Pitfalls in using counts of roaring stags to index red deer (Cervus elaphus) population size

2009 ◽  
Vol 36 (2) ◽  
pp. 126 ◽  
Author(s):  
Paolo Ciucci ◽  
Gianluca Catullo ◽  
Luigi Boitani
Keyword(s):  
Population Size ◽  
Cervus Elaphus ◽  
Red Deer ◽  
Population Monitoring ◽  
Weather Conditions ◽  
Error Rates ◽  
Type I ◽  
High Type ◽  
Abundance Estimates ◽  
Absolute Density

Counting roaring stags during the rut has been proposed as a means to assess deer population size and trends but few, if any, attempts have been made to evaluate the reliability of this technique. By means of a commonly used field protocol, we assessed to what extent relative abundance estimates of red deer (Cervus elaphus) based on roaring-stag counts in the northern Apennines (Italy) were susceptible to exogenous and unpredictable sources of variability. By using up to 26 simultaneous observers in an area of 5218 ha, we estimated densities from 0.45 to 0.61 roaring stags per 100 ha in 3 consecutive years (1992–94), corresponding to annual changes in the number of counted roaring stags ranging from –21% to +35.7%. However, only in two of the three years were seasonal trends and peaks in roaring activity apparent, and timing of the survey was not always synchronous with the roaring peak. In addition, annual and nocturnal variation in roaring activity, and weather conditions during the survey, might have influenced the counts to some extent, probably determining high Type I and Type II error rates. We contend that additional sources of error, associated with unknown demographic and ecological settings, may further increase unreliability of the technique when it is used to estimate absolute density of red deer populations. We conclude by emphasising that managers should not use this method for population monitoring unless they can prove it can yield reliable results.

scholarly journals Tracking red deer population size using deterministic cohort analysis

2021 ◽  
Author(s):  
Valerio Donini ◽  
Luca Corlatti ◽  
Luca Pedrotti
Keyword(s):  
Population Size ◽  
Cervus Elaphus ◽  
Red Deer ◽  
Cohort Analysis ◽  
Cost Effective ◽  
Natural Mortality ◽  
Relative Index ◽  
Deer Population ◽  
Monitoring Tools ◽  
Over Time

AbstractReliable and cost-effective monitoring tools to track population size over time are of key importance for wildlife management and conservation. Deterministic cohort analysis may be used to this aim, especially in hunted populations, but it requires that all mortality events are recorded and that individual age at death is known exactly. In this study, we investigated the reliability of cohort analysis as a relative index to track over-time variation in red deer (Cervus elaphus) abundance, in the absence of exact information about natural mortality and age. Visual tooth inspection was used to age 18,390 individuals found dead or hunted between 1982 and 2020 within the Trentino sector of the Stelvio National Park and the Val di Sole hunting district (Central Italian Alps). Temporal trend of reconstructed population size was checked using spring spotlight counts as a benchmark, through the Buishand range test and a linear model. Our results showed a significant and positive relationship between reconstructed population size and spring spotlight counts between 1982 and 2013, suggesting that cohort analysis could reliably track red deer population trend up to 7 years in the past. With a relative error of  +  1.1 (SD  =  1.5) years in the estimation of age, and fairly stable hunting pressure, our results support the use of deterministic cohort analysis as a relative index of abundance for monitoring red deer over time, even in the absence of exact information about natural mortality. Under violation of assumptions, however, the performance of deterministic reconstruction should be carefully inspected at the management scale.

scholarly journals Monitoring Population Size of Red Deer Cervus Elaphus: An Evaluation of Two Types of Census Data from Norway

2007 ◽  
Vol 13 (3) ◽  
pp. 285-298 ◽  
Author(s):  
Atle Mysterud ◽  
Erling L. Meisingset ◽  
Vebjørn Veiberg ◽  
Rolf Langvatn ◽  
Erling J. Solberg ◽  
...  
Keyword(s):  
Population Size ◽  
Cervus Elaphus ◽  
Red Deer ◽  
Census Data

scholarly journals Wildkundliche und jagdliche Veränderungen in den letzten 25 Jahren (1973 bis 1997), dargestellt anhand von Jagdstatistiken | Changes in Population and Harvesting of Game Species During 25 Years (1973-1997): an Interpretation of Hunting Statistics

