Wildlife Abundance Research Articles

Principles and application of wildlife abundance estimation—Bayesian methods—

Principles and application of wildlife abundance estimation—Bayesian methods—

Effect of habitat structure and type of farming on European hare ( Lepus europaeus ) abundance

European hare ( Lepus europaeus ) is a typical species of farmland habitat that has been negatively affected by agricultural intensification and, for this reason, may be considered a good indicator of farmland habitat quality. We carried out an exploratory analysis of hare abundance in 26 lowland farms in Tuscany, Central-Italy, with similar basic features (large estates with the same game management) but that differ for crops, landscape structure and farming options (organic vs. conventional farming). We used multiple regression analysis with theoretic information approach and multi-model inference to evaluate the effect of habitat variables and type of farming on hare abundance. Habitat structure (variety of crops) was the most important factor positively affecting hare abundance. We did not find a benefit of organic farming on this species; on the contrary, the highest hare densities were registered in conventional farms. Our findings suggest that organic farming regulations may fail to provide a sufficient habitat heterogeneity and, consequently, do not enhance wildlife abundance in farmland habitat. Click here to access supplementary files

Harmonizing methods for wildlife abundance estimation and pathogen detection in Europe-a questionnaire survey on three selected host-pathogen combinations.

BackgroundThe need for wildlife health surveillance as part of disease control in wildlife, domestic animals and humans on the global level is widely recognized. However, the objectives, methods and intensity of existing wildlife health surveillance programs vary greatly among European countries, resulting in a patchwork of data that are difficult to merge and compare. This survey aimed at evaluating the need and potential for data harmonization in wildlife health in Europe. The specific objective was to collect information on methods currently used to estimate host abundance and pathogen prevalence. Questionnaires were designed to gather detailed information for three host-pathogen combinations: (1) wild boar and Aujeszky’s disease virus, (2) red fox and Echinococcus multilocularis, and (3) common vole and Francisella tularensis.ResultsWe received a total of 70 responses from 19 European countries. Regarding host abundance, hunting bags are currently the most widely accessible data source for widely distributed mid-sized and larger mammals such as red fox and wild boar, but we observed large differences in hunting strategies among countries as well as among different regions within countries. For small rodents, trapping is the method of choice, but practical applications vary among study sites. Laboratory procedures are already largely harmonized but information on the sampled animals is not systematically collected.ConclusionsThe answers revealed that a large amount of information is available for the selected host-pathogen pairs and that in theory methods are already largely harmonized. However, the comparability of the data remains strongly compromised by local differences in the way, the methods are applied in practice. While these issues may easily be overcome for prevalence estimation, there is an urgent need to develop tools for the routine collection of host abundance data in a harmonized way. Wildlife health experts are encouraged to apply the harmonized APHAEA protocols in epidemiological studies in wildlife and to increase cooperation.Electronic supplementary materialThe online version of this article (doi:10.1186/s12917-016-0935-x) contains supplementary material, which is available to authorized users.

Endemic shrimp Macrobrachium pantanalense as a test species to assess potential contamination by pesticides in Pantanal (Brazil)

Pantanal is a biome characterized by an extraordinary diversity and abundance of wildlife and houses several endemic species such as the freshwater shrimp Macrobrachium pantanalense. However, the increase in agriculture and husbandry activities in the region has contributed with residues of pesticides reaching aquatic systems. The main objective of this study is to assess the sensitivity of the endemic shrimp M. pantanalense compared with other freshwater species: the shrimp M. amazonicum, the crustacean Daphnia similis and the fish Danio rerio. The sensitivity of these organisms was assessed through acute exposure to copper and cypermethrin (through the formulation Barrage®, widely used in Pantanal). For copper the species sensitivity decreased in the following order: D. similis (48 h-EC50 0.051 mg/L) > M. pantanalense > D. rerio > M. amazonicum (48 h-LC50 26.34 mg/L). Copper caused reduced length of shrimps and zebrafish and reduced heartbeat of zebrafish embryos. For cypermethrin the species sensitivity decreased in the following order: M. pantanalense (96 h-LC50 0.05 μg/L) > M. amazonicum > D. similis > D. rerio (144 h-LC50 1680 μg/L). Major effects of cypermethrin included reduced length of shrimps and zebrafish, as well as early hatching and increased incidence of developmental deformities in zebrafish embryos. This study highlights the importance of using endemic species for risk evaluations in sensitive biomes such as Pantanal. Moreover, it emphasizes the importance of testing pesticides toxicity as commercial formulations. Furthermore, we suggest that the endemic shrimp species M. pantanalense can be successfully used as a test species in ecotoxicology.

