Matches and Mismatches Between Seabird Distributions Estimated From At-Sea Surveys and Concurrent Individual-Level Tracking
Mapping the distribution of seabirds at sea is fundamental to understanding their ecology and making informed decisions on their conservation. Until recently, estimates of at-sea distributions were generally derived from boat-based visual surveys. Increasingly however, seabird tracking is seen as an...
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| Format: | Article |
| Language: | English |
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Frontiers Media S.A.
2019-09-01
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| Series: | Frontiers in Ecology and Evolution |
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| Online Access: | https://www.frontiersin.org/article/10.3389/fevo.2019.00333/full |
| _version_ | 1818578228023918592 |
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| author | Matthew J. Carroll Ewan D. Wakefield Ewan D. Wakefield Emily S. Scragg Ellie Owen Simon Pinder Mark Bolton James J. Waggitt Peter G. H. Evans Peter G. H. Evans |
| author_facet | Matthew J. Carroll Ewan D. Wakefield Ewan D. Wakefield Emily S. Scragg Ellie Owen Simon Pinder Mark Bolton James J. Waggitt Peter G. H. Evans Peter G. H. Evans |
| author_sort | Matthew J. Carroll |
| collection | DOAJ |
| description | Mapping the distribution of seabirds at sea is fundamental to understanding their ecology and making informed decisions on their conservation. Until recently, estimates of at-sea distributions were generally derived from boat-based visual surveys. Increasingly however, seabird tracking is seen as an alternative but each has potential biases. To compare distributions from the two methods, we carried out simultaneous boat-based surveys and GPS tracking in the Minch, western Scotland, in June 2015. Over 8 days, boat transect surveys covered 950 km, within a study area of ~6,700 km2 centered on the Shiant Islands, one of the main breeding centers of razorbills, and guillemots in the UK. Simultaneously, we GPS-tracked chick-rearing guillemots (n = 17) and razorbills (n = 31) from the Shiants. We modeled counts per unit area from boat surveys as smooth functions of latitude and longitude, mapping estimated densities. We then used kernel density estimation to map the utilization distributions of the GPS tracked birds. These two distribution estimates corresponded well for razorbills but were lower for guillemots. Both methods revealed areas of high use around the focal colony, but over the wider region, differences emerged that were likely attributable to the influences of neighboring colonies and the presence of non-breeding birds. The magnitude of differences was linked to the relative sizes of these populations, being larger in guillemots. Whilst boat surveys were necessarily restricted to the hours of daylight, GPS data were obtained equally during day and night. For guillemots, there was little effect of calculating separate night and day distributions from GPS records, but for razorbills the daytime distribution matched boat-based distributions better. When GPS-based distribution estimates were restricted to the exact times when boat surveys were carried out, similarity with boat survey distributions decreased, probably due to reduced sample sizes. Our results support the use of tracking data for defining seabird distributions around tracked birds' home colonies, but only when nearby colonies are neither large nor numerous. Distributions of animals around isolated colonies can be determined using GPS loggers but that of animals around aggregated colonies is best suited to at-sea surveys or multi-colony tracking. |
| first_indexed | 2024-12-16T06:42:28Z |
| format | Article |
| id | doaj.art-76e53d56685149f09b0cf0ae2267617c |
| institution | Directory Open Access Journal |
| issn | 2296-701X |
| language | English |
| last_indexed | 2024-12-16T06:42:28Z |
| publishDate | 2019-09-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Ecology and Evolution |