1999 ◽  
Vol 150 (9) ◽  
pp. 335-341
Author(s):  
Urs Zehnder
Keyword(s):  
Population Size ◽  
Cervus Elaphus ◽  
Red Deer ◽  
Roe Deer ◽  
Capreolus Capreolus ◽  
Population Trends ◽  
Game Species ◽  
Rupicapra Rupicapra ◽  
Adult Females ◽  
Hunting Statistics

Population trends, numbers of harvested adult females and harvest rates of red deer (Cervus elaphus) in Switzerland and in the canton of St. Gallen were analysed using freely accessible data from federal and regional hunting statistics. We did the same analyses with data from chamois (Rupicapra rupicapra) in Switzerland and in the cantons of Berne and St. Gallen. Data from roe deer (Capreolus capreolus) were analysed for Switzerland and the cantons of Solothurn and Vaud. The results show that the new Swiss hunting and forest laws have not had any effect on population size of red deer, chamois and roe deer yet. Regulative effects, however, could be shown locally for the red deer in the canton of St. Gallen and for the chamois in the cantons of Berne and St. Gallen. There is evidence that the present hunting statistics represent only an incomplete base for comprehensive harvest planning according to the law.

scholarly journals Analysis of accuracy of hunting plan in the Czech Republic

2012 ◽  
Vol 60 (3) ◽  
pp. 165-172 ◽  
Author(s):  
Radim Plhal ◽  
Jiří Kamler
Keyword(s):  
Czech Republic ◽  
Population Size ◽  
Cervus Elaphus ◽  
Calculation Method ◽  
Red Deer ◽  
Roe Deer ◽  
Capreolus Capreolus ◽  
Fallow Deer ◽  
Management Policy ◽  
The Czech Republic

This article analyses data on the reported and captured populations of red deer (Cervus elaphus), roe deer (Capreolus capreolus), fallow deer (Dama dama) and mouflon (Ovis musimon) in the Czech Republic during the years 2002–2006. Breeding and hunting plans collected by the State Hunting Authority have been summarized. The analyzed game population size (APS) for each individual territory, using the reverse calculation method, was compared to the counted population size (CPS) of each species. Next, the ratios between the specified population size (SPS) and the CPS were compared; and also the ratios of CPS and actual hunting bag were compared for individual years in the specified periods. Many errors in hunting management policy were found in all analyses regarding red deer. In many cases the APS, using the reverse calculation method, was several-times higher than the CPS. Also a large difference between SPS and CPS was very common. Similar results were also found in the analyses of fallow deer and mouflon populations, where the management policy was very similar to that of red deer. Evaluation of the roe deer management policy showed better results. Despite the fact that the APS was higher than the CPS, it was never several-times higher. Even in SPS and CPS ratios no extreme outcomes were found. From the official processed data it is evident that hunting association plans for game breeding and hunting indicate many significant problems, where the smallest problem is with roe deer and the biggest problem is with red deer.

scholarly journals Estimating red deer (Cervus elaphus) population size based on non-invasive genetic sampling

2021 ◽  
Vol 67 (2) ◽  
Author(s):  
Cornelia Ebert ◽  
Julian Sandrini ◽  
Bettina Welter ◽  
Bernhard Thiele ◽  
Ulf Hohmann
Keyword(s):  
Population Size ◽  
Density Estimation ◽  
Cervus Elaphus ◽  
Red Deer ◽  
Sex Ratios ◽  
Urn Model ◽  
Non Invasive ◽  
Deer Population ◽  
Genetic Sampling ◽  
Conservation Concern

