Chapter 8

Question 1

Raven and String

Answer 1

Food is a strong motivator to solve complex problems

Cognitive abilities of non human animals are readily evident where animals adapt to novel challenges faced while foraging

Here a common raven solve the problem of accessing a piece pf meat hanging from a string, despite never having encountered this before in nature

Raven first tried to pull the string straight up, but that did not work. The raven solved the problem by moving horizontally on the branch with the string in his mouth

Question 2

What does the snowy egret trailing behind the ibis show

Answer 2

A snowy egret trails behind a white ibis, opportunistically foraging on material released as the ibis wades through the marsh
The one animal can solve a problem
The other animal from another species capitalized this

This shows that selection has favoured the evolution of a variety of strategies that enhance the foraging success

Question 3

Procedure vs. Scroungers

Answer 3

Animals foraging as part of a group choose between searching for food on their own (procedure) versus searching for opportunities to capitalize on food located by others (scroungers)

The nutmeg mannikin shown in this video can been seen manifesting both procedure and scrounger strategies
Some are by themselves (producer strategy) and the scroungers are looking at who is successful at feeding and go to that environment or mimic the behaviour of the successful one

Question 4

Animals find food using sensory modalities - Lateral line system example

Answer 4

Natural selection favours the modality that will allow quick access to food
Fish often have to hunt in dark spaces, relying on vision is not the best way to hunt

Lateral Line System: On the side of the fish, it is a system. There are scales and spaces (pores) and neuro masks
A neuro mask contains cilia which allows movement of scales
The hairs connected to the scales are neurons

Mechanoreceptors: the neurons will go into an action potential as a result of the movement

• hearing
• detection of body position and orientation
• water pressure/velocity/direction
• movement /presence of others

If there is movement in the water, around the fish, the mechanoreceptors fire and give the fish information about what is around the animal
The mechanoreceptors are sensitive to the change in water pressure, movement of the water
The mechanoreceptors are cells
When the cells are moved due to the water, an action potential is released
This movement allows for the fish to hunt, important because they can’t see their prey

There are mechanoreceptors and a similar system in humans as well
- Inside our internal ear, there is fluid, the sound wave moves the fluid in the ear which is picked up by hair cells connected to neurons
-Action potential occur when the hair cells move in the ear
There is fluid in the ear moving the hair cells

Question 5

Catfish Track the Wake of Their Prey Experiment

Answer 5

Research Question:
How do nocturnal (Silurus glanis) catfish find food in the dark?

Hypothesis:
Catfish use their lateral line system to detect cues provided by the wake of their fish prey.

-Detect hydrodynamic cues with the mechanoreceptors
hydro=water
-Dynamic = movement
-Hydrodynamic cues are made by the wake of the fish. The wake leaves more disturbance

Prediction:
Catfish will follow the wake of their prey while hunting.
-Changes that occur in the hydrodynamic environment is the consequence of the wake, meaning there was an animal there

Methods:
Observed catfish hunting individual guppies
Observe predator prey interaction
Used an IR video system to track the movement of both predator and prey in complete darkness.
IR video: camera that doesn’t rely on light to capture the movement of the animal
Classified movement sequences as “path following,” “head-on encounters”, or “attack on stationary guppy”

Data set:
GRAPH
Visual representation of movement
The orange is information about the prey and the blue is the information about the predator
Two similar lines of movement, the catfish are good at tracking
Shows where the attack occurs
There is a close parallel between the movement of prey and predator
The catfish are using this path to gain access to the prey

Question 6

Catfish Experiment 2

Answer 6

Research Question:
Do catfish use chemical or hydrodynamic cues to track their prey in the dark?
Chemical = taste
Are the catfish using taste or hydrodynamic

Methods
Used an IR video system to track the movement
Manipulated either the lateral line or external gustation (taste)
Manipulate lateral line system using cobalt chloride. This causes the lateral line system to go numb
Manipulate taste by selectively removing sense of taste from the medulla oblongata → everything else about the animal stays the same except for taste
Classified hunting success and movement sequences of treatment fish