Combining Inverse and Transport Modeling to Estimate Bacterial Loading and Transport in a Tidal Embayment

Poquoson River is a tidal coastal embayment located along the Western Shore of the Chesapeake Bay about 4 km south of the York River mouth in the City of Poquoson and in York County, Virginia. Its drainage area has diversified land uses, including high densities of residence, agricultural, salt marsh land uses, as well as a National Wildlife Refuge. This embayment experiences elevated bacterial concentration due to excess bacterial inputs from storm water runoff, nonpoint sources, and wash off from marshes due to tide and wind-induced set-up and set-down. Bacteria can also grow in the marsh and small tributaries. It is difficult to use a traditional watershed model to simulate bacterial loading, especially in this low-lying marsh area with abundant wildlife, while runoff is not solely driven by precipitation. An inverse approach is introduced to estimate loading from unknown sources based on observations in the embayment. The estimated loadings were combined with loadings estimated from different sources (human, wildlife, agriculture, pets, etc.) and input to the watershed model. The watershed model simulated long-term flow and bacterial loading and discharged to a three-dimensional transport model driven by tide, wind, and freshwater discharge. The transport model efficiently simulates the transport and fate of the bacterial concentration in the embayment and is capable of determining the loading reduction needed to improve the water quality condition of the embayment. Combining inverse, watershed, and transport models is a sound approach for simulating bacterial transport correctly in the coastal embayment with complex unknown bacterial sources, which are not solely driven by precipitation.

Effects of extreme land fragmentation on wildlife and livestock population abundance and distribution

Fragmentation, degradation and loss of natural habitats are now recognised as major threats to wildlife conservation and mobile pastoralism in East African savannas. These processes are driven primarily by land tenure and policy, increasing human population, expansion of settlements and agricultural farms, road networks, urban development and fencing. To understand and characterise the forces driving habitat fragmentation, we analyse how biophysical (soils, slope, rainfall, rivers) and human-created (roads, towns, parks, quarries) features influence where people choose to fence the land in the Athi-Kaputiei ecosystem of Kenya. We also explore the consequences of land fragmentation through fencing on the abundance and distribution of wildlife and livestock populations. We show that fences are most highly concentrated along the major roads and around the major urban centres. Movements of migratory wildebeest and zebra between the Nairobi National Park and the pastoral Kitengela Plains adjoining the park on the south are getting increasingly impeded by increasing concentration of fences. Populations of wildebeest and other herbivores have collapsed to a small fraction of their former abundance largely owing to destruction of their habitats and obstruction of their movements between the park and the pastoral lands by fences and other land use developments. Conserving the key seasonal wildlife dispersal areas in the Athi-Kaputiei Plains is critical to ensuring the future viability of several key wildlife species in Nairobi National Park. Several initiatives, including a conservation land lease program has been launched, but their spatial coverage and funding levels would need to be greatly expanded to secure sufficient open spaces for both wildlife and livestock.

Examining disease prevalence for species of conservation concern using non‐invasive spatial capture–recapture techniques

