Cornelia Ebert - Academia.edu (original) (raw)

Papers by Cornelia Ebert

Animal Biodiversity and Conservation, 2012

U., 2012. Non-invasive genetic approaches for estimation of ungulate population size: a study on ... more U., 2012. Non-invasive genetic approaches for estimation of ungulate population size: a study on roe deer (Capreolus capreolus) based on faeces. Animal Biodiversity and Conservation,.

Summary For wild boar, until now no reliable and robust method to estimate population density exi... more Summary For wild boar, until now no reliable and robust method to estimate population density exists. The study pre- sented here aims to develop a method based on genotyping of non-invasively obtained tissue samples. Theoretical base of the method is a modified capture-recapture approach, with genotyping being considered as capture and sampling as recapture. The first question to answer was which kind of tissue sample and which sampling strategy is suitable to ensure an equal sampling probability for each individual in the sam- pled population. Therefore, two different strategies were tested in the field: hair and scat sampling. The hair sampling trials were carried out under video control in order to evaluate the behaviour of wild boar at the sampling stations. This procedure should help to detect potential bias in sampling probability due to age, sex or social status of the animals. Additionally, 8 wild boar were radio tagged in the same study area. Their movements were monitored ...

Animal Biodiversity and Conservation

Non–invasive genetic approaches for estimation of ungulate population size: a study on roe deer (... more Non–invasive genetic approaches for estimation of ungulate population size: a study on roe deer (Capreolus capreolus) based on faeces.— Estimating population size is particularly difficult for animal species living in concealing habitats with dense vegetation. This is the case for roe deer as for many other ungulates. Our objective was to develop a non–invasive genetic capture–mark–recapture approach based on roe deer faeces collected along transects. In a pilot study, we collected 1,790 roe deer faeces during five sampling days in a forested study area in south western Germany. We extracted DNA from 410 of these samples and carried out microsatellite analysis using seven dinucleotide markers. The analyses resulted in 328 useable consensus genotypes which were assigned to 174 individuals. The population size estimated using a Bayesian approach was 94 (82–111) male and 136 (121–156) female roe deer. Our study shows that non–invasive genetic methods are a valuable management tool for ...

Zusammenfassung Eine Fang-Wiederfang-Methode für die Zählung von Wildschweinen wird beschrieben. ... more Zusammenfassung Eine Fang-Wiederfang-Methode für die Zählung von Wildschweinen wird beschrieben. Die Identifizierung der Tiere erfolgte über eine genetische Analyse von gefundenem Kot. Die Beprobung wurde an 12 Tagen auf systematisch im Wildforschungsgebiet angelegten Transektlinien durchgeführt. Zur Auswertung wurden die Modelle von BURNHAM et al. (1978) und CHAO (1988) verwendet.

In many parts of Europe wild boar Sus scrofa population increase and dispersal into new areas is ... more In many parts of Europe wild boar Sus scrofa population increase and dispersal into new areas is accompanied by economic problems. Due to underestimation of population densities and reproduction rates harvest rates seem to be insufficient, especially proportions of shot females might be inadequate. Thus, we calculated mortality rates of several wild boar populations, to show the efficiency of hunting within 13 years from studies conducted in 16 different study areas distributed over 8 European states. For calculating mortality rates the daily probability of survival of radio telemetrically observed wild boar were analysed according to Mayfield (1961) for three age classes (0, 1, ≥2years) and both sexes. Of 872 animals observed by VHF- or GPS-telemetry 228 died during the total observation of 121998 days. The mortality rates of wild boar, especially piglets were low (about 0.5). About three third of all observed animals survived at least until the next period of reproduction. The sex...

Wildlife Biology, 2012

Increasing populations of wild boar and feral domestic pigs Sus scrofa have evoked growing concer... more Increasing populations of wild boar and feral domestic pigs Sus scrofa have evoked growing concern due to their potential as disease reservoir and as an origin of agricultural damages. Reliable population estimates are needed for effective management measures of this species. As an alternative to traditional methods, non-invasive genetic population estimation approaches based on hair or faeces sampling have yielded promising results for several species in terms of feasibility and precision. We developed and applied a non-invasive population estimation approach based on wild boar faeces in a study area situated in the Palatinate Forest, southwestern Germany. We collected 515 faeces samples along transects in January 2008. We carried out genotyping using six microsatellite markers to discriminate between individuals. During the trial, we identified 149 individual wild boar. Using multimodel inference and model averaging, we obtained relatively consistent estimates. Population densities calculated using the estimated population sizes ranged from 4.5 (2.9-7.8) to 5.0 (4.0-7.0) wild boar/km 2 . In the future, to further improve the precision of population estimates based on wild boar faeces, the detection probability should be increased. However, even when comparing a conservative population estimate to the hunting bag, our results show that the present hunting regime in our study area is not effective in regulating the wild boar population. The method which we present here offers a tool to calibrate hunting or other management measures for wild boar.