Data
GRAPH
They were accessing hunting success
The success rate is highest when the animal is intact and lowest when the lateral line system was silenced
Reducing the ability to taste has a similar capture success as intact
The table shows different strategies: wake following, head on attack, stationary
Head on: face to face
Stationary: prey wasn’t moving
Their typical strategy is to do wake following
When the lateral line system is taken away, they switch to head on encounters, but they are not very successful
Without taste, they are using wake following, and head on encounters
Increasing wake following increases rate of capturing

** primary mode of strategy is using wake following
** remove the lateral line system, and the strategy changes to head on encounters
** if external taste is removed, there are head on encounters and wake following
Support for wake following, the head on encounters seem to be working in some way
Not smart to only have one strategy to rely on, there should be some helper strategies should one not work
May be less efficient but it still helps you get to food

Question 7

How Do Lions Choose Their Prey

Answer 7

If you are a single lion, you may wanna go for the easy prey
If you have a partner, you may want something more difficult
As predicted the single lion Meg chose the smallest and easiest animal (pig)
1 male and 2 females:
They chose the buffalo first but then wind knocked it over
Is there cooperation in conspecific that allow them to go for the larger prey
See the camera technique on the backs on animals
Used more and more in research
Gives a real eye view of the animal
How does the animal navigate, move etc.
When researchers collect data, it is not just in the lab, we now have advanced technology that allow us to study the animals in the environment
Animals behaviours research is including more and more engineers

Question 8

Sensory Systems of Boas, Pythons and Pit Vipers

Answer 8

The goal of the research is the determination of the mechanism underlying the predatory and defensive behaviours guided by these extraordinary novel sensory skills in snake

They use heat to get a visual image of what is around them
They have special organs that allow them to make images in their brain

A blind snake can attack with precision
They are literally seeing heat

Organs are called Pit organs right around the mouth that allow them to see heat at the same time and produce a picture in the brain

Python must pick a door whether it senses head
Will retrieve a reward

Question 9

Why do research on animals

Answer 9

The researchers are making connections between how and why this research applies to humans
Researcher capitalize on 2 things. Gaining the information on sensory capabilities is important for:
Science
Apply to industries where people have to see in the dark
Military, police, search and rescue
The researchers also may say that the animal is invasive (taking up all resources and does not allow other species to survive)
Problem in maintaining the ecology in the environment

Question 10

Methodology: eye tracking in Orangutang

Answer 10

Before tsunami and after tsunami orangutans
Endangered
Try to get the animals back to doing wild behaviors that they may not use in captivity
In the wild they use their hands in vision together
Want to know how far they can see to ensure they are able to make an enriched environment for them
Eye tracker = backpack that transmits video from two camera on the head band
One camera sees what she sees
The other camera sees her right eye
Use software to see where she is looking

The eye tracking allows:
1 camera sees where the animal is looking, the distance
Other camera gains information about eye movement, pupil dilation
Make connections between the anatomy of the eye and how far and wide is the animal able to see
This helps to figure out the behaviours and also what enrichment would look like
The animals are endangered so they don’t become extinct
How can u make the enclosure the best

Question 11

Bees use multiple senses to enhance foraging efficiency - experiment

Answer 11

Research question:
Is foraging more efficient when multiple senses are used?
Using many senses might make foraging more efficient

Methods:
Trained individual bees to feed on artificial flowers.

Treatments:

Visual cue
Olfactory cue
Shape and olfactory cue

In the wild we see that animals can use visual cue, auditory and olfactory cues to forage for food
Is all of the modalities combined lead to higher foraging ?

