The second egg in the lesser spotted eagle (Clanga pomarina) clutch as a nesting insurance

Abstract Over an interval of 16 days, two eggs were laid by the same lesser spotted eagle female in her nest in the west-central Slovakia in 2021. The first egg failed to hatch, and the female ate it on the 45th day after she had laid it. Thereafter, the chick hatched from the second egg and later successfully fledged. The case contributes toward explaining why the species lays a second egg, even though the younger hatched chick is almost always prone to siblicide. In this case, the second egg acts as a reserve or an insurance if the first egg should not hatch, enabling the parents to breed successfully.