Birds have been found dead at wind and solar power plants throughout North America.
One question still needs an answer. Are these birds local or have they travelled from elsewhere across North America?
A new study looked at the feathers of birds found dead at renewable energy plants in California.
It showed that many birds found at solar energy plants had come from elsewhere.
Looking at birds found at California energy sites
They looked at 871 individual birds from 24 different species.
All of the birds were found dead at wind and solar energy plants in California.
They wanted to look further into where the birds came from.
How can you tell where a bird comes from using its feathers?
Chemical clues remained inside the feathers
Feathers contain natural chemical markers from the water the bird drinks.
These markers will vary depending on where in North America the water comes from.
Stable hydrogen isotope markers in the feathers helped reveal where the birds had come from.
These markers differ across North America because rainfall and water sources vary from region to region.
This can help us tell roughly where these feathers were formed.
That information can then be used to determine whether the birds were local or not.
Many of the birds had come from elsewhere
The results show that the birds aren’t all coming from one area.
They come from a wide range of areas throughout North America.
Depending on the species, some birds were local. However, others were travelling long distances to get to California.
The pattern was more noticeable in the solar energy plants.
Most of the birds dying there were not local but migratory, a finding highlighted by the University of Florida.
The findings suggest that the impact of solar energy plants may extend beyond local bird populations.
Migration season offered another important clue
Patterns in bird mortality pointed to the same conclusion.
The highest number of bird deaths occurred during migration periods in April, September, and October.
These months coincide with key migration periods across North America.
Many of the birds found at solar energy plants weren’t just local birds but were migrating through the area.
The results from the wind energy plants were slightly different. Nearly the same number of migratory birds were found.
Bird conservation may require a wider view
Knowing where the birds are coming from can change how conservation efforts are planned.
If many birds are coming from far away areas, then we cannot just look at reducing deaths at the energy plants.
The findings imply that conservation efforts may need to take into account the habitats of these birds throughout their range.
Knowing where the birds come from could help guide future mitigation efforts.
Managers may be able to see which populations of birds are most at risk and what areas could benefit most from conservation.
This could help direct conservation resources towards populations facing the greatest pressures.
A feather can reveal more than where a bird died
Stable isotope analysis could be very useful outside of renewable energy plants.
Using stable isotope analysis can help us understand movements that are often hard to observe.
This could help improve understanding of how populations change, how birds migrate, and what conservation challenges they may face throughout North America.
A feather can tell us not only where the bird died but also give us clues as to where it used to live.
Together, those clues can help build a larger picture of bird movement across North America.
This can help conservationists understand how populations move throughout the continent and how they can be conserved in the future.
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