Editing Cuckoo (section)

== Behaviour and ecology ==
[[File:Geococcyx californianus.jpg|thumb|The [[greater roadrunner]] is rarely seen flying.]]
The cuckoos are, for the most part, solitary birds that seldom occur in pairs or groups. The biggest exception to this are the anis of the Americas, which have evolved cooperative breeding and other social behaviours. For the most part, the cuckoos are also diurnal as opposed to nocturnal, but many species [[bird vocalisation|call]] at night (see below). The cuckoos are also generally a shy and retiring family, more often heard than seen. The exception to this is again the anis, which are often extremely trusting towards [[human]]s and other species.

Most cuckoos are [[insectivore]]s, and in particular are specialised in eating larger insects and [[caterpillar]]s, including noxious, hairy types avoided by other birds. They are unusual among birds in processing their prey prior to swallowing, rubbing it back and forth on hard objects such as branches and then crushing it with special bony plates in the back of the mouth.<ref>Kaiser, G.W. (2007) ''The Inner Bird; Anatomy and Evolution''. UBC Press. Vancouver. {{ISBN|978-0-7748-1343-3}}.</ref> They also take a wide range of other insects and animal prey. The [[saurothera|lizard cuckoos]] of the [[Caribbean]] have, in the relative absence of [[birds of prey]], specialised in taking [[lizard]]s.<ref name="Powell">{{cite journal|last1=Powell|first1=R|last2=Henderson|first2=R|title=Avian Predators of West Indian Reptiles|journal=Iguana|volume=15|issue=1|pages=8–11|url=http://www.anoleannals.org/wp-content/uploads/2013/04/Powell-and-Henderson.-2008.pdf}}</ref> 

Larger, ground types, such as coucals and roadrunners, also feed variously on snakes, lizards, small rodents, and other birds, which they bludgeon with their strong bills. Ground species may employ different techniques to catch prey. A study of two coua species in Madagascar found that [[Coquerel's coua]] obtained prey by walking and gleaning on the [[forest floor]], whereas the [[red-capped coua|red-capped ca-ca]] ran and pounced on prey. Both species also showed seasonal flexibility in prey and foraging techniques.<ref name="COUA">{{cite journal|last=Chouteau|first=Philippe |author2=Raymond Fenosoa | year = 2008|title=Seasonal effects on foraging behaviour of two sympatric species of couas in the western dry forest of Madagascar |journal= African Journal of Ecology|volume=46|issue=3 | pages = 248–57| doi = 10.1111/j.1365-2028.2007.00880.x |bibcode=2008AfJEc..46..248C }}</ref> 

[[File:Eudynamys scolopacea feeding.jpg|thumb|Unlike most cuckoos, the [[Asian koel]] is mostly [[Frugivore|frugivorous]].]]
The parasitic cuckoos are generally not recorded as participating in [[mixed-species feeding flock]]s, although some studies in eastern Australia found several species participated in the nonbreeding season, but were mobbed and unable to do so in the breeding season.<ref>{{cite journal | last1 = Bell | first1 = H | year = 1986 | title = The Participation by Cuckoos in Mixed-Species Flocks of Insectivorous Birds in South-eastern Australia | journal = Emu | volume = 86 | issue = 4| pages = 249–53 | doi = 10.1071/MU9860249b | bibcode = 1986EmuAO..86..249B }}</ref> Ground cuckoos of the genus ''[[Neomorphus]]'' are sometimes seen feeding in association with [[army ant]] swarms, although they are not obligate [[ant follower]]s, as are some [[antbird]]s.<ref>{{cite journal | last1 = Karubian | first1 = J | last2 = Carrasco | first2 = L | year = 2008 | title = Home Range and Habitat Preferences of the Banded Ground-cuckoo (''Neomorphus radiolosus'') | journal = The Wilson Journal of Ornithology | volume = 120 | issue = 1| pages = 205–9 | doi=10.1676/06-176.1| s2cid = 56090764 }}</ref> The anis are ground feeders that follow cattle and other large mammals when foraging. In a similar fashion to [[cattle egret]]s, they snatch prey flushed by the cattle, so enjoy higher foraging success rates in this way.<ref>{{cite journal | last1 = Smith | first1 = S | year = 1971 | title = The Relationship of Grazing Cattle to Foraging Rates in Anis | journal = The Auk | volume = 88 | issue = 4| pages = 876–80 | doi=10.2307/4083844| jstor = 4083844 | doi-access = free }}</ref>

