Quantitative ornithology with a commercial marine radar: standard‐target calibration, target detection and tracking, and measurement of echoes from individuals and flocks
Summary Marine surveillance radars are commonly used for radar ornithology, but they are rarely calibrated. This prevents them from measuring the radar cross‐sections (RCS) of the birds under study. Furthermore, if the birds are aggregated too closely for the radar to resolve them individually, the...
Published in: | Methods in Ecology and Evolution |
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Online Access: | http://dx.doi.org/10.1111/2041-210x.12699 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2F2041-210X.12699 https://onlinelibrary.wiley.com/doi/pdf/10.1111/2041-210X.12699 https://onlinelibrary.wiley.com/doi/full-xml/10.1111/2041-210X.12699 https://besjournals.onlinelibrary.wiley.com/doi/pdf/10.1111/2041-210X.12699 |
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crwiley:10.1111/2041-210x.12699 2024-06-23T07:56:59+00:00 Quantitative ornithology with a commercial marine radar: standard‐target calibration, target detection and tracking, and measurement of echoes from individuals and flocks Urmy, Samuel S. Warren, Joseph D. Parrini, Francesca Frank M. Chapman Memorial Fund of the AMNH 2016 http://dx.doi.org/10.1111/2041-210x.12699 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2F2041-210X.12699 https://onlinelibrary.wiley.com/doi/pdf/10.1111/2041-210X.12699 https://onlinelibrary.wiley.com/doi/full-xml/10.1111/2041-210X.12699 https://besjournals.onlinelibrary.wiley.com/doi/pdf/10.1111/2041-210X.12699 en eng Wiley http://onlinelibrary.wiley.com/termsAndConditions#vor Methods in Ecology and Evolution volume 8, issue 7, page 860-869 ISSN 2041-210X 2041-210X journal-article 2016 crwiley https://doi.org/10.1111/2041-210x.12699 2024-06-13T04:24:06Z Summary Marine surveillance radars are commonly used for radar ornithology, but they are rarely calibrated. This prevents them from measuring the radar cross‐sections (RCS) of the birds under study. Furthermore, if the birds are aggregated too closely for the radar to resolve them individually, the bulk volume reflectivity cannot be translated into a numerical density. We calibrated a commercial off‐the‐shelf marine radar, using a standard spherical target of known RCS. Once calibrated, the radar was used to measure the RCS of common and roseate terns ( Sterna hirundo L. and Sterna dougallii Montagu) tracked from a land‐based installation at their breeding colony on Great Gull Island, NY, USA. We also integrated echoes from flocks of terns, comparing these total flock cross‐sections with visual counts from photos taken at the same time as the radar measurements. The radar's calibration parameters were determined with 1% error. RCS measurements made after calibration were expected to be accurate within ±2 dB. Mean tern RCS was estimated at −28 dB relative to one square meter (dBsm), agreeing in magnitude with a simple theoretical model. RCS was 3–4 dB higher when birds’ aspect angles were broadside to the radar beam compared with head‐ or tail‐on. Integrated flock cross‐section was linearly related to the number of birds. The slope of this line, an independent estimate of RCS, was −32 dBsm, within an order of magnitude of the estimate from individual birds, and near the middle of the frequency distribution of RCS values. These results indicate that a calibrated marine radar can count the birds in an aggregation via echo integration. Field calibration of marine radars is practical, enables useful measurements, and should be done more often. Article in Journal/Newspaper Sterna hirundo Wiley Online Library Gull Island ENVELOPE(-55.315,-55.315,49.533,49.533) Montagu ENVELOPE(-26.333,-26.333,-58.417,-58.417) Methods in Ecology and Evolution 8 7 860 869 |
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Open Polar |
collection |
Wiley Online Library |
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crwiley |
language |
English |
description |
