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Chapter 6

Chapter 6 notes


Department
Psychology
Course Code
PSY352H5
Professor
Robert Gerlai
Chapter
6

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Chapter 6: Foraging Behaviour: Finding, Choosing & and Processing Food
Key points:
-The specific principles of foraging are common to all animal species, even if the actual
behaviour exhibited may be very diverse. The foraging process can be thought of as
number of decisions made by the forager such as: which item to eat? When and where to
forage? When to seek new pastures? When to share food?
-Behaviours that seem at first to disadvantage a forager, like sharing, can often actually
increase an individuals success. However, interference and factors such as predation risk
can limit foraging opportunities
-A range of alternative strategies can be used to maximize either the quality or quantity of
food available to an animal
-Its possible to describe the likely behaviour of an animal using a mathematical model,
this can help us focus our investigations of behaviour
-Foraging, easily described relationships develop between species, these may involve just
two species such as the relationship between the giant panda ailuropoda melanoleuca with
its specialist diet, feeding largely (but contra to popular myth not exclusively) upon the
shoots, leaves and stems of bamboo. At a far larger sale the relationships might involve
the complicated webs of predators and prey that may link, for example simple planktonic
plants to a top predator like the great white shark.
-The various modes of foraging employed by the animals into herbivores, carnivores and
omnivores. Within these groups we might consider specialists (reliant upon one type of
food, or perhaps even one species) and generalists(with a more varied diet). This
approach would be benefical if we were comparing the various modes of foraging
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involved, for example when a bivalve mollusc filters food from a water current or an ant-
lion ambushes a passing insect. However, in the context of this chapter we will place the
emphasis on the specific behavioural principles involved in foraging that are general to all
animals
Foraging behaviour has a range of motivations
-If you eat when you “feel hungry” than hunger must be considered a prime motivation for
foraging behaviour. However, hunger should not be thought of as the only factor that can
stimulate foraging or the onset of a meal.
-Humans often eat just because the clock tells them that its mealtime regardless of their
level of hunger, social cues can be important too. There is evidence to suggest that some
animals tend to take larger meals at one sitting when they share the resource with
conspecifics. This behaviour is advantageous because a solitary feeder may have an
opportunity to return to a food source later time to take another meal, but if the food is
shared there may be nothing left to return to
*Side Note: hunger has a physiological basis
Foraging Decisions
-Food is not uniformly distrubted and not all foodstuffs are of uniform quality, foraging
animals are therefore forced to make a number of decisions which shape their feeding
behaviour. When you visit a town and you get hungry you may ask urself
-Should I head home, or should I eat here in town?
-Do I feel like a huge meal or will a chocolate bar be okay?
-Do I eat too much chocolate? Should I buy an apple
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-If we ask similar questions to investigate the “decisions made by animals in the context
of our study of animal behaviour, we can gain a greater insight into animal foraging
*Side Note: Foraging, like other behaviours, can be thought of as a decision-making process.
Finding, choosing, processing and eating a food item may involve a sequence of behaviours
*Side Note: Learning plays an important role in foraging behaviour.
Learning can shape foraging behaviour
-A solitary animal may call upon its experiences in making decisions such as where to
forage and what to eat. For example: animals as diverse as octopus and rats can quickly
learn to navigate a maze to reach food, rats also exhibit an innate level of bait-shyness/
neophobia = a reluctance to try new foods, which protect them from poisoning (given
their pest status, poisoning is a real possibility for rats). In fact wild brown rats will avoid
a novel food source for several days even when familiar food is scarce or lacking.
Numerous experiments have repeatedly demonstrated that rats that do eat bait and survive
can learn very quickly to avoid the poison by associating the food that was eaten with
sickness.
-This occurs as a result of a specific form of learning called conditioned taste aversion
(CTA). Some labs research baits that will not be avoided by animals other labs do the
oppositite. Example: in lab trials starlings given a choice between untreated food/food
laced with garlic oil strongly avoid the latter. These birds have a good sense of small &
are thought to be reacting specifically to the sulphurous odour of the garlic, this is a good
strategy because sulphurous smell often indicate the presence of toxic selenium in
foodstuffs. Because starlings are agricultural pests this research could help crop
protection.
Animals exploit information provided by their neighbours
- successful foragers provide information (intentionally/unintentionally) that can be used by
an individual to enhance its own foraging success. Example: its been suggested that the
breeding colonies of some bird species may have an additional function as centers for
information transfer. However, not all birds that breed colonially take advantage of the
foraging information provided by their neighbour.
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