Several koels, couas, and the channel-billed cuckoo feed mainly on fruit,<ref>{{cite journal | last1 = Corlett | first1 = R | last2 = Ping | first2 = I | year = 1995 | title = Frugivory by koels in Hong Kong | journal = Memoirs of the Hong Kong Natural History Society | volume = 20 | pages = 221–22 }}</ref> but they are not exclusively [[frugivore]]s. The parasitic koels and channel-billed cuckoo in particular consume mainly fruit when raised by frugivore hosts such as the [[Australasian figbird]] and [[pied currawong]]. Other species occasionally take fruit, as well. Couas consume fruit in the dry season when prey is harder to find.<ref name="COUA"/>

=== Breeding ===
The cuckoos are an extremely diverse group of birds with regards to breeding systems.{{sfn|Payne|1997}} Most are [[monogamy in animals|monogamous]], but exceptions exist. The anis and the guira cuckoo lay their eggs in communal nests, which are built by all members of the group. Incubation, brooding, and territorial defence duties are shared by all members of the group. Within these species, the anis breed as groups of monogamous pairs, but the guira cuckoos are not monogamous within the group, exhibiting a polygynandrous breeding system.<ref name="Anis"/>

This group nesting behaviour is not completely cooperative. Females compete and may remove others' eggs when laying theirs. Eggs are usually only ejected early in the breeding season in the anis, but can be ejected at any time by guria cuckoos.<ref name="Anis">{{cite journal|last1=Riehl|first1=Christina|last2=Jara|first2=Laura|title=Natural History and Reproductive Biology of the Communally Breeding Greater Ani (Crotophaga major) at Gatún Lake, Panama|journal=The Wilson Journal of Ornithology|date=December 2009|volume=121|issue=4|pages=679–687|doi=10.1676/09-017.1|s2cid=9437145}}</ref> [[Polyandry in animals|Polyandry]] has been confirmed in the [[black coucal|African black coucal]] and is suspected to occur in the other coucals, perhaps explaining the reversed sexual dimorphism in the group.<ref>{{cite journal | last1 = Goymann | first1 = W | last2 = Wittenzellner | first2 = A | last3 = Wingfield | first3 = J | year = 2004 | title = Competing Females and Caring Males. Polyandry and Sex-Role Reversal in African Black Coucals, ''Centropus grillii''". | journal = Ethology | volume = 110 | issue = 10| pages = 807–23 | doi = 10.1111/j.1439-0310.2004.01015.x | bibcode = 2004Ethol.110..807G }}</ref>

Most cuckoo species, including malkohas, couas, coucals, and roadrunners, and most other American cuckoos, build their own nests, although a large minority engages in [[brood parasitism]] (see below). Most of these species nest in trees or bushes, but the coucals lay their eggs in nests on the ground or in low shrubs. Though on some occasions nonparasitic cuckoos parasitize other species, the parent still helps feed the chick.

The nests of cuckoos vary in the same way as the breeding systems. The nests of malkohas and Asian ground cuckoos are shallow platforms of twigs, but those of coucals are globular or domed nests of grasses. The New World cuckoos build saucers or bowls in the case of the New World ground cuckoos.{{sfn|Payne|1997}}

Nonparasitic cuckoos, like most other nonpasserines, lay white eggs, but many of the parasitic species lay coloured eggs to match those of their [[passerine]] hosts.