Wildlife Biology, 2010

In recent years much progress has been made in non-invasive genetic methods for various 25 purpos... more In recent years much progress has been made in non-invasive genetic methods for various 25 purposes including population estimation. Previous research focused on optimizing laboratory 42

Proceedings of the Royal Society B: Biological Sciences, 2006

Group decisions are required when group coordination is beneficial, but individuals can choose be... more Group decisions are required when group coordination is beneficial, but individuals can choose between alternatives. Despite the increased interest in animal group decision making, there is a lack of experimental field studies that investigate how animals with conflicting information make group decisions. In particular, no field studies have considered the influence of fission-fusion behaviour (temporary splitting into subgroups) on group decisions. We studied group decision making in two wild Bechstein's bat colonies, which are fission-fusion societies of stable individual composition. Since they frequently switch communal roosts, colony members must regularly make group decisions over where to roost. In the two-field experiments, we provided marked individuals with conflicting information about the suitability of potential roosts. We investigated whether conflicting information led to group decisions that followed a 'unanimous' or a 'majority' rule, or increased colony fission. Individual behaviour suggests that bats considered both their own information and the behaviour of others when deciding where to roost. Group decisions about communal roosts reflected the information available to a majority of the bats roosting together, but conflicting information led to an increased fission in one colony. Our results suggest that fission-fusion societies allow individuals to avoid majority decisions that are not in their favour.

European Journal of Wildlife Research, 2013

In many parts of Europe, wild boar Sus scrofa population increase, and thus, high densities and d... more In many parts of Europe, wild boar Sus scrofa population increase, and thus, high densities and dispersal into new areas are accompanied by economic problems. Due to many factors like insufficient hunting strategies as well as underestimation of population densities and reproduction rates, harvest rates seem to be insufficient. Thus, we calculated mortality rates of several wild boar populations from 1998 to 2009, to show the efficiency of hunting within several studies distributed over eight European states. For calculating mortality rates, the daily probability of survival of radio telemetrically observed wild boar was analysed according to Mayfield (Wilson Bull 73:255-261, 1961) and with survival analysis in R for three age classes (0, 1, ≥2 years) and both sexes. The mortality rates of wild boar per annum, especially piglets, were comparably low (about 0.5 for piglets and similar for total population). About three third of all observed animals survived at least until the next period of reproduction. Mortality rates differed between some study areas, the sexes and age classes. The sex ratio of the shot piglets equals the sex ratio of captured piglets; there seems to be no sex-biased Communicated by C. Gortázar

European Journal of Wildlife Research, 2010

Reliable estimation of population size remains a major challenge in wildlife ecology and manageme... more Reliable estimation of population size remains a major challenge in wildlife ecology and management. Lately, genotyping of non-invasively obtained tissue samples integrated in a modified capture-recapture approach provides new perspectives. Faeces, moulted feathers, or hairs can be easily sampled in the field. However, an important assumption is homogeneity of sampling across the population. In this pilot study, we tested the suitability of baited barbed wire hair sampling stations ('hair traps') for homogeneous genetic sampling for population estimation. A video system based on a new network internet protocol was used to observe the behaviour of wild boar visiting baited hair traps for gaining information about potential heterogeneities in the individual sampling probability. Within 92 monitoring nights at two sampling stations, 216 wild boar visits were recorded and 142 hair samples containing 2,124 single hairs were collected. Video analysis revealed distinct differences in the behaviour of wild boar with respect to the sampling station which are most likely to result in heterogeneous individual sampling probabilities. Adult and subadult animals differed in their behaviour dependent on their group status. This result indicates that hair sampling with baited hair traps is not suitable for representative non-invasive sampling of free ranging wild boar populations.

