Reed warblers have set up a "neighborhood watch" to protect their nests from invasive cuckoos, who lay their eggs in local nests for others to raise. When reed warblers spot a cuckoo, they mob it and emit alarm calls that alert neighbors a cuckoo is at large and they should monitor their eggs closely. This has greatly benefited warblers, but cuckoo populations appear to be suffering.
Female cuckoos are known for laying their eggs in the nests of other birds. A new study from the Norwegian University of Science and Technology reveals how females are able to lay a variety of different egg colors to match those of their hosts, thus ensuring they are not kicked out before they are full grown.
Cowbirds lay their eggs in neighboring nests and abandon the to be raised by surrogate bird parents. Researchers recently spent some attempting to figure out whether the birds know they are different from their adopted families and how they handle it in terms of feeding, mating and flocking.