• These are all signals -- a form of communication
• One individual - the signaler - gives a signal that causes a reaction in another individual - the receiver.
• What might a signal be communicating?
• Might indicate relative wealth of receiver -- the quality of the signaler
• fast car, gemstone, expensive drink, peacock tail may indicate wealth
• stotting may indicate quality to potential predator -- "See how high I can jump?"
• Might indicate location of food resources -- bee dancing
• May delineate boundaries of territory or defend receptive mate (territory)
• Serve as a call for assistance -- e.g. ravens yelling to "gang-up-on-the-territorial-residents," mobbing calls by tits and chickadees
• All these actions have another thing in common - they are all COSTLY.
• Energetically costly -- dragging around a huge tail, repeated vocalizations
• Increased predation risk -- stotting expends energy which could be used to outrun a predator; more exposed; producing sound that may attract a predator

So if signaling is costly, why signal? To answer that we need to look at different categories of signals or displays and examine the costs and benefits associated with each.

FIRST, lets define a display. Display is a stereotyped (ritualized) motor pattern that is involved in communication. Behavior makes information available to receivers.

Communication should make information available only if it has advantages for signaler. BUT receivers should respond to that information only if the response is beneficial to them as well.

This has lead to the evolution of displays for use in competitive or AGONISTIC situations.

Agonistic displays may involve aggression, threat, appeasement, or avoidance. Agonistic displays often arise from a CONFLICT caused by 2 stimuli for incompatible types of behavior that are present at the same time. This results in two conflicting motivational systems being activated at the same time. Common consequence of conflict behavior is the inhibition of one behavior -- one behavior overrides other.

BEHAVIORAL INHIBITION occurs whenever causal factors otherwise adequate for elicitation of two or more types of behavior are present but one is reduced in strength or eliminated because of the presence of causal factors for the other.

GREAT TIT territorial displays: males defend breeding territories. Along boundary, males attack and flee in turn, exhibiting a rapid series of postures and movements. *Handout FIG 5.6 & 16.3* "Head up" posture where bird stretches head upwards and cranes neck from side to side - body is almost vertical. This may be followed by flight either towards or away from the rival (or may subside to resting posture). This behavior is limited to along boundary region between territories. Intruding males get attacked and chased. "Horizontal display" associated with tendency to stay put.

These postures are examples of INTENTION MOVEMENTS -- the initial phase of a behavior that appears more elaborate or ritualized than seems necessary for the following behavior. An intention movement is a ritualized display to communicate intentions. Another example would be defensive threat in domestic cat (*Handout Fig. 2.1) (back arched, fur on end, etc..). ALSO -- *Handout FIG 11-8* threatening and submissive postures of dog; *Handout FIG 11.2* dog play position.

Section in Alcock called "Reconstructing the History of Communication Signals" read this for key definitions of:

• Intention movements
• Redirected behaviors
• Displacement activities

Conflict behavior may be directed toward a neutral (substitute) object -- remember film with grass pulling in gulls. REDIRECTED BEHAVIOR. Motivated by aggression and fear so take it out on neutral object -- substitute pulling grass for direct attack where gull tries to grasp and pull rival gull.

Sometimes animals in conflict situations show behaviors that seem totally irrelevant to any of the conflicting tendencies. These are DISPLACEMENT activities. *Handout FIG. 6.9* Bill wiping or preening feathers in courtship situation. Male ungulates often break off interactions and feed.

FOR EXAMPLE: dog yawning when put in down-stay.

NOT ALL STEREOTYPED BEHAVIORS are displays -- displays are one type of fixed action pattern. For example - lip curling (Flehmen) in ungulates is stereotyped and conspicuous but serves physiological function rather than communicative. (Olfaction of sex hormones.) YAWNING may also have a physiological function to rid accumulated CO₂ from system.

Alcock covers subject of receivers pretty well.

• You should also carefully read the sections on "Honeybee dances" and know how they work. Basically, bee does a "round dance" when food is close to hive (w/in 50m) Bee does "waggle dance" when food is farther away. Distance to food is conveyed by the intensity of the dance (number of waggles and number of times doing the whole dance). Waggle dance also tells direction of food relative to sun and hive.
• Look at Bernd Heinrich's approach to studying "yelling" in ravens. He looks at several hypotheses and eliminates some but finds support for the "gang-up-on-the-territorial-residents" hypothesis.
• Section on "Coping with illegitimate receivers" - know in detail the difference between a "seet" alarm call and a mobbing call as far as attributes and uses of each. *Fig 18* in Alcock (& handout). "Seet" call has a narrow frequency range and fades in & out (generally softer volume). Frequency range (7-8 kHz) outside the normal range of most hawks so does not usually alert predator to one's presence. Call is used to warn mates and offspring of potential danger from a flying predator. Signal attenuates at short distance so is not effective at reaching distant, illegitimate receivers. Mobbing call is used to warn others of a perching or roosting predator. Calls are louder than seet call and has most of energy in the 4.5 kHz range (lower than seet call). Sound can travel farther and attracts others to join in harassing predators.

So far the emphasis has been on behavioral signaling -- what about those peacock tails?

These fall under the category of display organs. Some are costly to produce and maintain - may be used in encounters / fighting (horns & antlers) and depend on animal's condition OR may just signal condition but not used directly in encounters (peacock tail). Others are BADGES and used in display but not costly to maintain or produce.

Two categories of signals:

• Assessment signals are correlated with fighting ability and "resource holding potential." This type of signal is generally considered "honest" because it would be difficult or impossible to cheat (if in poorer condition could not exhibit signal of animal in better condition). EXAMPLES include horns and antlers, peacock tails, roaring in red deer
• Conventional signals (e.g., badges) may or may not be honest depending on the response of the receiver. Not costly to maintain nor used directly in fighting. EXAMPLES include red winged blackbird epaulets and black badge on throat of sparrow. In Harris' sparrows, dominance rank is closely related to extent of black badge on throat. Most fighting occurs between males of roughly equal sized badges so if display a signal of dominance they are more likely to be challenged by similar individuals. If artificially enlarge badge, suffer higher rates of attacks by conspecifics.
• Why have both types of signals? Assessment signals should be used if cost of assessment is low and costs of escalated fighting are high. Conventional signals should replace or evolve instead of assessment if costs of giving and receiving signals are low compared to those for assessment.

Now comes the deception part. Some animals have evolved mechanisms for "cheating." In this cheating, the actor (signaler) may cause the receiver to respond in a way that is favorable to the signaler but potentially detrimental to the receiver, i.e., begging behavior of brown-headed cowbird chicks. False alarm calls to displace others from food: Great Tits. Tits gave false alarm calls when flock-feeding House Sparrows were using a feeder. Also subordinate gave false alarm calls when dominant conspecifics were at the feeder.

Signal amplification (see Handouts Fig. 1 & 20.8): Head tilting displays, caribou manes turn milky white during rut which makes the neck look bigger and a large neck indicates strength. Facial markings also accentuate the signal of horns.

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