Experiment:
VISUAL CUES
There are different shapes and there is a food source in the dish
One type of shape has a food item and the other shape does not have a food item
The plus shape make have sugar solution whereas the circle has just water
So over time, do the bees understand that the visual shape is associated to the food
Measure number of visits to the circle vs. cross

OLFACTORY
Isolate olfactory
Some of the item, regardless of if it was a cross or circle, had either a clove or peppermint scent
Bees had to learn that peppermint had the award associated with it and the clove scent has only water
Measure number of visits
**foraging efficiency is measure by how often they fly towards the item

COMBINED VISUAL AND OLFACTORY
Optimal strategy, results in the highest visit rate to flowers

GRAPH

Question 12

Blue Jays Use a Search Image to Find Prey - Experiment

Answer 12

GRAPH

Research question:
Do blue jays use a search image to find cryptic prey?
-How does experiences have an impact on hunting capability, do blue jays use a search image to find cryptic prey
-Why do we tend to park in the same place or sit in the same place in lecture
–>There is not a lot of thinking that needs to be done

Search image: a strategy developed from experience, “where should I look”

• -> Animals have experience with a visual landscape so the probability that they will find prey his high
• These birds feed on 2 kinds of moth, they are both very cryptic
• ->They prey are camouflaged but the birds live in this environment and see these types of trees and therefore become better at foraging these camouflaged moths

Methods:
Trained birds to search for moth images on a computer screen
Can the birds detect the moths on the computer screen? If so it is thought they will be good foragers
Scored correct and incorrect responses to images (moth present or absent on screen)

Two treatments (training):
-->Run and non run → both are experience the birds gets prior to the test 

Run: there was a very specific experience
Lots of experience with a specific moth with a specific tree

No run: there was not a very specific experience
More generalist

Want to train the birds to say yes I can see the moth on the tree on the screen
If the image was a positive image meaning that there is a food item on the tree, the bird had to peck on the screen 10 time
If the image was negative image meaning that there is a tree and there is no food item (moth), then you peck once

Results:
In the run condition, the animals learned very quickly to identify that particular moth
Orange and blue = run
Grey = non run = generalist = had experience with both species of moths
Their performance stayed the same and in fact declined a little
The animals form these search images with a particular image and therefore the foraging efficiency might become better with in this specific environment/domain

Question 13

Optimal Foraging Theory

Answer 13

Theory: animal is going to make the best choices that allow it to gain access to food

Many OFT models assume that fitness while feeding increases with energy intake rate
The behaviour that maximizes fitness is called the optimal behaviour

Two types OFT models:

• Diet model → which food item is optimal (energy)
• Patch-use model → how much time am I going to spend exploiting a particular area where food may be found

Question 14

The optimal diet model and the Assumptions

Answer 14

TABLES

The optimal diet model predicts the food types an animal should include in its diet

Assumptions:

1. Foragers maximize fitness by maximizing energy intake rate
   - -The E obtained from a food source is really important
2. Food items are encountered one at a time in proportion to their abundance
   - -Take one food item at a time, not all at the same time
3. Food items can be ranked by their profitability
   - -The amount of energy found in jule relative to the amount of time you spend handling that item

Question 15

Profitability and Handling Time Definitions

Answer 15

Profitability: Energy/handling time

Handling time: time to manipulate item prior to consumption

Question 16

2 Kinds of Foragers

Answer 16

Specialist: only eat specific type of food items

Generalist: explore different kind of food items

The specialist takes a lot longer to find it’s food items than the specialist does. The generalists are not as picky.
The specialist however spends less time handling the food than the generalist.

Question 17

What is the optimal strategy? How many food items in the diet is optimal

Answer 17

GRAPH
X axis: Number of food items
Y axis: Mean time spent per item

Between 2 and 3 items in the diet is optimal as this is where search and handling time together are lowest. You don’t want to be at either extreme

Question 18

Equation for energy intake rate / item

Answer 18

(avg. E obtained/item) / [(avg search time/item)+(average handling time/item)]

Energy is always relative to the amount of time taken to search for a food item and the time to handle it

Question 19

Diet Choice in Northwestern Crows Experiment

Answer 19

GRAPH
X:Clam length
Y:% Eaten

Research question:
Why do northwestern crows reject some clams while foraging?

Hypothesis:
Crows attempt to maximize energy intake rate according to the optimal diet model.

