Editing Common dolphin (section)

==Natural history==
[[File:CD 3.jpg|thumb|left|Common dolphin, Ireland]]
Common dolphins live in both warm-temperate and tropical waters ranging from [[40th parallel north|40]]–[[60th parallel north|60°N]] to [[50th parallel south|50°S]]. Long-beaked common dolphins mostly inhabit shallow, warm coastal water.<ref name=encyc/> Short-beaked common dolphins are common "along shelf edges and in areas with sharp bottom relief such as [[seamount]]s and [[escarpment]]s".<ref name="Audubon"/> Common dolphins have a varied diet consisting of many species of fish and squid. This includes both [[mesopelagic]] species and [[epipelagic]] schooling species. They have been recorded to make dives up to {{Convert|200|m|ft}} deep.

Common dolphins are a widely distributed species. They can be found around the world in both offshore and coastal waters. In the Northwest Atlantic, they can be found from Cape Hatteras North Carolina, to Newfoundland and are strongly associated with the Gulf Stream. Dolphins in this region can often be found in areas that have certain geological factors like underwater canyons and ridges because this is where up-welling occurs which result in greater nutrients. In the Eastern Pacific, common dolphins are found along the coast of California and are associated with the California current. Short-beaked common dolphins can also be found in Europe, particularly the Scotian shelf, the Black Sea and the Mediterranean. In the Southern Hemisphere, they are abundant in the southwestern Pacific, around New Zealand and southern Australia. They are generally a pelagic species that are often found in waters 650–6,500 feet deep, with the short-beaked type preferring deeper waters than the long-beaked type<ref name="Chavez-Rosales 5833">{{Cite journal|last1=Chavez-Rosales|first1=Samuel|last2=Palka|first2=Debra L.|last3=Garrison|first3=Lance P.|last4=Josephson|first4=Elizabeth A.|date=December 2019|title=Environmental predictors of habitat suitability and occurrence of cetaceans in the western North Atlantic Ocean|journal=Scientific Reports|language=en|volume=9|issue=1|pages=5833|doi=10.1038/s41598-019-42288-6|issn=2045-2322|pmc = 6456503|pmid=30967576|bibcode=2019NatSR...9.5833C }}</ref> Temperature also plays a large role in the congregation of dolphins. For example, in the western North Atlantic, almost all sightings of common dolphins took place in waters from 16 to 20&nbsp;°C. However, there were common dolphin sightings in waters as low as 5&nbsp;°C.<ref name="Chavez-Rosales 5833"/>

Common dolphins can live in aggregations of hundreds or even thousands of dolphins.<ref name="encyc">{{cite book|title=Encyclopedia of Marine Mammals|author=Perrin, W.|chapter=Common Dolphins|editor1=Perrin, W.|editor2=Wursig, B.|editor3=Thewissen, J.|pages=[https://archive.org/details/encyclopediaofma2002unse/page/245 245–248]|year=2002|publisher=Academic Press|isbn=978-0-12-551340-1|chapter-url=https://archive.org/details/encyclopediaofma2002unse/page/245}}</ref> Common dolphins are often seen in groups numbering several hundred individuals (with subgroups consisting of 20–30 individuals). Occasionally, different groups will come together to form mega-pods which can consist of over 10,000 dolphins. Genetic studies in the Northeast Atlantic suggest that common dolphin pods generally do not consist of close kin, but rather of members that are not closely related. Unlike many delphinids, common dolphins do not live in a matriarchal society. That being said, closely related individuals are usually found in similar geographical locations fairly consistently, providing evidence that this species displays site fidelity (at least in the Northeastern Atlantic). Male common dolphins display greater site fidelity in relation to their kin than females.<ref>{{Cite journal|last1=Ball|first1=Laura|last2=Shreves|first2=Kypher|last3=Pilot|first3=Małgorzata|last4=Moura|first4=André E.|date=2017-07-21|title=Temporal and geographic patterns of kinship structure in common dolphins (Delphinus delphis) suggest site fidelity and female-biased long-distance dispersal|journal=Behavioral Ecology and Sociobiology|language=en|volume=71|issue=8|pages=123|doi=10.1007/s00265-017-2351-z|issn=1432-0762|pmc=5522516|pmid=28794579|bibcode=2017BEcoS..71..123B }}</ref> Common dolphin pod structure often consists of nursery pods (which includes females and calves), bachelor pods (consisting of all males) and mixed groups of males and females, including sub-adults and calves. Genetic evidence seems to indicate that common dolphins live in fission-fusion societies, where dolphins form pods that are not necessarily stable and do not necessarily consist of related individuals. It is not known if common dolphins form lifelong bonds with other individuals like the long-term male alliances seen in bottlenose dolphins.<ref>{{Cite journal|last1=Viricel|first1=Amélia|last2=Strand|first2=Allan E.|last3=Rosel|first3=Patricia E.|last4=Ridoux|first4=Vincent|last5=Garcia|first5=Pascale|date=December 2008|title=Insights on common dolphin (Delphinus delphis) social organization from genetic analysis of a mass-stranded pod|journal=Behavioral Ecology and Sociobiology|language=en|volume=63|issue=2|pages=173–185|doi=10.1007/s00265-008-0648-7|bibcode=2008BEcoS..63..173V |s2cid=25991354|issn=0340-5443}}</ref>

