Uses of Herd Composition and Age Ratios in Ungulate Management

Bender, Louis C.

doi:10.2193/0091-7648(2006)34[1225:uohcaa]2.0.co;2

Cited by 36 publications

(42 citation statements)

References 8 publications

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“…Estimates of demographic parameters and statistics that depend on classification data are frequently used in conservation, monitoring, and adaptive management (Bassar et al, 2010;Lahoz-Monfort, Guillera-Arroita, & Hauser, 2014). Sex ratios are used in hunting and fishing regulations because optimal harvest yields depend on age and sex composition (Bender, 2006;Hauser, Cooch, & Lebreton, 2006;Jensen, 1996;Murphy & Smith, 1990). Disease management strategies based on prevalence and transmission rates depend on disease status obtained from imperfect diagnostic testing (PCR, ELISA, visual inspection, etc.)…”

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confidence: 99%

A hierarchical Bayesian approach for handling missing classification data

Ketz

Johnson

Hooten

et al. 2019

Ecology and Evolution

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Ecologists use classifications of individuals in categories to understand composition of populations and communities. These categories might be defined by demographics, functional traits, or species. Assignment of categories is often imperfect, but frequently treated as observations without error. When individuals are observed but not classified, these “partial” observations must be modified to include the missing data mechanism to avoid spurious inference. We developed two hierarchical Bayesian models to overcome the assumption of perfect assignment to mutually exclusive categories in the multinomial distribution of categorical counts, when classifications are missing. These models incorporate auxiliary information to adjust the posterior distributions of the proportions of membership in categories. In one model, we use an empirical Bayes approach, where a subset of data from one year serves as a prior for the missing data the next. In the other approach, we use a small random sample of data within a year to inform the distribution of the missing data. We performed a simulation to show the bias that occurs when partial observations were ignored and demonstrated the altered inference for the estimation of demographic ratios. We applied our models to demographic classifications of elk (Cervus elaphus nelsoni) to demonstrate improved inference for the proportions of sex and stage classes. We developed multiple modeling approaches using a generalizable nested multinomial structure to account for partially observed data that were missing not at random for classification counts. Accounting for classification uncertainty is important to accurately understand the composition of populations and communities in ecological studies.

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confidence: 99%

A hierarchical Bayesian approach for handling missing classification data

Ketz

Johnson

Hooten

et al. 2019

Ecology and Evolution

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“…Other demographic parameters, such as sex ratio and age proportions are of equal importance in supporting the management of ungulate species (Bender, 2006;Pohler et al, 2014). However, aerial surveys of the marsh deer do not provide these data (Mourão & Campos, 1995;Mourão et al, 2000;Tomas et al, 2001;Tiepolo et al, 2010), and it has been reported that sexual identification is not possible in 74% of sightings .…”

Section: Camera Trapmentioning

confidence: 99%

“…Similarly to sex ratios information, determining age proportions or detecting the frequency of fawns in a population are essential to understanding population recruitment and to infer about population dynamics (Bender, 2006;Pohler et al, 2014). In this regard, once again the camera traps were more informative.…”

Section: Camera Trapmentioning

confidence: 99%

Accessing camera trap survey feasibility for estimating Blastocerus dichotomus (Cetartiodactyla, Cervidae) demographic parameters

Peres

Polverini

Oliveira

et al. 2017

Iheringia, Sér. Zool.

