Communication

Communication:

• the action on the part of one organism that alters the probability pattern of behavior in another organism in a fashion adaptive to either one or both of the participants (E.O. Wilson)
• occurs when one organism emits a stimulus that, when responded to by another organism, confers some advantage (or the statistical probability of it) to the signaler or its group

Signalling = adaptive because the signaller gains a net benefit from the responses of receivers, even though some may harm them (e.g., frogs that call to attract mates may also attract rivals and/or predators)
 

SIGNALS - DISCRETE VS. GRADED:

• DISCRETE
• can be presented in an off-or-on manner
• no matter how weak or strong the stimulus evoking it, the behavior always stays about the same, e.g., flashing sequences of fireflies or signals of species or group identity
• GRADED
• increased variability
• the greater the motivation of the animal or the action about to be performed, the more intense and/or prolonged the signal given, e.g., many aggressive displays, ants may release alarm substances in relation to the degree to which they have been stimulated, & mobbing behavior of birds
• Morton's (1977. Am. Nat. 111:855-869) motivation-structural rules:

". . . natural selection has resulted in the structural convergence of many animal sounds used in 'hostile' and 'friendly' contexts. Simply stated, birds and mammals use harsh, relatively low-frequency sounds when hostile and higher-frequency, more pure tonelike sounds when frightened, appeasing, or approaching in a friendly manner. Thus, there appears to be a general relationship between the physical structure of sounds and the motivation underlying their use."

Source: http://courses.wcupa.edu/renner/psy335/communic/

Information = reduction in uncertainty of an observer about:

1) the signaller's future behavior (broadcast information), e.g., a threat display may be followed by an attack

2) the receiver's future behavior (transmitted information), e.g., a threat display may be followed by a retreat

Types of information:

1) Identity

• species identity
• group identity:
• Black-capped Chickadees modify features of their calls when joining a winter flock
• Bird song dialects
• Human speech dialects & clothing styles
• pairs
• sex
• individual identity, e.g., human speech, bird songs, olfactory clues in mammals, & parent-offspring in colonies of seabirds/penguins
• age
• quality or status

Milius, S. 2002. Elephants odor. Science News 161:133

When testosterone begins spiking in young Asian bull elephants, the animal secretes a liquid from their facial glands that smells like honey.  Researchers hypothesize that the honey like scent in a youngster’s secretions indicates to its elders that this male is still basically a kid.

Methods/Results:

• Researchers tested the reactions of captive elephants when they smelled gland secretions poured on a clean floor.  The mature elephants didn’t pay attention to the secretions of the young.
• Observations in the wild were consistent: when the mature bull elephant sniffed honey scent secretions of the young male, it didn’t pursue the youngster but stalked an older elephant secreting grown-up compounds.

                                                                                                                                                     Contributed by Andrea Pinkston

Roaring and social communication in African Lions: the limitations imposed by listeners -- In some mammals, loud calling (roaring) not only serves to advertise ownership of a territory and attract mates but also plays a vital role in allowing social companions to maintain contact when they are separated by long distances.  Grinnell and McComb (2001) suggested that individuals of social species may avoid giving long distance calls in circumstances where it would be of benefit  to keep their presence concealed.

Methods:

• Experiment was conducted with 20 resident and 11 nonresident male coalitions
• First they made recording of males roaring (single and in a group).
• Then they played the recording to males who lived more than 30km away from the site of the recording.  These males  were not feeding and /or there were no females around.
• They wanted to see if the males would approach the loudspeaker and how long it took them to approach and respond.

• They found that counter roaring was confined to the resident males only and only if they were in their home territory.  The nonresident males did not roar.

                                                                                                                                            Contributed by Emily Carmichael

The role of bright plumage in male-male interactions in the Ring-necked Pheasant -- Communication in the form of an organism’s coloration can be used as a method of assessing the quality of a competitor, meaning the brighter the individual the better quality (dominant) the individual is.  Mateos and Carranza (1997) investigated the role of plumage brightness in male-male interactions in captive Ring-necked Pheasants (Phasianus colchicus).

