Animal Density Research Articles

Counterintuitive scaling between population abundance and local density: Implications for modelling transmission of infectious diseases in bat populations.

Models of host-pathogen interactions help to explain infection dynamics in wildlife populations and to predict and mitigate the risk of zoonotic spillover. Insights from models inherently depend on the way contacts between hosts are modelled, and crucially, how transmission scales with animal density. Bats are important reservoirs of zoonotic disease and are among the most gregarious of all mammals. Their population structures can be highly heterogeneous, underpinned by ecological processes across different scales, complicating assumptions regarding the nature of contacts and transmission. Although models commonly parameterise transmission using metrics of total abundance, whether this is an ecologically representative approximation of host-pathogen interactions is not routinely evaluated. We collected a 13-month dataset of tree-roosting Pteropus spp. from 2,522 spatially referenced trees across eight roosts to empirically evaluate the relationship between total roost abundance and tree-level measures of abundance and density-the scale most likely to be relevant for virus transmission. We also evaluate whether roost features at different scales (roost level, subplot level, tree level) are predictive of these local density dynamics. Roost-level features were not representative of tree-level abundance (bats per tree) or tree-level density (bats per m2 or m3 ), with roost-level models explaining minimal variation in tree-level measures. Total roost abundance itself was either not a significant predictor (tree-level 3D density) or only weakly predictive (tree-level abundance). This indicates that basic measures, such as total abundance of bats in a roost, may not provide adequate approximations for population dynamics at scales relevant for transmission, and that alternative measures are needed to compare transmission potential between roosts. From the best candidate models, the strongest predictor of local population structure was tree density within roosts, where roosts with low tree density had a higher abundance but lower density of bats (more spacing between bats) per tree. Together, these data highlight unpredictable and counterintuitive relationships between total abundance and local density. More nuanced modelling of transmission, spread and spillover from bats likely requires alternative approaches to integrating contact structure in host-pathogen models, rather than simply modifying the transmission function.

The use of a long-acting tranquilizer (zuclopenthixol acetate) and live video monitoring for successful long-distance transport of caribou (Rangifer tarandus)

Long-distance transport of caribou (Rangifer tarandus) can result in morbidities and mortalities. This case report describes the use of a long-acting tranquilizer, zuclopenthixol acetate (ZA) and live video monitoring (LVM) to transport caribou over 2300 kilometers. Two groups of captive caribou were transported from Fort St. John, British Columbia to Dryden, Ontario (n=14; 28.5 h transport) and Anchorage, Alaska (n=11; 32 h transport). The day prior to transport, caribou were administered ZA at 1 mg/kg via deep intramuscular (IM) injection. Digital video cameras allowed for live observation of caribou during transport. Still images of videos from each compartment in the Ontario transport were analyzed for percentage (%) lying versus standing over three time periods (Day 1, Night, and Day 2). Overall, caribou spent 57% of the transport lying down, with the highest percentage occurring at night (73%). As group size and animal density decreased there was a trend for caribou to spend more time lying down. Three animals developed extrapyramidal effects to the ZA and were effectively treated with midazolam at 0.2 mg/kg IM. There were no significant visible injuries or mortalities during or up to 6 weeks post-transport. Zuclopenthixol acetate and LVM were used to successfully transport caribou over long distances and should be considered in future translocations to improve animal welfare during transport.

Antarctic krill likely avoid underwater gliders

The extent to which marine species avoid survey vessels is the subject of considerable debate, with stimuli such as noise and pressure waves receiving particular attention. By some estimates, avoidance behaviour is a major bias in the assessment of pelagic species distribution and density. Surveyors of the marine environment are increasingly using autonomous platforms; thus the question of avoidance of these novel platforms must be considered.A long-duration, underwater glider with an integrated echo-sounder was deployed to measure the density and distribution of Antarctic krill. We show that krill reacted to the glider, despite the low-noise profile of the platform. The weighted-mean depth of krill swarms was observed to deepen when a glider came within 30 m. In addition, we observed a near-range decrease in depth-integrated acoustic backscatter and we demonstrate that this effect is not explained by the instrument's acoustic footprint. The potential triggers for these behaviours are discussed.The list of sensors available for use on a glider is increasing, with some producing sound, light or other potential stimuli for behavioural response. Our paper demonstrates that caution should be used when designing mission payloads and in the interpretation of acoustic data for animal density from gliders. A key consideration for surveyors may be the factoring in of an exclusion zone from their analyses.