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ABSTRACT. Demographic information is the basis for evaluating and planning conservation strategies for an endangered species. However, in numerous situations there are methodological or financial limitations to obtain such information for some species. The marsh deer, an endangered Neotropical cervid, is a challenging species to obtain biological information. To help achieve such aims, the study evaluated the applicability of camera traps to obtain demographic information on the marsh deer compared to the traditional aerial census method. Fourteen camera traps were installed for three months on the Capão da Cruz floodplain, in state of São Paulo, and ten helicopter flyovers were made along a 13-kilometer trajectory to detect resident marsh deer. In addition to counting deer, the study aimed to identify the sex, age group and individual identification of the antlered males recorded. Population estimates were performed using the capture-mark-recapture method with the camera trap data and by the distance sampling method for aerial observation data. The costs and field efforts expended for both methodologies were calculated and compared. Twenty independent photographic records and 42 sightings were obtained and generated estimates of 0.98 and 1.06 ind/km², respectively. In contrast to the aerial census, camera traps allowed us to individually identify branch-antlered males, determine the sex ratio and detect fawns in the population. The cost of camera traps was 78% lower but required 20 times more field effort. Our analysis indicates that camera traps present a superior cost-benefit ratio compared to aerial surveys, since they are more informative, cheaper and offer simpler logistics. Their application extends the possibilities of studying a greater number of populations in a long-term monitoring.KEYWORDS. Aerial survey, capture-recapture, distance sampling, population estimate, sex ratio.RESUMO. Avaliação da viabilidade do uso de armadilhas fotográficas para estimar parâmetros demográficos de Blastocerus dichotomus (Cetartiodactyla, Cervidae). Informações demográficas constituem a base para a avaliação e planejamento de estratégias de conservação de uma espécie ameaçada. No entanto, em muitas situações existem limitações metodológicas ou financeiras para a obtenção de tais informações para algumas espécies. O cervo-do-pantanal, um cervídeo neotropical ameaçado de extinção, é uma espécie desafiadora para obtenção de informações biológicas. Para suprir essa demanda, o presente trabalho avaliou a aplicabilidade das armadilhas fotográficas para obtenção de informações demográficas de cervo-do-pantanal em comparação com o tradicional método de censo aéreo. Na várzea Capão da Cruz, Estado de São Paulo, foram instaladas 14 armadilhas fotográficas durante três meses e realizados dez sobrevoos de helicóptero num trajeto de 13 km para detecção dos cervos-do-pantanal ali residentes. Além da contagem dos animais, objetivou-se identificar o sexo, a faixa etária e a identificação individual dos machos galhados registrados. As es...

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“…Only a few demographic studies have been conducted for the mountain nyala; the first over 45 years ago [2], and two recently in a small isolated population in BMNP [10,11]. To successfully manage and conserve any wildlife species, a basic understanding of the population's structure and group dynamics are required [12][13][14][15]. Demographic parameters (i.e., vital rates) are often used as indices of population's health and stability, and to evaluate a species' status and viability [16,17].…”

Section: Introductionmentioning

confidence: 99%

Do Consumers Prefer Wild, Farmed Bear Bile or Substitutes?

Jiang¹

2015

J Biodivers Endanger Species

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The highlands of Ethiopia are inhabited by the culturally and economically significant mountain nyala Tragelaphus buxtoni, an endemic spiral horned antelope. The natural range of this species has become highly fragmented with increasing anthropogenic pressures; driving land conversion in areas previously considered critical mountain nyala habitat. Therefore, baseline demographic data on this species throughout its existing range are needed. Previous studies on mountain nyala demographics have primarily focused on a confined portion of its known range where trophy hunting is not practiced. Our objectives were to estimate group size, proportion of females, age class proportions, and calf and juvenile productivity for a sub-population of mountain nyala where trophy hunting is permitted and compare our results to recent and historical observations. We collected four years of demographic data using direct point counts in a controlled hunting area and summarized the data using the R statistical software. Our results show that estimated proportion of females (0.63; 0.56-0.69) was similar to recent studies of non-hunted populations, but group size (3.74; 3.34-4.13), juvenile productivity (0.47; 0.35-0.62) and age class proportions (calves: 0.17 juveniles: 0.19 adults: 0.64) were considerably different. Our results are more similar to historical accounts than those in a national park. We demonstrate that the mountain nyala's population structure and health varies across its range and may relate to the different management strategies and policies. We recommend using similar methods for remaining under surveyed sub-populations of mountain nyala to inform conservation actions at the landscape scale.

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Uses of Herd Composition and Age Ratios in Ungulate Management

Cited by 36 publications

References 8 publications

A hierarchical Bayesian approach for handling missing classification data

A hierarchical Bayesian approach for handling missing classification data

Accessing camera trap survey feasibility for estimating Blastocerus dichotomus (Cetartiodactyla, Cervidae) demographic parameters

Do Consumers Prefer Wild, Farmed Bear Bile or Substitutes?

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