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A Century of Global Warming and Its Impact on Bird Migration
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Mr. Sayantan Sur*
Email: sayantansur008@gmail.com
How much does 1 degree Celsius account for? Not much, if you think of the daily variation in the day and night
temperatures, but ask a climatologist and she/ he will apprise you that even a degree Celsius rise in the global temperature can induce a sudden shift in the annual rainfall and cause months of flood or drought, ultimately leading to a catastrophic decline in the net yield of crop production. As an ornithologist, I had to ask myself this very question of how this unexpected warming of our climate impacted the avian fauna.
Decades of observational and correlational studies from all around the world are pointing toward a single conclusion that climate change has severely affected the seasonal biology of birds. Birds, like most
animals in the world, show seasonal behaviors. For example, they breed in a particular season, when the climate is most suitable for growth and provides abundant resources for their offspring (i.e., their children). Similarly, when the seasons change, some birds embark upon an annual journey where they fly across continents to reach their destinations, which is known as migration. Now, to predict the correct time to begin their migratory flight or to breed, these birds rely upon certain environmental cues, such as daylength and temperature. Daylength is the most obvious cue, which all animals use to anticipate changes in seasons. Prior to spring migration, the birds sense the gradual increase in the daylength and start fueling themselves. So in essence, daylength gives them a broad window. However, the
* Mr. Sayantan Sur, Ph.D. Scholar from University of Delhi, Delhi, is pursuing his research on “Migration”. His popular science story entitled “A Century of Global Warming and its Impact on Bird Migration” has been selected for AWSAR Award.