Lesson 10: Foraging Behavior Flashcards
human beings are what kind of predators
visual
some other sensory modalities
- vibration detection
- taste ( a form of chemoreception like smell))
- heat detection
- electroreception
lateral line system
- fish have a series of sensory structures that detect movement in the water
- can compare info from both sides of body to localize source of movement
external chemical senses
fish also can sense chemicals in water from ‘external taste’ receptors
how do catfish track their prey if they live in murky water
- water movement (vibration)
- external taste ( dissolve chemicals in water)
Catfish Experiment
Observed Catfish hunting individual guppies - and used infared video system to track movement of both predator and prey in complete darkness
Identified 3 types of movement
1.) path following
2.) head-on encounters
3.) attack on stationary guppy
Results
- 80% of attacks occured on moving guppies
- catfish usually followed the same path as the guppy before the attack
Lateral Line Structures (more for the catfsish)
- hair cells are mechanoreceptors sensitive to deflections caused by water movements
- organized into “neuromast organs” distributed along the length of the body
Catfish Experimental Approach
Manipulated either:
1.) External gustation aka taste (reduced ability to detect chemical cues)
OR
2.) lateral line (reduced ability to detect hydrodynamic cues)
RESULTS:
Intact (control - 65%
External chemical detection ablated - 60%
Ablated lateral line - 17%
^^^
Suggests that lateral line is more important than taste in terms of success
Electroreception in Sharks
electroreception is the ability to detect electric fields - an electric field can travel from its source in water but not in air, so it is useful for aquatic species
Electroreception in Sharks (Tank + Setup )
the testing tank had a sandy bottom - water entered the tank through a buried pipe and emerged from the sand near the other side of the tank
- a special agar holding chamber was connected to the inflow pipe so that water could pass through the chamber and out the other side
Electroreception in sharks experiment
a.) buried live flounder – accurate attack
b.) live flounder in an agar chamber (control) – accurate attack
c.) flounder pieces in agar chamber – attack at displaced odor site
d.) buried live flounder with plastic insulation – no attack
e.) plain electrodes – attacked
f.) plain electrodes vs. actual chunk of dead fish – attacked electrodes first
lemurs
- small primates from the island of Madagascar
- almost entire nocturnal and feeds mostly on fruit and insects
lemur experiment
1.) trained lemurs to remove plastic lid from a bowl in order to get a mealworm
2.) then did choice experiment in which the lemurs had to identify which of the two bowls had the mealworm
Different cues : lemur experiment
olfactory cue: live mealworm in cup
No olfactory cue: live mealworm in air-filled bag
auditory cue: live mealworm in cup with paper
no auditory cue: dead mealworm in cup with paper
lemur experiment: results
3 modalities: best chance
2 modalities: V+A and V+O were the best (needed visual)
1 modality: visual was the best
evolutionary arms race
back and forth process of adaptation and counteradaption
counteradaption
in predators – adapt to better detect hidden or cryptic prey
2 possible behavioral counteradaptions if prey are cryptic
- search rate hypothesis
- search image hypothesis
search rate hypothesis
animal detects cryptic prey and then slows rate of search to find more
search image hypothesis
animal forms a mental image which helps it focus on the visual features of the prey
bobwhite foraging: search rate hypothesis
- trained birds to feed on food pellets on the floor of a large room
- then tested birds to see what happened if the pellets were hard to see
bobwhite foraging results:
the more cryptic the prey, the more slowly the birds walked around the room
blue jay foraging: search image hypothesis
- trained birds to search for month images on a computer screen
- started with easy-to-see moths and then swithed to cryptic ones (used catocala retecta)
blue jay foraging experiment and results
1st run: no moth or catacola relicta
2nd run: no moth or catacola retecta
3rd group or “non run”: no C. retecta or C. relicta or no moth
RESULTS
- in both of the run treatments (just one species in the run), the percent of correct responses increases
- in the nonrun treatment (both species mixed in) the percent of responses did not change over trials
CONCLUSTION
- this implies that the visual appearance of the moths mattered to the jays - otherwise the nonrun would not have differed from te run
foraging and cognition