There is some evidence that common dolphins use signature whistles, similar to that of the bottlenose dolphin. These whistles are believed to serve as an acoustic label, and provide identification information similar to that of a name. &nbsp;It takes approximately 1 year for a calf to learn its signature whistle after which it remains stable for the rest of a dolphin's life. In South Africa, as many as 29 common dolphin signature whistle types were detected. However, it was difficult to determine if each dolphin had its own signature whistle due to the vast number of dolphins present (over 1,000) and anthropogenic background noise. Additionally, considering the vast number of dolphins present and&nbsp; taking into account their feeding and diving behavior, it appears that common dolphin signature whistles are also used for group cohesion. Another hypothesis for the function of signature whistles is that they serve as a beacon for lost individuals.<ref>{{Cite journal|last1=Fearey|first1=J.|last2=Elwen|first2=S. H.|last3=James|first3=B. S.|last4=Gridley|first4=T.|date=September 2019|title=Identification of potential signature whistles from free-ranging common dolphins (Delphinus delphis) in South Africa|journal=Animal Cognition|language=en|volume=22|issue=5|pages=777–789|doi=10.1007/s10071-019-01274-1|pmid=31177344|s2cid=176078258|issn=1435-9448|hdl=2263/70689|hdl-access=free}}</ref>

Common dolphins sometimes associate with other dolphin species, such as [[pilot whale]]s.<ref name="encyc" />  In the Gulf of Corinth, common dolphins frequently display mixed species association, especially with striped and [[Risso's dolphin|Risso's]] dolphins.<ref>{{Cite journal|last1=Neumann|first1=Dirk R.|last2=Orams|first2=Mark B.|date=2003-01-01|title=Feeding behaviours of short-beaked common dolphins, ''Delphinus delphis'', in New Zealand|journal=Aquatic Mammals|volume=29|issue=1|pages=137–149|doi=10.1578/016754203101023997|bibcode=2003AqMam..29..137N |issn=0167-5427}}</ref> Over one third of all dolphin sightings in the gulf consisted of mixed species associations that partially consisted of common dolphins. In mixed species associations, the ratio of striped to common dolphins ranged from 6:1 to 11:1. When Risso's dolphins were present (there would usually be only one or two individuals), it appeared that many of their scars were the result of interactions with striped and spinner dolphins. In many of the interactions, the Risso's dolphins would chase and herd the common dolphins toward the boat, while the common dolphins would try and swim under the Risso's dolphins. When groups of common and striped dolphins would charge at each other, the Risso's dolphin would chase the striped dolphins. Sometimes these interactions appeared to be playful, and at other times aggressive. Synchronized swimming and surfacing were commonly observed. These interactions take place in the deepest part of the Gulf, furthest from shore, and usually consist of a total of about 60 dolphins from all three species.

