Aiming Far and Flying High
How meteorological radar observations can help the study of bird migration across oceans.
Located on the flight path of the migration tracks of raptors where the Asian Monsoon directly affects the weather, Taiwan is a very important site for studying migrating raptors in East Asia. For the past years Professor Chen-Jeih Pan and his colleagues at NCU, which is a member of the University System of Taiwan, have worked closely with Kenting National Park and the Central Weather Bureau, using a Doppler Weather Radar to investigate the migration tracks of raptors. The project originated from the use of meteorological radars in monitoring the conditions of clouds and rains with radar.
The Doppler weather radar at Kenting, first set up in 2001, is especially useful in monitoring severe weather systems like typhoons that may inflict terrible damage to the southern part of Taiwan. It occasionally also detects echoes reflected from flocks of migratory birds. That gave the bird-loving KTNP Headquarters the idea of tracking birds with radars. The first attempts failed as the data received was too complicated and required human interpretation, which was time-consuming and error-prone. After the NCU scientists put in place an information system which uses an all-sky camera to identify radar echoes and conduct surface surveys, and also to build up data flows, a database and Geographic Information System (Google Earth) to form a real-time display system. Weather, sea and man-made noise is removed automatically and only the raptor information is displayed. It has met with great success in collaborations with KTNP in tracking birds by radar. Now, not only can noise in the radar be identified and eliminated, but the directions and routes as well as the times and locations of landing can be accurately monitored and forecast. This is an important advance in both bird conservation and bird-watching activities.
Usually, it is a matter of “Luck” for bird-watchers to enjoy following raptors in spring as the birds usually come in from the sea. Unlike autumn, in spring the raptors stay overnight in the Kenting area before leaving Taiwan to continue their flights. People then can enjoy watching the raptors land in the evening as well as rising in the morning. Even the most experienced officers of KTNP cannot guarantee where and when one will see the birds in spring. With the help of radar, it is easier to know where and when the raptors are going to land in spring. On the other hand, we know where they are leaving for in autumn.
Analysis of radar echo data shows that it is now known that these birds have already decided where they are going to land when they are about 100 km from their destination,. Researchers can tell from the radar data the birds’ migration habits, flight altitude, speed, and other elements. They can even recognize when there is a coup among a flock of birds. However, more care must be taken in providing the information and promoting bird conservation; otherwise the project will help not just bird watchers but also hunters, and cause irreversible harm to the ecology.
Vocabulary
Doppler [n.] 多普勒效應
monitoring [n.] 監督、監控
KTNP [n.] 墾丁國家公園
irreversible [a.] 不可逆轉的
accurately [ad.] 準確的
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資料來源：Taiwan news