Management Of Wildlife Populations Research Articles

Contraceptive efficacy of recombinant fusion protein comprising zona pellucida glycoprotein-3 fragment and gonadotropin releasing hormone

Contraceptive vaccines have been used for the management of wildlife population. In the present study, we have examined the contraceptive potential of Escherichia coli-expressed recombinant fusion protein comprising of ‘promiscuous’ T cell epitope of tetanus toxoid [TT; amino acid (aa) residues 830–844] followed by dilysine linker (KK), dog ZP3 fragment (aa residues 307–346), triglycine spacer (GGG), T cell epitope of bovine RNase (bRNase; aa residues 94–104), GnRH, T cell epitope of circumsporozoite protein of Plasmodium falciparum (CSP; aa residues 362–383), and GnRH. SDS-PAGE analysis of the purified refolded protein revealed a dominant ∼12kDa band, which in Western blot reacted with mouse polyclonal antibodies against dog ZP3 fragment and mouse monoclonal antibodies against GnRH. Immunization of female FvB/J mice following two booster schedule with the above recombinant protein supplemented with alum led to high antibody titres against the immunogen as well as ZP3 and GnRH as determined by ELISA. The immune sera reacted with zona pellucida of mouse oocyte and also inhibited in-vitro fertilization. The qRT-PCR studies showed decrease in the ovarian GnRH receptor in mice immunized with the recombinant fusion protein. Mating studies revealed high contraceptive efficacy of the recombinant protein as in two independent experiments, 90% of the immunized female mice failed to conceive. Following one booster immunization schedule, 50% of the immunized female mice failed to conceive. However, in adjuvanted controls, all the female mice became pregnant. To conclude, the recombinant protein described herein has a good potential to be developed as candidate contraceptive vaccine.

Conservation implications of ameliorating survival of little brown bats with white-nose syndrome.

Management of wildlife populations impacted by novel threats is often challenged by a lack of data on temporal changes in demographic response. Populations may suffer rapid declines from the introduction of new stressors, but how demography changes over time is critical to determining long-term outcomes for populations. White-nose syndrome (WNS), an infectious disease of hibernating bats, has caused massive and rapid population declines in several hibernating species of bats in North America since the disease was first observed on the continent in 2006. Estimating annual survival rates and demographic trends among remnant colonies of hibernating bats that experienced mass mortality from WNS is needed to determine long-term population viability of species impacted by this disease. Using mark-recapture data on infected little brown bats (Myotis lucifugus), we estimated the first apparent annual survival rates for four years following WNS detection at a site. We found strong support for an increasing trend in annual survival, which improved from 0.68 (95% CI = 0.44-0.85) to 0.75 (95% CI = 0.51-0.89) for males and 0.65 (95% CI = 0.44-0.81) to 0.70 (95% CI = 0.50-0.84) for females. These results suggest that stabilization at remnant colonies after mass mortality from WNS may be due to improved survival and not from immigration from other areas. Despite ameliorating survival, our stochastic matrix projection model predicts continued declines for little brown bat populations (λ = 0.95), raising concern for the regional persistence of this species. We conducted a vital rate sensitivity analysis and determined that adult and juvenile survival, as opposed to fecundity, are the demographic parameters most important to target to maximize recovery potential of little brown bat populations in areas impacted by WNS.

Status of blue duiker (<i>Cephalophus monticola</i>) in the Lebialem-Mone- Banyang-Mbo landscape, South-West Cameroon

A survey of blue duikers ( Cephalophus monticola ) in the Lebialem-Mone-Banyang-Mbo (LMBM) landscape was conducted during the period of May to September 2012 with the aim of establishing a database for the enhancement of sustainable management of Wildlife population. The line transect method (Tsi, 2011) was used for data collection. Results revealed an encounter rate of 12.8 indexes per km, a density of 2.56 per km 2 and estimate of 1162 blue duikers in the entire landscape. The findings also showed that there is currently a high level of bush meat harvesting and a tragic forest transformation due to uncontrolled anthropogenic activities in the landscape. In comparison with the findings of Walhert in Korupt national park, the estimated density in the LMBM landscape was considered relatively high for a non protected area. It was concluded that this high population of blue duikers against a background of intense anthropogenic activities is indicative; It is strong evident that LMBM landscape serves as a natural wildlife corridor, linking it many surrounding protected areas. There the gazetment of the proposed Bechati- Mone wildlife corridor situated in the LMBM landscape will go a long way to enhance effective wildlife conservation in the region. Keywords : Conservation status, blue duiker, encounter rate, anthropogenic activities, sustainable management, wildlife corridor.

