An Integrated Vehicle-Mounted Telemetry System for VHF Telemetry Applications

Abstract: We designed and developed a vehicle-mounted very high frequency-based telemetry system that integrated an on-board antenna, receiver, electronic compass, Global Positioning System, computer, and Geographic Information System. The system allows users to accurately and quickly obtain fixes, estimate and confirm locations of radiomarked animals, and immediately record data into an electronic spreadsheet or database. The total cost of materials to build the system was $7,349 (United States currency). Mean error angle of 2.63 ± 12.1° (SD; range = −33.7–42.2°) and mean location error distance of 128 ± 91.3 m (SD; range = 0–408 m) suggested precision and accuracy of our system were comparable to other reported systems. Mean time to record 5 bearings/test transmitter was 6.28 ± 0.24 minutes (SE), which is the most efficient system reported to locate animals in the field. Vehicle-mounted telemetry systems like ours provide additional value to studies that involve tracking highly mobile species because investigators need not take bearings from established receiving stations and because investigators can immediately recognize bounced signals and take additional bearings and optimize accuracy of location estimates.     

Annual and seasonal trends in the use of garden feeders by birds in winter

Provision of bird food in gardens is a common activity that may provide an alternative food source to birds in winter. Long-term survey data recording the weekly presence of all bird species using garden feeders in the winter were analysed to see if there was any evidence of trends in feeder use between 1970 and 2000 and whether these trends were correlated with breeding bird population trends. Of 41 species analysed, 21 showed significant increases in occurrence at garden feeders between 1970 and 2000. Many of these increases were evident only in the last 10 years. Several species showed significant positive correlations between trends in winter garden use and trends in relative population size in the previous breeding season. This was especially the case for species with population change (either increase or decrease) of the greatest magnitude. There was no evidence that seasonal shifts in garden feeder use were associated with population change in any species. Temperature was an important predictor of garden use but could not explain the year-to-year trends. However, as the number of feeding stations had increased over time the response of birds to the greater food availability in gardens may have been responsible for the widespread increases in occurrence of several species.     

At what spatial scales does resource selection vary? A case study of koalas in a semi‐arid region

The conservation of any species requires understanding and predicting the distribution of its habitat and resource use, including the effects of scale‐dependent variation in habitat and resource quality. Consequently, testing for resource selection at the appropriate scales is critical. We investigated how the resource selection process varies across scales, using koalas in a semi‐arid landscape of eastern Australia as a case study. We asked: at what scales does tree selection by koalas vary across regions? We tested the importance of the variation of our ecological predictors at the following scales: (i) the site‐scale (a stand of trees representing an individual koala's perception of local habitat); (ii) the landscape‐scale (10 × 10 km area representing a space within which a population of koalas exists); and (iii) a combination of these scales. We used a mixed‐modelling approach to quantify variation in selection of individual trees by koalas among sites and landscapes within a 1600 km² study area. We found that tree species, and tree height, were the most important factors influencing tree selection, and that their effect did not vary across scales. In contrast, preferences for trees of different condition, which is the state of tree canopy health, did vary across landscapes, indicating spatial variation in the selection of trees with respect to tree condition at the landscape‐scale, but not at the site‐scale. We conclude that resource selection processes can depend on the quality of those resources at different scales and their heterogeneous nature across landscapes, highlighting the consequence of scale‐dependent ecological processes. Designing studies that capture the heterogeneity in habitat and resources used by species that have an extensive distribution is an important prerequisite for effective conservation planning and management.     

