Countdown to Shutdown #3: What’s on the Menu at the North Nest?

I hope you like sushi!

What’s on the menu at the North nest? We crunched the numbers to learn what Mr. North, DNF, and the eaglets were eating: breakfish, second breakfish, eightses, luncheon, afternoon raccoon, cowghetti dinner, and breakfish for supper! Read on to learn more!

Overall Prey Deliveries

Mr. North and DNF delivered 523 meals to the nest. He brought in 56% of all meals and a majority of the fish (64%), while she brought in 44% of all meals and a majority of the mammals (65%). It breakfishes down like this…

Total Meals 523 100%
Fish 381 73%
Mammals 71 14%
Unknown (UFO) 60 11%
Birds 10 1.9%
Reptiles 1 .1%
An eyeball? Absolutely! Nothing goes to waste in an eagle's nest.

An eyeball? Absolutely! Nothing goes to waste in an eagle’s nest.

While fish was the preferred meal in every month, taxa shifted ever so slightly from month to month and the percentage of fish brought into the nest increased quite a bit when suckers were spawning.

  • In March, fish made up 67% of meal deliveries
  • In April, fish made up 74% of meal deliveries
  • In May, fish made up 82% of meal deliveries
  • In June, fish made up 61% of meal deliveries
  • In July, fish made up just 56% of meal deliveries
  • In the last week of April and first week of May, fish made up an incredible 89% of all meal deliveries. I don’t have species detail, but this period coincides with the sucker spawn, which means that suckers are abundant and really, really easy to catch! Brown and brook trout aren’t spring spawners, but they might become more active as suckers migrate in and make more food available to everything around them. We’ll be exploring this food web more deeply!
Menu Details
Fish 381
UFO 60
Raccoon 15
Placenta/Cowghetti 15
Fawn Deer 10
Rabbit 8
Muskrat 5
Squirrel 5
Duck 5
Pheasant 5
Skunk 3
Suet/Fat 2
Cat 2
One Each Rat, Mink, Groundhog, Chipmunk, Buck Testicles, Hawkling, Turtle
Feeding and Eating

Who fed the kids more, DNF or Mr. North? Unsurprisingly, DNF fed 299 times to Mr. North’s 225 times. While the two evened out a little bit over time, DNF did 82% of the feedings and 41% of the meal deliveries during the eaglets’ first five days of life. Mr. North delivered a little more food than DNF, but we documented a bigger disparity between feeding activity than hunting and provisioning activity in those first crucial days. Does this hold true for Mr. and Mrs. North, Mom and DM2, or Mom and Dad? I hope to find out! Why did feedings even out? His feedings didn’t increase, but they dropped less precipitously than hers did! He fed slightly more than she did in April (50.7% of the feedings for him versus 49.3% the feedings for her) and quite a bit more in May (63% of the feedings for him versus 37% of the feedings for her).

2022 Feedings: DNF vs. Mr. North

2022 Feedings: DNF vs. Mr. North

When did self-feeding take over? DN16 started feeding on May 5, followed by her older brother on May 9. Parental feedings diminished pretty rapidly, perhaps because the ever-hungry tree-riffic two were a risk to parental toes, tails, and wings! May 23 marked the first day that neither parent fed, although they faithfully continued to deliver meals to their loudly squeeing offspring. Good luck, DN15 and DN16! You learned how to feed yourselves and did a very good job of it! We hope you continue to crush the dinner line as you graduate to Eagle College!

Feedings and Self-Feedings at the North Nest

Feedings and Self-Feedings at the North Nest

Further exploration…

Why does learning always lead to more questions? Several people have commented about the numbers of eagles nesting in NE Iowa. NE Iowa has been working hard to clear up its streams and rivers and build its fish populations: a magnet for nesting eagles that favor fresh fish! I want to explore riverine biology a little further. Where are sucker fish migrating from? How are they impacting riverine systems? What other animals are relying on them. This article from Chicago’s Shedd Aquarium is extremely interesting and I’ll be talking with Trout Unlimited as well. Link:

I also thought it was interesting that DN16 started self-feeding before her older brother did. Is it common for female eagles to begin self-feeding earlier? And I thought we would see a bigger disparity between prey deliveries in the eaglets’ first five to seven days of life. Mr. North delivered a few more prey items, but the meal delivery difference was nowhere near as great as the feeding difference. I also wonder how much of the ‘cowghetti’ is really deerghetti: the eagles regularly feast on fawn parts and placenta deliveries span March 28 through June 17 – a long period of time given that farmers usually regulate cattle breeding. As always, thank you for watching, sharing, learning, and especially for caring – and a special thanks to our camera operators and moderators for compiling and sharing data. This report would not exist without them.