Use of space, active and resting behaviour in fattening rabbits (Oryctolagus cuniculus) housed in a combi park system: A case study

AbstractIn this case study, a housing system for rabbits (Oryctolagus cuniculus) was developed, complying with the new German Welfare Regulation, and evaluated on-farm with regard to the rabbits’ behaviour during four fattening periods. The housing system was characterised by the large group size of fatteners (maximum 65 animals per group, 12 animals per m2) due to the merging of six former single units for does and their litters, post-weaning. A large elevated platform, a box with a roof (small elevated platform), a tube and gnawing materials were made available per unit. The aim being to assess the suitability of the housing system for rabbits with regard to animal welfare, based on behavioural analyses. Therefore, the use of space by the rabbits (n = 247) was investigated by video analysis (instantaneous scan sampling) during daytime. Additionally, the individual behaviour of 20 focal rabbits in different locations was assessed by continuous sampling. Results showed that rabbits preferred to huddle together in the outer units in the first weeks post-weaning. The highest animal densities were found under and in front of the large and on the small platforms. The large platforms were visited increasingly from the 10th fattening day onwards. Elevated platforms supported resting and comfort behaviours. Non-elevated open-top areas enabled upright positions and locomotor behaviours. Aggression and stereotypic behaviours rarely occurred. We conclude that the housing system supported species-specific behaviour and seemed to cater for the needs of rabbits in terms of welfare. Nevertheless, further investigation is needed to ascertain the effects on animal health and performance.

Spatial distribution of bed variables, animal welfare indicators, and milk production in a closed compost-bedded pack barn with a negative tunnel ventilation system

This research aimed to characterize, evaluate and compare the spatial distribution of the leading bed variables, animal welfare indicators, and milk production in a closed compost-bedded pack barn (CBP) with a negative tunnel ventilation system, for summer and winter periods. The study was carried out in a CBP located in the Zona da Mata region, Minas Gerais, Brazil. The geostatistical modeling technique evaluated the variables of temperature, moisture content, and pH (on the surface and depth of 0.20m) across the length of the bed. Bed samples were characterized for carbon (C), nitrogen (N), and C:N ratio. Cows housed in the CBP were assessed for locomotion and hygiene scores and average milk production. To evaluate the thermoregulation of the cows, the respiratory rate (RR) and surface temperature (ST) were measured. Geostatistical analysis showed spatial dependence and the non-uniformity of the spatial distribution of bed variables. The worst levels of bed temperature and moisture were found in the regions close to the evaporative cooling plate, surrounding the feeding alley, and in the region with the highest cow stocking. The C:N ratio, obtained in both climatic seasons of the year, remained outside the recommended range for ideal composting. During the summer and winter, the bed variables' values suggest that the material was below levels for optimal composting; however, the aerated inner layer was biologically active. The high animal density significantly impacted the worsening of the bed moisture content and internal temperature. In general, dairy cows showed adequate hygiene (score of 1 and 2) and locomotion (score of 0 and 1) scores for the two climatic seasons evaluated, indicating good welfare conditions. In relation to RR and ST, the summer period presented less favorable environmental conditions. During winter, the average milk production was 28.1±7.2kg day-1, and during summer, it was 26.9±6.7kg day-1.

Vocal communication in wild chimpanzees: a call rate study.

