Interspecies communication, interspecific communication, or heterospecific communication refers to communication among animals, plants, microorganisms, or other organisms of different species. Although researchers have explored the topic for many years, only recently has interspecies communication been recognized as an established field of inquiry.
Eavesdropping Heterospecific eavesdropping occurs when an organism of one species gleans information from a signal emitted by an organism of another species for the purpose of conveying information to conspecifics. In some cases, two species may exhibit bidirectional eavesdropping, in which organisms of both species acquire information from signals originating from organisms of the other. Eavesdropping is sometimes not considered a form of communication, but other models include it.
Heterospecific eavesdropping allows organisms to obtain and benefit from information they might not otherwise be able to access as quickly, and may occur as part of mutualistic, commensal, competitive, parasitic, or predator-prey interactions.
Alarm signals
Responses to heterospecific alarm calls have been documented in over 70 mammalian, avian, and even reptilian species, some of which produce no alarm calls themselves. When alarm calls contain more detailed information, their comprehension by heterospecifics varies, with some eavesdroppers extracting information on predator type or degree of danger. For instance, Diana monkeys appear to distinguish between Campbell's monkey alarm calls indicating leopards and those indicating eagles.Zuberbuhler, K. (2000) Interspecies semantic communication in two forest primates. Proc R Soc Lond Ser B Biol Sci 267:713–718. Furthermore, when one species elicits an alarm signal specific to a certain predator, the other species react in the same pattern as the species that called. For example, leopards hunt both species by capitalizing the elements of stealth and surprise. If the monkeys detect the leopard before it attacks (usually resulting in mobbing), the leopard will typically not attack. Therefore, when a leopard alarm call is given, both species respond by positioning near the leopard signaling that it has been found out. Eavesdropping on alarm calls can occur bidirectionally, as with redfronted lemurs and Verreaux's sificas, which both exhibit mixed alarm call systems and respond differently to distinct alarm calls of the other species.Fichtel, C. (2004) Reciprocal recognition of sifaka (Propithecus verreauxi verreauxi) and redfronted lemur (Eulemur fulvus rufus) alarm calls. Animal Cognition 7:45–52. Beyond distinguishing among distinct alarm calls, superb fairy-wrens and white-browed scrubwrens mutually understand variations in single calls as establishing degrees of danger.
Responses to heterospecific alarm calls have been identified in species that do not otherwise interact with one another, such as between the yellow-bellied marmot and golden-mantled ground squirrel. Animals also engage in alarm signal eavesdropping across classes, with mammals and the Galapagos marine iguana documented eavesdropping on the alarm calls of birds and bird species found to eavesdrop on the alarm calls of mammals. Red squirrels' acoustic response to raptors is near-identical to that of birds, making the latter also aware to a potential predatory threat, while eastern chipmunks are keen to mobbing calls by eastern tufted titmice. Whether heterospecific understanding is a learned behavior or not is unclear.
Alarm signal eavesdropping may benefit the signaling species as well as the eavesdropper, either by depriving a shared predator of prey and causing it to leave an area, or by leading eavesdroppers to participate in mobbing. For instance, black-capped chickadees produce mobbing calls that detail size and location information on predators, to which 24-50 different species are known to respond by participating in the mobbing. One of these species, the red-breasted nuthatch, has been shown to selectively respond only to chickadee mobbing calls indicating more dangerous predators in order to save energy, demonstrating comprehension of complex heterospecific signals.
Eavesdropping has been found in túngara frogs and their sympatric heterospecifics.Phelps, S.M.; Rand, A.S.; Ryan, M.J. (2007) The mixed-species chorus as public information: túngara frogs eavesdrop on a heterospecific. Behav. Ecol. 18:108–114. The scientists posit that mixed-species choruses may reduce their risk of predation without increasing mate competition.
In predation Heterospecifics may benefit from information obtained from eavesdropping differently from the intended conspecific receivers, and signalers may modify their behavior to combat effective eavesdropping. Fringe-lipped bats hunt by eavesdropping on frog mating calls, using these acoustic signals both to identify suitable prey species such as túngara frogs and to locate individuals. Because of this, male túngara frogs are known to produce less effective mating calls which are not preferred by fringe-lipped bats, but which are also not preferred by female túngara frogs.
Development of interspecific eavesdropping In 2000 it was found that age and interspecies experience were important factors in the ability for bonnet macaques to recognize heterospecific calls. Macaques who were exposed longer to other species' alarm calls were more likely to correctly respond to heterospecific alarm calls. Key to this early learning was the reinforcement of a predatory threat, when an alarm call was given a corresponding threat had to be presented in order to make the association. Interspecies communication may not be an innate ability but rather a sort of imprinting coupled with an intense emotion (fear) early in life. Other species, such as the fringe-lipped bat, display social learning of new signals associated with prey in maturity.
