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Wildlife researchers and conservation biologists are encountering growing research difficulties due to strong and effective advocacy of animal welfare concerns. However, collecting information on the basic biology of animals, which is often essential to effective conservation and management, frequently involves invasive research. The latter is unacceptable to some animal welfare advocates, even if it ultimately leads to better conservation outcomes. For effective biodiversity conservation it is imperative that conservation and wildlife researchers lucidly present the case for their research on individual animals. This requires conservation biologists and the research community in general, to present these arguments in the public domain as well as in peer-reviewed literature. Moreover, it is important to measure how these activities affect animals. Only then can we show that high quality research activities often have little or no effects on animal vital rates and performance.
Context. Fertility control appears as a publicly acceptable alternative to lethal methods for limiting population growth in wildlife. Recently developed single-dose immunocontraceptive vaccines have induced infertility in several mammals. However, the potential side-effects and the long-term effectiveness of these contraceptives have been poorly investigated.
Aims. We tested the long-term effectiveness and potential side-effects of the single-dose gonadotrophin-releasing hormone (GnRH) vaccine GonaCon™ on captive female wild boar.
Methods. We carried out two sequential trials: Trial 1 (n = 6 GonaCon™-treated and 6 control wild boar) and Trial 2 which started two years later and replicated Trial 1. We assessed the effectiveness of GonaCon™ to cause infertility by measuring GnRH antibody titres, by monitoring the oestrous cycle through the concentration of faecal progesterone and by recording the sows’ reproductive output in the 4–6 years following treatment. We evaluated the potential side-effects by monitoring behaviour, bodyweight and haematological and biochemical variables.
Key results. GnRH-antibody titres decreased with time but were still detectable in all females six years after vaccination with a single dose of GonaCon™. In Trial 1 none of the treated females gave birth in the six years after vaccination. In Trial 2, progesterone indicated that two of the six treated females were cycling. One of the cycling treated females gave birth one year after vaccination; the other five, including the second cycling sow, did not reproduce in the four years following vaccination. We found no differences in bodyweight, haematology, biochemistry and behaviour and no obvious sign of injection site reaction.
Conclusions. GonaCon™ can suppress reproduction in wild boar with no long-term effects on behaviour and physiology. Therefore, GonaCon™ can be regarded as an effective and safe contraceptive for this species.
Implications. The lack of evidence of adverse effects and the longevity of effect of GonaCon™ suggest that this contraceptive could be now tested in field trials and in contexts where culling of overabundant populations of wild boar is unfeasible, illegal or unacceptable. These instances include urban areas, parks, and management of diseases where culling might cause social perturbation and result in increased disease transmission rates.
Context. There is growing evidence that vertebrates inhabiting the extensive savannas of northern Australia are undergoing a widespread decline as a result of the effects of anthropogenic land management such as the grazing of domestic stock. Despite the ubiquity of pastoral grazing in the Australian savannas, few studies have examined the changes in terrestrial vertebrate fauna following destocking.
Aims. The present study monitored the response of birds, mammals and reptiles to destocking of a newly acquired conservation reserve in north-eastern Australia.
Methods. The vertebrate fauna was sampled over a 5-year period. Standardised 1-ha survey was conducted twice a year in 2006, 2007 and 2010, at 40 sites representing six habitat types.
Key results. The fauna assemblage, the abundance and richness of major taxa, and the abundance of a suite of individual species were found to vary significantly with time since destocking. Although some of the observed trends were consistent with previously reported responses of vertebrates to grazing, in general species richness and abundance did not increase linearly over time since destocking, with an overall decline in the first year, and an increase in the subsequent survey. Mammals remained at very low abundance and displayed a trend contrary to that for birds and reptiles, and variation was often confounded by habitat type.
Conclusions. In general, where there has been a long history of pastoral land management, destocking alone may not induce short-term increases in the vertebrate fauna thought to be affected by grazing in Australian savannas.
Implications. Monitoring the outcomes of conservation management activity is a critical component of understanding the success, failures and adaptation needed to maximise the costs and benefits of conservation investment. The recovery of the vertebrate fauna thought to be of conservation concern in relatively intensively used, long-grazed landscapes may be lengthy and contingent on other factors, such as periods of favourable weather, or understanding the interactive effects of herbivore removal, fire pattern and feral predators. In such landscapes, it is possible that recovery of some elements of the vertebrate fauna may not occur without deliberate interventions, such as reintroductions or intense predator control.
