Older Cranes Help Their Group Find Better Migration Routes

Researchers have found that whooping cranes are changing their migration patterns in response to the changing landscape and climate. Flocks with older, experienced cranes are more likely to engage in shortstopping behavior, allowing the birds to conserve energy and resources. The findings are in a paper that was just published in the journal Nature Communications.

Birds are rapidly changing their migration patterns to adapt to land use change and global warming. As temperatures rise and favored habitats are developed by humans, old migration routes are no longer the most efficient paths. A new behavior called shortstopping has been recorded in 27 bird species. Shortstopping is the shortening of a migration route, achieved by utilizing wintering grounds closer to the birds’ breeding grounds. As long as the birds can find suitable spots to winter, the technique can save time and energy.

A team of researchers studied 175 whooping cranes (Grus americana) over a 14 year period. They found that migration groups with older birds were much more likely to use the shortstopping tactic. The age of the oldest crane in the group mattered most, with an additional year reducing the migration route by an average of 25 miles. Older cranes were more likely to choose wintering grounds they were already familiar with, showing that the experience of those cranes were leading the change.

Global warming was attributed to the increase in the number of suitable wintering grounds. Grain is an important food source for whooping cranes. During winter, grain is only found in warmer climates that haven’t been covered in snow. As temperatures rise, food is easier to find in northern latitudes and the cranes don’t need to travel as far.

The team believes that older whooping cranes are helping their group find shorter migration routes. This allows the birds to adapt to changing landscapes and climates. By understanding what drives these new migration behaviors, researchers can identify migration groups and bird species that will be more vulnerable to climate change.

REFERENCE

Claire S. Teitelbaum et al. Experience drives innovation of new migration patterns of whooping cranes in response to global change. Nature Communications (2016).

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