Eaglet excitement
Great news! For the first time since 2021, John’s neighboring Bald Eagle pair have successfully hatched a chick. John spotted it peering out of the nest on Friday, April 26!
Have you ever stared enviously at an eagle soaring above you? You may be less inclined to covet the eagle’s life when you think back to its first few weeks of life.
Sibling rivalry soars to new heights
The mother eagle begins to incubate immediately after the first egg is laid. The next egg, if there is one, is not laid until 1-4 days later, so there is a notable discrepancy between the size of the hatchlings.
The first egg laid will hatch first, be fed first, and begin to grow first. Even a short 1-2 day age difference between siblings can make a considerable difference in their size and power!
When food is scarce, the younger chicks are in peril. Their older sibling, desperate to get enough food, may have murder on its rapidly developing mind. First-born eaglets have been known to shove their hapless siblings out of the nest; they are more likely to do so if food is scarce. This behavior, called fratricide or siblicide, has two forms: obligate fratricide, meaning that the younger sibling always dies, and facultative fratricide, in which the younger sibling sometimes survives.
Bald Eagle chicks show facultative fratricidal behavior: the younger sibling(s) have a decent chance at survival if food is plentiful.
If the older chick chooses violence, younger siblings have a marked disadvantage in this small-scale avian wrestling match. According to Birds of the World, “In one nest, the masses of 6-day-old, 8-day-old, and 9-day-old siblings were 80 g, 260 g, and 477 g, respectively.” This behavior typically occurs during the first month of life. If the younger sibling(s) make it through that window, the outlook is sunnier.
Even if the older sibling has embraced a pacifistic attitude, the later-born offspring faces another challenge: parent eagles will feed the largest chick first, as it is the most likely to survive. That means the younger siblings only get fed if the parents can find enough food to sustain more than one chick. Starvation is as much of a risk to a younger eaglet as siblicide.
The good news
Luckily, these incidences aren’t commonplace. Generally speaking, food is plentiful and nobody needs to die at the hand (wing?) of their sibling or die of starvation. Second-born eaglets often survive to leave the nest, and a considerable number of third-born and even fourth-born siblings survive as well. (See some fun stats here!)
Despite everything, do you still find yourself jealous of those beautiful eagles soaring on a thermal? Me, too.
Topics
- Introduction (0:00-0:23)
- Birds (0:24-5:54)
- Bald Eaglets (0:24-1:27, 1:50-4:50)
- Loons (1:27-1:50, 5:36-5:42)
- Turkeys, Sandhill Cranes (4:50-5:00)
- Juncos, Pine Siskins (5:00-5:36)
- Purple Finches, American Goldfinches (5:42-5:54)
- Plants (5:54-13:33)
- Leafing out/leaf bud break (5:54-8:07, 8:38-9:23, 12:42-13:17)
- Speckled alder and hazel (6:10-8:07)
- Wild roses (8:38-9:23)
- Red maple (12:42-13:17)
- Flowering development (8:07-8:38, 9:41-12:42, 13:17-13:33)
- Blueberries breaking flower bud (8:07-8:38)
- Aspens losing flowers (9:41-9:57)
- Maples (9:57-11:09)
- Trilliums (11:09-11:29)
- Forsythia (11:29-11:44)
- Tamaracks (11:44-12:21)
- Balsam poplar, also known as balm of Gilead (12:21-12:42)
- Pennsylvania sedge (13:17-13:33)
- Leafing out/leaf bud break (5:54-8:07, 8:38-9:23, 12:42-13:17)
- A roller-coaster spring (7:08-8:07, 9:23-9:41, 13:33-13:41)
- How falling flowers help the forest floor (10:18-11:09)
- Conclusion (13:33-14:46)
- Addendum – upcoming workshops (14:46-16:53)
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).
