environmental signals resource recruitment signals –costs and benefits –types –examples...

Environmental signals

• Resource recruitment signals– Costs and benefits– Types– Examples

• Predator detection signals– Types– Examples

Give Game

Why signal food location?

• Costs– Increases competition– Signal production takes time and energy

• Potential Benefits– Increasing number of foragers improves foraging

success and/or decreases predation risk– Increases reproduction of relatives– Food may allow long-term survival of group which

increases chance of discovering sites in future

Types of location signals

• Discoverer broadcasts signal from the resource and receivers recruit to the site

• Discoverer goes to receivers (often at nest or colony), communicates discovery, and then leads receivers to site

• Discoverer goes to receivers and provides directional information about site

Ravens recruit to carcasses

Cliff swallow recruitment calls

Food signalling by osprey

Males give display to females after catching preferred fish

Rhesus macaque food calls

Chimpanzee pant-hoots

Pant-hootsadvertise discoveryof divisible foodand are given bymales

Grunts are givenfor any amountof preferred food

Mole rats recruit to roots

Food recruitment in ants

Food recruitment in honey bees:dance angle indicates direction

Dance duration indicates distance

Dance divergence indicates patch size

Advertisement distance is constrained by dance duration

Bee dialects reflect foraging distances

Azimuth encoding in bee dances

Summary of food-associated signals

Vertebrates:Food signalling is rare.Most signals occur at food (except mole-rats)

Social insects:Food signalling is common.Signals to food from hive using pheromones or“language”

Predator alarm signals

• Cause– Alert conspecifics– Deter predator

• Types– Low risk - elicit scans– Predator inspection and mobbing signals – High risk - prompts escape– Distress signals

Private alarm calls

Benefits of alarm calls

Ground squirrel alarm calls

Alarm calls do not coordinate movements

Alarm calls differ by age and sex

Alarm calls and kinship

Referential signalling

• Do alarm calls convey information about predator type or just urgency associated with potential attack?

Vervet alarm calls

Alarm calls refer to predators

Development of vervet

alarm calls

Vervet calls, relatedness and dominance

Meerkat alarm calls signal predator class and urgency

Intertrophic level signalling

• Detection notification signals

• Condition notification signals

• Aposematic signals

• Distress signals

Predator notification

displays

Aposemitism

Prey advertise tasteto predators

Initial evolution requires kin groups

Can be invaded by mimics, but mustremain at low frequencies