Optimal Control of a Threatened Wildebeest-Lion Prey-Predator System in the Serengeti Ecosystem

We develop a two-species prey-predator model in which prey is wildebeest and predator is lion. The threats to wildebeest are poaching and drought while to lion are retaliatory killing and drought. The system is found in the Serengeti ecosystem. Optimal control theory is applied to investigate optimal strategies for controlling the threats in the system where anti-poaching patrols are used for poaching, construction of strong bomas for retaliatory killing and construction of dams for drought control. The possible impact of using a combination of the three controls either one at a time or two at a time on the threats facing the system is also examined. We observe that the best result is achieved by using all controls at the same time, where a combined approach in tackling threats to yield optimal results is a good approach in the management of wildlife populations.

Road development and the geography of hunting by an Amazonian indigenous group: consequences for wildlife conservation.

Protected areas are essential for conservation of wildlife populations. However, in the tropics there are two important factors that may interact to threaten this objective: 1) road development associated with large-scale resource extraction near or within protected areas; and 2) historical occupancy by traditional or indigenous groups that depend on wildlife for their survival. To manage wildlife populations in the tropics, it is critical to understand the effects of roads on the spatial extent of hunting and how wildlife is used. A geographical analysis can help us answer questions such as: How do roads affect spatial extent of hunting? How does market vicinity relate to local consumption and trade of bushmeat? How does vicinity to markets influence choice of game? A geographical analysis also can help evaluate the consequences of increased accessibility in landscapes that function as source-sink systems. We applied spatial analyses to evaluate the effects of increased landscape and market accessibility by road development on spatial extent of harvested areas and wildlife use by indigenous hunters. Our study was conducted in Yasuní Biosphere Reserve, Ecuador, which is impacted by road development for oil extraction, and inhabited by the Waorani indigenous group. Hunting activities were self-reported for 12–14 months and each kill was georeferenced. Presence of roads was associated with a two-fold increase of the extraction area. Rates of bushmeat extraction and trade were higher closer to markets than further away. Hunters located closer to markets concentrated their effort on large-bodied species. Our results clearly demonstrate that placing roads within protected areas can seriously reduce their capacity to sustain wildlife populations and potentially threaten livelihoods of indigenous groups who depend on these resources for their survival. Our results critically inform current policy debates regarding resource extraction and road building near or within protected areas.

Canine zona pellucida glycoprotein-3: Up-scaled production, immunization strategy and its outcome on fertility

Zona pellucida (ZP) glycoproteins based contraceptive vaccines have been proposed for the management of wildlife population. In the present study, a fusion protein encompassing promiscuous T cell epitope of tetanus toxoid [TT; amino acid (aa) residues 830–844] followed by a dilysine linker and an ectodomain of dog ZP3 (ZP3; aa residues 23–348) without any affinity tag (TT-KK-ZP3) has been expressed in Escherichia coli. The recombinant protein was successfully produced in fed-batch fermentor and purified. The average yield of purified refolded protein was 12.20±0.61mg/2g wet cell pellet. Female FvB/J mice immunized with the varying doses of recombinant TT-KK-ZP3 supplemented with alum/PetGel A as adjuvants following a three injection schedule, showed dose dependent increase in serum IgG titer. Antibodies against TT-KK-ZP3 recognized native mouse/dog ZP and significantly inhibited mouse in-vitro fertilization (p=0.012). Immunized mice showed significant reduction in fertility (p<0.05). Higher antibody titers were associated with a decrease in the number of pups born to the immunized female mice. To reduce the number of injections, two injection schedule using various dose combinations of TT-KK-ZP3 supplemented with alum revealed lower immunogenicity and contraceptive efficacy as compared to the three injection schedule. To overcome this, CpG motif was included in addition to alum and both intraperitoneal and intranasal route of immunization following the two injection schedule was investigated. Inclusion of CpG significantly enhanced the antibody titer and improved contraceptive efficacy. In the mice immunized following intraperitoneal route, serum/vaginal IgG and in the mice immunized through intranasal route, vaginal IgA seemed to be important for curtailment in fertility. To conclude, the recombinant protein described herein may be a good candidate for developing contraceptive vaccine for the wildlife population management, in particular street dogs.