| spelling | doaj.art-76e53d56685149f09b0cf0ae2267617c2022-12-21T22:40:38ZengFrontiers Media S.A.Frontiers in Ecology and Evolution2296-701X2019-09-01710.3389/fevo.2019.00333459673Matches and Mismatches Between Seabird Distributions Estimated From At-Sea Surveys and Concurrent Individual-Level TrackingMatthew J. Carroll0Ewan D. Wakefield1Ewan D. Wakefield2Emily S. Scragg3Ellie Owen4Simon Pinder5Mark Bolton6James J. Waggitt7Peter G. H. Evans8Peter G. H. Evans9Royal Society for the Protection of Birds Centre for Conservation Science, The Lodge, Sandy, United KingdomRoyal Society for the Protection of Birds Centre for Conservation Science, The Lodge, Sandy, United KingdomInstitute of Biodiversity Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United KingdomRoyal Society for the Protection of Birds Centre for Conservation Science, The Lodge, Sandy, United KingdomRoyal Society for the Protection of Birds Centre for Conservation Science, The Lodge, Sandy, United KingdomRoyal Society for the Protection of Birds Centre for Conservation Science, The Lodge, Sandy, United KingdomRoyal Society for the Protection of Birds Centre for Conservation Science, The Lodge, Sandy, United KingdomSchool of Ocean Sciences, Bangor University, Bangor, United KingdomSchool of Ocean Sciences, Bangor University, Bangor, United KingdomSea Watch Foundation, Amlwch, United KingdomMapping the distribution of seabirds at sea is fundamental to understanding their ecology and making informed decisions on their conservation. Until recently, estimates of at-sea distributions were generally derived from boat-based visual surveys. Increasingly however, seabird tracking is seen as an alternative but each has potential biases. To compare distributions from the two methods, we carried out simultaneous boat-based surveys and GPS tracking in the Minch, western Scotland, in June 2015. Over 8 days, boat transect surveys covered 950 km, within a study area of ~6,700 km2 centered on the Shiant Islands, one of the main breeding centers of razorbills, and guillemots in the UK. Simultaneously, we GPS-tracked chick-rearing guillemots (n = 17) and razorbills (n = 31) from the Shiants. We modeled counts per unit area from boat surveys as smooth functions of latitude and longitude, mapping estimated densities. We then used kernel density estimation to map the utilization distributions of the GPS tracked birds. These two distribution estimates corresponded well for razorbills but were lower for guillemots. Both methods revealed areas of high use around the focal colony, but over the wider region, differences emerged that were likely attributable to the influences of neighboring colonies and the presence of non-breeding birds. The magnitude of differences was linked to the relative sizes of these populations, being larger in guillemots. Whilst boat surveys were necessarily restricted to the hours of daylight, GPS data were obtained equally during day and night. For guillemots, there was little effect of calculating separate night and day distributions from GPS records, but for razorbills the daytime distribution matched boat-based distributions better. When GPS-based distribution estimates were restricted to the exact times when boat surveys were carried out, similarity with boat survey distributions decreased, probably due to reduced sample sizes. Our results support the use of tracking data for defining seabird distributions around tracked birds' home colonies, but only when nearby colonies are neither large nor numerous. Distributions of animals around isolated colonies can be determined using GPS loggers but that of animals around aggregated colonies is best suited to at-sea surveys or multi-colony tracking.https://www.frontiersin.org/article/10.3389/fevo.2019.00333/fulldistribution mappingguillemotrazorbillGPS tagstrackingat-sea surveys |
| spellingShingle | Matthew J. Carroll Ewan D. Wakefield Ewan D. Wakefield Emily S. Scragg Ellie Owen Simon Pinder Mark Bolton James J. Waggitt Peter G. H. Evans Peter G. H. Evans Matches and Mismatches Between Seabird Distributions Estimated From At-Sea Surveys and Concurrent Individual-Level Tracking Frontiers in Ecology and Evolution distribution mapping guillemot razorbill GPS tags tracking at-sea surveys |
| title | Matches and Mismatches Between Seabird Distributions Estimated From At-Sea Surveys and Concurrent Individual-Level Tracking |
| title_full | Matches and Mismatches Between Seabird Distributions Estimated From At-Sea Surveys and Concurrent Individual-Level Tracking |
| title_fullStr | Matches and Mismatches Between Seabird Distributions Estimated From At-Sea Surveys and Concurrent Individual-Level Tracking |
| title_full_unstemmed | Matches and Mismatches Between Seabird Distributions Estimated From At-Sea Surveys and Concurrent Individual-Level Tracking |
| title_short | Matches and Mismatches Between Seabird Distributions Estimated From At-Sea Surveys and Concurrent Individual-Level Tracking |
| title_sort | matches and mismatches between seabird distributions estimated from at sea surveys and concurrent individual level tracking |
| topic | distribution mapping guillemot razorbill GPS tags tracking at-sea surveys |
| url | https://www.frontiersin.org/article/10.3389/fevo.2019.00333/full |
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