The young of all species are [[altricial]]. Nonparasitic cuckoos leave the nest before they can fly, and some New World species have the shortest incubation periods among birds.{{sfn|Payne|2005}}

==== Brood parasitism ====

{{Main|Brood parasite}}
[[File:Pallid Cuckoo juv.ogv|thumb|A pallid cuckoo juvenile being fed by three separate foster-parent species]]

About 56 of the Old World species and three of the New World cuckoo species ([[pheasant cuckoo|pheasant]], [[pavonine cuckoo|pavonine]], and [[striped cuckoo|striped]]) are brood parasites, laying their [[Egg (biology)|eggs]] in the nests of other birds{{sfn|Payne|2005}} and giving rise to the metaphor [[Cuckoo's egg (metaphor)|"cuckoo's egg"]]. These species are obligate brood parasites, meaning that they only reproduce in this fashion. The best-known example is the European common cuckoo. In addition to the above noted species, others sometimes engage in nonobligate brood parasitism, laying their eggs in the nests of members of their own species, in addition to raising their own young.<ref>{{cite journal | last1=Antonov | first1=Anton | last2=Stokke | first2=Bard G. | last3=Moksnes | first3=Arne | last4=Roeskaft | first4=Eivin | year=2008 | title=Does the cuckoo benefit from laying unusually strong eggs? | journal=Animal Behaviour | volume=76 | issue=6 |pages=1893–900 |doi= 10.1016/j.anbehav.2008.08.016| s2cid=54375519 }}</ref>

Brood parasitism has even been seen in greater roadrunners, where their eggs were seen in the nests of [[common raven]]s and [[northern mockingbird]]s.  The shells of the eggs of brood-parasitic cuckoos are usually thicker and stronger than those of their hosts.<ref>{{cite journal | last1=Antonov | first1=Anton | last2=Stokke | first2=Bard G. | last3=Moksnes | first3=Arne | last4=Roeskaft | first4=Eivin | year=2008 | title=Does the cuckoo benefit from laying unusually strong eggs? | journal=Animal Behaviour | volume=76 | issue=6 |pages=1893–900 |doi= 10.1016/j.anbehav.2008.08.016| s2cid=54375519 }}</ref> This protects the egg if a host parent tries to damage it, and may make it resistant to cracking when dropped into a host nest.<ref name=Davies_book>{{cite book | last = Davies | first = Nick B. | title = Cuckoo: Cheating by Nature | year = 2015 | publisher = Bloomsbury |url=https://books.google.com/books?id=xIGKBgAAQBAJ |isbn = 978-1-4088-5658-1 |access-date=24 October 2020}}</ref> 

Cuckoo eggshells have two distinct layers. In some nesting cuckoos, a thick, outer, chalky layer is not present on the eggs of most brood-parasitic species, with some exceptions, and the eggshells of Old World parasitic cuckoos have a thick outer layer that is different from that of nesting cuckoos.{{sfn|Payne|2005|p=127}}

===== Parasitic cuckoo advanced laying and hatching =====
The cuckoo egg hatches earlier than the host eggs, and the cuckoo chick grows faster. In most cases, the chick evicts the eggs and/or young of the host species. The chick has no time to learn this behavior, nor does any parent stay around to teach it, so it must be an [[instinct]] passed on genetically.