BackgroundPatterns of vocal communication have implications for species conservation: a change in calling behaviour can, for instance, reflect a disturbed habitat. More importantly, call rate is a parameter that allows conservation planners to convert call density into animal density, when detecting calls with a passive acoustic monitoring system (PAM).MethodsWe investigated chimpanzee (Pan troglodytes schweinfurthii) call rate during the late dry season in the Issa Valley, western Tanzania by conducting focal follows. We examined the socio-ecological factors that influence call production rate of savanna woodland chimpanzees.ResultsWe found that sex, proportion of time spent in a vegetation type, proportion of time spent travelling, time of the day, party size and swollen parous female presence had a significant effect on the call rate. Call rate differed among the different demographic classes with subadult and adult males vocalising twice as often as the subadult and adult females and three times as often as the juveniles.ApplicationsThe use of PAM and recent statistical developments to estimate animal density is promising but relies on our knowing individual call rate, often not available for many species. With the improvement in automatic call detection, we anticipate that PAM will increasingly be broadly applied to primates but also across taxa, for conservation.

Surveillance for hemorrhagic fever with renal syndrome in Zhejiang, 2016–2020

Objective To understand the epidemiological characteristics of hemorrhagic fever with renal syndrome (HFRS), the distribution, density and virus carriage of host animals in Zhejiang province, and provide scientific basis for the formulation of prevention and control measures. Methods The incidence data of HFRS in Zhejiang from 2016 to 2020 were collected for a descriptive epidemiological analysis to understand its time, place and population distributions. The host animals were investigated at 5 surveillance areas in Zhejiang, the capture rate was investigated by the night method, and rat-shaped animal lungs and blood were collected for the hantavirus antigen and antibody detections, and analysis on the distribution and virus carriage of rodents in Zhejiang were conducted. Results The annual reported case numbers and incidence rate of HFRS in Zhejiang were 349 and 0.62/100 000 in 2016, 353 and 0.63/100 000 in 2017, 327 and 0.59/100 000 in 2018, 369 and 0.63/100 000 in 2019, and 260 and 0.46/100 000 in 2020. From 2016 to 2020, a total of 14 068 rat traps were deployed in residential areas, and 622 rodents were captured, the capture rate was 4.42%, and a total of 31 875 rat traps were deployed in the field, and 2 112 rodents were captured, the capture rate was 6.63% in the 5 surveillance areas. The differences in rodent density in the filed among the 5 surveillance areas were significant (F=2.941, P=0.046). A total of 3 065 rodents were captured in the 5 surveillance areas. The predominant rodent species in the field was Apodemus agrarianus, (1 830, 59.71%); the predominant rodent species in residential areas was Rattus norvegicus (330, 10.77%), the difference was significant (χ2=1675.401, P＜0.001). A total of 3065 rodent serum samples were tested, and the antibody positive rate was 8.7% (236/2808), and a total of 3065 rodent lung specimens were tested, the antibody positive rate was 3.66% (103/2815), and the differences in rodent species which were antibody positive among the 5 surveillance areas were significant (χ2=235.762, P＜0.001); and the differences in rodent species which were antigen positive among the 5 surveillance areas were significant (χ2=116.195, P＜0.001). Conclusion The density and virus carrying rate of rodents were high in the areas with high incidence of HFRS in Zhejiang. It is necessary to take targeted prevention and control measures in key areas for the better prevention and control of HFRS.

Data inaccessibility at sub-county scale limits implementation of manuresheds.

The manureshed concept aims to rebalance surplus manure nutrients produced at animal feeding operations (sources) and the demands from nutrient-deficient croplands (sinks) to reduce negative environmental impacts and utilize nutrients more efficiently. Due to water quality implications, studies focused on this rebalancing have typically created domain boundaries that match a particular watershed. However, a majority of agricultural datasets that are used to inform these analyses-specifically, livestock populations-are only available at the county scale, which generally does not match watershed boundaries. The common method used to address this mismatch is to weight the county statistics based on the proportion of watershed area within the county. However, these straightforward assumptions imply that animal density is uniform across a county, which can be highly problematic, especially in an era of increasing concentration of livestock production on a smaller land area. We present a case study of the Lake Mendota watershed in south-central Wisconsin using both a typical county-based downscaled dataset as well as a more spatially explicit dataset of livestock counts from the Census of Agriculture that aggregates a set of zip codes that best matches the watershed boundary. This comparison reveals a substantial difference in estimated livestock numbers and their associated manure production that is due to a concentration of dairy operations within the watershed compared with the rest of the county. We argue that sub-county scale data need to become more available and integrated into nutrient and water quality management efforts so that manuresheds can be more effectively delineated and implemented.