Methods:

• Bright and experimentally dulled males were presented to a group of captive male pheasants and agnostic interactions were recorded.
• Experiment 1, the males came from the same group of pheasants they were presented to.
• Experiment 2, the males presented were from a different group.  After two weeks the coloration of both individuals was switched (dull became bright and bright became dull). This was done to eliminate any individual recognition that may have played a role in the first experiment.

• In both experiments, dulled males were shown more aggression to than brighter males.  In experiment 2, the new individuals were shown more aggression than any other individuals within the flock.  Also,  bright individuals were only attacked by other bright (dominant) individuals, while dulled individuals were attacked more by dull (subordinate) individuals than bright ones (dominant).

                                                                                                                                            Contributed by Mark R. Bostrom

2) INTERACTIONAL INFORMATION, i.e., some displays correlate with attempts by communicator either to interact or to shun interaction

• Readiness to interact:
• bow display of Adelie penguins (during pair formation, precopulatory, etc.)
• upturned palm display of Chimpanzees
• humans - greet and seek to interact with head toss, raising eyebrows, vocalizing, & smiling
• Seeking to interact:
• spontaneous song of birds may serve to attract potential mates for interaction
• "loud" displays of many other animals, e.g., howling wolves, bellowing alligators, & "croaking" fish
• humans-what do humans do when seeking to interact?
• Shunning interaction - communicators behave as if hesitant to interact and avoid encounters if easily possible:
• tongue-showing by humans and gorillas [tongue shows when in or faced with interactions that disrupt preferred activities, cause delay, or are inherently aversive, e.g., when reprimanded, meeting a stranger, or is misunderstood in an argument]
• Black-tailed Prairie Dogs utter a chittering bark as they reject attempts by others to interact in any way from play to copulation

Calling by male midwife toads stimulates females to maintain reproductive condition -- In many anurans, male vocalizations function in courtship and mating.  However, no experiments have been conducted to see what effect male calls have on reproductive physiology.  Lea et al.  (2001) investigated the effects of calls made by male Mallorcan midwife toads (Alytes muletensis) on female conspecifics.

Methods:
· Three groups of six, gravid females were assigned to one of three treatments.  One treatment was silence, another was advertisement calls of heterospecific males, and the third was conspecific male advertisement calls.
· The gravid status was assessed and given a score that ranged from 0 (not ready to breed) to 5 (heavily gravid and ready to breed)

Results:
· In both the silent and heterospecific treatments there was a large reduction in average egg status.
· In the conspecific treatment there was little change.  Females remained gravid longer.

Conclusions:
· Conspecific calls have a stimulatory effect on the reproductive physiology of females, such that females remain gravid longer.
· This is important because there are a limited number of receptive males and females must compete for them.  To remain gravid for the entire breeding season waiting for a receptive male is energetically expensive and could reduce reproductive fitness.  Male vocalizations allow a female to know when and how long she should ripen and maintain her eggs.
· This is the first experiment to show vocalizations of male anurans affects reproductive status.

                                                                                                                                                                    Contributed by Mark R. Bostrom

3) ATTACK AND ESCAPE - displays correlated with attack- or escape-related behavior

• attack = acts that, if completed, will harm another individual
• escape = avoidance, e.g., ranging from fleeing to turning aside
• message of attack behavior is widespread among species, & the escape message even more so, & many species encode these messages in more than one display . . . which is not surprising considering that aggressive interactions must be dealt with immediately (with some risk) & they may recur quite frequently (particularly in "social" animals)

• e.g., fruit fly "vibration" display always precedes copulation
• e.g., copulation displays/calls of many birds (females of many species indicate readiness for copulation by soliciting with a posture that facilitates mounting by a male)
• advantage of signalling in advance = faster, more efficient copulation = better transfer of sperm & reduced susceptibility to predation