[[File:Reed warbler cuckoo.jpg|thumb|upright|A [[reed warbler]] raising the young of a [[common cuckoo]]]]
One reason for the cuckoo egg's hatching sooner is that, after the egg is fully formed, the female cuckoo holds it in her oviduct for another 24 hours prior to laying.<ref name=Davies_book /> This means that the egg has already had 24 hours of internal incubation. The cuckoo's internal temperature is 3–4&nbsp;°C higher than the temperature at which the egg is incubated in the nest, and the higher temperature means that the egg incubates faster, so at the time it is laid, the egg has already had the equivalent of 30 hours incubation in a nest.<ref name=Davies_book />

The chick encourages the host to keep pace with its high growth rate with its rapid begging call<ref name=Adams>{{cite news |url= https://www.telegraph.co.uk/earth/wildlife/4109282/Cuckoo-chicks-dupe-foster-parents-from-the-moment-they-hatch.html |archive-url= https://web.archive.org/web/20090213190416/http://www.telegraph.co.uk/earth/wildlife/4109282/Cuckoo-chicks-dupe-foster-parents-from-the-moment-they-hatch.html |url-status= dead |archive-date= February 13, 2009 | work=The Daily Telegraph | location= London | title=Cuckoo chicks dupe foster parents from the moment they hatch | quote=Cuckoo chicks start to mimic the cries that their foster parents' young make from the moment they hatch, a scientist has proved. | first=Stephen | last=Adams | date= 2009-01-04 | access-date=2010-04-30}}</ref> and the chick's open mouth which serves as a [[sign stimulus]].<ref name=Campbell>''Biology'' (4th edition) NA Campbell, p. 117 'Fixed Action Patterns' (Benjamin Cummings NY, 1996) {{ISBN|0-8053-1957-3}}</ref>

===== Evolutionary arms race between cuckoo and host =====
Since obligate brood parasites need to successfully trick their host for them to reproduce, they have evolved adaptations at several stages of breeding. High costs of parasitism are exerted on the host, leading to strong selections on the host to recognize and reject parasitic eggs. The adaptations and counter-adaptations between hosts and parasites have led to a coevolution "arms race". This means that if one of the species involved were to stop adapting, it would lose the race to the other species, resulting in decreased fitness of the losing species.<ref>{{Cite journal |last1=Spottiswoode |first1=Claire N. |author1-link= Claire Spottiswoode |last2=Stevens |first2=Martin|date=May 2012 |title=Host-parasite arms races and rapid changes in bird egg appearance |journal=The American Naturalist |volume=179 |issue=5 |pages=633–648 |doi=10.1086/665031|pmid=22504545|bibcode=2012ANat..179..633S |hdl=11427/34950|s2cid=10287985|hdl-access=free }}</ref> The egg-stage adaptation is the best studied stage of this arms race.

Cuckoos have various strategies for getting their eggs into host nests. Different species use different strategies based on host defensive strategies. Female cuckoos have secretive and fast laying behaviors, but in some cases, males have been shown to lure host adults away from their nests so that the females can lay their eggs in the nest.<ref name=Davies>{{cite journal |last=Davies |first=N.B. |title=Cuckoo adaptations: trickery and tuning |journal=Journal of Zoology |date=2011 |volume=284 |pages=1–14 |doi=10.1111/j.1469-7998.2011.00810.x|doi-access=free }}</ref> Some host species may directly try to prevent cuckoos laying eggs in their nest in the first place – birds whose nests are at high risk of cuckoo-contamination are known to "mob" attack cuckoos to drive them out of the area.<ref>{{Cite journal| first1=D.| title=Co-evolution: A Behavioral 'Spam Filter' to Prevent Nest Parasitism| journal=Current Biology| volume=19| issue=4| last1=Wheatcroft| pages=R170–R171| date=Feb 2009 | issn=0960-9822| pmid=19243694| doi=10.1016/j.cub.2008.12.034| s2cid=10357373| doi-access=free| bibcode=2009CBio...19.R170W}}</ref> Parasitic cuckoos are grouped into [[Gens (behaviour)|gentes]], with each gens specializing in a particular host. Some evidence suggests that the gentes are genetically different from one another.