Monitoring and prospects for conservation and rational use of the resources of the Eurasian beaver (<i>Castor fiber</i> Linnaeus, 1758) on the example of the Samara Region

The paper examines characteristics of the Eurasian beaver population (Castor fiber Linnaeus, 1758) on territories with different anthropogenic load. Monitoring the beaver population and habitat, including the landscape basis and natural zoning with the allocation of natural, natural-anthropogenic and anthropogenic territories as natural ecological systems allows you to manage and rationally use the resources of these animals. Previously there were mainly natural territories in the studied region, however with the growth of the human population and its economic activity their properties have changed. According to biotic criteria, geochemical circulation, significant (formerly natural) territories functionally already correspond to natural-anthropogenic and anthropogenic objects, since the supply of fodder, population density and density of animals have changed. According to natural zoning, taking into account the identified changes in the habitat of beavers (by biotic criteria), we have examined their territorial distribution as well as the number of settlements in various natural objects of the region. On the studied rivers the density of the beaver population in the channel decreases in the following order: natural territory natural-anthropogenic anthropogenic, but the indicator of private abundance (the density of animals on the territory where beavers live directly) and aggregation (crowding of individuals) increases. The population density of the river bed of the studied rivers by beavers on anthropogenic territories is from 0,93,7 individuals/km, which is lower than on natural and natural-anthropogenic territories, where this indicator is from 1,5 to 6 individuals/km. The length of the river bed, where beavers live directly, without taking into account significant buffer zones, varies in natural areas from 60 to 100%, which is more than in areas with anthropogenic load, where this indicator in the study area decreases to 40%. A decrease in the size of river channel sections suitable for beaver colonization leads to overcrowding (aggregation) of individuals. Compared with the total density of beaver population in the river channel 0,93,7 individuals/km of the channel (excluding the Kondurcha River 6 individuals/km of the channel) the population density, locally, on anthropogenic and natural-anthropogenic territories increases to 47,5 individuals/km.

Systematic Evaluation of the Effects of Toxicant Exposure on Survival in Zebrafish Embryos and Larvae.

The use of whole animal models in toxicological studies is essential for understanding the physiological responses caused by chemical exposures. However, such studies can face reproducibility challenges due to unaccounted experimental parameters that can have a marked influence on toxicological outcomes. Zebrafish embryos and larvae are a popular vertebrate animal model for studying cellular, tissue, and organ responses to toxicant exposures. Despite the popularity of this system, standardized protocols that control for the influence of various experimental parameters and culture conditions on the toxicological response in these animals have not been widely adopted, making it difficult to compare findings from different laboratories. Here, we describe a detailed approach for designing and optimizing protocols to assess the impact of chemical exposures on the development and survival of zebrafish embryos and larvae. We first describe our standard procedure to determine two key toxicological thresholds, the maximum tolerable concentration (MTC) and the lethal concentration (LC50 , defined as that in which 50% of larvae die), in response to an exposure that persists from early development through larval maturation. We then describe two protocols to systematically test how key experimental parameters, including genetic background, culture media, animal density, volume, plate material, and developmental stage in which the embryos are exposed, alter the MTC and LC50 . Finally, we provide a step-by-step guide to assess the interaction between two chemicals using this model. These protocols will guide the standardization of toxicological studies using zebrafish and maximize reproducibility. © 2021 Wiley Periodicals LLC. Basic Protocol 1: Zebrafish embryo collection and culture, and establishment of the MTC and LC50 Basic Protocol 2: Evaluation of the impact of culture conditions on toxicant responses of zebrafish embryo and larvae Basic Protocol 3: Identification of the developmental window of sensitivity to toxicant exposure Basic Protocol 4: Testing interaction between multiple toxicants.

