A common loon is released after biologists have taken blood samples for mercury analysis and have banded the bird. The banding of loons provides a reliable field method to re-observe individuals over many years and to track whether or not they are returning to their breeding lakes each summer. Additionally, banded loons are occasionally encountered alive or deceased on their non-breeding areas. A recovered banded loon provides important information on that individuals or possibly, an entire breeding populations wintering range. La Mauricie national park. Quebec. Canada