Female bald eagles are bigger than males!
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- Both sexes bring nesting materials to the nest, but most of the arranging is done by the female. It’s not unusual to see the female take charge over the male during nest building.
- Incubation duties are shared, but not equally. The female tends to spend much more time incubating eggs than the male. As hatching begins, the female takes even greater control over the nest. For about two weeks after hatching, the young eaglets cannot thermo-regulate. Without body heat from the parent, they could quickly perish. Logically, the maternal instinct is powerful and probably ensures that, come what may, the adult female is dedicated to keeping the nestlings warm. It also makes sense that during this time, when the chicks are at their most vulnerable, being the bigger, more powerful bird would come in handy to keep the nest safe from predators.
- In the first weeks after hatching, the male will do most of the hunting, and bring food to the female and to the young. I’ve witnessed males, upon delivering food, try and settle onto the nest – only to have the female stand her ground and not allow him access. It’s not unusual to see a male attempt to feed a fish he’s just brought in to the young, only to have the female take the fish away and push the male to the side of the nest. In cases like this, size would seem to matter.
At the same time, the leaner the male, the more advantage he might have chasing down and trying to outmaneuver prey.
Once the young are old enough to regulate their internal temperature, and don’t need to be kept warm by the adults, nest duties become more evenly shared.
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