitat use of terrestrial salamanders in relation to season, year, and weather conditions. We found that time since rain (TSR) was the best predictor of relative salamander microhabitat use, but the strength of this relationship varied among years. In addition, TSR was also the best predictor of salamander surface activity. We captured most salamanders within leaf litter, but the proportion of leaf litter captures varied with TSR. Our results illustrate the importance of accounting for variable detectability when sampling for terrestrial salamanders. Disturbances which affect leaf litter depth and decomposition rates could influence the availability and quality of microhabitats and potentially increase competition among individuals for natural cover objects.

Vulnerability of small and medium-sized prey mammals in relation to their habitat preferences, age classes and locomotion types in the temperate Monte Desert, Argentina

In this study we examined predation by small felids upon small and medium-sized prey mammals in the central region of the Monte Desert. We analyzed the degree of vulnerability of prey mammals in relation to their habitat use patterns, modes of locomotion and age classes. Medium and small rodents were the predominant prey in the diet of small cats. The most consumed small mammal was Akodon molinae, which inhabits areas of dense cover, while species occurring in open habitats such as Eligmodontia typus were less consumed. Among medium-sized mammals, Galea leucoblephara that depends on patches with high plant cover for refuge was more consumed than Microcavia australis that lives in colonies and displays a complex set of antipredator strategies. Prey selectivity on small rodents showed that E. typus, which uses bipedal locomotion and an erratic escape behaviour, was consumed in greater proportion than its availability. We suggest that although its specialized locomotory mode would diminish predator attacks, its preference for open habitats would increase the probability of predator–prey encounter. Consumption of small mammals focuses mostly on adult individuals. However, we found a significant consumption of senile individuals of A. molinae, which points out that vulnerability tends to be high towards the age of maturity in this species.

Stability of nest range, home range and movement of the northern bettong (Bettongia tropica) following moderate-intensity fire in a tropical woodland, north-eastern Queensland

Nest use, home-range characteristics and nightly movements by the northern bettong (Bettongia tropica) were examined before and after a low- to moderate-intensity fire in sclerophyll woodland in north-eastern Australia using radio-telemetry. In all, 23 animals were radio-tracked at three-month intervals between February 1995 and May 1996. During November 1995 a low-intensity experimental fire burned the entire home range of most animals. The northern bettong appeared fairly catholic in choice of nest site, with a variety of nest locations and nesting materials used. Prior to the fire, nests were generally located in areas of dense cover, such as the skirts of grass trees (46%) or grass close to a log (29%). After fire removed most ground cover in the nesting areas of most animals, bettongs used remaining shelter such as boulder piles (45%), recently fallen trees (8%) and patches of unburnt vegetation (21%). Nest areas (10.1 ha) of males were significantly larger than those of females (5.4 ha). Home ranges of both sexes were large (59 ha) and most ranges lacked distinct core areas, suggesting that bettongs used all parts of their home ranges equally. High mean rates of nightly movement by the northern bettong indicated that large distances were moved within home ranges during nightly foraging. No significant fire-related changes were detected in home-range size, home-range location, nest-area location or mean rates of nightly movement, suggesting that the northern bettong is well adapted to the low- and medium-intensity fires that characterise its habitat.

The use of small wire-mesh traps in sampling juvenile salmonids

Abstract. Sampling of juvenile salmonids is often difficult or impractical in deep pools or areas of dense cover. Small, wire-mesh ‘minnow’ traps can be used successfully in these conditions, however, and are now a standard sampling tool in the Pacific Northwest of North America. The use and application of the traps in studies of juvenile salmonids is discussed and an experimental study described in which the relationship between traps soak-time and catch size was investigated. In areas of high population density, catches of juvenile salmonids reached a peak after l-2h whereas in lower density areas catch continued to increase over 24h.

On the Adaptive Significance of Leaf Height in Forest Herbs

Based on the premise that competition for light is the most important selection pressure on leaf height in forest herbs, I present a game theoretic model for the evolution of this trait which balances the structural costs of a given height increment over an opponent with the resultant photosynthetic benefits. Herbs growing in areas with sparse herbaceous cover are unlikely to be next to and thus under an opponent. Hence, they reap little advantage by being taller, whereas the opposite is true in areas of dense cover. Therefore, the evolutionarily stable strategy favors greater leaf height in productive herb communities having dense coverage than in less productive communities with sparse coverage. In deciduous, cool temperate forests, winter photosynthesis may be limited more by leaf temperature than by light intensity, and thus may favor recumbent basal leaves in evergreen or wintergreen species and seasonal morphs. These ideas are confirmed by data on plant height and coverage from a study along a topographic gradient from a dry oak woods, through a mesic forest, to a floodplain forest. Maximum leaf height roughly doubles with each 7% increase in herbaceous cover, corresponding rather closely to quantitative predictions based on independent measures of the allometry of support tissue as a function of leaf height. The low stature of evergreen herbs favored by winter conditions appears to restrict their occurrence to dry, sterile sites with low coverage by summer competitors, and may be another factor favoring an association between evergreenness and soil poverty in temperate forest herbs. Patterns of leaf height among orchids native to the northeastern United States correspond to the qualitative predictions of the model. Extensions of the model are sketched for herbs in open habitats; woody plants; higher leaves in reproductive individuals; selection on flower or fruit height; evolutionary advantages of the herbaceous habit in relation to height growth; and the evolution of altruism along relatives. If a species occurs in herbaceous communities of high density only when its neighbors are close relatives, selection may favor the evolution of lower, more "altruistic" leaf heights than with unrelated competitors. Aster macrophyllus, which usually has basal leaves even though it occurs in dense herb communities, is advanced as a possible case of altruism in that its stands are nearly monospecific and appear to be maintained by allelopathic compounds.

Ecological Distributin of Mice in the Medicine Bow Mountains of Wyoming

The distribution of six species of native mice with regard to plant communities, vegetative ground cover, and proximity of water was studied in the Medicine Bow Range of Southern Wyoming. The eight types of plant communities sampled were: mountain mahogany, sagebrush, aspen, subalpine meadow, willow—alder bog, lodgepole pine, spruce—fir, and alpine tundra. The western jumping mounse (Zapus princeps) and long—tailed vole (Microtus longicaudus) both reached their greatest densities in three habitats: Willow—alder, aspen forest, and subalpine meadows. Both species preferred sites adjacent to water and having dense ground cover. The montane vole (Microtus montanus) was most abundant in meadow situations as exemplified by alpine tundra and subalpine forb—sedge meadows. This species preferred moderate to dry situations and dense to intermediate ground cover. The redbacked vole (Clethrionomys gapperi) was by far the most abundant species taken in lodgepole pine and spruce—fir communities. This species occurred commonly at a distance from water and was equally abundant in areas of dense, intermediate, or sparse vegetative ground cover. The heather vole (Phenacomys intermedius) was not trapped in great numbers at any locale but was most frequently taken in subalpine meadows, spruce—fir forest, and alpine tundra, indicating the species is primarily a high altitude form. Heather voles exhibited no preferences with regard to proximity of water or density of ground cover. The deer mouse (Peromyscus maniculatus) was the most widely distributed species studied, but displayed particularly high densities in mountain mahogany and sagebrush communities. The habitats yielding the highest overall mouse production were those located at lower elevations in the mountains, i.e. the sagebrush, mountain mahogany, aspen, and subalpine meadows; while those habitats yielding the lowest number of mice were at highest elevations, i.e. lodgepole pine, spruce—fir, and alpine tundra. The proximity of water seemed to have no clearcut effect on the overall production of mice, although areas of dense cover were on the average twice as productive as those with sparse cover.