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.
A new identification key highlights 74 species of cuckoo wasps -- wasps known for their propensity to steal other insects' nests, as cuckoo birds do with other birds -- found in the Nordic and Baltic countries. This includes the "Northern" cuckoo wasp (Chrysis borealis), which is new to science.