Eagle Nest Update: 3/3/2017

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This Eagle Nest Update is brought to you by MN DNR's Nongame Wildlife Program

What a difference a day makes

Today there are three eggs in the nest. Tomorrow there may be two eggs and one chick! The incubation period for bald eagles is approximately 35 days, and it’s been 34 days since the first egg was laid on January 28. Excitement is in the air, and “bets” for first egg hatch day and time have been placed by eagle enthusiasts from nine states (check out this BabyHunch Pool). Who will earn top bragging rights this year?!

Similar to egg laying, egg hatching is an asynchronous process. This means that not all three eggs will hatch at the same time. Instead, the eggs will hatch in the order they were laid, with 1–4 days between hatching events. Numerous evolutionary explanations have been proposed for asynchronous hatching, including reduced sibling rivalry; fewer nest failure events, such as the predation of all chicks; and the distribution of the chicks’ peak energy, or feeding, requirements.

When they’re ready, the chicks will pip, or break through their eggs, with the help of an egg tooth. An egg tooth is a temporary protrusion, or point, on the chicks’ bills used to penetrate the egg membranes and shell. This process may take 1–2 days, so it’s very likely that the oldest chick is pipping right now!

Be sure to keep your eyes on the nest, and please let us know via our Minnesota Nongame Wildlife Program Facebook page when the first eaglet hatches.

Phenomenal feats by unordinary species

Have you recently noticed some birds in the neighborhood that you haven’t seen for a while? Approximately 250 species of birds breed in Minnesota; however, most move, or migrate, to warmer places for the winter. Now that spring is near, many of these fair-weather feathered friends have started migrating back to our great state.

Migration, as it applies to wildlife, refers to round-trip movements between habitats or regions that typically correspond with seasonal changes. Dispersal, on the other hand, is a one-way movement by individuals away from their birth site.

Both types of movements occur across a wide range of spatial (space) and temporal (time) scales. For example, salamanders generally migrate hundreds or thousands of feet between breeding and overwintering habitats each year, whereas salmon generally migrate hundreds or even thousands of miles between ocean and freshwater habitats only once in their life.

Not surprisingly, long distance migraters get all the glory! Have your heard about the Arctic tern that migrates 20,000 miles between the Arctic and Antarctic every year? This truly is a phenomenal feat; however, to be fair, movement comparisons should be standardized by species’ body sizes. One study determined that the annual migration of wood frogs is comparable to that of the barren ground caribou and 13 times greater than that of the wildebeest!

Many Minnesotans anxiously await the arrival of spring migrant birds. These transients provide splashes of color for our eyes, melodious tunes for our ears, and the opportunity to exercise our winter-laden bodies as we get out to observe them! It’s no wonder we have so many festivals celebrating their return! Check out Midwest Weekends’ list of spring bird festivals to find an event near you.


Like what you read here? Want to learn more? Your MN DNR Nongame Wildlife Program and the educational products it provides (including the popular EagleCam), are made possible by donations from the public. Please give today.