Light-level geolocation as a tool to monitor polar bear (Ursus maritimus) denning ecology: a case study
Abstract Background Monitoring polar bears is logistically challenging and expensive. Traditionally, reproductive history has been assessed using permanent marks from physically captured individuals, which requires assumptions about reproductive history based on their status at the time of capture....
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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BMC
2023-03-01
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| Series: | Animal Biotelemetry |
| Subjects: | |
| Online Access: | https://doi.org/10.1186/s40317-023-00323-4 |
| _version_ | 1797865240053940224 |
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| author | Benjamin Merkel Jon Aars Kristin L. Laidre James W. Fox |
| author_facet | Benjamin Merkel Jon Aars Kristin L. Laidre James W. Fox |
| author_sort | Benjamin Merkel |
| collection | DOAJ |
| description | Abstract Background Monitoring polar bears is logistically challenging and expensive. Traditionally, reproductive history has been assessed using permanent marks from physically captured individuals, which requires assumptions about reproductive history based on their status at the time of capture. This is often supplemented with economically costly satellite telemetry (ST) collars restricted to adult females, which yield data on space use and reproductive history. Methods This study assesses the potential of adapting light-level geolocation (Global location sensing or GLS) tags, developed for birds and fish, to estimate life history metrics for polar bears. Traditionally, GLS uses light intensity and time of day to estimate approximate twice-daily locations. This information, combined with temperature data, can be used to assess approximate locations of maternity denning events, denning timing, general space use, and population connectivity. Results Adult females (n = 54) were equipped, some several times, with a total of 103 GLS in Svalbard and Greenland from 2012 to 2021. Of these, 44 were also equipped with 80 ST collars during this period. This yielded GLS and ST data records for each individual up to 9.4 years (mean (Ø) 4.0 years) and 5.1 years (Ø 1.5 years), respectively. Combined with capture information, the GLS and ST collars were used to score reproductive history (determined presence or absence of maternity denning events) for 72–54% of bear winters during this period, respectively. Using GLS yielded on average 4.3 years of unbroken reproductive history records (up to 8 years for some individuals) including denning phenology and age at first reproduction. Additionally, geographic locations could be estimated during spring and autumn (when twilight was present) with an average daily accuracy of 93 km (4–1042 km) and 58 km (5–550 km) when aggregating by season. Conclusions This study establishes GLS as a powerful, low-cost method for polar bear population monitoring that can provide data on reproductive history, including age at first reproduction, and maternity denning location and phenology in programs with ongoing recapture. GLS can also be used to monitor males and immatures that cannot wear ST collars. |
| first_indexed | 2024-04-09T23:04:53Z |
| format | Article |
| id | doaj.art-1fc4d9ad6722400099b695de86520bab |
| institution | Directory Open Access Journal |
| issn | 2050-3385 |
| language | English |
| last_indexed | 2024-04-09T23:04:53Z |
| publishDate | 2023-03-01 |
| publisher | BMC |
| record_format | Article |
| series | Animal Biotelemetry |
| spelling | doaj.art-1fc4d9ad6722400099b695de86520bab2023-03-22T10:44:51ZengBMCAnimal Biotelemetry2050-33852023-03-0111111110.1186/s40317-023-00323-4Light-level geolocation as a tool to monitor polar bear (Ursus maritimus) denning ecology: a case studyBenjamin Merkel0Jon Aars1Kristin L. Laidre2James W. Fox3Akvaplan-Niva AS, Fram CentreNorwegian Polar Institute, Fram CentrePolar Science Center, Applied Physics Laboratory, University of WashingtonMigrate Technology LtdAbstract Background Monitoring polar bears is logistically challenging and expensive. Traditionally, reproductive history has been assessed using permanent marks from physically captured individuals, which requires assumptions about reproductive history based on their status at the time of capture. This is often supplemented with economically costly satellite telemetry (ST) collars restricted to adult females, which yield data on space use and reproductive history. Methods This study assesses the potential of adapting light-level geolocation (Global location sensing or GLS) tags, developed for birds and fish, to estimate life history metrics for polar bears. Traditionally, GLS uses light intensity and time of day to estimate approximate twice-daily locations. This information, combined with temperature data, can be used to assess approximate locations of maternity denning events, denning timing, general space use, and population connectivity. Results Adult females (n = 54) were equipped, some several times, with a total of 103 GLS in Svalbard and Greenland from 2012 to 2021. Of these, 44 were also equipped with 80 ST collars during this period. This yielded GLS and ST data records for each individual up to 9.4 years (mean (Ø) 4.0 years) and 5.1 years (Ø 1.5 years), respectively. Combined with capture information, the GLS and ST collars were used to score reproductive history (determined presence or absence of maternity denning events) for 72–54% of bear winters during this period, respectively. Using GLS yielded on average 4.3 years of unbroken reproductive history records (up to 8 years for some individuals) including denning phenology and age at first reproduction. Additionally, geographic locations could be estimated during spring and autumn (when twilight was present) with an average daily accuracy of 93 km (4–1042 km) and 58 km (5–550 km) when aggregating by season. Conclusions This study establishes GLS as a powerful, low-cost method for polar bear population monitoring that can provide data on reproductive history, including age at first reproduction, and maternity denning location and phenology in programs with ongoing recapture. GLS can also be used to monitor males and immatures that cannot wear ST collars.https://doi.org/10.1186/s40317-023-00323-4Breeding phenologyDenningGLSPolar bearReproductive historySpace use |
| spellingShingle | Benjamin Merkel Jon Aars Kristin L. Laidre James W. Fox Light-level geolocation as a tool to monitor polar bear (Ursus maritimus) denning ecology: a case study Animal Biotelemetry Breeding phenology Denning GLS Polar bear Reproductive history Space use |
| title | Light-level geolocation as a tool to monitor polar bear (Ursus maritimus) denning ecology: a case study |
| title_full | Light-level geolocation as a tool to monitor polar bear (Ursus maritimus) denning ecology: a case study |
| title_fullStr | Light-level geolocation as a tool to monitor polar bear (Ursus maritimus) denning ecology: a case study |
| title_full_unstemmed | Light-level geolocation as a tool to monitor polar bear (Ursus maritimus) denning ecology: a case study |
| title_short | Light-level geolocation as a tool to monitor polar bear (Ursus maritimus) denning ecology: a case study |
| title_sort | light level geolocation as a tool to monitor polar bear ursus maritimus denning ecology a case study |
| topic | Breeding phenology Denning GLS Polar bear Reproductive history Space use |
| url | https://doi.org/10.1186/s40317-023-00323-4 |
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