Summary Marine surveillance radars are commonly used for radar ornithology, but they are rarely calibrated. This prevents them from measuring the radar cross‐sections (RCS) of the birds under study. Furthermore, if the birds are aggregated too closely for the radar to resolve them individually, the bulk volume reflectivity cannot be translated into a numerical density. We calibrated a commercial off‐the‐shelf marine radar, using a standard spherical target of known RCS. Once calibrated, the radar was used to measure the RCS of common and roseate terns ( Sterna hirundo L. and Sterna dougallii Montagu) tracked from a land‐based installation at their breeding colony on Great Gull Island, NY, USA. We also integrated echoes from flocks of terns, comparing these total flock cross‐sections with visual counts from photos taken at the same time as the radar measurements. The radar's calibration parameters were determined with 1% error. RCS measurements made after calibration were expected to be accurate within ±2 dB. Mean tern RCS was estimated at −28 dB relative to one square meter (dBsm), agreeing in magnitude with a simple theoretical model. RCS was 3–4 dB higher when birds’ aspect angles were broadside to the radar beam compared with head‐ or tail‐on. Integrated flock cross‐section was linearly related to the number of birds. The slope of this line, an independent estimate of RCS, was −32 dBsm, within an order of magnitude of the estimate from individual birds, and near the middle of the frequency distribution of RCS values. These results indicate that a calibrated marine radar can count the birds in an aggregation via echo integration. Field calibration of marine radars is practical, enables useful measurements, and should be done more often. |
author2 |
Parrini, Francesca Frank M. Chapman Memorial Fund of the AMNH |
format |
Article in Journal/Newspaper |
author |
Urmy, Samuel S. Warren, Joseph D. |
spellingShingle |
Urmy, Samuel S. Warren, Joseph D. Quantitative ornithology with a commercial marine radar: standard‐target calibration, target detection and tracking, and measurement of echoes from individuals and flocks |
author_facet |
Urmy, Samuel S. Warren, Joseph D. |
author_sort |
Urmy, Samuel S. |
title |
Quantitative ornithology with a commercial marine radar: standard‐target calibration, target detection and tracking, and measurement of echoes from individuals and flocks |
title_short |
Quantitative ornithology with a commercial marine radar: standard‐target calibration, target detection and tracking, and measurement of echoes from individuals and flocks |
title_full |
Quantitative ornithology with a commercial marine radar: standard‐target calibration, target detection and tracking, and measurement of echoes from individuals and flocks |
title_fullStr |
Quantitative ornithology with a commercial marine radar: standard‐target calibration, target detection and tracking, and measurement of echoes from individuals and flocks |
title_full_unstemmed |
Quantitative ornithology with a commercial marine radar: standard‐target calibration, target detection and tracking, and measurement of echoes from individuals and flocks |
title_sort |
quantitative ornithology with a commercial marine radar: standard‐target calibration, target detection and tracking, and measurement of echoes from individuals and flocks |
publisher |
Wiley |
publishDate |
2016 |
url |
http://dx.doi.org/10.1111/2041-210x.12699 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2F2041-210X.12699 https://onlinelibrary.wiley.com/doi/pdf/10.1111/2041-210X.12699 https://onlinelibrary.wiley.com/doi/full-xml/10.1111/2041-210X.12699 https://besjournals.onlinelibrary.wiley.com/doi/pdf/10.1111/2041-210X.12699 |
long_lat |
ENVELOPE(-55.315,-55.315,49.533,49.533) ENVELOPE(-26.333,-26.333,-58.417,-58.417) |
geographic |
Gull Island Montagu |
geographic_facet |
Gull Island Montagu |
genre |
Sterna hirundo |
genre_facet |
Sterna hirundo |
op_source |
Methods in Ecology and Evolution volume 8, issue 7, page 860-869 ISSN 2041-210X 2041-210X |
op_rights |
http://onlinelibrary.wiley.com/termsAndConditions#vor |
op_doi |
https://doi.org/10.1111/2041-210x.12699 |
container_title |
Methods in Ecology and Evolution |
container_volume |
8 |
container_issue |
7 |
container_start_page |
860 |
op_container_end_page |
869 |
_version_ |
1802650417254891520 |