Lecture 3: The Evolution of Feeding Behaviour Flashcards
predators and prey are often locked into a___
co-evolutionary struggle
Tinbergens discovery regarding search images
he observed that when a new type of caterpillar appeared in woodlands, songbirds rarely brought it to their nests. But once a few had been located, birds collected them at a greater rate –> birds has come to recognise the caterpillars and formed a search image
search images in Humans:
look for cues that match what you’re looking for
Pietrewicz and Kamil used operant conditioning to investigate search images in captive blue jays::
blue jays were shown slides of cryptic moths of either the same or 2 different species
- -the birds built up a search image only when shown one species, not when given both species
- favours rare moths?? Can’t learn multiple
are search images always using sight?
NO, other senses can be used : Olfactory
example of animal who uses olfactory senses to create search image
Striped skunk, nocturnal forager and finds food by odour
-as skunks aged they could find food at further distances away & max distance it could be found also increased
Lizard foraging: 2 methods for predation (Vision/ambush and Olfaction/searching) Evolutionary history
3 evolutionary events?
started as Ambush, some evolved to become olfactory searchers
whats the difference in Social Insects and Other Group living animals??
- social insects: groups
- -composed of related individuals, cooperation
- -favoured by kin selection
- Other group living animals:
- -groups normally composed on unrelated individuals
- -cooperation not favoured by kin selection
social insects communication is
deliberate communication with nestmates, e.g. waggle dancing, direct leading, pheromone trails
Other group living animals communication is
incidental communication with conspecifics , e.g. observing location of successful foragers
other foraging advantages for groups:
Take much larger prey than themselves e.g. wolves take moose; army ants take large anthropoids/other insect colonies
Social insects:
- Groups composed of related individuals
- workers help by capturing prey (e.g. army ants) or defending a food patch, communicating the location of food to nest mates (wage dances in honey bees)
Key man for the Waggle Dance
Karl von Frisch
two types of waggle dance
- Round dance = food < 50m
- Figure of Eight Dance = food >50m
Figure of 8 waggle dance =
- food >50m
- Dances are performed in nest on vertical combs in darkness
waggle dance = what provides the distance and direction information and two tests used by karl von frisch
- duration of entire circuit
- duration of waggle run
- direction = angle
- -Fan test & feeding stations along transect
Experiment on honey bee foragers: removing directional information
- natural combs are vertical
- when put horizontal combs, bees dance orientating to a directional light source instead of gravity
Social foraging in birds: Ospreys
- watch other birds returning to nest with fish, others leave in same direction to find shoaling fish
- informed fish find food quicker than naive birds
army ant colony =
small ants can capture larger prey by working together
Group hunting in Female Lions
they live in groups and hunt together. Group hunting carnivores take larger prey than solitary hunters
-6-12X higher
group hunting in varying females number of groups and food intake
- prey abundant = high one alone and in small groups
- prey scarcity = high when alone low in small groups, big food in high groups
why continue to hunt in group? Creel and Creel
benefits in meat gained but also in terms of energy expended chasing prey