[[File:Brush Cuckoo Oct 2007.JPG|thumb|{{audio|Brush Cuckoo song Nov2007.ogg|The call}} of the [[brush cuckoo]] ]]

===== Host egg mimicry =====
Female parasitic cuckoos sometimes specialize and lay eggs that closely resemble the eggs of their chosen host. Some birds are able to distinguish cuckoo eggs from their own, leading to those eggs least like the host's being thrown out of the nest.<ref name="Campbell" /> Parasitic cuckoos that show the highest levels of egg mimicry are those whose hosts exhibit high levels of egg rejection behavior.<ref>{{cite journal |vauthors=Stoddard MC, Stevens M |title=Avian vision and the evolution of egg color mimicry in the common cuckoo |journal=Evolution; International Journal of Organic Evolution |volume=65 |issue=7 |pages=2004–13 |date=July 2011  |pmid=21729055 |doi=10.1111/j.1558-5646.2011.01262.x|s2cid=334052 }}</ref> Some hosts do not exhibit egg rejection behavior and the cuckoo eggs look very dissimilar from the host eggs. It has also been shown in a study of the European common cuckoos that females lay their egg in the nest of a host that has eggs that look similar to its own.<ref>{{cite journal |vauthors=Avilés JM, Stokke BG, Moksnes A, Røskaft E, Asmul M, Møller AP |title=Rapid increase in cuckoo egg matching in a recently parasitized reed warbler population |journal=Journal of Evolutionary Biology |volume=19 |issue=6 |pages=1901–10 |date=November 2006  |pmid=17040387 |doi=10.1111/j.1420-9101.2006.01166.x|s2cid=37592779 }}</ref> 

Other species of cuckoo lay "cryptic" eggs, which are dark in color when their hosts' eggs are light.<ref name="Davies" /> This is a trick to hide the egg from the host, and is exhibited in cuckoos that parasitize hosts with dark, domed nests. Some adult parasitic cuckoos completely destroy the host's clutch if they reject the cuckoo egg.<ref name="Davies" /> In this case, raising the cuckoo chick is less of a cost than the alternative, total clutch destruction.

Cuckoo egg physiology can limit the degree of mimetic accuracy. Due to larger chick size on average for parasites compared to hosts, this is a physiological constraint on egg size, a minimum egg size needed to support a healthy cuckoo chick.<ref name=":1">{{Cite journal |last1=Akkaynak |first1=Derya |first2=Mary Caswell |last2=Stoddard |title=Common cuckoos do not mimic the size and shape of host eggs |journal=[[Behavioral Ecology]] |date=September–October 2023 |volume=34 |issue=5 |pages=804–815 |doi=10.1093/beheco/arad044 |doi-access=free |via=Oxford Academic }}</ref> In these cases, there is selective pressure on cuckoos to lessen their egg size to be a more effective mimic, but physiological constraints hinder the species from doing so.<ref name=":1" />

Mimicry may also be imperfect due to a lack of strong selection pressures towards the parasite. Oriental reed warbler hosts do not discriminate between warbler-sized model eggs and slightly larger model cuckoo eggs.<ref>{{Cite journal |first1=Donglai |last1=Li |first2=Xiaoshuang |last2=Li |first3=Yan |last3=Zhang |first4=Shuang |last4=Guan |first5=Yanan |last5=Ruan |title=Contrasting effects of egg size and appearance on egg recognition and rejection response by Oriental reed warblers  |journal=[[Ecology and Evolution]] |date=October 2020 |volume=10 |issue=19 |pages=10508–10519 |doi=10.1002/ece3.6707 |doi-access=free |pmid=33072276 |pmc=7548169 |bibcode=2020EcoEv..1010508L }}</ref> Since cuckoos in this situation can effectively parasitize despite laying eggs slightly larger than those of their hosts, there are little selective pressures to evolve "perfect" mimicry.

