Model-derived southern elephant seal arrival curves for King Edward Point and St Andrews Bay, South Georgia
GB/NERC/BAS/PDC/02236
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Summary
Abstract:
This dataset comprises modelled x-y fits to three arrival curves that describe the number of female southern elephant seals (Mirounga leonina) present on the beaches over the breeding season (September - December) at South Georgia. The curves are: (i) a historical multi-year curve derived from the King Edward Point (KEP) long-term count series (1995, 1996, 1998, 2000, 2015-2024), (ii) a curve derived from St Andrews Bay count data for 2024, and (iii) a weighted combined curve generated from the fitted KEP and St Andrews Bay curves. For each curve, the dataset provides date, day-of-year, and fitted proportion of peak abundance across the breeding season, which can be used to correct counts made either side of the breeding peak, to predicted peak haul-out abundance.
This dataset forms a component of Darwin Plus 214's efforts to re-census the southern elephant seal (Mirounga leonina) population at South Georgia for the first time in 30 years. These data are intended to enable independent reproduction of the published arrival-curve figures, and reuse of the fitted seasonal correction curves.
This project was funded through Biodiversity Challenge Fund Darwin Plus Main stage grant, DPLUS214.
Keywords:
Mirounga leonina, South Georgia, arrival curve, southern elephant seal
Citation
Bamford, C.C.G, Coleman, J., & Fenney, N. (2026). Model-derived southern elephant seal arrival curves for King Edward Point and St Andrews Bay, South Georgia (Version 1.0) [Data set]. NERC EDS UK Polar Data Centre. https://doi.org/10.5285/08e01a9a-5881-4928-834d-c9d2677fc30a
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Constraints
| Access Constraints: | Under embargo until publication of the associated manuscript. |
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| Use Constraints: | This data is governed by the NERC data policy http://www.nerc.ac.uk/research/sites/data/policy/ and supplied under Open Government Licence v.3 http://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/. |
Basic Information
| Creation Date: | 2026-07-06 |
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| Dataset Progress: | Complete |
| Dataset Language: | English |
| ISO Topic Categories: |
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| Parameters: |
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| Personnel: | |
| Name | UK Polar Data Centre |
| Role(s) | Metadata Author |
| Organisation | British Antarctic Survey |
| Name | Dr Connor C G Bamford |
| Role(s) | Investigator, Technical Contact |
| Organisation | British Antarctic Survey |
| Name | Mr Jamie Coleman |
| Role(s) | Investigator |
| Organisation | British Antarctic Survey |
| Name | Mr Nathan Fenney |
| Role(s) | Investigator |
| Organisation | British Antarctic Survey |
| Parent Dataset: | N/A |
Additional Information
| Reference: | Bamford, C.C.G., Bowler, E., Gascoyne, M., Coleman, J., Fenney, N., Fox-Clarke, C., Fedak, M., Huckstadt, L., Hollyman, P., Cleeland, J., Owen, K. and Fretwell, P. An updated census of southern elephant seals Mirounga Leonina at South Georgia using satellite imagery. Frontiers in Marine Science (in press). | |
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| Quality: | These data are fitted model outputs derived from count data collected at different beaches and times during the breeding season. Zero values in the source count series represent true zero counts, whereas missing values (NA) indicate that no count was available for that date. Prior to modelling, counts were standardised within year to the proportion of the observed annual maximum. Exported x-y values are direct outputs from the fitted Gaussian models. | |
| Lineage/Methodology: | This dataset contains fitted seasonal arrival curves for female southern elephant seals (Mirounga leonina) at South Georgia, expressed as fitted proportion of peak abundance by date and day-of-year. Three curves are included: an averaged timeseries curve from King Edward Point (KEP), a St Andrews Bay curve from 2024, and a weighted combined curve derived from both sources. The simplified curve-fitting workflow used two input CSV files: one containing the KEP long-term count series and one containing the St Andrews Bay count series. In each file, rows represented observation dates and columns represented breeding seasons. Counts were standardised within each year to the proportion of that year's observed maximum female count. For both KEP and St Andrews Bay, Gaussian arrival curves were fitted using bounded nonlinear least squares in R. For yearly fits, time was defined as days since the first observation in that series. For each dataset, fitted yearly values were then aligned by day-of-year on a non-leap reference year (2001), averaged across years by day-of-year, and a Gaussian was fitted to the resulting mean curve. This produced a single fitted KEP curve and a single fitted St Andrews Bay curve on a common reference-year axis. The combined curve was not fitted to pooled raw counts. Instead, the fitted KEP and St Andrews Bay Gaussian curves were evaluated on a shared day-of-year grid and blended in function space using a weighted average of 30:70 (KEP : Andrews Bay). The weighting favoured the outer beach colonies due to their predominance at South Georgia. A further Gaussian was then fitted to this blended series to yield a single combined arrival curve. For each curve, the dataset provides the fitted x-y values required to reproduce the published arrival-curve figures. X values are supplied as date (day-month format) and day-of-year, and y values are supplied as fitted proportion of peak abundance. The script used to obtain these data are available on Zenodo: Bamford, C. (2026). DPLUS214_Southern_Elephant_Seal_arrival_curves (1.0). Zenodo. https://doi.org/10.5281/zenodo.21228072 The count data are available from the BAS KEP Science Manager (data paper in prep). |
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Locality
| Temporal Coverage: | |
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| Start Date | 1995-09-12 |
| End Date | 2024-12-13 |
| Spatial Coverage: | |
| Latitude | |
| Southernmost | -54.28333 |
| Northernmost | -54.28333 |
| Longitude | |
| Westernmost | -36.5 |
| Easternmost | -36.5 |
| Altitude | |
| Min Altitude | N/A |
| Max Altitude | N/A |
| Depth | |
| Min Depth | N/A |
| Max Depth | N/A |
| Latitude | |
| Southernmost | -54.43333 |
| Northernmost | -54.43333 |
| Longitude | |
| Westernmost | -36.18333 |
| Easternmost | -36.18333 |
| Altitude | |
| Min Altitude | N/A |
| Max Altitude | N/A |
| Depth | |
| Min Depth | N/A |
| Max Depth | N/A |
| Data Resolution: | |
| Latitude Resolution | N/A |
| Longitude Resolution | N/A |
| Horizontal Resolution Range | N/A |
| Vertical Resolution | N/A |
| Vertical Resolution Range | N/A |
| Temporal Resolution | 1x per day, Sep-Dec each year |
| Temporal Resolution Range | N/A |
| Location: | |
| Location | South Georgia Island |
| Detailed Location | King Edward Point |
| Location | South Georgia Island |
| Detailed Location | St Andrews Bay |
Instrumentation
| Data Collection: | Source counts were obtained from long-term in situ counts at King Edward Point, which were made from either counting from UAV imagery or physical beach walks. The St Andrews data were taken from counts of UAV imagery. Counts of UAV images were made in ArcGIS v10.4, ArcPro 2022 and QGIS v3.40. The fitting of the arrival curves was conducted in R (v4.4.2) using the packages dplyr, tidyr, readr, stringr, lubridate, tibble, and minpack.lm. |
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Storage
| Distribution: | |
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| Distribution Media | Online Internet (HTTP) |
| Distribution Size | N/A |
| Distribution Format | ASCII |
| Fees | N/A |
| Data Storage: | 1x .csv file [14 KB] |