J. C. Z. Woinarski, A. Fisher, M. Armstrong, K. Brennan, A. D. Griffiths, B. Hill, J. Low Choy, D. Milne, A. Stewart, S. Young, S. Ward, S. Winderlich, M. Ziembicki
Context. A previous study reported major declines for native mammal species from Kakadu National Park, over the period 2001–09. The extent to which this result may be symptomatic of more pervasive biodiversity decline was unknown.
Aims. Our primary aim was to describe trends in the abundance of birds in Kakadu over the period 2001–09. We assessed whether any change in bird abundance was related to the arrival of invading cane toads (Rhinella marina), and to fire regimes.
Methods. Birds were monitored at 136 1-ha plots in Kakadu, during the period 2001–04 and again in 2007–09. This program complemented sampling of the same plots over the same period for native mammals.
Key results. In contrast to the decline reported for native mammals, the richness and total abundance of birds increased over this period, and far more individual bird species increased than decreased. Fire history in the between-sampling period had little influence on trends for individual species. Interpretation of the overall positive trends for bird species in Kakadu over this period should be tempered by recognition that most of the threatened bird species present in Kakadu were unrecorded in this monitoring program, and the two threatened species for which there were sufficient records to assess trends – partridge pigeon (Geophaps smithii) and white-throated grass-wren (Amytornis woodwardi) – both declined significantly.
Conclusions.The current decline of the mammal fauna in this region is not reflected in trends for the region’s bird fauna. Some of the observed changes (mostly increases) in the abundance of bird species may be due to the arrival of cane toads, and some may be due to local or regional-scale climatic variation or variation in the amount of flowering. The present study provides no assurance about threatened bird species, given that most were inadequately recorded in the study (perhaps because their decline pre-dated the present study).
Implications. These contrasting trends between mammals and birds demonstrate the need for biodiversity monitoring programs to be broadly based. The declines of two threatened bird species over this period indicate the need for more management focus for these species.
Context. Turtles are one of the most imperilled taxonomic groups worldwide and information about population ecology is essential to species recovery. Although the spatial ecology and demography of adults of several turtle species have been well studied, little is known about early life stages. The small size, soft shell, and limited mobility of hatchling turtles may cause differences in survivorship and habitat selection compared with adults.
Aims. We tested the hypothesis that hatchling turtles select habitat as they move away from nests, so as to reduce the risk of predation and desiccation.
Methods. We examined survivorship, behaviour and habitat selection at two spatial scales in hatchling Blanding’s turtles (Emydoidea blandingii) and wood turtles (Glyptemys insculpta) in 2009 and 2010, using radio-telemetry in Algonquin Provincial Park, Ontario, Canada. In addition, temperatures of sites used by hatchlings during winter were compared with those at haphazard stations in various habitats.
Key results. The mortality rate was high, with 42% of E. blandingii and 11% of G. insculpta hatchlings surviving to winter; most mortality was caused by predation. Most behavioural observations for both species were of individuals hiding under cover. Both species showed evidence of macrohabitat and microhabitat selection as they dispersed from nests towards overwintering sites, and important variables in the models differed between species. Likewise, the adult stages of these two species differ in their macrohabitat specialisation. There was also evidence that hatchlings chose overwintering sites on the basis of temperature.
Conclusions. Despite significant differences in survivorship between hatchlings and adults, resource selection was similar between these two demographic stages, and conservation plans based on adult habitat use should simultaneously protect hatchlings.
Implications. Understanding habitat selection by juveniles is important for testing hypotheses about ontogenetic shifts in resource selection and for protecting habitat for species at risk.
Context. Central Australia has been a graveyard for native mammals, with many small and medium-sized species becoming extinct or persisting in reduced geographical ranges in this region since the advent of European settlement. Species in the critical weight range (35–5500 g) have been affected most dramatically.
Aims. We compared the dynamics of two geographically distant populations of a medium-sized surviving desert mammal, the brush-tailed mulgara (Dasycercus blythi, ∼100 g), and tested the hypothesis that this species’ persistence can be explained by its demographic plasticity.
Methods. Paired sampling grids, each 31.5 ha, were set up in the Tanami Desert on the northern edge of the species’ geographical range and near Uluru Kata Tjuta National Park (UKTNP) on the southern boundary. Animals were live-trapped every 3 months between 1992 and 1995, and estimates made of population size, residency, reproduction, bodyweight and tail width; the latter was used as an index of condition.
