Week 6: Animal communication Flashcards
Acoustic communication in crickets
Males produce species-specific calling songs
Females orient towards calling males
They have scraper and file that rub together to produce sound
And tympanum on foreleg to hear the sound
Close-range and long-range mating behaviours in crickets
Close range:
- Antennal contact: mate recognition
- Courtship song: male’s willingness for mating
- Mounting: female’s willingness for mating
Long range:
- male calling songs
- female phonotaxis
Fitness = eggs
Communication
the transfer of information from a signaler to a receiver.
Operational definition of communication:
- signaler and receiver
- signal
- information transfer
Terms:
- Signaler: an individual which emits signal
- Receiver: an individual which receives signal
- Signal: the behavior emitted by the signaler
Types of communication
Intraspecific communication: communication within a single species
- sexual interaction
- social integration
Interspecific communication: communication between members of two or more species
- prey to predator: warning coloration in wasps
- predator to prey: some predators communicate to prey make them easier to catch, in effect deceiving them. eg. angler fish
- human-animal communication: during domestication of animals
Anglerfish
Most adult female anglerfish have a luminescent organ, called esca, at the tip of a modified dorsal ray (the illicium or fishing rod).
The organ is proposed to serve the purpose of luring prey in dark, deep-sea environments.
Modes of communication
Visual communication
Acoustic communication
Chemical communication
Tactile communication
Electric communication
Channels: a pathway through which a signal travels
Visual communication
Light is the electromagnetic radiation of all wavelengths.
The source of light on earth is the sun or bioluminescence.
Information transmitted by lights is called visual communication.
Visual signals
Movement
Posture or shape of the body
Facial expressions
Color identification
Visual signals are used most often by species that are active during the day
Acoustic communication
Sound is the propagation of a perturbation in local pressure away from an initial location.
- Molecules oscillate from their positions.
- Instead, it is the disturbance that is propagated to greater distances from the sound source
Sending information from one member to another by sound is called acoustic communication.
Sound signals
Sound is more effect signal at night and darkness.
It can go around obstacles that would interfere with visual signals.
good for communicating over long distances both in air and water.
Chemical communication
molecular transfer from sender to receiver
the most primitive (oldest) type of communication
- Single-celled organisms - detect and selectively take in chemicals needed for cellular metabolism.
- Detection of food
universal
the easiest type of receptor to evolve
Semiochemical (info chemical)
is a generic term used for a chemical substance or mixture that carries a message.
Hormones:
Pheromones: chemicals that facilitate communication between conspecifics
Allomones: chemicals that facilitate communication between conspecifics
Ex) a maned wold urinating on a tree to mark its territory, adult silkworm moth
Comparison of communication modalities: Speed, amount of info, range, directionality, darkness, obstacle and production
Speed of transmission:
- Visual - very fast
- Acoustic - fast
- chemical - slow
Amount of information:
- visual - greatest
- acoustic - great
- chemical - poor
Range:
- visual - good
- acoustic - great
- chemical - greatest
Directionality:
- visual - highly
- acoustics - highly
- chemical - not directional, except in current
Obstacle:
- visual - blocked
- acoustic - go around
- chemical - go around
Production:
- visual - easy
- acoustic - difficult
- chemical - difficult
Darkness:
- visual - limited
- acoustic - transmissible
- chemical - transmissible
Functions of communication
Communication systems evolve to solve problems that animals encounter in their natural environments.
- Foraging: Yelling in common ravens
- Mating: ripple communication in water striders
- Predation: alarm calls in great tits
The common raven
is a large all-black passerine bird
is the most widely distributed of all corvids
is extremely versatile and opportunistic in finding sources
Breeding:
- Young birds may travel in flocks and may find mates.
- Once paired, they tend to nest together for life, usually in the same location.
- A breeding pair must have a territory before they begin nest-building and reproduction.
- A breeding pair aggressively defends a territory and its food resources.
Yelling is a response to hunger level, as hungry birds call more often than satiated birds.
Yelling by juvenile ravens attracts other juvenile ravens to a food resource in order to overpower resident adult ravens.
Yelling attract others, who together with the yeller can overpower those originally found at the food source.
Roosting
Many populations of ravens roost at the same spot for years, but some populations change roosting locations.
Marzluff and his team studied juvenile ravens in the forested mountains of Maine.
Individuals form roosts near a newly discovered food source—a large animal carcass.
Such roosts are very mobile—the ravens move where new prey has been discovered
Roosting as information centers
Marluff’s team hypothesized that these mobile roosts served as ‘information centers’ that provided roostmates with the information about prey.
A roost is comprised of both knowledgeable individuals—who know about nearby prey—and naive individuals who do not.
And yet, when birds leave the roost in the morning, they all tend to go in the same direction, suggesting that one or a few knowledgeable individuals lead the way.
Water striders
live in freshwater lakes, ponds, streams, and small rivers.
Ripples are usually produced by an up-and-down movement of the legs, with both right and left legs in synchrony and in constant contact with the water surface.
They produce different kinds of behaviors, including signals for calling mates, courtship, copulation, postcopulation, sex discrimination, mate guarding, spacing, territoriality, and food defense.
In the water strider Rhagadotarsus anomalus, males produce ripple signals that can travel more than 60 cm, and females find such ripple signals very attractive.
Great tit alarm calls
The small songbirds sometimes approach a perched hawk or owl and give a loud mobbing call whose dominant frequency is about 4.5 kHz. This easily located acoustical signal helps other birds find the mobbers and join in the harassment of their mutual enemy.
If a great tit spots a flying hawk, it gives a much quieter “seet” alarm call, which appears to warn mates and offspring of possible danger.
The purple trace shows the difference between the softest sound of a given frequency that great tits and sparrow hawks can hear.
A sparrow hawk can hear sounds in the 0.5-4 kHz range that are fainter (5-10 dB lower in intensity) than those that great tits can hear.
But great tits can detect an 8 kHz sound (in the range of the “seet” call) that is fully 30 dB fainter than any 8 kHz sound that a sparrow hawk can detect.
Convergent evolution in a signal
The great tit’s high-pitched “seet” alarm call is very similar to the alarm calls given by other unrelated songbirds when they spot an approaching hawk.
Common predator (bird-eating hawks) has favored the evolution of alarm calls that are hard for hawks to hear.
Downy woodpeckers
Downy woodpeckers are native to forested areas, mainly deciduous, of North America.
Downy woodpeckers nest in a tree cavity excavated by the nesting pair in a dead tree or limb. In the winter, they roost in tree cavities.
Downy Woodpeckers forage on trees. They mainly eat insects, also seeds and berries.
They have a black tail with white outer feathers barred with black. Adult males have a red patch on the back of the head.