Effect of synchronized breeding on genetic evaluations of fertility traits in dairy cattle

Estrus detection has become more difficult over the years due to decreases in the estrus expression of high-producing dairy cows, and increased herd sizes and animal density. Through the use of hormonal synchronization protocols, also known as timed artificial insemination (TAI) protocols, it is possible to alleviate some of the challenges associated with estrus detection. However, TAI masks cows' fertility performance, resulting in an unfair comparison of treated animals and innately fertile animals. Consequently, genetically inferior and superior cows show similar phenotypes, making it difficult to distinguish between them. As genetic programs rely on the collection of accurate phenotypic data, phenotypes collected on treated animals likely add bias to genetic evaluations. In this study, to assess the effect of TAI, the rank correlation of bulls for a given trait using only TAI records were compared with the same trait using only heat detection records. A total of 270,434 records from 192,539 animals split across heifers, first and second parity cows were analyzed for the traits: calving to first service, first service to conception, and days open. Results showed large reranking across all traits and parities between bulls compared based on either having only TAI records or only heat detection records, suggesting that a bias does indeed exist. Large reranking was also observed for both the heat detection and TAI groups among the top 100 bulls in the control group, which included all records. Furthermore, breeding method was added to the model to assess its effect on bull ranking. However, there were only minor changes in the rank correlations between scenario groups. Therefore, more complex methods to account for the apparent bias created by TAI should be investigated; for this, the method by which these data are collected needs to be improved through creating a standardized way of recording breeding codes. Though the results of this study suggest the presence of bias within current fertility evaluations, additional research is required to confirm the findings of this study, including looking at high-reliability bulls specifically, to determine if the levels of reranking remain. Future studies should also aim to understand the potential genetic differences between the fertility traits split via management technology, possibly in a multiple-trait analysis.

Distribution, Population Size, and Habitat Characteristics of the Endangered European Ground Squirrel (Spermophilus citellus, Rodentia, Mammalia) in Its Southernmost Range

The European ground squirrel (Spermophilus citellus) is an endangered species, endemic to Central and Southeastern Europe, inhabiting burrow colonies in grassland and agricultural ecosystems. In recent years, agricultural land-use changes and increased urbanization have largely contributed to a severe population decline across its range, particularly in its southernmost edge. Assessing the population and habitat status of this species is essential for prioritizing appropriate conservation actions. The present study aims to track population size changes and identify habitat characteristics of the species in Greece via a literature search, questionnaires, and fieldwork for assessing trends in population size as well as spatial K-means analysis for estimating its relation to specific habitat attributes. We found that both distribution size (grid number) and colony numbers of the species decreased in the last decades (by 62.4% and 74.6%, respectively). The remaining colonies are isolated and characterized by low density (mean = 7.4 ± 8.6 ind/ha) and low number of animals (mean = 13 ± 16 individuals). Most of the colonies are situated in lowlands and did not relate to specific habitat attributes. Habitat aspect and system productivity (NDVI) were the main factors contributing mostly to the clustering of the existing colonies. These results demonstrate that the species is confined to small, isolated anthropogenic habitats. Specific conservation actions such as population reinforcement, habitat improvement, and specific common agricultural policy measures could effectively improve agroecological zones that are suitable for the maintenance and protection of existing and potential habitats for populations of the species.