Key results. The UKTNP site supported a larger population of D. blythi than did the Tanami Desert site. In both areas, the population fluctuated annually, declining during the breeding season (June to October) and increasing again following the influx of juveniles in spring. Females had one litter per year, with a median and maximum litter size of six; births in the Tanami occurred in July, at least a month earlier than they did at UKTNP. Bodyweights and tail widths peaked before breeding and then declined until spring, with animals retaining better body condition in the Tanami than at UKTNP. In both regions, individuals were resident for 1–2 years; daughters remained near their mother’s home range but males moved to other areas.
Conclusions. The results provided little support for our initial expectation that populations of D. blythi would behave differently in disparate parts of the species’ geographical range, and suggested instead that this mulgara exhibits a predictable life history, with limited demographic flexibility.
Implications. The persistence of D. blythi in central Australia is most likely a result of its striking flexibility in use of food resources, its ability to enter torpor and to tolerate large declines in bodyweight and condition, and its propensity to dig deep burrows. We suggest that these attributes buffer mulgaras from the impacts of introduced predators that have contributed to extinctions of other medium-sized marsupials, and from climatic and resource uncertainties that shape the dynamics of many smaller desert mammals.
Context. The phylogenetic diversity and biogeography of most animal and plant lineages endemic to the Australian Monsoonal tropics remains poorly understood. Of particular note (and in contrast to many other tropical regions in both Australia and elsewhere) is the current paucity of evidence for diverse endemic radiations of restricted-range taxa.
Aims. To use recently collected material from major surveys of the Kimberley Islands, Western Australia, to expand on a previous study that provided preliminary evidence of very high levels of geographically structured phylogenetic diversity in a lineage of tiny geckos (Crenadactylus).
Methods. Mitochondrial (ND2) and nuclear (RAG-1) sequence data were used to estimate the relationships, phylogenetic diversity and timescale of diversification of all populations of Crenadactylus from northern Australia from which samples for genetic analysis were available.
Key results. In striking contrast to the two subspecies currently recognised in the Kimberley, our analyses confirm the existence of a notable diversity of highly divergent and apparently allopatric lineages within the Kimberley, including at least 10 that are estimated to date to the late Pliocene/early Miocene (or earlier) and seven that we recognise as candidate new species. Most of this diversity is concentrated in the high-rainfall zone along the western edge of the Kimberley.
Key conclusions. A growing number of genetic datasets are revealing northern Australian vertebrate clades characterised by the juxtaposition of deeply divergent and highly geographically structured genetic diversity on the one hand, and major geographic gaps in sampling that impede full assessment of the distribution and taxonomic significance of this diversity on the other.
Implications. There is a pressing need for further surveys, voucher material and phylogenetic analyses to allow us to properly understand the diversity, biogeography and conservation needs of the northern Australian biota.
Context. Fire and grazing have complex and interacting impacts on food resources available to endangered herbivores and can potentially be manipulated as part of conservation strategies.
Aims. We examined the interacting impacts of fire and grazing on the food resources available to a colony of endangered brush-tailed rock-wallabies (Petrogale penicillata) to test fire as a potential management tool.
Methods. We conducted two manipulative experiments using a repeated-measures split-block design. We measured the effects of grazing and strategic burning on total vegetation biomass and on particular plants selected by rock-wallabies. In the first experiment we measured the impact of rock-wallaby grazing alone. In the second experiment we measured grazing impacts by both rock-wallabies and potentially competitive sympatric macropods. Grazing was manipulated with three treatments: grazed (open), ungrazed (fenced) and procedural control (half fence).
Key results. In both experiments, burning resulted in greater above-ground biomass of plants selected by rock-wallabies. The response of different plant functional groups to fire was staggered, with forb biomass peaking early and browse biomass increasing above unburnt levels a year after burning.
Conclusions. Despite the limited grazing pressure exerted by the small colony of rock-wallabies in Experiment 1 we detected a negative grazing effect on forbs growing after fire in burnt plots. In Experiment 2, grazing pressure was much more marked due to the high densities of sympatric macropods. In this case, while burning resulted in greater biomass of plants selected by rock-wallabies, grazing (predominantly by sympatric macropods) negated this effect.
