Bernheim Arboretum and Research Forest has lost contact with a golden eagle known as Harper that researchers have been monitoring since 2015.
Bernheim Conservation Director Andrew Berry has been tracking Harper and his partner, Athena, using solar-powered GPS trackers attached to the raptors’ backs.
Ordinarily, the pair winter at Bernheim and summer in the Canadian wilderness near the Hudson Bay in Manitoba. Last year, Harper and Athena flew 1,700 miles across opposite sides of Lake Superior from Kentucky to reunite in Canada.
This year, Athena returned to Bernheim on Nov. 26th after traveling through Canada and Minnesota. Harper has been missing since late April.
Berry wrote in a blog post that Harper was last picked up hunting over frozen marshland near Churchill, Manitoba. Athena had been exhibiting signs she was preparing to lay eggs, but that changed when Harper didn’t come back.
In early May she left the nest and traveled on a 340-mile loop lasting 12 days. After, she returned to the nest only for brief periods.
“The tracks of Athena from May – October suggest something happened to Harper. When he did not return, Athena had to abandon nesting due to lack of food during the critical egg-laying period,” Berry wrote.
He speculates that Harper’s absence drove Athena to search widely for food. Golden eagle pairs rely on cooperation and division of labor when nesting and laying eggs. It would have been unlikely for Harper to abandon the nest site, Berry said.
Harper’s last transmission appeared on April 25th, showing him just 300 feet from a clearing along a railroad amid the frozen landscape. It’s unclear what happened, but Berry said Harper could have been killed, perhaps by another golden eagle or a human. If he was scavenging, he could have been poisoned by lead shot, incidental trapping or even intentional poisoning, Berry wrote.
“Late April in northern Manitoba is a dangerous place, with frozen lakes, snowy ground, high winds, and low temperatures making survival difficult even for a golden eagle,” he wrote.
Bernheim researchers will continue to watch Athena and might glean new insights into the behaviors of golden eagles after losing a partner.
“Will she find another mate, and if so, would they return to her old nest site? Can she defend her winter territory at Bernheim, or would she allow a new bird into her winter range?” Berry wrote.
Berry said researchers believe that golden eagles ordinarily pair for life, but may search anew if they lose their mate.