Brown bear population densities in the Slovenian Dinaric mountains estimated with the use of camera traps from 2018 to 2023
(2024) BION02 20232Degree Projects in Biology
- Abstract
- Understanding the dynamic of a population via either abundance or density is crucial for wildlife conservation. The brown bear (Ursus arctos) is a commonly distributed, yet elusive species, playing a major role in the ecosystem. Usually monitored with genetic sampling, hunted bags, or telemetry data, the use of camera traps for bear monitoring is still to this day a rarely used, yet promising method. In this study I estimated the density of brown bears in Slovenia using the by-catch dataset from the national-scale monitoring program for the Eurasian lynx (Lynx lynx) that took place in Slovenia and Croatia, ran between 2018 and 2023. I used camera trapping data of brown bear from five consecutive years and analysed it with the Random... (More)
- Understanding the dynamic of a population via either abundance or density is crucial for wildlife conservation. The brown bear (Ursus arctos) is a commonly distributed, yet elusive species, playing a major role in the ecosystem. Usually monitored with genetic sampling, hunted bags, or telemetry data, the use of camera traps for bear monitoring is still to this day a rarely used, yet promising method. In this study I estimated the density of brown bears in Slovenia using the by-catch dataset from the national-scale monitoring program for the Eurasian lynx (Lynx lynx) that took place in Slovenia and Croatia, ran between 2018 and 2023. I used camera trapping data of brown bear from five consecutive years and analysed it with the Random Encounter Modelling method (REM). This technique has not been previously used on the Slovenian bear population and is overall a new way of monitoring this species. As of today, I found only 5 studies using the REM to monitor a bear population, with only one on the European brown bear. These different studies were completed on much smaller scales, both spatially and temporally, while my 2500 km² study area used on average 150.4 camera trapping sites per survey, yielding on average 19444 camera trapping days per survey. This study thus presents a notably larger effort than any study before, including a multi-year assessment, which no study using the REM for assessing the brown bear population density has done so far. My results show that the latest bear density in Slovenian Dinaric Mountains (estimated for 2022/2023) is 16.0 individuals / 100 km² (SD ± 0.39), however the densities seem to fluctuate over the years. Moreover, the lowest density was detected in 2021/2022; 13.0 individuals / 100 km² (SD ± 0.36), which fits with the only existing information on bear density available in Slovenia so far (13 individual / 100 km²). My thesis shows that the use of by-catch camera trapping data from national lynx monitoring program for estimation of the density of brown bear in Slovenia is a promising new tool for the future of bear monitoring and management at the national or even international level. (Less)
- Popular Abstract
- Brown bears in Slovenia, what can we get from camera traps
The brown bear (Ursus arctos) is an emblematic and important species of our environment, yet they are threatened in many ways. As other carnivores in the world, bears were almost hunted to extinction until the 20th century, as a results, many of their local population are now endangered. It is critical that we ensure their protection on the long term to maintain the balance in the environment. To do so, we need to acquire knowledge on their population dynamics, such as the density and distribution to understand the level of threat the bears are facing and manage accordingly in the protection plans.
In Slovenia, bears are regulated by hunting to maintain the population... (More) - Brown bears in Slovenia, what can we get from camera traps
The brown bear (Ursus arctos) is an emblematic and important species of our environment, yet they are threatened in many ways. As other carnivores in the world, bears were almost hunted to extinction until the 20th century, as a results, many of their local population are now endangered. It is critical that we ensure their protection on the long term to maintain the balance in the environment. To do so, we need to acquire knowledge on their population dynamics, such as the density and distribution to understand the level of threat the bears are facing and manage accordingly in the protection plans.
In Slovenia, bears are regulated by hunting to maintain the population between 800 and 1000 individuals since 2018. This hunting take place every year at different times but there are currently no real way of knowing how many bears are right now in Slovenia. There are currently only three methods used to assess the change of the population, i) counting of bears at bear artificial feeding sites, which is done by volunteers going at these feeding twice a year to count how many animals they see, ii) counting of every bear found dead in Slovenia, iii) non-invasive genetic sampling, which consists of getting scats and hair of bears to run genetic analysis to identify every individuals to know how many bears are there, which is done only every 8 years. However, the counting at artificial feeding sites and the counting of dead bears isn't really precise on the real bear numbers and trends, and since the non-invasive genetic sampling takes place every 8 years, there are no current precise way of estimating the bear population, and that's when our study starts.