Eimeria spp. in naturally infected beef cattle: Dynamics of oocysts excretion, prevalence, and comparison between parasitological diagnostics

Eimeria spp. infections cause mortality, reduced well-being, and substantial economic losses implications for cattle production worldwide. The present work followed up the excretion of Eimeria spp. oocysts in two naturally infected beef herds, from two different properties, to investigate the dynamics of oocyst excretion and the prevalence of Eimeria spp. in different animal categories and seasons of the year (rainy season - October to April; dry season - May to September). Even that, the species of Eimeria were identified and the parasitological techniques of Gordon and Whitlock modified and Mini-FLOTAC were used. In both herds, animals up to 14 months had a mean total OPG counts higher than older animals (after 15–16 months of age), and the species E. zuernii and E. bovis were more frequently identified, the first species being more frequent in animals from 1 to 2 months of age, while E. bovis prevailed from three months old. On property 1, the highest mean OPG counts (P ≤ 0.05) were obtained between October 2017 and September 2018, with the highest mean OPG counts in October 2017, when the animals were aged between 4–5 months. The prevalence of the pathogen on property 1 was 59.16 % and 43.62 % in the rainy and dry season, respectively, a higher parasitic load (P ≤ 0.05) was verified in the rainy season. On property 2, the mean OPG counts of Eimeria spp. was higher (P ≤ 0.05) in animals between 8–16 months, with the highest peak in November 2019, when they were one year old. The on-site prevalence during the rainy season on property 2 was 53.09 % and 49.79 % on dry season, and no difference (P = 0.92) in the mean OPG counts of Eimeria spp. during the seasons. There was a difference (P ≤ 0.05) in the count of oocysts in females after 18 months of age than males, which was probably due to the increase in animal density. Both tested techniques can be used for quantification of the excretion of oocysts of Eimeria spp. in cattle feces showing the same OPG mean count (r = 0.9287; p = 0.0025; R² = 0.8625). Mini-FLOTAC showed higher prevalence for Eimeria spp., however, can be an obstacle depending on the number of fecal samples that need to be processed.

Home range variation in leopards living across the human density gradient

AbstractHome range size is a fundamental measure of animal space use, providing insight into habitat quality, animal density, and social organization. Human impacts increasingly are affecting wildlife, especially among wide-ranging species that encounter anthropogenic disturbance. Leopards (Panthera pardus) provide a useful model for studying this relationship because leopards coexist with people at high and low human densities and are sensitive to human disturbance. To compare leopard home range size across a range of human densities and other environmental conditions, we combined animal tracking data from 74 leopards in multiple studies with new analytical techniques that accommodate different sampling regimes. We predicted that home ranges would be smaller in more productive habitats and areas of higher human population density due to possible linkage with leopard prey subsidies from domestic species. We also predicted that male leopards would have larger home ranges than those of females. Home ranges varied in size from 14.5 km2 in India to 885.6 km2 in Namibia, representing a 60-fold magnitude of variation. Home range stability was evident for 95.2% of nontranslocated individuals and 38.5% of translocated individuals. Leopard home range sizes were negatively correlated with landscape productivity, and males used larger areas than females. Leopards in open habitats had a predicted negative correlation in home range size with human population density, but leopards in closed habitats used larger home ranges in areas with more people.

A random walk model that accounts for space occupation and movements of a large herbivore

Animal movement has been identified as a key feature in understanding animal behavior, distribution and habitat use and foraging strategies among others. Large datasets of invididual locations often remain unused or used only in part due to the lack of practical models that can directly infer the desired features from raw GPS locations and the complexity of existing approaches. Some of them being disputed for their lack of biological justifications in their design. We propose a simple model of individual movement with explicit parameters, based on a two-dimensional biased and correlated random walk with three forces related to advection (correlation), attraction (bias) and immobility of the animal. These forces can be directly estimated using individual data. We demonstrate the approach by using GPS data of 5 red deer with a high frequency sampling. The results show that a simple random walk template can account for the spatial complexity of wild animals. The practical design of the model is also verified for detecting spatial feature abnormalities and for providing estimates of density and abundance of wild animals. Integrating even more additional features of animal movement, such as individuals’ interactions or environmental repellents, could help to better understand the spatial behavior of wild animals.