because foraging is a fundamental activity of animals and of such greater importance, we often can observe the “thinking” of animals when they are foraging
Yellow eyed junco experiment
if practice makes perfect, then the older animals should be better at certain tasks than the younger ones
- presented mealworms of different sizes to different ages of bird: recently fledged, young and older juveniles, as well as adults
Results:
- adults had the lowest handling times and the highest energy intake
- suggests that adults had learned with practice AND the benefit is greater efficiency
do animals teach their offspring
teaching is defined ass “active participation” of an experienced individual in facilitation learning by a native individual
how can we tell if teaching is happening
- teacher modifies its behavior only in the presence of a pupil
- the pupil acquires knowledge or skill more rapidly due to the behavior of the teacher
- the behavior is costly to the teacher (this is debatable)
white-tailed ptarmigan hen experiemnt
Observaiton: chicks follow mothers for several weeks, mother will drop food and give a unique vocalization, a food call. chicks run to the mother and feed (looks like the hen is teaching her chicks)
Hyptothesis: hens teach chicks what food plant to eat
Prediction: chicks should primarily eat foods associated with their mother’s food calls (recall that chicks are precocial so mostly select their own foods_
To test this:
- observed 7 hens and their chicks
- recorded food eaten by hen and her chicks
- recorded all food calls given by hen and the food plant associated with the call
Results: there was a positive correlation between the proportion of food calls associated with a plant species and the proportion of that plant in the chick’s diet
Conclusion: chicks learn their diet from their mother’s food calls
Tool use video examples
- dog moving a chair
- heron using bread to lure a fish
- badger using a small log as a ramp to escape an enclosure
capuchin monkey using stone to open nuts
- stones vary in their size, weight and composition, which affects their fragility (fragile sandstone will break before cracking the nut)
wanted to know how individuals select the correct stones to open hard nutes
— visalberghi
capuchin tool use experiment
wanted to know how individuals select the correct stones to open hard nuts
Methods:
- offered individuals a nut and stones that different in functionality based on type (soft sandstone or hard quartzite_, r size and weight (heavy or light_
- recorded the first stone used to hit the nut - that is, which stone did the money pick first
- repeated 5 times with different combinations of stones
Results: in each experiment, individuals used the more functional stone based on its composition, size, and weight
Conclusion: capuchins can access the relevant features of a stone tool based on its size, weight, and composition
elephants displaying insight learning
- insight learning occurs when an animal solves a problem by “thinking it out” and not by “trial and error”
- with no experience, Kandula (elephant) moved a large cube underneath hanging fruit to stand on it and obtain the food
– hard to demonstrated becasue the animal needs to have no prior experience
dolphin tool use:
dolphins use marine sponges to protect their snouths as they hunt bottom-dwelling fish: the seafloor is strewn with sharp rubblr and they’d get all scraped up otherwise
dolphin tool use: example of social learning
this is a learned behavior that mothes pass on to offspring - mostly daughters, apparentlt, females soend years with their calves and “sponging’ for fish is a fairly low cost way to get food, since the mother is with the offspring so long, there is time to teach them
why don’t female dolphins teach their sons
sons disperse away from home and won’t live i nthis area in the future so there is no reason for mothers to go to the effort of teaching them
crows can make tools for retrieving food
humans aren’t the only ones to make tools
decisions on what to eat: numerical competency in new zealand robins
researchers designed a branch with 2 covered cache sites
- while the robin watched, researchers placed different numbers of mealworms one at a time in caches, then released the bird and recorded which cache was chosen first
- when the total number of food items in both caches was less than 10, robins preferred larger cache (items above dashed line yielded results that were significantly different from random)
- in a second experiment, researchers mixed mealworms with rocks so that each cache had the same number (and volume) of objects, but different numbers of mealworms