Interspecies communication between an older caretaker animal and a younger animal is observed in the animal world only rarely. In the case of Owen and Mzee, a orphaned baby hippopotamus bonded with a 130-year-old Aldabran tortoise named Mzee (Swahili for a wise old man). According to staff at their animal sanctuary, they vocalized to each other in neither a stereotypical tortoise nor a hippopotamus fashion.Owen & Mzee Owen does not respond to hippopotamus calls. It is likely that when Owen was first introduced to Mzee he was still young enough to be imprinted.
Intentional signaling
Intentional signaling occurs when an organism of one species produces a signal whose intended recipient or recipients belong to another species. This includes flowering plants’ uses of colors and scents to signal to pollinators that they contain nectar. As with flowering plants and pollinators, signalling may be deceptive: some flowering plants such as slipper orchids signal that they contain nectar through color and scent, but provide no benefit to pollinators.
Work by Gorissen, Gorissen, and Eens (2006) on song matching (or "song imitation") found that while great tits imitate the vocalizations of blue tits, other great tits do not respond to these imitations, suggesting they may use these imitations to signal to blue tits, rather than other great tits.
Much of the communication between predators and prey can be defined as signaling. In some animals, the best way to avoid being preyed upon is an advertisement of danger or unpalatability, or aposematism. Given the effectiveness of this, it is no surprise that many animals employ styles of mimicry to ward off predators. Some predators also use aggressive mimicry as a hunting technique. For example, Photuris fireflies mimic female Photinus fireflies by scent and glow patterns in order to lure interested male Photinus fireflies, which they then kill and eat. Lophiiformes, or anglerfish, are also famous for their use of escas as bait for small unsuspecting fish.
Two examples of predator–prey signaling were found in caterpillars and ground squirrels. When physically disturbed, Lepidoptera larvae produce a clicking noise with their mandibles followed by an unpalatable oral secretion.Brown, S.G.; Boettner, G.H.; Yack, J.E. (2007) Clicking caterpillars: acoustic aposematism in Antheraea polyphemus and other Bombycoidea. J Exp Biol 210:993–1005. Scientists believe this to be "acoustic aposematism" which has only been previously found in a controlled study with bats and tiger moths. While the defense mechanisms of ground squirrels to predatory rattlesnakes have been well studied (i.e. tail flagging), only recently have scientists discovered that these squirrels also employ a type of infrared heat signaling.Rundus, A.S.; Owings, D.H.; Joshi, S.S.; Chinn, E; Giannini, N. Ground squirrels use an infrared signal to deter rattlesnake predation. Proceedings of the National Academy of Sciences 104:14372-14376. By using robotic models of squirrels, the researchers found that when infrared radiation was added to tail flagging, rattlesnakes shifted from predatory to defensive behavior and were less likely to attack than when no radiation component was added.
Allomones
Kairomones
Synomones
Human-animal communication Since the 1970s, primatologist Sue Savage-Rumbaugh has been working with primates at Georgia State University's Language Research Center (LRC), and more recently, the Iowa Primate Learning Sanctuary. In 1985, using lexigram symbols, a keyboard and monitor, and other computer technology, Savage-Rumbaugh began her groundbreaking work with Kanzi, a male bonobo (P. paniscus). Her research has made significant contributions to a growing body of work in sociobiology studying language learning in non-human primates and exploring the role of language and communication as an evolutionary mechanism.
Koko, a lowland gorilla, began learning a modified American Sign Language as an infant, when Francine "Penny" Patterson, PhD, started working with her in 1975. Penny and Koko worked together at the Gorilla Foundation in one of the longest interspecies communication studies ever conducted until Koko's death in 2018. It was claimed that Koko had a vocabulary of over 1000 signs, and understood a greater amount of spoken English. However, scientific consensus is that Koko did not demonstrate a true understanding of language, due to a lack of regard for syntax or grammar.
In April 1998, Koko gave an AOL live chat. Sign language was used to relay to Koko questions from the online audience of 7,811 AOL members. The following is an excerpt from the live chat.
AOL: MInyKitty asks Koko are you going to have a baby in the future? PENNY: OK, is that for Koko? Koko are you going to have a baby in the future? KOKO: Koko-love eat ... sip. AOL: Me too! PENNY: What about a baby? You going to have baby? She's just thinking...her hands are together... KOKO: Unattention. PENNY: Oh poor sweetheart. She said 'unattention.' She covered her face with her hands..which means it's not happening, basically, or it hasn't happened yet. . . I don't see it. AOL: That's sad! PENNY: It is responding to the question. In other words, she hasn't had one yet, and she doesn't see a future here. The way the situation is actually with Koko & Ndume, she has 2 males to 1 female which is the reverse of what she needs. I think that is why she said that, because in our current situation, it isn't possible for her to have a baby. She needs several females and one male to have a family.
Criticism