Conservation Genetics Resources, 2013

Several methods have been applied to calculate genotyping error rates (GER) for non-invasive popu... more Several methods have been applied to calculate genotyping error rates (GER) for non-invasive population size estimations. However, there is a lack of comparability between these methods. Here we focused on the comparison of methods for determination of GER within one study using faeces samples of wild boars (Sus scrofa). Error rates were calculated by (1) comparison of reference tissue samples and rectum faeces samples (2) the number of deviations between replicates and the assumed consensus genotypes, (3) re-analysis of a subsample interpreted by allelic and genotype comparisons, and (4) a blind-test of anonymously subdivided faecal samples. The error rates differed widely between these four methods (0-57.5 %) and underline the need of a consensus approach. The blindtest resulted in a GER of 4.3 %. We recommend conducting such a blind-test for estimating realistic GER when starting a pilot study in wildlife forensics.

Behaviour, 2005

Animals are often confronted with environmental challenges and the way in which they cope with th... more Animals are often confronted with environmental challenges and the way in which they cope with these challenges can have important fitness consequences. There is increasing evidence that individuals differ consistently in their reaction to the environment (personality traits). However, little is known about whether different life-styles (e.g., resident or migratory) influence personality traits and if so, in what manner.

Proceedings of the Royal Society B: Biological Sciences, 2006

Group decisions are required when group coordination is beneficial, but individuals can choose be... more Group decisions are required when group coordination is beneficial, but individuals can choose between alternatives. Despite the increased interest in animal group decision making, there is a lack of experimental field studies that investigate how animals with conflicting information make group decisions. In particular, no field studies have considered the influence of fission-fusion behaviour (temporary splitting into subgroups) on group decisions. We studied group decision making in two wild Bechstein's bat colonies, which are fission-fusion societies of stable individual composition. Since they frequently switch communal roosts, colony members must regularly make group decisions over where to roost. In the two-field experiments, we provided marked individuals with conflicting information about the suitability of potential roosts. We investigated whether conflicting information led to group decisions that followed a 'unanimous' or a 'majority' rule, or increased colony fission. Individual behaviour suggests that bats considered both their own information and the behaviour of others when deciding where to roost. Group decisions about communal roosts reflected the information available to a majority of the bats roosting together, but conflicting information led to an increased fission in one colony. Our results suggest that fission-fusion societies allow individuals to avoid majority decisions that are not in their favour.

Animal Biodiversity and Conservation, 2012

U., 2012. Non-invasive genetic approaches for estimation of ungulate population size: a study on ... more U., 2012. Non-invasive genetic approaches for estimation of ungulate population size: a study on roe deer (Capreolus capreolus) based on faeces. Animal Biodiversity and Conservation,.

Summary For wild boar, until now no reliable and robust method to estimate population density exi... more Summary For wild boar, until now no reliable and robust method to estimate population density exists. The study pre- sented here aims to develop a method based on genotyping of non-invasively obtained tissue samples. Theoretical base of the method is a modified capture-recapture approach, with genotyping being considered as capture and sampling as recapture. The first question to answer was which kind of tissue sample and which sampling strategy is suitable to ensure an equal sampling probability for each individual in the sam- pled population. Therefore, two different strategies were tested in the field: hair and scat sampling. The hair sampling trials were carried out under video control in order to evaluate the behaviour of wild boar at the sampling stations. This procedure should help to detect potential bias in sampling probability due to age, sex or social status of the animals. Additionally, 8 wild boar were radio tagged in the same study area. Their movements were monitored ...

Animal Biodiversity and Conservation

Non–invasive genetic approaches for estimation of ungulate population size: a study on roe deer (... more Non–invasive genetic approaches for estimation of ungulate population size: a study on roe deer (Capreolus capreolus) based on faeces.— Estimating population size is particularly difficult for animal species living in concealing habitats with dense vegetation. This is the case for roe deer as for many other ungulates. Our objective was to develop a non–invasive genetic capture–mark–recapture approach based on roe deer faeces collected along transects. In a pilot study, we collected 1,790 roe deer faeces during five sampling days in a forested study area in south western Germany. We extracted DNA from 410 of these samples and carried out microsatellite analysis using seven dinucleotide markers. The analyses resulted in 328 useable consensus genotypes which were assigned to 174 individuals. The population size estimated using a Bayesian approach was 94 (82–111) male and 136 (121–156) female roe deer. Our study shows that non–invasive genetic methods are a valuable management tool for ...