Implications. Small patchwork burning can be a useful tool to improve food resources for brush-tailed rock-wallabies, with effects sustained over more than two years. However, when rock-wallabies are sympatric with possible competitor species, the grazing impacts of sympatric macropods may cancel out any benefits to rock-wallabies.
Context. In many countries, hunting has emerged as a major source of funding for wildlife conservation and research or habitat acquisition. In some countries, recent declines in recruitment of hunters have generated concerns about the consequences of the rapid demographic change within society in general, and among hunters in particular. Gaining a better understanding of how these demographic changes influence dedication to and motivation for hunting has therefore become an important task.
Aims. Our aims included documenting the demographic transition among Danish hunters, and identifying correlates of hunter recruitment age, motivations and dedication.
Methods. We addressed these aims using a national survey of Danish hunters in 2000 (n = 1186) and 2006 (n = 701). Survey data were analysed using multiple regression models.
Key results. Whereas recruitment numbers remained stable, the average age of recruitment for hunters increased from 21 to 34 between 1984 and 2006, and the percentage of new hunters younger than 20 declined from 63% to 19% during the same period. Respondents who hunted to experience nature were recruited at older ages than other hunters. Recruitment age was negatively related to number of days hunting per year and relative importance placed on hunting as a recreational activity, and positively related to being recruited by friends, female gender, being married, and having an urban childhood.
Conclusions. The global demographic transition towards an older and more urban populace may drive a change in hunter demographics rather than a decline of hunting.
Implications. The present study suggests that hunting can persist in the face of rapid demographic change. However, the study also indicates several important structural barriers for new hunters, favouring those hunters being economically most well off and leading to a decline in hunting dedication. To meet these challenges, the study suggests that modifications will be needed in hunter education programs and hunter recruitment campaigns, so as to maintain hunting as a significant positive factor within wildlife conservation.
Context. To interpret spatial utilisation distributions, there is a need to translate animal locations obtained from global positioning system (GPS) telemetry into the activities performed and, hence, benefits derived, from particular places and times of day. Derived activity patterns also reveal how animals cope in changing environmental conditions.
Aim. The aim of our research was to develop and test an objective, consistent and biologically faithful method for deriving activity states from movement rates between successive GPS locations.
Methods.The method entails fitting mixtures of component statistical distributions to the frequency distribution of hourly step displacements. Breakpoints indicating transitions between predominant movement modes were identified by fitting exponential segments. Breakpoints were incorporated as off-sets for gamma distributions, but not needed for log-normal distributions. This procedure was applied to movement data for three large grazing ungulates.
Key results. Models consistently distinguished four movement modes interpreted as representing resting, foraging, mixed movement and travelling activity. Breakpoints and parameter estimates were consistent among seasons and herds of each ungulate species. The exponential-segment model and both mixture models closely represented observed daily activity patterns. However, some adjustment of the derived time budgets was needed to be consistent with observations.
Key conclusions.Mixture models provide an objective, reliable and biologically meaningful procedure for assessing seasonal, annual and spatial variation in the activity patterns of large ungulates from GPS data.
Implications. The method can potentially be applied to other mobile foragers large enough to carry GPS collars.
Context. Life-history strategies are the means that organisms use to achieve successful reproduction in environments that vary in time and space. Individual animals maximise life-time reproductive success (LRS) through optimal timing of reproduction and investment in offspring. A crucial factor affecting LRS is predation risk in a highly seasonal environment. According to the breeding-suppression hypothesis (BSH), females should delay breeding under short periods of high predation risk. Delayed breeding under risk is suggested to have substantial consequences for females’ fitness.
Aims. We tested the BSH in an iteroparous boreal small rodent, the bank vole, Myodes glareolus.
Methods. We used caged-live weasels and spread weasel scent to simulate increased predation risk in four of eight 0.25-ha outdoor enclosures. We monitored females’ reproduction in three periods (May, July, August), i.e. during the breeding season over the course of summer.
Key results. Contrary to our main prediction, predation risk did not affect timing of mating, pregnancy rate or litter size in any study period.
Conclusions and implications. We conclude that during the short but resource-rich breeding season of boreal summer, postponing breeding does not seem to be an optimal strategy for females, even under high risk of predation. Under favourable summer condition, i.e. in circumstances without any constraining factors such as food or conspecific density, females manage to balance the costs of predation against benefits of resource availability and do not suppress breeding. Although the BSH has been studied widely, also our results reveal the intricacies of this adaptive behaviour.
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