Summary Non‐invasive techniques have long been used to estimate wildlife population abundance and density. However, recent technological breakthroughs have facilitated non‐invasive estimation of the proportion of animal populations with certain diseases. Giraffes Giraffa camelopardalis are increasingly becoming recognized as a species of conservation concern with decreasing population trajectories across their range in Africa. Diseases may be an important component impacting giraffe population declines, and the emerging ‘giraffe skin disease’ (GSD), characterized by the appearance of wrinkled skin and alopecic lesions on the limbs, neck and chest of infected giraffe, may hinder movement causing increased susceptibility to predation. We examined the prevalence of GSD in Tanzania's Ruaha National Park over a 4‐month period in 2015, using photographic capture–recapture surveys via road‐based transects. We divided the study area into five circuitous survey units, each approximately 100 km in length ( = 99·22 km, SD = 3·72), and surveyed for giraffes for 4 months. From these surveys, we developed a data base of spatially explicit giraffe photographs. We processed these photographs for individual identification and fitted spatial capture–recapture models to predict the spatial configuration of giraffe abundance and GSD prevalence within the study area. Our results indicated that >86% of the giraffe population showed signs of GSD and that the disease was more prevalent in the northern and north‐eastern portion of Ruaha National Park. Synthesis and applications. Our research shows that data from non‐invasive surveys can be used in spatial capture–recapture (SCR) models to estimate the proportion of a population affected by a visible disease. Researchers and conservationists can use SCR models to better examine the variation in parameters associated with these populations such as sex, age class, movement, and encounter rate, which may be linked to the prevalence of the disease, while incorporating broad spatial and temporal dimensions of the population in such areas. We discuss the implications of this research for conservation of threatened species with an emphasis on disease ecology and vulnerability to predations, and more broadly, for wildlife conservation.

Snapping shrimp: Changes in environmental noise in Laguna de Términos, Campeche, México, after hurricanes

Laguna de Términos, Campeche, México, is one of the largest coastal lagoons in Mexico where snapping shrimp is the main source of biological sound. We measured the environmental noise from 2004 to 2008 in stations distributed homogeneously in this lagoon during 17 sampling periods using a digital audio tape recorder sampling at 48 kHz with 16 bits for 1 minute at each station. The environmental noise in the recordings was measured with a semi-automatic MATLAB routine designed for this purpose. Results indicate that environmental noise in the lagoon changes from one sampling to another, but it changed drastically after the hurricanes of 2005 in some of the stations. This changes in submarine environmental noise helps us in understanding the effects of natural phenomena in the distribution and abundance of marine wildlife, such as snapping shrimps and bottlenose dolphins. [Work supported by CONACyT-Campeche and PAPIIT&PASPA-UNAM.]

Wildlife population trends in protected areas predicted by national socio-economic metrics and body size.

Ensuring that protected areas (PAs) maintain the biodiversity within their boundaries is fundamental in achieving global conservation goals. Despite this objective, wildlife abundance changes in PAs are patchily documented and poorly understood. Here, we use linear mixed effect models to explore correlates of population change in 1,902 populations of birds and mammals from 447 PAs globally. On an average, we find PAs are maintaining populations of monitored birds and mammals within their boundaries. Wildlife population trends are more positive in PAs located in countries with higher development scores, and for larger-bodied species. These results suggest that active management can consistently overcome disadvantages of lower reproductive rates and more severe threats experienced by larger species of birds and mammals. The link between wildlife trends and national development shows that the social and economic conditions supporting PAs are critical for the successful maintenance of their wildlife populations.

Australian native gardens: Is there scope for a community shift?

The negative impacts of urbanization on biodiversity are well known, and the use of native vegetation in private gardens and streetscapes have been shown to improve the species richness and abundance of native wildlife, thereby improving the biodiversity of the local area. This study poses the question of whether the general public is interested in planting native species, to determine whether a cultural shift in garden planting style is feasible. A total of 3707 questionnaires relating to nature in the backyard were delivered to residents in metropolitan Melbourne, Australia with 417 responses received (11.2% response rate). The results indicate that the public perception of the aesthetic appeal of native gardens is fairly positive and that Melbournians have considerable interest in planting native species in residential gardens and that a large number would like wildlife in their yards. The paper concludes that there is scope to encourage the use of native plants in residential landscaping.

Improving the use of biological data in Antarctic management

AbstractThe Antarctic Treaty System requires that the effects of potential human disturbance be evaluated, such as through the development and evaluation of Initial and Comprehensive Environmental Evaluations (IEEs and CEEs), and through the implementation of Management Plans for Antarctic Specially Protected Areas (ASPAs) and Antarctic Specially Managed Areas (ASMAs). The effectiveness of these management processes hinges on the quality and transparency of the data presented, particularly because independent validation is often difficult or impossible due to the financial and logistical challenges of working in the Antarctic. In a review of these documents and their treatment of wildlife survey data, we find that the basic elements of best data practices are often not followed; biological data are often uncited or out-of-date and rarely include estimates of uncertainty that would allow any subsequent changes in the distribution or abundance of wildlife to be rigorously assessed. We propose a set of data management and use standards for Antarctic biological data to improve the transparency and quality of these evaluations and to facilitate improved assessment of both immediate and long-term impacts of human activities in the Antarctic.