Integrating demographic data: towards a framework for monitoring wildlife populations at large spatial scales

SummaryLandscapes are becoming increasingly intensively managed resulting in greater anthropogenic disturbance of ecosystems. Effective policies for conservation and management of wildlife populations will require a mechanistic understanding of the processes underlying the population responses to these changes. Detailed demographic studies are often of individual populations in relatively stable habitats, whereas there is a need to characterize demographic variation at larger scales in wider landscapes that are subject to environmental change.We use long‐term (18–46 years) data sets, gathered by volunteers acrossBritain, to parameterizeBayesian state‐space demographic population models for 17 widely occurring bird species. As some demographic processes were not quantified directly, we introduce a scaling parameter (ρ) to account for this unmeasured variation, and assess the extent to which this influences our ability to understand the processes driving population change.The population models provided a good fit to the population trajectory in all but one species (the nocturnal tawny owlStrix aluco). The scaling parameter generally showed little annual variation and did not make a major contribution (&lt;12%) to population change among passerine species. For five non‐passerine species, the contribution was still not large (11–21%), but did indicate the importance of unmeasured demographic variables in these species.We were able to retrieve known demographic signals both within and across species. The importance of the nest failure rates was greater for species that construct nests in open rather than cavity situations. We also confirmed the demographic causes of population decline in two species of conservation concern, song thrush and lapwing, as changes in juvenile survival and reproductive success respectively. Furthermore, we show that population dynamics of declining species are generally driven more by recruitment than increasing species (for which variation in adult survival is more important).These analyses demonstrate that volunteer‐based monitoring programmes can provide insight into population changes at large spatial scales across a range of species. By facilitating the combination of data sets on different demographic parameters, the integrated approach adopted here allows important demographic parameters to be identified, even if they are not measured directly.

Quantitative analysis of woodpecker habitat using high-resolution airborne LiDAR estimates of forest structure and composition

Light detection and ranging (LiDAR) technology has the potential to radically alter the way researchers and managers collect data on wildlife–habitat relationships. To date, the technology has fostered several novel approaches to characterizing avian habitat, but has been limited by the lack of detailed LiDAR-habitat attributes relevant to species across a continuum of spatial grain sizes and habitat requirements. We demonstrate a novel three-step approach for using LiDAR data to evaluate habitat based on multiple habitat attributes and accounting for their influence at multiple grain sizes using federally endangered red-cockaded woodpecker (RCW; Picoides borealis) foraging habitat data from the Savannah River Site (SRS) in South Carolina, USA. First, we used high density LiDAR data (10returns/m2) to predict detailed forest attributes at 20-m resolution across the entire SRS using a complementary application of nonlinear seemingly unrelated regression and multiple linear regression models. Next, we expanded on previous applications of LiDAR by constructing 95% joint prediction confidence intervals to quantify prediction error at various spatial aggregations and habitat thresholds to determine a biologically and statistically meaningful grain size. Finally, we used aggregations of 20-m cells and associated confidence interval boundaries to demonstrate a new approach to produce maps of RCW foraging habitat conditions based on the guidelines described in the species' recovery plan. Predictive power (R2) of regression models developed to populate raster layers ranged from 0.34 to 0.81, and prediction error decreased as aggregate size increased, but minimal reductions in prediction error were observed beyond 0.64-ha (4×4 20-m cells) aggregates. Mapping habitat quality while accounting for prediction error provided a robust method to determine the potential range of habitat conditions and specific attributes that were limiting in terms of the amount of suitable habitat. The sequential steps of our analytical approach provide a useful framework to extract detailed and reliable habitat attributes for a forest-dwelling habitat specialist, broadening the potential to apply LiDAR in conservation and management of wildlife populations.