AbstractSome deer species are of conservation concern; others are officially managed as a food source or for their trophies, whereas in many regions, deer are regarded as overabundant or even as a nuisance causing damages. Regardless of local management issues, in most cases, reliable data on deer population sizes and sex ratios are lacking. Non-invasive genetic approaches are promising tools for the estimation of population size and structure. We developed and tested a non-invasive genetic approach for red deer (Cervus elaphus) population size and density estimation based on faeces collected from three free-ranging red deer populations in south-western Germany. Altogether, we genotyped 2762 faecal samples, representing 1431 different individuals. We estimated population density for both sexes separately using two different approaches: spatially explicit capture-recapture (SECR) approach and a single-session urn model (CAPWIRE). The estimated densities of both approaches were similar for all three study areas, ranging between total densities of 3.3 (2.5–4.4) and 8.5 (6.4–11.3) red deer/km2. The estimated sex ratios differed significantly between the studied populations (ranging between 1:1.1 and 1:1.7), resulting in considerable consequences for management. In further research, the issues of population closure and approximation of the effectively sampled area for density estimation should be addressed. The presented approach can serve as a valuable tool for the management of deer populations, and to our knowledge, it represents the only sex-specific approach for estimation of red deer population size and density.

scholarly journals A new gene mapping resource: interspecies hybrids between Père David's deer (Elaphurus davidianus) and red deer (Cervus elaphus).

Genetics ◽  
1995 ◽  
Vol 139 (3) ◽  
pp. 1383-1391
Author(s):  
M L Tate ◽  
H C Mathias ◽  
P F Fennessy ◽  
K G Dodds ◽  
J M Penty ◽  
...  
Keyword(s):  
Cervus Elaphus ◽  
Red Deer ◽  
Restriction Enzymes ◽  
Specific Protein ◽  
F1 Hybrids ◽  
Type I ◽  
Linkage Groups ◽  
Gene Map ◽  
Père David’S Deer ◽  
Species Specific

Abstract Three male F1 hybrids between Père David's deer and red deer were mated to red deer to produce 143 backcross calves. The pedigrees are a rare example of a fertile hybrid between evolutionarily divergent species. We examined the use of these families for genetic mapping of evolutionarily conserved (Type I) loci by testing for genetic linkage between five species-specific protein variants and 12 conserved DNA probes. Two probes were homologous, and the remainder syntenic, to the protein coding loci in cattle or humans. Using six restriction enzymes, each DNA probe detected one or more restriction fragments specific to Père David's deer. Linkage analyses among the species-specific variants placed the loci into four linkage groups within which linkage between adjacent loci and gene order was supported by a LOD > 3. The linkage groups were (HPX, HBB)-FSHB-ACP2, LDHA-CD5-IGF2, BMP3-(GC, ALB)-(KIT, PDGFRA) and LDLR-C3-FGF1. Southern and protein analysis of LDHA and ALB provided identical segregation data. These linkage groups were consistent with the cattle gene map and provide new information for comparing the gene maps of ruminants, humans and mice. The deer hybrids are an important new resource that can contribute to the comparative analysis of the mammalian genome.

scholarly journals Of power and despair in cetacean conservation: estimation and detection of trend in abundance with noisy and short time-series

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e9436 ◽  
Author(s):  
Matthieu Authier ◽  
Anders Galatius ◽  
Anita Gilles ◽  
Jérôme Spitz
Keyword(s):  
Time Series ◽  
Population Decline ◽  
Error Rates ◽  
Small Sample ◽  
Type I ◽  
Power Type ◽  
Short Time Series ◽  
Informative Prior ◽  
Abundance Estimates ◽  
Short Time

Many conservation instruments rely on detecting and estimating a population decline in a target species to take action. Trend estimation is difficult because of small sample size and relatively large uncertainty in abundance/density estimates of many wild populations of animals. Focusing on cetaceans, we performed a prospective analysis to estimate power, type-I, sign (type-S) and magnitude (type-M) error rates of detecting a decline in short time-series of abundance estimates with different signal-to-noise ratio. We contrasted results from both unregularized (classical) and regularized approaches. The latter allows to incorporate prior information when estimating a trend. Power to detect a statistically significant estimates was in general lower than 80%, except for large declines. The unregularized approach (status quo) had inflated type-I error rates and gave biased (either over- or under-) estimates of a trend. The regularized approach with a weakly-informative prior offered the best trade-off in terms of bias, statistical power, type-I, type-S and type-M error rates and confidence interval coverage. To facilitate timely conservation decisions, we recommend to use the regularized approach with a weakly-informative prior in the detection and estimation of trend with short and noisy time-series of abundance estimates.

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