Between 2018 and 2023, 5 surveys took places between August and April to monitor lynx (Lynx lynx) within the European LIFE Lynx project. It consisted of camera traps spread all across Slovenia but mainly in the south to collect information about this species. These cameras also collected pictures of brown bears and we then used these pictures for our study. We wanted to find a better way of monitoring the bears than the current methods by using the data from the camera traps that were already there for the lynx. We decided to use the Random Encounter Model, a model created by Rowcliffe et al. in 2008. This model has been used only 5 times with bears worldwide and we chose it to study our bears with the pictures collected from the cameras as we believe it was the most fitting to our data. It uses the number of bears in each picture, the total time that the camera were active, the movement speed of the bears, and the camera field of view to estimate the density of bears in an area.
Thanks to it, we managed to estimate the density of bears through these 5 surveys fluctuating between 13 (2021/2022) and 16.6 (2020/2021) individuals per 100 km² in the south of Slovenia, with a rather stable trend over the 5 surveys. These densities are around what we expected from previous results here and are really high compared to other populations in the world, 0.3 to 8 bears per 100 km² in North America; between 1.1 and 2.9 bears per 100 km² in Scandinavia; around 3 bears per 100 km² in the Italian Alps. We are not entirely sure on the accuracy and reality of these results; however, we believe that they represent a fitting density for the Slovene bear. The last density estimate in Slovenia was of 13 individuals per 100 km² in 2013, which is identical to the result we obtained for 2021/2022 but since it’s more than 10 years ago, a lot could have change in the meanwhile. There was as well a non-invasive genetic sampling that occurred in 2023 but the results weren’t published yet when this project was being completed, it will be a good way of assessing the accuracy of our results with the density obtained from the genetic sampling and prove or not the efficiency of this method in our study.
This method is still really new with bears, meaning there are still some uncertainties on the way of using it with this species and creating an efficient study design for it. However, we believe that it is a promising technique to monitor bear and help their management. Indeed, it’s a really cost-efficient method that potentially can give accurate densities and distribution which are great tools for bear conservation. Overall, it could mean the implementation of this method as a yearly monitoring for bears in Slovenia to ensure perennially their conservation and durability in this habitat.
Master’s Degree project in Conservation Biology, 45 credits fulfilled in 2024, Department of Biology, Lund University
Advisors: Ola Olsson / Urša Fležar, Miha Krofel
Advisors Department: BECC: Biodiversity and Ecosystem services in a Changing Climate, Lund University / Department of Forestry and Renewable Forest Resources, Biotechnical faculty of Ljubljana (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/student-papers/record/9175966
- author
- Pinzio, Alexis
- supervisor
- organization
- course
- BION02 20232
- year
- 2024
- type
- H2 - Master's Degree (Two Years)
- subject
- language
- English
- id
- 9175966
- date added to LUP
- 2024-10-03 12:16:00
- date last changed
- 2024-10-03 12:16:00
@misc{9175966,
abstract = {{Understanding the dynamic of a population via either abundance or density is crucial for wildlife conservation. The brown bear (Ursus arctos) is a commonly distributed, yet elusive species, playing a major role in the ecosystem. Usually monitored with genetic sampling, hunted bags, or telemetry data, the use of camera traps for bear monitoring is still to this day a rarely used, yet promising method. In this study I estimated the density of brown bears in Slovenia using the by-catch dataset from the national-scale monitoring program for the Eurasian lynx (Lynx lynx) that took place in Slovenia and Croatia, ran between 2018 and 2023. I used camera trapping data of brown bear from five consecutive years and analysed it with the Random Encounter Modelling method (REM). This technique has not been previously used on the Slovenian bear population and is overall a new way of monitoring this species. As of today, I found only 5 studies using the REM to monitor a bear population, with only one on the European brown bear. These different studies were completed on much smaller scales, both spatially and temporally, while my 2500 km² study area used on average 150.4 camera trapping sites per survey, yielding on average 19444 camera trapping days per survey. This study thus presents a notably larger effort than any study before, including a multi-year assessment, which no study using the REM for assessing the brown bear population density has done so far. My results show that the latest bear density in Slovenian Dinaric Mountains (estimated for 2022/2023) is 16.0 individuals / 100 km² (SD ± 0.39), however the densities seem to fluctuate over the years. Moreover, the lowest density was detected in 2021/2022; 13.0 individuals / 100 km² (SD ± 0.36), which fits with the only existing information on bear density available in Slovenia so far (13 individual / 100 km²). My thesis shows that the use of by-catch camera trapping data from national lynx monitoring program for estimation of the density of brown bear in Slovenia is a promising new tool for the future of bear monitoring and management at the national or even international level.}},
author = {{Pinzio, Alexis}},
language = {{eng}},
note = {{Student Paper}},
title = {{Brown bear population densities in the Slovenian Dinaric mountains estimated with the use of camera traps from 2018 to 2023}},
year = {{2024}},
}