Effects of a GnRH vaccine on the movement and activity of free-living wild boar (Sus scrofa)

Context Fertility control is being promoted as a non-lethal means of managing wildlife populations. We recently evaluated a single-dose injectable immunocontraceptive vaccine (GonaCon™) on captive female wild boar for effectiveness and potential side effects; reproductive output was inhibited for 4–6 years, with no obvious detrimental effects on physiology and behaviour. Aims We injected individual free-living wild boar individuals with the fertility-control vaccine GonaCon™ to examine its effectiveness (measured as raised levels of GnRH antibodies) and looked for potential changes in movement and activity patterns. Methods We trapped, fitted telemetry devices to, and released wild boar individuals living in woodland in the West Midlands region of England between 2006 and 2010. We compared data on movements and activity among 10 adult females treated with the vaccine and 11 controls treated with saline only. We measured anti-GnRH antibody titres in six recaptured boar individuals as an indicator of the effectiveness of the vaccine. Key results Post-treatment GnRH antibody titres varied among the boar individuals; four of five treated sows resampled between 9 and 30 weeks post-injection had antibody titres high enough to block reproduction (detectable at 1 : 32 000–1 : 64 000 dilution). At least three treated females were pregnant at the time of vaccination; there was no subsequent evidence that the vaccine interfered with pregnancy. According to the distances moved per hour over a 24-h cycle and the daily activity cycle in relation to season, there were no differences in the behaviour of treated and control females that were likely to be biologically significant. The behaviour of two treated females monitored soon after vaccination and again 12 months later also showed no major differences. Conclusions Free-living wild boar responded to treatment with a 1.0-mL (1000 µg) dose of an anti-GnRH vaccine and no major adverse effects on activity and movement were subsequently detected. Implications Our results indicated that the vaccine could be more widely evaluated in the field against overabundant or nuisance populations. Such populations are increasingly found in urban areas and parks, where culling may not be an option. We suggest that further refinement of this approach for managing wild boar populations, including development of an oral vaccine, are warranted.

FROM THE PENS TO THE FIELD: REAL-WORLD WILDLIFE CONTRACEPTION

There are only two nonlethal approaches with which to manage wildlife populations: remove excess individuals or decrease reproductive rates. In the case of wild horse management, the latter has already been shown to be a more humane and less costly approach. Contraception has been known for many years to be effective in wild horses with regard to both fertility and population alteration. Field testing under real-world management situations is a critical aspect of wildlife contraception assessment. Field testing also requires documentation to justify eventual large-scale use of fertility control in population management. Furthermore, it is likely that full support by the managing agencies and acceptance of fertility control by the public will not occur until success has been demonstrated at the population level in the field. Because the transition from laboratory and captive animal trials to the real world of field research and testing of management potential in free-ranging wildlife is both essential and difficult, we identify considerations for optimizing success in the field, especially for controlling wild horse and white-tailed deer populations. This study identified the following categories for assessment: 1) field-specific logistics and tactics (including access to and identification of horses, censuses, pregnancy testing, and behavior monitoring), 2) training of field personnel and managers (including vaccine biology, preparation and delivery, and basic field methodology), 3) essential field considerations for enabling management (including population variables, environmental variables, and modeling), and 4) pitfalls of field contraception. In this assessment, we will highlight the capability for coincident pursuit of research and management and will explore field considerations applicable to many species where fertility control has potential as a management tool.

Supplemental feeding drives endoparasite infection in wild boar in Western Spain

Wildlife population management is thought to destabilize existing host–parasite equilibriums in opposing directions, that is, it may increase parasite success or host resilience once infection takes place. This process is of special importance for species such as the wild boar (Sus scrofa) that are managed for game purposes throughout much of Europe. However, little is known about how this practices influcences either gastrointestinal or pulmonary parasitism in the wild boar. Twelve hunting estates were chosen in order to study the relationship of management measures (feeder density, wild boar abundance, the ratio of wild boar per feeder and the percentage of sclerophyllous vegetation) and host factors (age and sex) with gastrointestinal and pulmonary parasite aggregation, richness, infection probability and intensity of infection. Parasitological analyses from 300 wild boar gastrointestinal and 269 respiratory tracts were performed for this purpose. A set of general linear models with combinations of the explanatory variables was built and the model with the smallest Akaike Information Criterion was selected as the best. The feeder density increased gastrointestinal parasite traits (richness, infection probability and intensity of infection), probably due to the contamination of feeding sites with infective parasite forms. Pulmonary parasite traits, on the other hand, were only influenced by host sex and age class, and parasite aggregation was as expected for a wild population. Managers should be aware of the consequences on parasitism when implementing supplemental feeding in hunting estates.

