Application In Wildlife Management Research Articles

Assessing efficacy of cellular transmission technology in camera trapping for wildlife research

AbstractCamera traps are an important noninvasive tool used by scientists to monitor wildlife efficiently and at reduced costs. New camera trap features improve performance and encourage increased use by researchers and the public. Cellular transmission of image data, which provides users the ability to digitally receive images instead of retrieving or downloading images in the field is a useful new feature. Cellular data transmission has 2 key benefits for wildlife research in that it reduces travel time required for downloading image data and the uncertainty involving storage capacity of SD cards and battery life, and cellular transmission allows for near real‐time analysis of images, which could redistribute the time usually devoted to processing a large data set when the memory card is retrieved. Despite potential benefits, cellular transmission technology in camera traps is still new and questions remain about its reliability. Our objective was to determine the efficacy of cellular transmission technology in wildlife research by designing a camera trap study as part of a senior‐level class (Wildlife Management Applications and Planning; NREM 4522) project at Oklahoma State University. We used ArcGIS to generate a stratified random sample of trap locations, deploying five cellular transmission camera traps in open grassland and five in closed canopy forest areas from 5 September to 5 October 2021. We monitored the number of transmitted images each day online, and after camera trap retrieval, we compared the number of transmitted images to those stored on the memory card to determine transmission efficiency. Our data indicated the majority of the images taken each day were transmitted successfully; however, transmission efficiency (i.e., number transmitted divided by total number taken by the camera trap) tended to be lower in forested areas (47%) compared to open grassland (86%). Though cellular transmission technology shows promise, the combination of cellular signal, landscape features, and transmitted data quality may limit the effectiveness of cellular transmission technology for near real‐time data analysis. Based on our results, we recommend that researchers consider advantages and disadvantages of cellular transmission when designing studies and note that researchers may need to adopt an adaptive approach or conduct pilot testing that includes quantifying the transmission functionality.

A camera trap method for estimating target densities of grey squirrels to inform wildlife management applications

Effective wildlife population management requires an understanding of the abundance of the target species. In the United Kingdom, the increase in numbers and range of the non-native invasive grey squirrel Sciurus carolinensis poses a substantial threat to the existence of the native red squirrel S. vulgaris, to tree health, and to the forestry industry. Reducing the number of grey squirrels, is crucial to mitigate their impacts. Camera traps are increasingly used to estimate animal abundance, and methods have been developed that do not require the identification of individual animals. Most of these methods have been focussed on medium to large mammal species with large range sizes and may be unsuitable for measuring local abundances of smaller mammals that have variable detection rates and hard to measure movement behaviour. The aim of this study was to develop a practical and cost-effective method, based on a camera trap index, that could be used by practitioners to estimate target densities of grey squirrels in woodlands to provide guidance on the numbers of traps or contraceptive feeders required for local grey squirrel control. Camera traps were deployed in ten independent woods of between 6 and 28 ha in size. An index, calculated from the number of grey squirrel photographs recorded per camera per day had a strong linear relationship (R2 = 0.90) with the densities of squirrels removed in trap and dispatch operations. From different time filters tested, a 5 min filter was applied, where photographs of squirrels recorded on the same camera within 5 min of a previous photograph were not counted. There were no significant differences between the number of squirrel photographs per camera recorded by three different models of camera, increasing the method’s practical application. This study demonstrated that a camera index could be used to inform the number of feeders or traps required for grey squirrel management through culling or contraception. Results could be obtained within 6 days without requiring expensive equipment or a high level of technical input. This method can easily be adapted to other rodent or small mammal species, making it widely applicable to other wildlife management interventions.

