Nature is violent, cruel, deadly. Survival of the fittest. Natural selection just happens. Competition between species typically leads to extinction of the lessor species. 99% of all species have gone extinct. Invasive species are deadly for native species.
The cuckoo chick has just hatched and now the reed Warblers have lost everything. Their lives will be totally dominated by this impostor and there is nothing they can do about it. Just 24 hours old and still naked and blind the cuckoo chick instinctively pushes out any other eggs in the nest. So why is it left to the newborn hatchling to take on this Herculean task? You might think that one of the things the female cuckoo could do is simply remove all the host eggs and leave her egg instead. Well the host laws desert a single egg so she can’t do that and that explains very nicely why it’s the young cuckoo it has to take on this task of rejecting the host eggs because although the hosts always desert a single egg they never desert a single chick. The cuckoo chick is astonishingly strong and has a distinctive hollow back that helps balance the hosts egg or chick before throwing it out of the nest. Nothing the little ogre does alarms the foster parents even when their own eggs are being forced out of the nest from right beneath them. The simple fact is that a Warbler nest won’t be big enough to hold both Reed Warbler chicks and the growing cuckoo chick. The imposter will need all the food that its adopted parents can bring. Sometimes the reed Warblers eggs are more advanced and both Warbler and cuckoo chicks hatch together. Again it falls to the blind cuckoo chick to deal with the situation…