Estimating ungulate abundance while accounting for multiple sources of observation error

ABSTRACTWhether a species is rare or overabundant, accurate estimates of population abundance are essential for the development and assessment of conservation plans and management goals. Aerial surveys are commonly used to estimate population abundance and a variety of methods have been used to account for recognized biases associated with imperfect detection. Rarely addressed, however, is the possibility of recording duplicate observations and the influence of duplicate observations on estimates of abundance. Using data provided by Global Positioning System (GPS)‐collared bison (Bison bison) and helicopter survey paths conducted during 2011–2013 in the Henry Mountains, Utah, USA, we determined whether GPS‐collared bison were observed, missed, or observed multiple times. Using these data, covariates hypothesized to influence observation errors, and generalized linear models, we found the probability of detecting a GPS‐collared bison (study‐wide mean of 95%) was consistently greater for individuals in larger groups and less rugged terrain. We also found that the probability of recording a duplicate observation (study‐wide mean of 4.4%) increased with time since the prior survey observation. By incorporating both types of observation error into a modified Horvitz–Thompson estimator, more accurate estimates of bison abundance can be attained, particularly in years when animals segregate into small groups, utilize terrain that makes them difficult to see, or have ample time to move into areas not yet surveyed and be counted again. Our approach of accounting for multiple sources of observation error can easily be applied to aerial surveys for other species in other systems, and has the potential to improve the rigor of wildlife abundance estimation from aerial surveys. © 2016 The Wildlife Society.

Wilderness or pure land: tourists’ perceptions of Antarctica

In a survey of 222 cruise passengers to the Antarctic Peninsula in 2013, nearly 90% of respondents valued Antarctica as one of the world’s last great wildernesses. Passengers from Europe and the USA were more likely than those from China to value Antarctica as wilderness. While respondents shared a common perception of wilderness being a place in which human impacts are limited, regional differences were observed. Europeans perceived wilderness as remote, Chinese perceived it as desolate, and Americans valued the psycho-spiritual benefits of being in wilderness. Respondents’ wilderness perceptions were nourished by icons of wilderness, mostly from their home countries but also from international destinations. Nearly all respondents agreed that Antarctica should be protected as a wilderness reserve. When asked what human activities should be allowed to take place in an Antarctic wilderness reserve, they supported the protection of Antarctica with no resource extraction and controlled and limited tourism and scientific research. As wilderness or “pure land”, Antarctica, with its abundant wildlife, its wildness and its majestic landscapes, inspires awe and desires for its protection from its visitors, potentially playing a crucial role in providing the common experiences and meanings that can bring about a convergence of wilderness perceptions.

Contribution to the knowledge of Medicinal plants used in the Treatment of Arterial Hypertension by traditional Practitioners Bouar in CAR

This research was conducted in Bouar (Nana, Mambere). The city is located 450 km away from Bangui the capital city of Central African Republic. Bouar is a mountainous city is covered by the Yade Mountains. It is between 15 ° and 16 ° east longitude and between 6 ° and 7 ° of latitude north with an area of 26,600 km 2 . The Bouar city occupies relatively the entire Northwest Territory, sharing border with the Republic of Cameroon and comprises about 5% of the total population. Census of the area population took place in December 2003 which was 172.754 habitants, with a density population on average of 8.8 to 10 inhabitants per km2. Bouar city is endowed with immense natural resources and varied rainfall, rich soils and a basement of mining, a diverse and abundant wildlife, and a diversity of savanna. Despite all these potentials, Bouar is in a continuous cycle of impoverishment. Socio-sanitary situation continues to deteriorate, access to health care is very difficult, life has become increasingly complex with varied needs and people expect favorable actions from their leaders and efficiency in meeting their immediate needs based on the improvement of their health conditions. The objective of this paper is assessment of medicinal plants used as medicines in the treatment of hypertension in Bouar. Ethno botanical method is recognized as the safest and least expensive method of plant-based drugs on the one hand, but also to help poor farmers who can not afford modern drugs on the other. Bouar has nineteen (19) medicinal species that have been identified and belong to 14 different families with a predominance of Magnoliopsida (Dicotyledonous) on 19 species, 10 are not in the visible flora. This paper is an avenue of our modest contribution to knowledge on medicinal plants used for the treatment of sion in Bouar ( Aloe vera, Voacanga africana Lophira lanceolata, Zea mays, Bambusa vulgaris, Elaeis guineensis, Bridelia ferrugenea Protea madiannesis, Lycopersicum esculentum and Capsicum Annuun) . Furthermore other hypertension, treating plants are Aloe vera which treats diabetes and the madianensis protea that is used to treat epilepsy, malaria and fever. These plants are commonly used in the treatment of hypertension and other related diseases

