Editing Coevolution (section)

===Brood parasites===
{{Main|Brood parasitism}}

[[Brood parasite|Brood parasitism]] demonstrates close coevolution of host and parasite, for example in some [[cuckoo]]s. These birds do not make their own nests, but lay their eggs in nests of other species, ejecting or killing the eggs and young of the host and thus having a strong negative impact on the host's reproductive fitness. Their eggs are camouflaged as eggs of their hosts, implying that hosts can distinguish their own eggs from those of intruders and are in an evolutionary arms race with the cuckoo between camouflage and recognition. Cuckoos are counter-adapted to host defences with features such as thickened eggshells, shorter incubation (so their young hatch first), and flat backs adapted to lift eggs out of the nest.<ref name=Weiblen>{{cite web |last1=Weiblen |first1=George D. |title=Interspecific Coevolution |url=http://geo.cbs.umn.edu/Weiblen2003.pdf |publisher=Macmillan |date=May 2003}}</ref><ref>{{cite journal |last1=Rothstein |first1=S.I |year=1990 |title=A model system for coevolution: avian brood parasitism |journal=Annual Review of Ecology and Systematics |volume=21 |pages=481–508 |doi=10.1146/annurev.ecolsys.21.1.481}}</ref><ref>{{Cite book |last=Davies |first=Nicholas B. |others=McCallum, James (Wildlife artist) |title=Cuckoo : cheating by nature |date=7 April 2015 |isbn=978-1-62040-952-7 |edition=First U.S. |location=New York, NY |oclc=881092849}}</ref>