There have been confirmed cases of hybridization between striped and common dolphins in this region. There have been 15 cases of common dolphin and striped dolphin hybrids. Genetic and observational evidence has demonstrated that the hybrids are fertile and are capable of not only reproducing with other hybrids, but are capable of reproducing with each of the parent species.<ref>{{Cite journal|last1=Antoniou|first1=Aglaia|last2=Frantzis|date=2018|title=Evidence of introgressive hybridization between Stenella coeruleoabla and Delphinus delphis in the Greek Seas|journal=Molecular Phylogenetics and Evolution|volume=129|pages=325–337|doi=10.1016/j.ympev.2018.09.007|pmid=30218775|bibcode=2018MolPE.129..325A |s2cid=52279448 }}</ref> Striped dolphins have been known to mate with other dolphins, as the Clymene dolphin is the result of hybrid speciation between striped and spinner dolphins. However, this is unlikely to happen with common dolphins, as their population in the Gulf of Corinth is too low.<ref>{{Cite journal|last=Aglaia|first=Antoniou|date=2018|title=Evidence of introgressive hybridization between Stenella coeruleoabla and Delphinus delphis in the Greek Seas.|journal=Molecular Phylogenetics and Evolution|volume=129|pages=325–337|doi=10.1016/j.ympev.2018.09.007|pmid=30218775|bibcode=2018MolPE.129..325A |s2cid=52279448 }}</ref> Common dolphins and bottlenose dolphins have been known to interbreed in captivity. There is one confirmed case of a hybrid between a bottlenose and common dolphin in southern Spain, an important feeding ground for both species. The mother was a female bottlenose dolphin (dubbed Billie) who had spent 10 years in a common dolphin pod. Billie was observed assisting common calves reach the surface three different times and would babysit the calves after the mother went through labor. The length of the calf was similar to that of a bottlenose dolphin calf, with the lateral stripes and coloration of a common dolphin. The calf was seen with its mother almost daily on dolphin-watching tours among a nursery pod of common dolphins which also contained some immature striped dolphins. Sightings of the calf took place when temperatures were between 14 and 26&nbsp;°C. The calf was mainly observed swimming alongside the mother and was seen rubbing its head on its mother, jumping backwards over its mother and engaging in flipper-to flipper, belly-to flipper and belly-to belly contact.<ref>{{Cite journal|last1=Espada|first1=Rocío|last2=Olaya-Ponzone|first2=Liliana|last3=Haasova|first3=Luisa|last4=Martín|first4=Estefanía|last5=García-Gómez|first5=José C.|date=2019-04-16|title=Hybridization in the wild between Tursiops truncatus (Montagu 1821) and Delphinus delphis (Linnaeus 1758)|journal=PLOS ONE|volume=14|issue=4|pages=e0215020|doi=10.1371/journal.pone.0215020|issn=1932-6203|pmc=6467441|pmid=30990845|bibcode=2019PLoSO..1415020E |doi-access=free}}</ref> 

Common dolphins have been observed bow riding on [[baleen whale]]s, and they also bow ride on boats.<ref name="encyc" /> They are fast swimmers, and [[Whale surfacing behaviour|breaching]] behavior and aerial acrobatics are common with this species.<ref name="princeton" /> They are known to display altruistic behaviors to support injured members.<ref>Walker M. (2013-01-28). [https://www.bbc.co.uk/nature/21146455 Dolphins try to save dying companion]. [[BBC Natural History Unit|BBC Nature News]]. retrieved on 24-05-2014</ref><ref>{{cite journal|doi=10.1111/mms.12012|title=An unusual case of care-giving behavior in wild long-beaked common dolphins (''Delphinus capensis'') in the East Sea|journal=Marine Mammal Science|pages=E508–E514|volume=29|issue=4|year=2012|last1=Park|first1=Kyum J.|last2=Sohn|first2=Hawsun|last3=An|first3=Yong R.|last4=Moon|first4=Dae Y.|last5=Choi|first5=Seok G.|last6=An|first6=Doo H.}}</ref>

The short-beaked common dolphin has a [[gestation period]] of 10 to 11 months.<ref name="encyc" />  The newborn calf has a length of {{Convert|70|to|100|cm|ft|lk=on}} and weighs about {{Convert|10|kg|lb}}.<ref name="princeton" />  For the [[Black Sea]] population, [[weaning]] occurs at between five and six months, but occurs later (up to about 19 months) in other areas.<ref name="princeton" /><ref name="encyc" />  Typical interbirth interval ranges from one year for the Black Sea population to three years for eastern [[Pacific Ocean]] populations.<ref name="encyc" />  Age of sexual maturity also varies by location, but can range between 2 and 7 years for females and 3 and 12 years for males.<ref name="princeton" /><ref name="encyc" /> No evidence exists of any major reproductive differences between the two species.<ref name="Audubon" /> In captivity, the long-beaked common dolphin has [[Hybrid (biology)|hybridized]] with the [[common bottlenose dolphin]] (''Tursiops truncatus'').<ref name="encyc" /> One of the hybrids has been bred back to a bottlenose dolphin, demonstrating such hybrids are fertile.<ref name="hybrid" />