• individuals remain together & usually remain at some minimum individual distance; do not seek contact through fighting or copulating
• displays providing information about associating are widespread in persistently social species in which mates or members of larger groups spend much time together
• displays used primarily when other behavior may disrupt the group, e.g., attack by a predator or foraging behavior
• 'contact calls' of birds, such as white-breasted nuthatches . . . . also known to be given by flocks of migrating birds at night
• Halkin's work with Northern Cardinals (i.e., song-type matching by female on the nest is a stay-away signal to male)
• calls given by adults approaching a nest or den
• many mammals, such as old world monkeys use vocalizations to keep groups together

tail-flashing by juncos

Long-call vocalizations are hypothesized to serve as communicative signals within and between tamarin species.  Windfelder’s (2001) findings indicated that long calls serve as interspecific signal between associating species.

Methods:

• Taped wild saddleback and emperor tamarins calls and then played them back to the tamarins.  The study consisted of three groups of saddleback and emperor tamarins.  One of the saddleback tamarin groups and one of the emperor tamarin groups shared a common territory.
• Performed playback trials with just single groups so as not to have interactions from other groups.  Analyzed the responses of the tamarins to calls from their own species, the other species, the group of the other species that they shared a territory with, and with a control call from a species that they would not recognize at all.

• Saddleback tamarins called in response and approached the speaker to the calls of their own species and to those of the emperor that they shared a territory with.  Emperor tamarins showed similar results.

                                                                                                                                Contributed by Emily Carmichael

6) INDECISION

• Giving a display that encodes information about several possible actions, none of which is likely to be performed.
• Alternating intention movements of approach & withdrawal
• Moving laterally with respect to the pertinent stimulus
• Perform actions that appear irrelevant in the circumstance
• Specific behavioral information may be encoded by indecisive behavior
• e.g., intention movements may be used along with the incompatible alternatives

7) LOCOMOTION

• vocalizations given prior to movement by a pair or a group
• honeybee "waggle dance"
• Canada Geese & other waterfowl

8) ENVIRONMENTAL INFORMATION, e.g., vocalizations that announce location of food

Chemical transfer of warning information in non-injured fish  -- Pacus fish (Piaractus mesopotamicus), a non-predatory fish species, chemically warn conspecifics of predator threats.  Jordão and Volpato (2000) separated four captive bred pacus in one tank (the donor tank) and one in another tank (the receiver tank).  The two tanks were attached by a tube.  Three stimuli were introduced to the donor fish to illicit a response.  The control was a tank without other fish in it; the second had piracanjuba (Brycon orbignyanus), a non-predatory fish in it; and the third stimulus had a trahira (Hoplias malabaricus) in it which is a predator of pacus.  The test fish were not able to see the stimuli at first but then a sheet was lifted between the two tanks.  Water was transferred from the donor tank to the receiver tank to identify the responses of the receiver fish.  The receiver fish responded by distancing itself from the chemicals released by the donors when the predator was identified.  When the stimulus was a non-predatory fish, both the receiver and the donor fish moved closer to it and when the stimulus tank was empty, there was no response.  So fish chemically communicate with other fish in response to visual stimuli.                                        - contributed by Barbara Kieffer

Pacus fish (Piaractus mesopotamicus) Piracanjuba (Brycon orbignyanus) Trahira (Hoplias malabaricus)

Useful links:

Signalling theory and animal communication

The Graded Signal Hypothesis

Grinnell, J. and K. McComb. 2001. Roaring and social communication in African Lions: the limitations imposed by listeners. Animal Behaviour 62:93-98.

Jordão, L. C. and G. L. Volpato. 2000. Chemical transfer of warning information in non-injured fish. Behaviour 137:681-690.

Lea, J., M. Dyson, and T. Halliday. 2001. Calling by male midwife toads stimulates females to maintain reproductive condition. Anim. Behav. 61:373-377.

Mateos, C. and J. Carranza. 1997. The role of bright plumage in male-male interactions in the Ring-necked Pheasant. Anim. Behav. 54:1205-1214.

Windfelder, T. L. 2001. Interspecific communication in mixed-species groups of tamarins: evidence from playback experiments. Animal Behaviour 61:1193-1201.

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