Antelope Predation by Nigerian Forest Baboons: Ecological and Behavioural Correlates

Baboons are well studied in savannah but less so in more closed habitats. We investigated predation on mammals by olive baboons (Papio anubis) at a geographical and climatic outlier, Gashaka Gumti National Park (Nigeria), the wettest and most forested site so far studied. Despite abundant wildlife, meat eating was rare and selective. Over 16 years, baboons killed 7 bushbuck (Tragelaphus scriptus) and 3 red-flanked duiker (Cephalophus rufilatus), mostly still-lying ‘parked' infants. Taking observation time into account, this is 1 predation per group every 3.3 months - far lower than at other sites. Some features of meat eating resemble those elsewhere; predation is opportunistic, adult males monopolize most prey, a targeted killing bite is lacking and begging or active sharing is absent. Carcass owners employ evasive tactics, as meat is often competed over, but satiated owners may tolerate others taking meat. Other features are unusual; this is only the second study site with predation records for bushbuck and the only one for red-flanked duiker. The atypical prey and rarity of eating mammals probably reflects the difficulty of acquiring prey animals when vegetation cover is dense. Our data support the general prediction of the socioecological model that environments shape behavioural patterns, while acknowledging their intraspecific or intrageneric plasticity.

Unmanned aircraft systems in wildlife research: current and future applications of a transformative technology

Unmanned aircraft systems (UAS) – also called unmanned aerial vehicles (UAVs) or drones – are an emerging tool that may provide a safer, more cost‐effective, and quieter alternative to traditional research methods. We review examples where UAS have been used to document wildlife abundance, behavior, and habitat, and illustrate the strengths and weaknesses of this technology with two case studies. We summarize research on behavioral responses of wildlife to UAS, and discuss the need to understand how recreational and commercial applications of this technology could disturb certain species. Currently, the widespread implementation of UAS by scientists is limited by flight range, regulatory frameworks, and a lack of validation. UAS are most effective when used to examine smaller areas close to their launch sites, whereas manned aircraft are recommended for surveying greater distances. The growing demand for UAS in research and industry is driving rapid regulatory and technological progress, which in turn will make them more accessible and effective as analytical tools.

Practical Bias Correction in Aerial Surveys of Large Mammals: Validation of Hybrid Double-Observer with Sightability Method against Known Abundance of Feral Horse (Equus caballus) Populations

Reliably estimating wildlife abundance is fundamental to effective management. Aerial surveys are one of the only spatially robust tools for estimating large mammal populations, but statistical sampling methods are required to address detection biases that affect accuracy and precision of the estimates. Although various methods for correcting aerial survey bias are employed on large mammal species around the world, these have rarely been rigorously validated. Several populations of feral horses (Equus caballus) in the western United States have been intensively studied, resulting in identification of all unique individuals. This provided a rare opportunity to test aerial survey bias correction on populations of known abundance. We hypothesized that a hybrid method combining simultaneous double-observer and sightability bias correction techniques would accurately estimate abundance. We validated this integrated technique on populations of known size and also on a pair of surveys before and after a known number was removed. Our analysis identified several covariates across the surveys that explained and corrected biases in the estimates. All six tests on known populations produced estimates with deviations from the known value ranging from -8.5% to +13.7% and <0.7 standard errors. Precision varied widely, from 6.1% CV to 25.0% CV. In contrast, the pair of surveys conducted around a known management removal produced an estimated change in population between the surveys that was significantly larger than the known reduction. Although the deviation between was only 9.1%, the precision estimate (CV = 1.6%) may have been artificially low. It was apparent that use of a helicopter in those surveys perturbed the horses, introducing detection error and heterogeneity in a manner that could not be corrected by our statistical models. Our results validate the hybrid method, highlight its potentially broad applicability, identify some limitations, and provide insight and guidance for improving survey designs.

