A camera trap method for estimating target densities of grey squirrels to inform wildlife management applications
Effective wildlife population management requires an understanding of the abundance of the target species. In the United Kingdom, the increase in numbers and range of the non-native invasive grey squirrel Sciurus carolinensis poses a substantial threat to the existence of the native red squirrel S....
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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Frontiers Media S.A.
2023-06-01
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| Series: | Frontiers in Ecology and Evolution |
| Subjects: | |
| Online Access: | https://www.frontiersin.org/articles/10.3389/fevo.2023.1096321/full |
| _version_ | 1827926131905396736 |
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| author | Sarah E. Beatham Sarah E. Beatham Philip A. Stephens Julia Coats John Phillips Giovanna Massei |
| author_facet | Sarah E. Beatham Sarah E. Beatham Philip A. Stephens Julia Coats John Phillips Giovanna Massei |
| author_sort | Sarah E. Beatham |
| collection | DOAJ |
| description | Effective wildlife population management requires an understanding of the abundance of the target species. In the United Kingdom, the increase in numbers and range of the non-native invasive grey squirrel Sciurus carolinensis poses a substantial threat to the existence of the native red squirrel S. vulgaris, to tree health, and to the forestry industry. Reducing the number of grey squirrels, is crucial to mitigate their impacts. Camera traps are increasingly used to estimate animal abundance, and methods have been developed that do not require the identification of individual animals. Most of these methods have been focussed on medium to large mammal species with large range sizes and may be unsuitable for measuring local abundances of smaller mammals that have variable detection rates and hard to measure movement behaviour. The aim of this study was to develop a practical and cost-effective method, based on a camera trap index, that could be used by practitioners to estimate target densities of grey squirrels in woodlands to provide guidance on the numbers of traps or contraceptive feeders required for local grey squirrel control. Camera traps were deployed in ten independent woods of between 6 and 28 ha in size. An index, calculated from the number of grey squirrel photographs recorded per camera per day had a strong linear relationship (R2 = 0.90) with the densities of squirrels removed in trap and dispatch operations. From different time filters tested, a 5 min filter was applied, where photographs of squirrels recorded on the same camera within 5 min of a previous photograph were not counted. There were no significant differences between the number of squirrel photographs per camera recorded by three different models of camera, increasing the method’s practical application. This study demonstrated that a camera index could be used to inform the number of feeders or traps required for grey squirrel management through culling or contraception. Results could be obtained within 6 days without requiring expensive equipment or a high level of technical input. This method can easily be adapted to other rodent or small mammal species, making it widely applicable to other wildlife management interventions. |
| first_indexed | 2024-03-13T05:34:08Z |
| format | Article |
| id | doaj.art-084ccb5dc1f24f0d92c9c55f9f4eef6c |
| institution | Directory Open Access Journal |
| issn | 2296-701X |
| language | English |
| last_indexed | 2024-03-13T05:34:08Z |
| publishDate | 2023-06-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Ecology and Evolution |
| spelling | doaj.art-084ccb5dc1f24f0d92c9c55f9f4eef6c2023-06-14T10:51:06ZengFrontiers Media S.A.Frontiers in Ecology and Evolution2296-701X2023-06-011110.3389/fevo.2023.10963211096321A camera trap method for estimating target densities of grey squirrels to inform wildlife management applicationsSarah E. Beatham0Sarah E. Beatham1Philip A. Stephens2Julia Coats3John Phillips4Giovanna Massei5National Wildlife Management Centre, APHA, York, United KingdomConservation Ecology Group, Department of Biosciences, Durham University, Durham, United KingdomConservation Ecology Group, Department of Biosciences, Durham University, Durham, United KingdomNational Wildlife Management Centre, APHA, York, United KingdomNational Wildlife Management Centre, APHA, York, United KingdomBotstiber Institute for Wildlife Fertility Control, Department of Environment and Geography, University of York, York, United KingdomEffective wildlife population management requires an understanding of the abundance of the target species. In the United Kingdom, the increase in numbers and range of the non-native invasive grey squirrel Sciurus carolinensis poses a substantial threat to the existence of the native red squirrel S. vulgaris, to tree health, and to the forestry industry. Reducing the number of grey squirrels, is crucial to mitigate their impacts. Camera traps are increasingly used to estimate animal abundance, and methods have been developed that do not require the identification of individual animals. Most of these methods have been focussed on medium to large mammal species with large range sizes and may be unsuitable for measuring local abundances of smaller mammals that have variable detection rates and hard to measure movement behaviour. The aim of this study was to develop a practical and cost-effective method, based on a camera trap index, that could be used by practitioners to estimate target densities of grey squirrels in woodlands to provide guidance on the numbers of traps or contraceptive feeders required for local grey squirrel control. Camera traps were deployed in ten independent woods of between 6 and 28 ha in size. An index, calculated from the number of grey squirrel photographs recorded per camera per day had a strong linear relationship (R2 = 0.90) with the densities of squirrels removed in trap and dispatch operations. From different time filters tested, a 5 min filter was applied, where photographs of squirrels recorded on the same camera within 5 min of a previous photograph were not counted. There were no significant differences between the number of squirrel photographs per camera recorded by three different models of camera, increasing the method’s practical application. This study demonstrated that a camera index could be used to inform the number of feeders or traps required for grey squirrel management through culling or contraception. Results could be obtained within 6 days without requiring expensive equipment or a high level of technical input. This method can easily be adapted to other rodent or small mammal species, making it widely applicable to other wildlife management interventions.https://www.frontiersin.org/articles/10.3389/fevo.2023.1096321/fullcamera indicesinvasive specieshit rateeradicationsoral contraceptiveslive trapping |
| spellingShingle | Sarah E. Beatham Sarah E. Beatham Philip A. Stephens Julia Coats John Phillips Giovanna Massei A camera trap method for estimating target densities of grey squirrels to inform wildlife management applications Frontiers in Ecology and Evolution camera indices invasive species hit rate eradications oral contraceptives live trapping |
| title | A camera trap method for estimating target densities of grey squirrels to inform wildlife management applications |
| title_full | A camera trap method for estimating target densities of grey squirrels to inform wildlife management applications |
| title_fullStr | A camera trap method for estimating target densities of grey squirrels to inform wildlife management applications |
| title_full_unstemmed | A camera trap method for estimating target densities of grey squirrels to inform wildlife management applications |
| title_short | A camera trap method for estimating target densities of grey squirrels to inform wildlife management applications |
| title_sort | camera trap method for estimating target densities of grey squirrels to inform wildlife management applications |
| topic | camera indices invasive species hit rate eradications oral contraceptives live trapping |
| url | https://www.frontiersin.org/articles/10.3389/fevo.2023.1096321/full |
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