White-tailed eagles, also known as sea eagles, typically lay between 1 to 3 eggs at a time, with 2 eggs being the most common clutch size. The female lays the eggs asynchronously, at intervals of between two and five days, from early March onwards. Incubation takes place after the first egg is laid and lasts for an average of 38 days.
The Most Common Clutch Size: 2 Eggs
White-tailed eagles are known to lay between 1 to 3 eggs at a time, but the most common clutch size is 2 eggs. This is the typical number of eggs that a pair of white-tailed eagles will lay during the breeding season.
| Clutch Size | Frequency |
|---|---|
| 1 egg | Less usual |
| 2 eggs | Most common |
| 3 eggs | Less usual |
| 4 eggs | Rare and unclear |
While clutches of one and three eggs are less usual, there have been instances where a pair on the Isle of Canna successfully reared three chicks from a nest in 2011. Four eggs have also been reported, but it is unclear whether this was the result of two separate females laying in the same nest.
Asynchronous Egg Laying
Image source: white tailed eagle by Andreas Weith
The female white-tailed eagle lays the eggs asynchronously, meaning that she lays them at intervals of between two and five days. This is a common strategy among birds of prey, as it allows the first chick to hatch and gain a size advantage over its younger siblings.
The asynchronous egg laying also means that the incubation period begins after the first egg is laid, rather than waiting for the entire clutch to be laid. This helps to ensure that the first chick hatches first and has a better chance of survival, especially during periods of food scarcity.
Incubation Period
The incubation period for white-tailed eagle eggs lasts for an average of 38 days. This is the time from when the first egg is laid until the first chick hatches.
During the incubation period, both the male and female white-tailed eagles take turns sitting on the nest to keep the eggs warm and protected. This is a crucial time for the development of the chicks, as they are completely dependent on their parents for survival.
Sibling Rivalry and Survival
The first chick to hatch is always the largest and strongest, and during periods of food scarcity, it often forces its younger sibling(s) to starve. This is a common phenomenon among birds of prey, where the older, larger chick is able to outcompete its younger siblings for food and resources.
Despite its larger size, the oldest chick rarely shows any aggression towards its younger sibling(s). Instead, the younger chicks are simply unable to compete with their older, stronger sibling and often succumb to starvation or other environmental factors.
Conclusion
In summary, white-tailed eagles typically lay between 1 to 3 eggs at a time, with 2 eggs being the most common clutch size. The female lays the eggs asynchronously, at intervals of between two and five days, and the incubation period lasts for an average of 38 days.
During the incubation and nestling periods, the first chick to hatch is often the largest and strongest, and it may outcompete its younger siblings for food and resources. However, the older chick rarely shows any aggression towards its younger siblings, and the younger chicks simply succumb to starvation or other environmental factors.
Understanding the nesting and breeding habits of white-tailed eagles is important for conservation efforts, as these majestic birds of prey face a variety of threats, including habitat loss, human disturbance, and environmental pollution. By studying their breeding behavior and ecology, we can better protect and preserve these iconic birds for future generations.
References:
– White-tailed Eagles in Poland
– White-tailed Eagles on the Isle of Mull
– The Peregrine Fund: White-tailed Eagle