To select the most suitable host nests, cuckoos may "egg-match" as well. Daurian redstarts (''Phoenicurus auroreus''), another cuckoo host, lay clutches of either pink or blue eggs. Cuckoo eggs are more similar in reflectance and color to blue redstart eggs than pink ones. In-field observations revealed parasitism occurred more frequently in blue-egg redstart nests (19.3%) than in pink-egg redstart nests (7.9%).<ref name=":2">{{Cite journal |first1=Jinggang |last1=Zhang |first2=Peter |last2=Santema |first3=Zixuan |last3=Lin |first4=Lixing |last4=Yang |first5=Meijun |last5=Liu |first6=Jianqiang |last6=Li |first7=Wenhong |last7=Deng |first8=Bart |last8=Kempenaers |title=Experimental evidence that cuckoos choose host nests following an egg matching strategy |journal=[[Proceedings_of_the_Royal_Society#Proceedings_of_the_Royal_Society_B:_Biological_Sciences|Proceedings of the Royal Society B: Biological Sciences]] |date=22 February 2023 |volume=290 |issue=1993 |doi=10.1098/rspb.2022.2094 |doi-access=free |pmid=36809803 |via=The Royal Society Publishing |pmc=9943643 }}</ref> This suggests cuckoos prefer parasitizing nests containing eggs resembling their own. Experiments in the lab show similar findings: cuckoos parasitized artificial nests containing blue eggs more frequently than pink ones.<ref name=":2" />

Two main hypotheses on the cognitive mechanisms mediate host distinguishing of eggs. One hypothesis is true recognition, which states that a host compares eggs present in its clutch to an internal template (learnt or innate), to identify if parasitic eggs are present.<ref name=":0">{{Cite journal |last=Rothstein |first=Stephen I. |date=May 1975 |title=Mechanisms of avian egg-recognition: Do birds know their own eggs? |journal=Animal Behaviour |volume=23 |issue=Part 2 |pages=268–278 |doi=10.1016/0003-3472(75)90075-5|s2cid=53268458 }}</ref> However, memorizing a template of a parasitic egg is costly and imperfect and likely not identical to each host's egg. The other one is the discordancy hypothesis, which states that a host compares eggs in the clutch and identifies the odd ones.<ref name=":0" /> However, if parasitic eggs made the majority of eggs in the clutch, then hosts ends up rejecting their own eggs. More recent studies have found that both mechanisms more likely contribute to host discrimination of parasitic eggs since one compensates for the limitations of the other.<ref>{{Cite journal |last1=Feeney |first1=William E.|last2=Welbergen |first2=Justin A. |last3=Langmore |first3=Naomi E. |date=2014 |title=Advances in the Study of Coevolution Between Avian Brood Parasites and Their Hosts |journal=Annual Review of Ecology, Evolution, and Systematics |volume=45 |issue=1 |pages=227–246 |doi=10.1146/annurev-ecolsys-120213-091603|hdl=1885/66602 |hdl-access=free }}</ref>

===== Possible evidence of host benefits in the face of cuckoo parasitism =====
The parasitism is not necessarily entirely detrimental to the host species. A 16-year dataset was used in 2014 to find that [[carrion crow]] nests in a region of northern [[Spain]] were more successful overall (more likely to produce at least one crow fledgling) when parasitised by the [[great spotted cuckoo]]. The researchers attributed this to a strong-smelling predator-repelling substance secreted by cuckoo chicks when attacked, and noted that the interactions were not necessarily simply parasitic or mutualistic.<ref name = cuckoo_mutual_journal>{{Cite journal | last1=Canestrari | first1=Daniela | last2=Bolopo | first2=Diana | last3=Turlings | first3=T.C.J | last4=Röder | first4=Gregory | last5=Marcos | first5=J.M. | last6=Baglione | first6=Vittorio | journal=Science | volume=343 | issue=6177 | pages=1350–1352 | doi=10.1126/science.1249008 | url=https://www.science.org/doi/full/10.1126/science.1249008 | title=From Parasitism to Mutualism: Unexpected Interactions Between a Cuckoo and Its Host | date = March 2014| pmid=24653032 | bibcode=2014Sci...343.1350C | s2cid=25309832 | url-access=subscription }}</ref><ref name=cuckoo_mutual_news>{{Cite web|url=https://www.aaas.org/news/science-parasitic-cuckoos-provide-nest-protection-crow-hosts|title=Science: Parasitic Cuckoos Provide Nest Protection for Crow Hosts|website=American Association for the Advancement of Science|access-date=May 30, 2020|archive-url=https://web.archive.org/web/20200804084045/https://www.aaas.org/news/science-parasitic-cuckoos-provide-nest-protection-crow-hosts|archive-date=4 August 2020}}</ref> This relationship was not observed for any other host species, or for any other species of cuckoo. Great spotted cuckoo chicks do not evict host eggs or young, and are smaller and weaker than carrion crow chicks, so both of these factors may have contributed to the effect observed.

