Last week, John was very happy to see his neighboring bald eagle pair looking amorous. They’ve been very busy carting sticks and grasses to the nest as they prepare for nesting, as well as performing courtship displays.
Bald eagles have a variety of courtship displays. The most dramatic is the "cartwheel display,” in which the partners fly to a great height, clasp talons and plummet to the earth, breaking apart at the last moment. (Now that’s a trust fall!)
Other courtship displays include chase displays, where the partners pursue each other, perform barrel rolls and occasionally lock talons, and the roller coaster display, where they fly to a great height and plummet to earth, only pulling up from their dive when they’re about to collide with the earth or water.
What are those big birdies up to?
The result of all this bonding is — when all goes well — one to three eggs. In the 40 years he’s been keeping records, John’s resident bald eagles typically lay eggs around March 8.
Once the eagles have laid eggs, you’ll almost always see an adult in the nest. The eggs must be kept warm. Field and captive observations show that parents are on the eggs for over 95% of the 35 days between egg laying and hatching. The female eagle, which has a slightly more developed brood patch, incubates for 52-75% of the total time.
As you might imagine, keeping eggs warm in inclement weather is tiring work. In the worst conditions, the parents’ best efforts aren’t enough, and the eggs don’t hatch. Last year was such a year for John’s eagles. By mid-April, the parents had given up and left the nest for the season. Here’s hoping this year is more successful!
Timestamps
- Plants not breaking bud as much as suspected in the warm weather (0:26-3:32)
- Nature’s Notebook and “the beguiling nature of the lilac bud” (3:32-5:37)
- Nesting Bald Eagles in John’s backyard (5:37-7:14)
- Tamarack budding habits (7:14-8:13)
- Chipmunks emerging (8:13-9:01)
- Skunk mating activities (9:01-9:37)
- Roadside birds, colors and carcasses (9:01-11:50)
- Willow colors (10:03-11:50)
- Trumpeter swans and why they love ice (11:51-13:05)
- Early spring mating displays: bird edition (13:05-14:43)
- Woodpecker society: who’s allowed in a territory and who’s not (13:34-14:23)
- Maple sap harvest (14:43-16:17)
- Trailing arbutus (16:17-17:07
- Trembling aspen buds (17:07-18:07)
- Ticks emerging (18:07-19:00)
- Migrating waterfowl (19:00-19:52)
Sidenote
I really enjoyed this excerpt about play behavior in eagles, written by Milton B. Trautman in 1940 in The Birds of Buckeye Lake, Ohio.
“Upon 2 occasions 3 to 6 eagles were observed playing with a stick. Such a habit appears to be not well known, and therefore a brief description of an observation is given. While standing on Sellars Point on the rather warm, sunny afternoon of February 15, 1930, I watched 6 of these great hawks playing with a stick. The birds were grouped about an open hole in the ice-covered lake and were approximately 250 yards south of the Point. The stick was about 18 inches long and 1.5 inches in diameter. A bird, followed by 2 or 3 of the others, took the stick and began to ascend in great spirals until it attained a height so great that it could be seen by the naked eye only with difficulty. Thereupon the bird dropped the stick; the others stooped and attempted to catch it with their talons before it hit the ice. The bird catching the stick began to ascend again, screaming all the while, and followed by the others. The game of dropping and recovering the stick continued for more than 10 minutes, after which the birds came down and stood upon the ice about the open hole. During the downward plunges, these usually heavy, awkward hawks appeared surprisingly swift and graceful.”
That does it for this week! For more phenology, subscribe to our Season Watch Newsletter or visit the Season Watch Facebook page.
Funding for this project was provided by the Minnesota Environment and Natural Resources Trust Fund as recommended by the Legislative-Citizen Commission on Minnesota Resources (LCCMR).