Disproportionate Climate-Induced Range Loss Forecast for the Most Threatened African Antelopes

Despite increasing evidence that climatic changes are having a widespread effect on the global distribution and abundance of wildlife [1, 2], the key question of whether the ranges of species that are already threat-listed are likely to be disproportionately affected lacks quantitative assessment. According to the "small-range climate-hypersensitivity hypothesis," we predict small range size to be directly linked to large climate-induced range reduction. Antelopes, an exemplary macroecological model due to their striking ecological diversity and species richness, present an ideal opportunity to test this. Here we provide the first empirical evidence that climate change will cause a disproportionate decline in African antelopes with small geographic ranges, which places the most threatened taxa in double jeopardy. This substantiates our theoretical expectation that the link between small range size and large climate-induced range reduction is a general phenomenon. Our empirically based models also allow specific recommendations for mitigating climate-induced species declines. Gap analysis shows high priorities for antelope conservation to include creation of new protected areas in the horn of Africa and Liberia, aswell as improved connectivity between existing protected areas. Predicted extinction of four species unable to reach areas with suitable climatic conditions by 2080 moreover highlights a potentially important role for ex situ conservation. The study emphasizes the urgent need to incorporate climate change into the IUCN threat assessment by extending the timeframe over which population trends are assessed [3].

Using citizen‐collected wildlife sightings to predict traffic strike hot spots for threatened species: a case study on the southern cassowary

Summary Assessing the causal factors underpinning the distribution and abundance of wildlife road‐induced mortality can be challenging. This is particularly ubiquitous for rare or elusive species, because traffic strikes occur infrequently for these populations and information about localized abundance, distribution and movements are generally lacking. Here, we assessed whether citizen‐collected sightings data may serve as a low cost and efficient means of gathering long‐term animal roadside presence and road‐crossing information, which could then be used to assess the causative factors and direct mitigation actions aimed at reducing wildlife traffic strike frequency. We explored this principle using two decades of traffic strike records and citizen‐collected sightings of the southern cassowary Casuarius casuarius johnsonii. Roads have bisected the cassowaries’ rain forest habitat and despite considerable investment into mitigation strategies for this species, road‐induced mortality is considered one of the primary threatening processes affecting the population. Using a Bayesian approach and controlling for spatial autocorrelation with conditional autoregressive models, we demonstrate that traffic strikes are primarily a density‐dependent process in the southern cassowary. That is, traffic strike clusters occurred along stretches of road where cassowaries were most frequently sighted. There were, however, road stretches where traffic strike frequency was greater than predicted by the number of roadside sightings, illustrating when and where density‐independent processes increased the mortality potential for a road‐crossing cassowary. Synthesis and applications. This is the first time that citizen‐collected sightings data have been used to systematically inform upon the abundance and distribution of wildlife traffic strike. The technique not only predicts where incidents are likely to occur but also helps us to understand the factors responsible for strike clustering. While not a replacement for systematic surveys, we highlight citizen‐collected sightings data as a low‐cost option when assessing contributing factors to vehicle‐induced mortality. Accounting for density‐dependent and density‐independent processes will ensure the most effective allocation of resources when implementing wildlife traffic strike mitigation.

Influence of the Expert Effect on Cultural Models

ABSTRACTWe examined hunters’ perceptions of fauna to see if expert hunters and other hunters perceive wildlife abundance similarly. We used cultural consensus analysis (CCA) to assess the knowledge of 25 hunters in the Bolivian Amazon about the abundance of 38 animals. CCA indicated highly shared beliefs among hunters concerning wildlife abundance (average agreement = .62). However, expert hunters (as judged by their reported successful hunts of rare species, having hunted recently, and consuming more game in their diet) perceived more animals as abundant than did non-experts, although they all shared the same model. Since the expert hunters did not always agree on which species was more abundant, they had low cultural knowledge scores in CCA results. These experts may be unwilling to curtail hunting efforts on key species that they perceive to be abundant.