Subsequent research using a dataset from southern Spain <ref name = cuckoo_mutual_false>{{Cite journal | last1=Soler | first1=Manuel | last2=de Neve | first2=Liesbeth | last3=Roldán | first3=María | last4=Pérez-Contreras | first4=Tomás | last5=Soler | first5=J.J. | journal=PLOS ONE | doi=10.1371/journal.pone.0173080 | title=Great spotted cuckoo nestlings have no antipredatory effect on magpie or carrion crow host nests in southern Spain | date = April 2017| volume=12 | issue=4 | pages=e0173080 | pmid=28422953 | pmc=5396876 | bibcode=2017PLoSO..1273080S | s2cid=31416408 | doi-access=free }}</ref> failed to replicate these findings, and the second research team also criticised the methodology used in experiments described in the first paper. The authors of the first study have responded to points made in the second <ref name = cuckoo_mutual_response>{{Cite journal | last1=Canestrari | first1=Daniela | last2=Bolopo | first2=Diana | last3=Turlings | first3=T.C.J | last4=Röder | first4=Gregory | last5=Marcos | first5=J.M. | last6=Baglione | first6=Vittorio | journal=PLOS ONE | title=Formal comment to Soler et al.: Great spotted cuckoo nestlings have no antipredatory effect on magpie or carrion crow host nests in southern Spain | doi=10.1371/journal.pone.0184446 | date=September 2017| volume=12 | issue=9 | pages=e0184446 | pmid=28922382 | pmc=5602529 | bibcode=2017PLoSO..1284446C | doi-access=free }}</ref> and both groups agree that further research is needed before the mutualistic effect can be considered proven.

=== Calls ===
Cuckoos are often highly secretive, and in many cases, best known for their wide repertoire of [[bird song|calls]]. These are usually relatively simple, resembling whistles, flutes, or hiccups.<ref name=BH>{{cite book | last = Brooke | first = Michael de L | author2 = Horsfall, John A. | year = 2003 | title = Firefly Encyclopedia of Birds | chapter = Cuckoos | editor = Christopher Perrins | editor-link = Christopher Perrins | pages = [https://archive.org/details/fireflyencyclope0000unse/page/312 312–15] | publisher = Firefly Books | isbn = 978-1-55297-777-4 | chapter-url-access = registration | chapter-url = https://archive.org/details/fireflyencyclope0000unse | url = https://archive.org/details/fireflyencyclope0000unse/page/312 }}</ref> The calls are used to demonstrate ownership of a [[territory (animal)|territory]] and to attract a mate. Within a species, the calls are remarkably consistent across the range, even in species with very large ranges. This suggests, along with the fact that many species are not raised by their true parents, that the calls of cuckoos are innate and not learnt.{{Citation needed|date=November 2019}} Although cuckoos are diurnal, many species call at night.{{sfn|Payne|2005}}

The cuckoo family gets its English and scientific names from the call of the male [[common cuckoo]], also familiar from [[cuckoo clock]]s. In most cuckoos, the calls are distinctive to particular species, and are useful for identification. Several [[cryptic species]] are best identified on the basis of their calls.