Rapid, non-destructive analysis of calcium and strontium in eggshells by WD-XRF

We developed a simple method of analyzing the strontium (Sr) and calcium (Ca) content of intact eggshell samples in support of a broader study of how dietary Sr uptake impacts waterfowl eggshell quality. We used wavelength dispersive - x-ray fluorescence spectrometry (WD-XRF) to analyze eggshell pieces ranging in size from ∼6-mm2 fragments to intact half-shells. We verified this approach on a subset of reference shells by subjecting the same region and volume of shell material from which x-ray signals were measured to analysis by inductively-coupled plasma mass spectrometry (ICP-MS). An analysis of the sources of analytical uncertainty yielded total internal error estimates of ±0.3 and 5% relative for Ca and Sr, respectively, on the basis of which the chemistry of intact shell material analyzed by WD-XRF in this study is compared. The total external errors associated with the WD-XRF results of this study in relation to certified reference material (National Institute of Standards and Technology [NIST] 1400 [a bone ash]) are ±9 and 13.5% relative for Ca and Sr, respectfully (95% CL). Our results demonstrate this method is acceptably accurate and precise for many wildlife management applications. WD-XRF analysis is a quick and inexpensive alternative to traditional methods for determining eggshell Sr and Ca that require acid digestion, allowing for generation of larger datasets that might otherwise be cost-prohibitive, while preserving sample material intact.

個体群モデルとコンピュータシミュレーションの使いみち( 個体群研究のフロンティア : 個体群生態学の新たな発展)

個体群モデルとコンピュータシミュレーションの使いみち( 個体群研究のフロンティア : 個体群生態学の新たな発展)

Rigorous home range estimation with movement data: a new autocorrelated kernel density estimator.

Quantifying animals' home ranges is a key problem in ecology and has important conservation and wildlife management applications. Kernel density estimation (KDE) is a workhorse technique for range delineation problems that is both statistically efficient and nonparametric. KDE assumes that the data are independent and identically distributed (IID). However, animal tracking data, which are routinely used as inputs to KDEs, are inherently autocorrelated and violate this key assumption. As we demonstrate, using realistically autocorrelated data in conventional KDEs results in grossly underestimated home ranges. We further show that the performance of conventional KDEs actually degrades as data quality improves, because autocorrelation strength increases as movement paths become more finely resolved. To remedy these flaws with the traditional KDE method, we derive an autocorrelated KDE (AKDE) from first principles to use autocorrelated data, making it perfectly suited for movement data sets. We illustrate the vastly improved performance of AKDE using analytical arguments, relocation data from Mongolian gazelles, and simulations based upon the gazelle's observed movement process. By yielding better minimum area estimates for threatened wildlife populations, we believe that future widespread use of AKDE will have significant impact on ecology and conservation biology.

Batcheler-corrected point distance versus belt transect for sampling habitat and woody vegetation

Density estimates for habitat objects are used for a variety of forestry and wildlife management applications, but supporting field work can be costly. We used point simulations and field studies of snags and shrub stems to evaluate and compare the plotless Batcheler-corrected point distance (BCPD) method of data collection with the plot-based belt transect (BT) method for estimating object density (snags and shrub stems). The program Transect Point Density ( http://www.cnfer.on.ca/SEP/ ) was used to calculate density and confidence limits. Relative to the BT method, we found the BCPD method performs well under a range of clustered and random dispersion patterns and point densities, with measurements made to the nearest neighbour of the initial point object allowing correction of bias caused by nonrandom spatial dispersion patterns. The BCPD parameter of spatial dispersion, A1, was correlated with I, the variance-to-mean ratio used to estimate spatial dispersion in plot-based samples. The BCPD method also allows measurement to the third object (next-nearest neighbour) to account for second-order clumping, but we found that this estimate was sensitive to measurement error or technique where dense mats of wetland shrub species Ledum groenlandicum Oeder or Myrica gale L. occurred. We also used BCPD to characterize shrub community structure and found no evident bias, relative to BT data, for estimating relative species composition, richness, and diversity. The BCPD method was cost-effective relative to the BT method, with cost ratios 4–47 times higher for the BT method, and for a given investment allowed sampling of a greater area and diversity of stand conditions. Consequently, the BCPD method will facilitate collection of better data for developing and testing habitat models as well as evaluating the effects and effectiveness of forest management options at both the stand and landscape scales.

