Wednesday, October 17, 2018

Who's on N2B? Welcome to the Confusion Couch!

Welcome to the Confusion Couch! Many of our followers are asking "Who is that eagle?" after watching the Decorah and Decorah North nests this week. In Decorah, an adult male eagle that we've been calling DM isn't DM (or Dad - sorry, everyone!). And we can't decide who we're seeing ar Decorah North. Is that Mr. and Mrs. North, or are we seeing somebody else?

Let's start with Decorah. We originally thought that DM came to N2B a couple of days ago, but started to rethink it after taking a closer look. We needed iris patterns and John was able to get some yesterday. We're going to start with head studies...

Decorah Male, FKA UME, June 2018. DM lost feathers during a blackfly strike, which left him pretty tattered looking. He presumably would have grown them in since then.
DM? October 16, 2018. While DM would have regrown feathers lost in the black fly attack, this head study gave us pause. It sure didn't look like DM!
Dad Decorah, February 2018. Rumors quickly began to fly that the October 16 eagle was Dad returning to N2B.

The three head studies offered a tantalizing hint that our October 16th eagle was not DM, but more was needed to prove it. Fortunately, irises are very helpful in ID’ing individual eagles. Like fingerprints, each iris is unique.

DM? Male eagle from October 16, 2018
DM, June 2018
Dad Decorah, February 2018

We are looking at the left side of the eagle’s face in every photo, so we’re comparing left iris to left iris. The irises of all three eagles have distinctly different patterns and markings. The eagle we thought was DM, who we will refer to as UME-2 from now on, has an iris with some patterning around the center and a distinct small blotch at around 3:00. Like UME-2, DM’s eye has some central patterning, but he has two eye spots instead of one, and his eye spots are located at about 5:30 and 7:00. Dad’s eye has less central patterning and more eye spots than either UME-2 or DM. I checked earlier iris surveys and found that Dad’s iris splotches and dots didn’t change much over the years we watched him, which rules out a return. UME-2’s irises are simply too different for him to be Dad.

So why did we think this eagle was DM at first? First and foremost, that’s who we expected to see. DM has been identified recently and has been on territory pretty consistently since he showed up in April. Mom’s response didn’t give us any reason to question the eagle’s identity – a prey chase is often game on and Mom has chased DM around! – and he seemed quite comfortable at the Y and on N2B. We’re reminding ourselves to look closer before ID’ing eagles, especially in a rapidly changing situation like this. Bald eagle mate changeovers are a new thing for us and we’re learning a lot about what that can look like. We’re also wondering if this eagle hasn’t been here a little longer than we thought. Has Mom been perching with UME or DM or some other eagle in the maple tree? At this point, we don’t know.

How about Decorah North? We’re in an active discussion about Mr. and Mrs. North as I write this. We aren’t seeing white pantaloon streaks on the female eagle that is visiting the nest now, but the head and facial features are very similar. Are the white pantaloon feathers really a good marker? I checked in with our eagle panel, who felt that they were pretty reliable given that Mrs. North has had them for the three years we’ve watched her. But no one could say for sure. Both eagles have been seen pretty consistently and they are spending time in familiar spots. However, those spots might be desirable to any eagle, so that’s not really an indicator either. I’ve put myself on the Confusion Couch here, but we will be trying to get some good close-ups for iris and leg scale comparison.

So what’s going to happen next? Is Mom going to bond with a new male this year? Will it be DM or has another male pushed him out? How long will it be until we know? Unfortunately, we have no idea. Until last April, it seemed like Mom and Dad would be together forever. As of this fall, it seemed like Mom and DM might enter into a pair bond. And now we’re throwing our hands up into the air, getting back to eagle time, and waiting for Mom to show us what she’s going to do. Eagles are moving around right now, which means that Mom may have plenty of suitors to choose from and UME-2 may not be the last new male we see at N2B this year. We’ll continue to get eye patterns when we can at both of our nests, we’ll do our best to count the visitors, and we’re looking forward to learning more about this stage of eagle life. Go eagles – and the best of luck to both nests this year.

The takeaway? We don’t always know as much as we think we know and ID takes time and skill…especially in a situation like this. We need to make sure we don’t let our personal stories and ideas about the eagles interfere with our eagle observations – not an easy task when we spend so much time watching and thinking about them! Behavior can help guide observations, but may not be especially helpful given that good perching and nesting spots might appeal to multiple eagles.

A Guide to the Acronyms

  • DM stands for Decorah Male. Formerly known as UME (Unknown Male Eagle), he showed up in mid-April, right after Dad disappeared. 
  • UME-2 stands for Unknown Male Eagle 2. UME-2 has been on site since at least October 15. While we don’t give every eagle we see an ID, UME-2 has been in N2B, perched near N1, and been pursued by Mom. He’s been on site long enough to get an ID. 
  • N2B: N2B stands for Nest Two-Bob. N2, or Nest 2, went down in a storm in 2015. Bob approved the starter nest plan but died before it could be completed. We named the nest in his honor. 
  • N1: N1 is the second nest on this territory. It was over in a tree across Siewers Spring Road, but has mostly disintegrated since the eagles left it in 2012.