Zusammenfassung Eine Fang-Wiederfang-Methode für die Zählung von Wildschweinen wird beschrieben. ... more Zusammenfassung Eine Fang-Wiederfang-Methode für die Zählung von Wildschweinen wird beschrieben. Die Identifizierung der Tiere erfolgte über eine genetische Analyse von gefundenem Kot. Die Beprobung wurde an 12 Tagen auf systematisch im Wildforschungsgebiet angelegten Transektlinien durchgeführt. Zur Auswertung wurden die Modelle von BURNHAM et al. (1978) und CHAO (1988) verwendet.

In many parts of Europe wild boar Sus scrofa population increase and dispersal into new areas is ... more In many parts of Europe wild boar Sus scrofa population increase and dispersal into new areas is accompanied by economic problems. Due to underestimation of population densities and reproduction rates harvest rates seem to be insufficient, especially proportions of shot females might be inadequate. Thus, we calculated mortality rates of several wild boar populations, to show the efficiency of hunting within 13 years from studies conducted in 16 different study areas distributed over 8 European states. For calculating mortality rates the daily probability of survival of radio telemetrically observed wild boar were analysed according to Mayfield (1961) for three age classes (0, 1, ≥2years) and both sexes. Of 872 animals observed by VHF- or GPS-telemetry 228 died during the total observation of 121998 days. The mortality rates of wild boar, especially piglets were low (about 0.5). About three third of all observed animals survived at least until the next period of reproduction. The sex...

Wildlife Biology, 2012

Increasing populations of wild boar and feral domestic pigs Sus scrofa have evoked growing concer... more Increasing populations of wild boar and feral domestic pigs Sus scrofa have evoked growing concern due to their potential as disease reservoir and as an origin of agricultural damages. Reliable population estimates are needed for effective management measures of this species. As an alternative to traditional methods, non-invasive genetic population estimation approaches based on hair or faeces sampling have yielded promising results for several species in terms of feasibility and precision. We developed and applied a non-invasive population estimation approach based on wild boar faeces in a study area situated in the Palatinate Forest, southwestern Germany. We collected 515 faeces samples along transects in January 2008. We carried out genotyping using six microsatellite markers to discriminate between individuals. During the trial, we identified 149 individual wild boar. Using multimodel inference and model averaging, we obtained relatively consistent estimates. Population densities calculated using the estimated population sizes ranged from 4.5 (2.9-7.8) to 5.0 (4.0-7.0) wild boar/km 2 . In the future, to further improve the precision of population estimates based on wild boar faeces, the detection probability should be increased. However, even when comparing a conservative population estimate to the hunting bag, our results show that the present hunting regime in our study area is not effective in regulating the wild boar population. The method which we present here offers a tool to calibrate hunting or other management measures for wild boar.

Wildlife Biology, 2010

In recent years much progress has been made in non-invasive genetic methods for various 25 purpos... more In recent years much progress has been made in non-invasive genetic methods for various 25 purposes including population estimation. Previous research focused on optimizing laboratory 42

Proceedings of the Royal Society B: Biological Sciences, 2006

Group decisions are required when group coordination is beneficial, but individuals can choose be... more Group decisions are required when group coordination is beneficial, but individuals can choose between alternatives. Despite the increased interest in animal group decision making, there is a lack of experimental field studies that investigate how animals with conflicting information make group decisions. In particular, no field studies have considered the influence of fission-fusion behaviour (temporary splitting into subgroups) on group decisions. We studied group decision making in two wild Bechstein's bat colonies, which are fission-fusion societies of stable individual composition. Since they frequently switch communal roosts, colony members must regularly make group decisions over where to roost. In the two-field experiments, we provided marked individuals with conflicting information about the suitability of potential roosts. We investigated whether conflicting information led to group decisions that followed a 'unanimous' or a 'majority' rule, or increased colony fission. Individual behaviour suggests that bats considered both their own information and the behaviour of others when deciding where to roost. Group decisions about communal roosts reflected the information available to a majority of the bats roosting together, but conflicting information led to an increased fission in one colony. Our results suggest that fission-fusion societies allow individuals to avoid majority decisions that are not in their favour.