Estimates of maximum annual population growth rates (rm) of mammals and their application in wildlife management

Summary 1. The maximum annual population growth rate (rm) is a critical parameter in many models of wildlife dynamics and management. An important application of rm is the estimation of the maximum proportion of a population that can be removed to stop population growth (p). 2. When rm cannot be estimated in the field, one option is to estimate it from demographic data. We evaluate the use of the relationship between rm and female age at first reproduction (α), which is independent of phylogeny, to estimate rm. We first demonstrate that the relationship between field and demographic estimates of rm is unbiased. We then show that the relationship provides an unbiased and simple method to estimate rm using data for 64 mammal species. We also show that p declines exponentially as α increases. 3. We use the fitted relationship to estimate annual rm and p for 55 mammal species in Australia and New Zealand for which there are no field estimates of rm. The estimates differ by species but have low precision (wide 95% credible intervals CIs). Our estimate of rm for the Tasmanian devil Sarcophilus harrisii is high (0·6, 95% CI: 0·05–2·39) and suggests devils would become extinct if >0·34 of the population is removed annually (e.g. by facial tumour disease). Our estimate of rm (0·77, 95% CI: 0·71–1·05) for brushtail possum Trichosurus vulpecula is much greater than published estimates and highlights the need for further field estimates of rm for the species in New Zealand. 4. Synthesis and applications. Since rm has not been estimated in the field for the majority of mammal species, our approach enables estimates with credible intervals for this important parameter to be obtained for any species for which female age at first reproduction is known. However, the estimates have wide 95% CIs. The estimated rm, and associated uncertainty can then be used in population and management models, perhaps most importantly to estimate the proportion that if removed annually would drive the population to extinction. Our approach can be used for taxa other than mammals.

Effects of cutline density and land-cover heterogeneity on landscape metrics in western Alberta

Forest cutlines are narrow, linear features created in geophysical surveys. In many areas of Canada, forest cutlines are not consistently detected using relatively coarse spatial resolution land-cover maps, such as those produced by classification of Landsat Thematic Mapper (TM) imagery. However, such features may be important in certain wildlife management applications, including those which require an assessment of landscape structure, or forest fragmentation, at various scales. Higher spatial resolution satellite imagery obtained from sensors on platforms such as Satellite Pour l’Observation de la Terre (SPOT) and the Indian Remote Sensing (IRS) system may be used to map forest cutlines for these applications. In this study, a TM-based land-cover map of western Alberta is analyzed with forest cutlines mapped from a TM-IRS fusion image, and the effect of increasing cutline density is quantified on five commonly used landscape metrics used to characterize landscape structure in grizzly bear habitat assessment. The accuracy of the fusion image interpretation was determined to be 88%. Simulated landscapes were tested first, and the study area was divided into 104 hexagon-shaped sample landscapes of about 6 km diameter each. Across these sample landscapes, cutline density and initial landscape heterogeneity were significant parameters in explaining change in three metrics, namely edge density, mean patch size, and patch context (expressed as mean nearest-neighbour distance). Patch size variability (expressed as the coefficient of variation of mean patch size) and patch dispersion (expressed as the coefficient of variation of mean nearest-neighbour distance) required additional information on cutline positioning. Overall, the density of the introduced cutline network and the pre-cutline metric value reliably predicted and quantified the response of landscape metrics of interest to grizzly bear biologists. This study shows the importance of mapping forest cutlines regarding their role in changing landscape structure quantification and points out the necessity of using additional remotely sensed data when the feature responsible for the landscape transformation is of too small a size to appear reliably in common TM-based classified imagery.

