After two heavy snowstorms in mid-April, the parent eagles in Decorah, Iowa, spent the day feeding and brooding their newly hatched chicks in their nest. Mom warmed and protected the eaglets overnight while Dad took off. He was last seen on the nest about 7:30 p.m. on April 18.

Experts at the Raptor Resource Project, which monitors and livestreams the nest, became concerned when Dad didn't return to replace Mom for the morning shift. They thought perhaps he was resting from the intense activity following the two large storms. However, as the day continued with no sign of Dad, they became worried and made plans to go look for him. An on-the-ground observer believed Dad was nearby, but he didn't return to feed the eagles or take care of them.

On the second day without Dad, Mom continued to take care of the eaglets on her own. They were well-fed, but Mom was obviously aware he was gone. She cried out several times and received no response. She was also very wary of activity around the nest.

Camera operators for the Raptor Resource Project caught glimpses of another eagle in the area. Eagle experts determined he was male and called him "unidentified male eagle" or UME, uncertain if he could be Dad.

"If it isn't, why is Mom tolerating him so close to the nest?" they write in a timeline of events. "He spends part of the day perched above it and Mom at one point perches near him. If it is, why isn't he giving Mom a break, bringing in prey, responding to her peal calls, and harassing an osprey that has perched by the pond? Why does she seem so wary of his presence?"

Based on the male eagle's behavior and appearance, experts were convinced he is not Dad.

Searching for Dad

About 20 residents, volunteers and Raptor Resource Project staff, as well as the Decorah Fire Department Search & Rescue Team, looked for Dad, scouring his favorite perch places, as well as dangerous areas along the highway. The search and rescue team used a drone to access more challenging areas. They found no trace of the eagle patriarch.

Fortunately, though Dad may be gone, Mom is excelling as a solo parent.

"While we worry, the eaglets are eating, sleeping, pooping, playing house with nest materials, and growing like weeds in the warm bright sunshine. Mom has been doing an excellent job caring for them and has even been able to take a little 'me' time as she babysits from the Skywalk or a nearby perch," the RRP posted on Facebook.

Here's a close-up video of Mom with the eaglets as they doze and play.

What could have happened to Dad?

The search was structured based on several possibilities: that the unidentified male eagle injured Dad in a fight, that Dad was struck by a vehicle when eating or getting roadkill for the eaglets, that he was electrocuted or caught in a power line, or that he was caught inside a building. There's also a chance he was sick, shot or kidnapped.

Although they still don't know why Dad is missing, a panel of eagle experts suggest that a fight with the other male eagle is the most likely reason for his disappearance.

"Given the high density of the surrounding eagle population and number of floaters, or non-breeding adults, intra-species fighting has become a major source of natural mortality for bald eagles," the group posted.

"While the panel didn't entirely reject hypothermia or illness, they felt it was not very likely given that Dad didn't appear sick, didn't have green mute stains on his tail, and had previously gone through bad weather, including wet April snow storms, with no problem. They also mentioned electrocution and car collisions as potential sources of mortality, and rejected the idea that Dad simply gave up and left. We found no evidence at all of Dad being shot or kidnapped."

The role of the other male eagle

An unidentified male eagle (UME) gets close to Mom Decorah. An unidentified male eagle (UME) gets close to Mom Decorah. (Photo: Raptor Resource Project)

As of late April, the unidentified male eagle is still in the area. He has not shown any aggressive behavior toward the eaglets or Mom so far. The experts are watching to see if he brings food to Mom or shows any other courtship behavior.

Over the past several days, a third eagle has appeared near the nest. Although observers were hopeful he could be Dad, the consensus is that based on his behavior, it is not. The original unidentified male eagle has been spotted chasing off the interloper, briefly locking talons with him as Mom perched nearby.

Saying good-bye

On May 2, the Raptor Resource Project will hold a remembrance for Dad on its Facebook page so watchers can post memories, poems, stories and artwork of the beloved eagle.

Director John Howe shared a message of admiration for Dad Decorah, "who has captivated the hearts and minds of so many," he writes.

"For over 10 years, he has served as the subject of enjoyment, education, and wonder for millions of people, while being an eagle partner to Mom Decorah and Dad to many eaglets. It is amazing to think that after the successful fledge of D29, D30 and D31, he will have brought so many fish to the nest, gathered and shimmied so many eaglets underneath him, and delivered so many eaglet meals to 31 eaglets that we know!"

Howe points out that what watchers are seeing is difficult, but very normal in eagle life.

"Death and the succession of eagles is part of the natural order, but that doesn't make it any less sad when it happens. We watch the Decorah eagles and love them, but they belong to no one but themselves. Their lives are a gift we are privileged to share and learn from."

Mary Jo DiLonardo writes about everything from health to parenting — and anything that helps explain why her dog does what he does.