Prediction:
Crows should eat all clams greater than 29 mm in size and reject all clams < 29 mm in size.
Using the model, there should be a particular size of food item accepted
Over 29 should be accepted and under should be rejected

Methods:
Recorded the size of clams that were eaten and the size of clams picked up but not eaten (rejected)
Measured handling times of differently sized clams
Measured energy content of differently sized clams

Results:
The bigger the food item, the more likely it is to be chosen
The animals sometime will chose the other food items, but on average the larger food item is chosen
Sometimes there is not big clams available
This experiment nicely shows the prediction made by this model

Question 20

The Optimal Patch Use Model

Assumptions

Answer 20

GRAPH
X: time in patch
Y: cumulative energy gains. How much energy gain there is with time.
The graph plateau is where the diminishing return occurs.
Time 0 is when the animal has just arrived

This is an optimal strategy based on the amount of time that should be spent foraging in a particular area

Diminishing returns:
When a forager enters a food patch, it initially harvest good at a high rate.
But as the patch is depleted, its harvest rate declines.
If you are constantly digging around in that area, the hard work does give you more food if there is no more food

Assumptions

1. Foragers attempt to maximize energy intake rate
2. All patches are identical
   You are always going to have the same amount of food in the different patches. Not realistic but needs similarity for the mathematical model
3. Travel time between patches is constant
   The travel time between the patch are the same. Also not true in the real world.
4. The instantaneous harvest rate declines as forager depletes a patch; the forger experiences diminishing returns in each patch.
   As you continue to eat in the particular patch you get to the point where there are diminishing returns
   Instantaneous harvest rate is central to this model

Question 21

Cumulative Gain GRAPH explanations

Answer 21

GRAPH
T1 is travel time, T2 is the time the animal spends in the patch
The orange line shows when diminishing return beginning
The lines is drawn from where the animal begins to travel to the patch
Where the orange line reaches the blue line, this is where the diminished returns and should stop foraging this patch

The Y axis is the cumulative energy gain and the X axis is the time spent in the patch (Tp)
There is a certain time that the animal takes to get to the patch. The blue dot is where the animal began to travel to the patch, until time 0 where it has reached the patch (Tt)
Draw a straight line from where the animal began to travel to the food patch
Where the line hits the curve (the tangent) is the maximal amount of time the animal should spend in the patch

Energy intake for any Tp = slope of the line (black)
Line = start of Tt to cumulative growth curve at Tp (orange)
Tangent = patch time that maximizes energy intake rate (grey)
Where the line touches the cumulative growth curve

Question 22

Marginal Value Theorem

Answer 22

For a fixed travel time, Tt, energy intake rate is maximized when the forager spends Tp time in the patch

The theorem tries to predict when the maximal energy intake will occur
Takes the time intervals and says what the max time spent there should be

A shorter time period is denoted by a smaller arrow and a longer time period is denoted by a long arrow
How much time should the animal spend in the patch depending on the travel time
If the animal has spent a less amount of time traveling, they should spend less time feeding in the patch
If the time increases to travel to the patch, they should spend more time in the patch

Question 23

Patch Use by Ruddy Ducks

Answer 23

GRAPH
X: individuals 
Y: mean number eaten 
orange: long travel
Blue: short travel 

Look at the amount of time the animals take diving down to the patch of food under water
Sometimes they have to travel a short distance and sometimes they have to travel a long distance
If the animal is traveling a short distance, they are eating less than the long travellers
If the animal is travelling a long distance, they eat more

If there is an animal traveling short time and eat less, what about the energy? Well if they spend less time traveling, they will go there more often therefore over time, the gain of energy is the same
If the animal has to travel a long time to a patch, they spend a long time there and get a lot of energy but may not return
Eating less items in the site is compensated for by being able to travel there multiple times

Question 24

The Optimal Patch-Use Model - Revised

Answer 24

Optimal patch use with multiple costs:
When feeding, animals experience
-Energetic costs
-Predation risk costs
-Missed opportunity costs
      -There is food in an environment that an animal can’t see or smell etc

Question 25

Browns patch model

Answer 25

Browns patch use model incorporates these costs
Holds less constants
Model predicts that patches with identical benefits and costs should be harvested down to the same quitting harvest rate.
It is always eating the same amount at the same rate