Field testing of single-administration porcine zona pellucida contraceptive vaccines in white-tailed deer (Odocoileus virginianus)

Context Many contraceptive agents have demonstrated effectiveness in wild species, most notably immunocontraceptives such as GnRH conjugates and porcine zona pellucida (PZP). The major challenge in using these agents to control deer and other wildlife populations in the field now lies with safe, effective and efficient delivery to a large-enough proportion of the population to suppress growth. Aims Because deer and other wildlife are typically difficult to access for treatment, contraceptives that require multiple or repeated treatments will be of limited management value. To address this constraint, we conducted a field study of white-tailed deer (Odocoileus virginianus) on Fripp Island, SC, USA, to test two different technologies for achieving single-administration, multi-year efficacy in PZP vaccines. Methods Between 2005 and 2010, we captured, ear-tagged and blood-sampled a total of 245 individual adult and yearling female deer. Deer were hand-injected at capture with one of two preparations of SpayVac or a combination native PZP–adjuvant emulsion plus PZP–adjuvant incorporated into lactide–glycolide polymer pellets engineered to release at 1, 3 and 12 months post-treatment. Pregnancy was determined from serum assays of pregnancy-specific protein B sampled from captured deer. Key results Aqueous SpayVac, and the PZP–adjuvant-containing polymer pellets manufactured through a heat extrusion (H/X) method administered simultaneously with PZP–AdjuVac or modified Freund’s complete adjuvant emulsions reduced pregnancy rates from control levels by 95–100% in the first year after treatment, and by 65–70% in the second year after treatment. Conclusions A single, hand-injected vaccination with SpayVac or PZP–adjuvant emulsion combined with H/X PZP pellets reduced fertility for multiple years. Implications Single-treatment, multi-year immunocontraceptive vaccines bring contraceptive management of wildlife populations one step closer. Future efforts should focus on improving handling and storage, developing technologies for remote delivery, and addressing remaining regulatory and management concerns.

基于MAXENT模型的贺兰山岩羊生境适宜性评价

Habitat evaluation has an important significance for management of wildlife populations and conservation planning. Geographic Information Systems( GIS) and abundant landscape-level data provide new opportunities for biologists to evaluate wildlife habitat quality. Maximum Entropy( MAXENT) is a recently introduced modeling technique,achieving high predictive accuracy and enjoying several additional attractive properties. With the purpose of predicting habitat for blue sheep( Pseudois nayaur) in the Helan Mountain Range,we collected the occurrence records for this species and the environmental factors,the occurrence records were collected from the study area from 2010 to 2011,and the date of environmental factors were extracted from the Thematic Mapper( TM) image of Helan Mountain in 2007. The method relies on the combined use of GIS and Maximum Entropy( MAXENT) model in this research. GIS was used to produce the data needed in the model,MAXENT can model species geographic distributions with presence-only data,and is suitable for the research because absence data are not available for blue sheep. A map indicated the distribution of habitat suitability of blue sheep in Helan Mountain generated from the data and software. In this paper,the method of Receiver Operating Characteristic( ROC) curve analysis was used to assess the accuracy of MAXENT model,the area under ROC curve( AUC) of the model was 0. 915,indicating that the result of assessment was excellent,and the results showed the relationships between the distribution of blue sheep and the environmental factors,the result of Jackknife test indicated that the mining,slope,altitude and road were the main factors influencing habitat selection of blue sheep. Along with the increase of slope,distance from mine and road,the habitat suitability increased gradually,and habitat suitability decreased gradually with the increasing distance from water. Suitable habitat was mainly distributed in southwest of Ningxia Helan Mountain National Nature Reserve( east part) and lesser distributed in the Inner-Mongolia Helan Mountain National Nature Reserve( west part),with the total area of 1 006. 9km2,accounting for 28% of the total assessment area. Blue sheep preferred to use montane savanna dominated and the rugged slopes at elevations of 1 500—2 300 m. There were two factors interfered in achieving accurate results,one was difficult to reach occurrence points for the steep terrain,and the other was that we could not get the information of traffic flow on every road. During the research,we reduced the error by recording the nearest position to the target point and choosing the main road on the maps. The results showed that the most serious human interferences were mining and road,more regulatory actions are needed to be taken in those aspects to improve the habitat's quality as well as promote the progress of the population.