Bayesian population estimation for small sample capture-recapture data using noninformative priors

One critical issue in the Bayesian approach is choosing the priors when there is not enough prior information to specify hyperparameters. Several improper noninformative priors for capture-recapture models were proposed in the literature. It is known that the Bayesian estimate can be sensitive to the choice of priors, especially when sample size is small to moderate. Yet, how to choose a noninformative prior for a given model remains a question. In this paper, as the first step, we consider the problem of estimating the population size for M t model using noninformative priors. The M t model has prodigious application in wildlife management, ecology, software liability, epidemiological study, census under-count, and other research areas. Four commonly used noninformative priors are considered. We find that the choice of noninformative priors depends on the number of sampling occasions only. The guidelines on the choice of noninformative priors are provided based on the simulation results. Propriety of applying improper noninformative prior is discussed. Simulation studies are developed to inspect the frequentist performance of Bayesian point and interval estimates with different noninformative priors under various population sizes, capture probabilities, and the number of sampling occasions. The simulation results show that the Bayesian approach can provide more accurate estimates of the population size than the MLE for small samples. Two real-data examples are given to illustrate the method.

Optimizing Presence–Absence Surveys For Detecting Population Trends

Presence–absence surveys are a commonly used method for monitoring broad-scale changes in wildlife distributions. However, the lack of power of these surveys for detecting population trends is problematic for their application in wildlife management. Options for improving power include increasing the sampling effort or arbitrarily relaxing the type I error rate. We present an alternative, whereby targeted sampling of particular habitats in the landscape using information from a habitat model increases power. The advantage of this approach is that it does not require a trade-off with either cost or the Pr{type I error} to achieve greater power. We use a demographic model of koala (Phascolarctos cinereus) population dynamics and simulations of the monitoring process to estimate the power to detect a trend in occupancy for a range of strategies, thereby demonstrating that targeting particular habitat qualities can improve power substantially. If the objective is to detect a decline in occupancy, the optimal strategy is to sample high-quality habitats. Alternatively, if the objective is to detect an increase in occupancy, the optimal strategy is to sample intermediate-quality habitats. The strategies with the highest power remained the same under a range of parameter assumptions, although observation error had a strong influence on the optimal strategy. Our approach specifically applies to monitoring for detecting long-term trends in occupancy or abundance. This is a common and important monitoring objective for wildlife managers, and we provide guidelines for more effectively achieving it.

A Modeling Approach to Evaluating Potential Applications of Emerging Fertility Control Technologies in the UK

There is increasing demand for benign approaches to the resolution of conflicts between human interests and wildlife. One non-lethal method to reduce the growth and expansion of overabundant wildlife populations is fertility control. Significant progress has been made in recent years on the development of fertility control agents, culminating in the availability of single-dose injectable immunocontraceptive vaccines that inhibit the fertility of individuals for several years. The potential application of such technology is explored here using the European rabbit, gray squirrel, wild boar, and European badger as examples of species that pose problems of damage to agricultural and forestry interests, disease transmission and threats to biodiversity. A simple model is developed that predicts the likely general population consequences of varying levels of infertility for species with differing demographic characteristics. This suggests that low levels of fertility control will have little impact on population size in species with high reproductive rates and high population turnover rates. Modest levels of infertility can significantly reduce the populations of species with relatively low intrinsic rates of increase. However, these reductions may take longer than those arising from high levels of imposed infertility in species with rapid population turnover rates. The modeling approach, as outlined here, could be used to inform future field studies by identifying suitable target species and making predictions about population responses that can be tested empirically. These studies will be necessary to realize the potential of the emerging fertility control technologies in the form of practical wildlife management applications.

