Roller-coaster flight: How geese save energy while migrating

Written by: Lisa Stelzner

Primary Source: Daily Dose of Science Blog

Bar-headed geese migrate annually between Mongolia and Tibet or India, which means they have to cross the high-elevation Himalayas. Scientists used to believe they flew at a constant, high altitude before coming down to land. However, after implanting tracking devices in migrating geese, scientists found out that they fly up and down to follow mountains’ countours closer to the ground than would seem to make sense. It turns out that if they flew at a much higher altitude, the low air density would require them to use up more energy (flap their wings more) to produce lift.  There is also less oxygen that high.  By flapping their wings less when they stay closer to the ground, they reduce their heart beat and save energy.

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Lisa Stelzner
I'm a plant biology PhD student studying monarch butterflies in Michigan, but I'm interested in lots of other types of science, too. I am interested in how breeding monarch butterflies choose their habitat based on floral species richness and abundance. Few studies have been conducted on optimal foraging theory when it involves an organism searching for two different kinds of resources, and butterflies are an ideal study system to investigate this, since many species are ovipositing specialists and only lay eggs on one species of hostplant, but are feeding generalists and nectar from a broad variety of flowering forbs.