European Journal of Wildlife Research, 2013

In many parts of Europe, wild boar Sus scrofa population increase, and thus, high densities and d... more In many parts of Europe, wild boar Sus scrofa population increase, and thus, high densities and dispersal into new areas are accompanied by economic problems. Due to many factors like insufficient hunting strategies as well as underestimation of population densities and reproduction rates, harvest rates seem to be insufficient. Thus, we calculated mortality rates of several wild boar populations from 1998 to 2009, to show the efficiency of hunting within several studies distributed over eight European states. For calculating mortality rates, the daily probability of survival of radio telemetrically observed wild boar was analysed according to Mayfield (Wilson Bull 73:255-261, 1961) and with survival analysis in R for three age classes (0, 1, ≥2 years) and both sexes. The mortality rates of wild boar per annum, especially piglets, were comparably low (about 0.5 for piglets and similar for total population). About three third of all observed animals survived at least until the next period of reproduction. Mortality rates differed between some study areas, the sexes and age classes. The sex ratio of the shot piglets equals the sex ratio of captured piglets; there seems to be no sex-biased Communicated by C. Gortázar

European Journal of Wildlife Research, 2010

Reliable estimation of population size remains a major challenge in wildlife ecology and manageme... more Reliable estimation of population size remains a major challenge in wildlife ecology and management. Lately, genotyping of non-invasively obtained tissue samples integrated in a modified capture-recapture approach provides new perspectives. Faeces, moulted feathers, or hairs can be easily sampled in the field. However, an important assumption is homogeneity of sampling across the population. In this pilot study, we tested the suitability of baited barbed wire hair sampling stations ('hair traps') for homogeneous genetic sampling for population estimation. A video system based on a new network internet protocol was used to observe the behaviour of wild boar visiting baited hair traps for gaining information about potential heterogeneities in the individual sampling probability. Within 92 monitoring nights at two sampling stations, 216 wild boar visits were recorded and 142 hair samples containing 2,124 single hairs were collected. Video analysis revealed distinct differences in the behaviour of wild boar with respect to the sampling station which are most likely to result in heterogeneous individual sampling probabilities. Adult and subadult animals differed in their behaviour dependent on their group status. This result indicates that hair sampling with baited hair traps is not suitable for representative non-invasive sampling of free ranging wild boar populations.

Conservation Genetics Resources, 2013

Several methods have been applied to calculate genotyping error rates (GER) for non-invasive popu... more Several methods have been applied to calculate genotyping error rates (GER) for non-invasive population size estimations. However, there is a lack of comparability between these methods. Here we focused on the comparison of methods for determination of GER within one study using faeces samples of wild boars (Sus scrofa). Error rates were calculated by (1) comparison of reference tissue samples and rectum faeces samples (2) the number of deviations between replicates and the assumed consensus genotypes, (3) re-analysis of a subsample interpreted by allelic and genotype comparisons, and (4) a blind-test of anonymously subdivided faecal samples. The error rates differed widely between these four methods (0-57.5 %) and underline the need of a consensus approach. The blindtest resulted in a GER of 4.3 %. We recommend conducting such a blind-test for estimating realistic GER when starting a pilot study in wildlife forensics.

Behaviour, 2005

Animals are often confronted with environmental challenges and the way in which they cope with th... more Animals are often confronted with environmental challenges and the way in which they cope with these challenges can have important fitness consequences. There is increasing evidence that individuals differ consistently in their reaction to the environment (personality traits). However, little is known about whether different life-styles (e.g., resident or migratory) influence personality traits and if so, in what manner.

Proceedings of the Royal Society B: Biological Sciences, 2006

Group decisions are required when group coordination is beneficial, but individuals can choose be... more Group decisions are required when group coordination is beneficial, but individuals can choose between alternatives. Despite the increased interest in animal group decision making, there is a lack of experimental field studies that investigate how animals with conflicting information make group decisions. In particular, no field studies have considered the influence of fission-fusion behaviour (temporary splitting into subgroups) on group decisions. We studied group decision making in two wild Bechstein's bat colonies, which are fission-fusion societies of stable individual composition. Since they frequently switch communal roosts, colony members must regularly make group decisions over where to roost. In the two-field experiments, we provided marked individuals with conflicting information about the suitability of potential roosts. We investigated whether conflicting information led to group decisions that followed a 'unanimous' or a 'majority' rule, or increased colony fission. Individual behaviour suggests that bats considered both their own information and the behaviour of others when deciding where to roost. Group decisions about communal roosts reflected the information available to a majority of the bats roosting together, but conflicting information led to an increased fission in one colony. Our results suggest that fission-fusion societies allow individuals to avoid majority decisions that are not in their favour.