Birds Inner Thermometer Adjusts Timing of Spring Migration
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Various studies have explored the relationship between atmospheric conditions on periodic cycles of bird migration, however, there are limited knowledge on how weather condition really affect birds migration on an individual fitness level. The informations gathered were not sufficient to describe the birds internal self-sustained circadian rhythm and the external signal to guarantee suitable departure and arrival timing of migration. This research elaborated on the factors contributing to the timing of migration by using a long-term statistical dataset covering longitudinal range in northwestern Europe. The environment conditions including: spring vegetation in Europe, local spring temperature in northern Europe and the North Atlantic Oscillation index.
The phenological data were derived from spring data on migratory passerines from various remote islands: Heligoland in the North Sea, Christians, and Jury in the Baltic Sea. A standard of 20 birds captured and observed per season at each ringing station for at least 12 years were incorporated in the research. Various species were excluded from the study due to segregation migration route. These specification narrowed down 12 species which six of these are short-distance migrants and the other six are long-distance migrants.
The environmental data consist of monthly normalized difference vegetation index (NDVI), an average monthly temperature of local weather station, and the winter index. The NDVI demonstrate an approximation of ecological condition between regions and years. By calculating the average of different weather stations and take the mean of each of the month of spring, an overall provincial temperatures for the months can be calculated. This was necessarily due to...
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... in weather condition will drastically affect the migratory bird populations if only a small fraction of the migratory bird can adapt to changes in environment.
Evidence of global warming driven the phenological changes in species is quickly elevating. The limited knowledge of the control mechanism of bird migration genetically, physiologically and behaviorally restrict the ability of scientists to predict the significant affect of environment changes for migratory bird. The lacks of understand toward phenological changes in individual species disable scientist to devise a plan for future protection of the migratory organism.
Anders P. Tøttrup, Kalle Rainio, Timothy Coppack, Esa Lehikoinen, Carsten Rahbek,and Kasper Thorup. 2010 “Local Temperature Fine-Tunes the Timing of Spring Migration in Birds.” Integrative and Comparative Biology 50:293-304.