基于核密度估计的动物生境适宜度制图方法

Habitat suitability mapping can provide information on spatial variation of wildlife habitat suitability which is useful for wildlife population management and conservation planning. The key issue of habitat suitability mapping is how to construct habitat suitability model( HSM). Existing presence-only based methods of constructing HSM cannot explicitly express the quantitative relationship between wildlife habitat suitability and environmental factors. So the resulted HSM would be insufficient to express the ecological effects of environmental factors on wildlife habitat use. In this paper we proposed a kernel density estimation-based method of using wildlife occurrence data to construct HSM for wildlife habitat suitability mapping,which can obtain the quantitative ecological relationship between habitat suitability and environmental factors. Under the assumption that habitat should be more suitable where wildlife presented more frequently,the presence probability density function( PDF) estimated from wildlife occurrence data was used to express the quantitative ecological relationship between habitat suitability and each individual environmental factor. Then,assuming that habitat suitability is determined by the limiting factor,a minimum operation was applied to construct the final HSM by synthesizing all these relationships on an environmental factor set. In the case study we applied the proposed kernel density estimation-based method to habitat suitability mapping of the White-tailed deer( Odocoileus virginianus) in Voyageures National Park based on 365 deer occurrence points from aerial survey and environmental data characterizing its living environment,with the aid of geographic information system techniques. The environmental factors selected were snow depth,land cover type,forest edge length,and slope gradient. Cross validation was used to evaluate the performance of the proposed method. Results showed that the mean of continuous Boyce Indexes calculated from 10 repetitions of 2-fold cross validation was 0.75 with a standard deviation of 0. 11. This suggests that the HSM from the proposed method has a good predictive capability. The proposed kernel density estimation-based method well captures the ecological effects of environmental factors on the wildlife habitat use in the form of quantitative relationship between wildlife habitat suitability and environmental factors. From the perspective of model interpretability,the proposed method is better than other HSM-constructing methods.

Heterozygote deficiencies caused by a Wahlund effect: Dispelling unfounded expectations

AbstractPopulation genetic tools can facilitate successful conservation and management of wildlife populations. However, the ability of such approaches to inform wildlife management and conservation programs depends upon assumptions linking genetic patterns to ecological processes, one implicit assumption usually being that genetic parameters (e.g., population genetic differentiation) estimated using a set of loci accurately reflect underlying demographic and microevolutionary forces affecting the population(s) under study. This is an important assumption because it also implies that we have acknowledged that genetic parameters estimated by a set of target loci inherently are associated with a sampling variance. Specifically, a perception exists that heterozygote deficits caused by biological mechanisms (e.g., a Wahlund effect) and null alleles can be differentiated by the expectation that the former leads to a concordant pattern across all loci, whereas the latter leads to locus‐specific effects. We use Monte‐Carlo simulation to demonstrate that these expectations do not always hold under biologically realistic conditions. Our analyses indicate that the conservative approach of discarding loci deviating from Hardy‐Weinberg equilibrium expectations could rob us of our most informative markers, weakening our ability to interpret biological phenomena. © 2012 The Wildlife Society.

Factors Influencing Survival of Female Elk in a Harvested Population

Abstract Understanding the influence of management actions and environmental conditions on demographic vital rates is important for effective conservation and management of wildlife populations. We used radio-telemetry to monitor annual and seasonal survival of 34 female elk Cervus elaphus at Fort Riley, Kansas in a 3.5-y field study (November 2003 to February 2007). We modeled the relationship between individual and environmental covariates and survival rates of female elk. We observed eight mortalities, and harvest was the primary cause of mortality in our study population. Annual survival rates of female elk in Kansas (0.76) were similar to other harvested populations of elk. Among the candidate model set, models that included age as a covariate were most supported. Parameter estimates from top models provided support for a slight negative relationship between age and survival. Monthly survival estimates during hunting season declined with age from 0.98 for 1.5-y-old females to 0.80 for 16.5-y-old females.

