One day old cuckoo hatchling with two host reed warbler (Acrocephalus scirpaceus) eggs.
A critical moment in the life of every cuckoo - the eviction behaviour is as a rule released within a day after hatching. Eviction instinct works even when the nestling is tree days old.
Here a young cuckoo nestling evicts the last egg of its fosterer (the sedge warbler Acrocephalus schoenobaenus).
A cuckoo nestling 7 day old.
A cuckoo chick 14 days old.
A 17-day old cuckoo fledgling dwarfs host - reed warbler - nest.
A female fledgling - a rare brown form.
A cuckoo nestling at the end of the nestling period is bigger than host`s (reed warbler) nest.