The current state of the golden jackal population in the Lower Dnister National Nature Park

With the advent of the golden jackal in the Lower Dnister, certain changes have taken place in natural complexes, which are primarily related to the impact of the new species on the local fauna. Under such conditions, the number of jackals in certain areas, the spatial structure and location of separate packs are important information for the development of measures aimed at maintaining an optimal abundance of this species. Given the active impact of wildlife on natural systems, there are a number of both biological and purely social problems that need to be addressed. The effectiveness of solving such problems directly depends on the level of study of various aspects of biology and ecology of jackals. In addition, knowledge of the current state of the Dnister jackal population allows timely and effective response to new environmental challenges, which are associated with an increase in the abundance of new species and in its impact on the native mammal fauna. The results of the research indicate a certain competition of the jackal with other species of predatory mammals, in particular the fox and the raccoon dog. Thus, within the territories where the study was carried out, with the appearance of the jackal at the lower course of the Dnister, the red fox was not observed at all and the number of raccoon dogs decreased significantly. Habitats of separate jackal groups within the Lower Dnister National Nature Park have been identified and their total abundance has been established. The dynamics of settlement by the species of the Lower Dnister area is analysed, the conservatism of the species in relation to the residential areas is indicated. It has been established that in some parts of the park, in particular on the northern bank of the Dnister Estuary, the density of animals is about 12 individuals per 1000 hectares, which significantly exceeds the permissible sanitary and epidemiological standards. At the same time, in some parts of the floodplains of the Lower Dnister, density exceeds 0.5 individuals per 1000 ha, which indicates a complex spatial distribution of separate packs and groups of jackals. Mapping of the number of jackals in the park showed that groups far from the estuary are smaller in number (6–14 individuals), whereas groups near the estuary are more abundant (13–20 individuals).

Kepadatan Nyamuk Mansonia dan Anopheles dengan Prevalensi Penyakit Filariasis di Kecamatan Taniwel Kabupaten Seram Bagian Barat

Filariasis is an infectious disease caused by filarial worms and transmitted by Mansonia and Anopheles mosquitoes. The prevalence of filariasis is influenced by the density of Mansonia and Anopheles mosquitoes. The purpose of this study was to determine the density of Mansonia, Anopheles mosquitoes, and zoonotic animals, and their relationship to the prevalence of filariasis in Taniwel District, West Seram Regency. This type of research is survey research and case control. The population in this study was the density of Mansonia and Anopheles mosquitoes, and cases of filariasis. While the research sample is people who suffer from filariasis, larval density, Mansonia and Anopheles mosquitoes. Data on the density of larvae/mosquitoes of Mansonia and Anopheles were analyzed descriptively, and analysis of the relationship between density of community habits and prevalence of filariasis was carried out by using the chi square test with SPSS version 20.0 program. The results showed that people used mosquito repellent lotion or brought mosquito rackets before doing activities at night. The density of Mansonia mosquitoes in Sohuwe Village is 4.00-5.85; Lumahlatal Village 5.00-6.60; and Maloang Village 4.00-6.20. Meanwhile, the density of Anopheles mosquitoes in Sohuwe Village is 7.00-9.85; Lumahlatal Village 5.89-6.82; and Maloang Village 5.00-6.50. The prevalence rate of filariasis in Sohuwe Village is 0.66; Lumahlatal Village 0.88; and Maloang Village 1.54; and there is a significant relationship between people's habits and the incidence of filariasis.

