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First to hatch
The cuckoo's egg hatches one or two days before the others. Ten hours later, something remarkable happens: Still naked and blind, the cuckoo hatchling begins to work the other eggs up the wall of the nest with its back, then shoves them over the edge. This operation is repeated until only the cuckoo hatchling remains in the nest.
Head start
The cuckoo hatchling is thus larger than its nest-mates, which makes it easier to eject the other eggs or smaller hatchlings.
Murder witness
The reed warbler is sometimes witness to this gruesome operation. But it never interferes. Even if the reed warbler sees its eggs or chicks discarded outside the nest, it does not return them to the nest. Why not?
Djur med koll
Det är stor skillnad mot djur som lever tillsammans i grupper. Där är det viktigt att alla känner igen varandra och vet sin plats i rangordningen. Vargen, som du kan se i en annan monter i utställningen, är ett sådant exempel.