Wildlife law and policy

Wildlife law and policy

Seasonal Variation in Body Condition of Impala at Manyeleti Game Reserve, South Africa

The physiological condition of animals connects resources in the environment to demographic responses through reproduction, survival and abundance, and it provides critical information for conservation and management of wildlife populations. We used archived data (early-wet season 1987, late-wet and early-dry season 1988) from culls of impala (Aepyceros melampus) to compare how the kidney fat index (KFI, short-term index of body condition) and carcass mass (long-term index) varied seasonally. For females, KFI increased across seasons, a pattern similar for all age classes. For males, KFI was low and relatively invariable for juveniles and yearlings. For adults, KFI varied with reproductive cycle; highest KFI occurred early in the rut for males and around the second trimester for females. Carcass mass increased over time for growing juveniles and yearlings. For adults, female carcass mass varied according to reproductive cycle and was highest when KFI was highest. Male carcass mass was highest toward the end of the rut when KFI was relatively low. Although changes in body condition can be associated with seasonal changes in forage and activity, KFI and carcass mass are most useful when comparing across years with varying conditions, but within age, sex, and season.

Density dependence: Applications in wildlife management

AbstractKnowledge of density‐dependent processes is regarded as important for making decisions on the management of wildlife populations. Using published data on ungulates and upland game birds, we discuss density‐dependent effects on population growth, harvest management under the logistic model, and management to increase or decrease survival and production. Empirical data show density‐dependent growth for white‐tailed deer (Odocoileus virginianus), reindeer (Rangifer tarandus), ring‐necked pheasants (Phasianus colchicus), and northern bobwhites (Colinus virginianus), although the logistic model provided, at best, an approximation of growth. Managing harvest according to logistic theory is rare for ungulates and upland game; we suspect this owes to scarce data on population growth and complexity in density‐dependent processes. Under density dependence, managing to increase production or survival may be self‐defeating because an increase in 1 demographic variable entails a decrease in the other for sustaining populations (λ = 1). The problem can be addressed by providing space for population growth (λ &gt; 1), at least until growth re‐establishes the density‐dependent response (λ = 1). © 2012 The Wildlife Society.

Rescaling of aerial survey data with information from small numbers of telemetry tags to estimate the size of a declining harbour seal population

ABSTRACT Estimates of both absolute abundance and trends in abundance are among the most basic pieces of information required for planning the conservation and management of wildlife populations. They are important for understanding both the current situation of species and potential risks to them. This study presents estimates of the size of the harbour seal (Phoca vitulina) population associated with the Orkney Islands, a part of northern Scotland that used to contain one of the largest concentrations of this species in Europe. The numbers of animals counted during aerial surveys of this area have decreased substantially over the period 2001–2010. ARGOS transmitters attached to flipper tags were used to rescale the counts into estimates of abundance and to confirm the rate of decline of this population. Females hauled out for more of the survey window (0.84; bootstrap 95% CI: 0.63–0.99) than males (0.61; bootstrap 95% CI: 0.34–0.86). The animals hauled out less during weekends (0.57; bootstrap 95% CI: 0.40–0.74) than during the week (0.76; bootstrap 95% CI: 0.58–0.91). The sex‐ratios of this population is unknown. Assuming it was close to 1:1, then there were around 3586 (bootstrap 95% CI: 2970–4542) harbour seals in Orkney in 2010. A female‐skewed sex‐ratio would reduce the population estimate, and a changing sex‐ratio might mean the counts understate the real decline. The mean annual rate of decline in the Orkney population of harbour seals, over the period 2001–2010, is estimated at 13% (95% CI: 10.8–14.8). Similar data for Arisaig, on the west coast of Scotland, shows an increase of around 2% (95% CI: 1.5–2.4) and, assuming an equal sex‐ratio, 923 animals (95% CI: 765–1169) in 2007. Copyright © 2012 John Wiley &amp; Sons, Ltd.