Serological detection and genetic characterization of foot-and-mouth disease virus from cattle in northern sudan, 2016‑2018

Northern Sudan is an important corridor cluster between pools of foot-and-mouth disease virus (FMDV) in East and North Africa. It involves almost the whole border area with Egypt and represents a considerable part of a projected disease-free zone in Sudan. The study monitored FMD infection between 2016 and 2018 in Northern Sudan. Clinical and serological surveillance were carried out. Results largely confirmed previous reports that have described the relatively lower circulation of FMDV in the area than in other parts of the country. Clinical FMD was confirmed, once in the three years period, as serotype O of an unnamed lineage within the topotype East Africa 3 (EA3). Using serial testing (the ID ELISA and virus neutralization test), sero-prevalence estimates of serotype-specific antibodies in the two States of Northern Sudan ranged between 15.4% (serotype A) in the River Nile State to 3.4% (serotype SAT2) in the Northern State. Striking disparities between patterns of FMD in Northern Sudan and the rest of Sudan were observed. Unlike Western, Eastern, Central and Southern Sudan, no predominance of serotype O antibodies was detected in Northern Sudan. Concurrently, a serotype O isolate from Northern Sudan in 2016 was found to be of transboundary nature circulating in East and North Africa and in the Middle East (nt. id. > 99%); like serotype O that caused the last episode of disease in Northern Sudan in 2012. Molecular findings were compatible with the inferred low circulation of FMDV in Northern Sudan. Elsewhere in Sudan, endogenous serotype O viruses seemed to be circulating more unabated. It was concluded that low animal density and limited animal movement in Northern Sudan together with the high antibody levels against serotype O in immediately neighbouring States (Khartoum and Kassala) effectively decreased infiltration of endogenous O viruses.

Abundance and Foraging Ecology of the Black and White Colobus Monkey (Colobus guereza ssp. guereza) in Nech Sar National Park, Ethiopia

We estimated the abundance of Colobus guereza ssp. guereza in the moist evergreen riparian forest part of Nech Sar National Park, Ethiopia. The survey was conducted using the distance sampling method. Based on a preliminary study, 17 newly cut line transects were randomly aligned across the study area. The survey data were then collected for three consecutive months. Transects were walked once per month for 14-16 days. Abundance estimates were analyzed using the program 'DISTANCE'. The half-normal key function with cosine adjustment fitted our data sets best. Mean group density and mean animal density were 14 animals km-2 and 102 animals km-2, respectively, resulting in a mean estimated abundance of 2,153 animals distributed over thestudy area. The mean estimated group size was 7.24 with an estimated encounter rate of 1.72. Compared to similar studies from tropical forests in Africa, our population density estimates were intermediate between the mean values (100 to 168 animals km-2). We conclude that such intermediate density estimates reflect the fact that guerezas have suffered from human-induced reductions in habitat availability. We also suggest that the natural forest is still in a reasonable condition that likely provides them with sufficient food supply to compensate for such intermediate densities. However, a replication of this study would lead to a more comprehensive abundance estimate. We also recommend studies that would address the activity-time budget and populationdemographics of these monkeys. Nonetheless, our results provide a reference point for future studies in this area, particularly to assess population trends of C. g. guereza.

A comparison of three methods for estimating call densities of migrating bowhead whales using passive acoustic monitoring

Various methods for estimating animal density from visual data, including distance sampling (DS) and spatially explicit capture-recapture (SECR), have recently been adapted for estimating call density using passive acoustic monitoring (PAM) data, e.g., recordings of animal calls. Here we summarize three methods available for passive acoustic density estimation: plot sampling, DS, and SECR. The first two require distances from the sensors to calling animals (which are obtained by triangulating calls matched among sensors), but SECR only requires matching (not localizing) calls among sensors. We compare via simulation what biases can arise when assumptions underlying these methods are violated. We use insights gleaned from the simulation to compare the performance of the methods when applied to a case study: bowhead whale call data collected from arrays of directional acoustic sensors at five sites in the Beaufort Sea during the fall migration 2007–2014. Call detections were manually extracted from the recordings by human observers simultaneously scanning spectrograms of recordings from a given site. The large discrepancies between estimates derived using SECR and the other two methods were likely caused primarily by the manual detection procedure leading to non-independent detections among sensors, while errors in estimated distances between detected calls and sensors also contributed to the observed patterns. Our study is among the first to provide a direct comparison of the three methods applied to PAM data and highlights the importance that all assumptions of an analysis method need to be met for correct inference.