Cuckoos
The cuckoo mother has some sketchy, extremely harsh tactics for raising her young, who are just as tactful as she is. She tricks other mothers into raising her own young by birthing her eggs in another mother bird’s nest. This is so she can enjoy her life as a single mother bird. But the cuckoo chick hatches earlier and grows faster than all the other birds already in the nest, forcing them out of the nest to die (SN Explores).