Anthropogenic changes to the landscape resulted in colonization of koalas in north‐east New South Wales,Australia

Significant changes in the distribution and persistence of species have been driven by Pleistocene cyclical climate changes and, more recently, by human modification of the environment. In eastern Australia, Pleistocene cyclical patterns in temperature and aridity led to the expansion and retraction of rainforest and likely affected the distribution of the koala (Phascolarctos cinereus, family Phascolarctidae), a species preferring dry or open woodland. More recently, anthropogenic landscape modification has led to a large‐scale change in distribution of the koala following the destruction of approx. 75 000 ha of subtropical rainforest in north‐east New South Wales termed the ‘Big Scrub’. Sharing of the control region haplotypes to the north and south of this region indicate historical connectivity of coastal koala populations. However, the majority (110/115) of sampled koalas from this region shared a single mitochondrial control region haplotype, suggesting that koalas did not persist in multiple refugial pockets within a heterogenous rainforest but expanded into the region following deforestation. Bayesian cluster analysis of microsatellite data consistently identified two clusters of koalas. One cluster, in the north of the area, had high microsatellite diversity (10 alleles per locus, He = 0.79) and clustered with koalas further to the north, thus suggesting a southerly expansion into the cleared area. To the south was a cluster with significantly lower diversity (six alleles per locus, He = 0.59, P < 0.001). It is possible there has been restricted or filtered movement of koalas between these clusters, which coincides with a cleared river valley and associated roads or immigration from populations both to the north and to the south. This study gives an insight into the timescale of changes in species distribution following rapid alterations to suitable habitat.     

A High Arctic soil ecosystem resists long‐term environmental manipulations

We evaluated above‐ and belowground ecosystem changes in a 16 year, combined fertilization and warming experiment in a High Arctic tundra deciduous shrub heath (Alexandra Fiord, Ellesmere Island, NU, Canada). Soil emissions of the three key greenhouse gases (GHGs) (carbon dioxide, methane, and nitrous oxide) were measured in mid‐July 2009 using soil respiration chambers attached to a FTIR system. Soil chemical and biochemical properties including Q₁₀ values for CO₂, CH₄, and N₂O, Bacteria and Archaea assemblage composition, and the diversity and prevalence of key nitrogen cycling genes including bacterial amoA, crenarchaeal amoA, and nosZ were measured. Warming and fertilization caused strong increases in plant community cover and height but had limited effects on GHG fluxes and no substantial effect on soil chemistry or biochemistry. Similarly, there was a surprising lack of directional shifts in the soil microbial community as a whole or any change at all in microbial functional groups associated with CH₄ consumption or N₂O cycling in any treatment. Thus, it appears that while warming and increased nutrient availability have strongly affected the plant community over the last 16 years, the belowground ecosystem has not yet responded. This resistance of the soil ecosystem has resulted in limited changes in GHG fluxes in response to the experimental treatments.     

Inside the Neolithic Mind: Consciousness, Cosmos, and the Realm of the Gods

Inside the Neolithic Mind: Consciousness, Cosmos, and the Realm of the Gods. David Lewis-Williams and David Pearce. New York: Thames and Hudson, 2005. 320 pp.     

One hundred years of eruptions of house mice in Australia – a natural biological curio

The house mouse has adapted well to the cereal crops of south-eastern Australia where populations show aperiodic outbreaks over large areas. A 20-year population study has provided a wealth of information on breeding ecology, demographic changes, spatial behaviour and epidemiology. The breeding season can be as short as 4.5 months and as long as 10 months with litter size changing seasonally from high values in spring to low values in autumn. There are marked changes in litter size between years. Rates of increase of populations also vary between years. The rate of change of populations during the breeding season is independent of density effects, but if the population density is high at the commencement of breeding then the litter size is depressed throughout that breeding season. There are density-dependent effects on survival during the non-breeding season. Rates of increase of populations over spring and summer are highly correlated with accumulated rainfall from the previous winter–spring (April–October). Studies of helminths and viruses indicate that Australian mice carry only a subset of the helminths found in Europe. There have been no published studies on murine viruses in Europe. Perhaps a reduced diversity of diseases partially accounts for the ability of mice to increase rapidly to extreme population densities in cereal-growing areas of south-eastern Australia.  © 2005 CSIRO, Biological Journal of the Linnean Society , 2005, 84 , 617–627.