Masking the taste of the conditioned taste aversion agent levamisole using an ion‐exchange resin, for practical application in wildlife management

For a conditioned taste aversion (CTA) agent to be successful in wildlife management applications, the compound must not be detectable by the animal. Levamisole is an effective CTA agent when administered by oral intubation, but it is readily detected by a number of species when mixed directly in food. This paper describes the development of an ion-exchange resin complex (resinate) to mask the taste of levamisole. Two different resins were evaluated, Amberlite IRP-64 and Amberlite IRP-69, and release studies indicated that the resinate formed using IRP-64 resin would be most suitable for use in wildlife management. Although it contained a relatively low loading of levamisole (77 g kg(-1)), the results indicated that the IRP-64 resinate should be stable in the mouth and release the levamisole quickly in the acid environment of the stomach (93% of levamisole was released into 0.1 M HCl in 5 min). In a bioassay using laboratory rats (Rattus norvegicus Berk), we showed that the taste of levamisole was successfully masked in a biscuit bait using the IRP-64 resinate and that a CTA was generated to untreated bait. The use of ion-exchange resins is a new approach in the taste-masking of CTA agents and could be applied to other wildlife management applications.

Development of chemical coyote attractants for wildlife management applications

Coyote attractants are inherently variable because they are usually derived by mixing and fermenting complex biologically derived substances. We designed the present study to address this problem. We collected volatiles by purge and trap headspace analyses from 33 commercially available attractants, and analyzed the trapped odors by gas chromatography with mass selective detection. We then statistically evaluated chromatographic peak area data to produce recipes for seven new chemical attractants. We presented these attractants to coyotes in one-choice tests at the Predation Ecology and Behavioral Applications Field Station of the USDA-APHIS-WS National Wildlife Research Center near Logan, Utah. Our results indicated that there were both seasonal and sexual differences in stimulus attractiveness. We also found that several attractants were more effective than Fatty Acid Scent (FAS), a commonly employed coyote attractant. A field trial to evaluate the effectiveness of new candidate attractants is planned.

Fecal Indices to Dietary Quality of Cervids in Old-Growth Forests

Determination of dietary quality for wild ungulates can be both time-consuming and expensive. Because fistulation is usually not possible, determinations require a measure of diet (e.g., fecal analyses, direct feeding observations, tame animals, etc.) and simultaneous measures of nutritional attributes of each dietary component. An alternative approach is to measure a chemical characteristic of fecal material that bears a relationship to the quality or quantity of ingested diets (e.g., Cordova et al. 1978, Holechek et al. 1982b). Fecal nitrogen (FN) is a common index that has been shown to be positively correlated with intake (Arnold and Dudzinski 1963, Langlands et al. 1963, Stallcup et al. 1975), dietary digestibility (Lancaster 1949, Greenhalgh et al. 1960, Marten et al. 1963, Holloway et al. 1981), dietary protein (Raymond 1948, Greenhalgh and Corbett 1960, Hebert 1973, Arman et al. 1975, Erasmus et al. 1978, Mould and Robbins 1981, Holechek et al. 1982a), and weight changes (Gates and Hudson 1981) in a variety of wild and domestic ruminants. Difficulties with using FN as an index of dietary quality have usually resulted from seasonal changes in digestibility of forages (Greenhalgh et al. 1960, Minson and Kemp 1961, Holloway et al. 1981). Fecal indices to dietary quality have received limited application in wildlife management. Arman et al. (1975) contended that FN could be a valuable index if the relationships of dietary nitrogen (DN) and FN could be established for a particular ruminant in a given locality; widespread use was limited because of variability in species, forages, and seasons. Mould and Robbins (1981:327) rejected its utility as a simple indicator of dietary quality of wild ruminants because of protein-complexing properties of phenolics and other secondary metabolites in plants (McLeod 1974) that may elevate FN irrespective of DN. However, Gates and Hudson (1981) found that FN reflected changes in quality of forages used by Rocky Mountain elk (Cervus elaphus nelsoni). This paper summarizes the relationships of FN and fecal phosphorus (FP) to DN, dietary phosphorus (DP), and dietary digestibility (DD) of Roosevelt elk (C. e. roosevelti) and Columbian black-tailed deer (Odocoileus hemionus columbianus) in old-growth, coniferous forests of western Washington.