Chapter 3: Methods for Studying Animal Behaviour
3.1 Scientists Study Both The Proximate Mechanisms That Generate
Behaviour And The Ultimate Reasons Why The Behaviour Evolved.
1. The behavior oft en is initiated by seasonal changes in day length. These changes
trigger hormonal responses that lead to increased feeding, fat deposition, and the onset of
longdistance movement (Ramenofsky &Wingfield 2007).
2. In some species, migration behavior is genetically determined and requires no
learning, while in others, migration routes must be learned by following experienced
individuals (e.g., Lishman et al. 1997) (Figure 3.2)
3. Migration allows individuals to track resources and thus avoid places where
resource availability is greatly limited in some seasons; in short, it promotes survival (Cox
4. Niko Tinbergen (1963) summarized the different types of research by outlining four
basic questions that can be asked about animal behavior:
1. What is the mechanism that causes the behavior?
2. How does the behavior develop?
3. What is the function of the behavior?
4. How did the behavior evolve?
5. Answers to Questions 1 and 2 are often referred to as proximate explanations
because they focus on understanding the immediate causes of a behavior (Mayr 1961).
These explanations often incorporate studies of genetics, sensory systems, neurons,
hormones, and learning.
6. Answers to Questions 3 and 4 are known as ultimate explanations, because they
require evolutionary reasoning and analysis (Mayr 1961). Understanding the effects of
migration on survivorship and why migration evolved are examples of ultimate
3.2 Researchers Use Observational. Experimental, And Comparative
Methods To Study Behaviour
• Three common methods used in behavioral research are the observational,
experimental, and comparative methods (Altmann 1974; Lehner 1998; Bateson & Martin
THE OBSERVATIONAL METHOD
7. In the observational method, scientists observe and record the behavior of an
organism without manipulating the environment or the animal (Figure 3.3).
8. This method is commonly used both to test hypotheses and to describe behavioral
1. For example, the observational method is used to construct ethogram, as we saw in
9. Researchers studying animals in zoological parks frequently use the observational
method, because behavior is oft en an important indicator of wellbeing or level of stress.
1. For instance, changes in the behavior of an animal may indicate changes in its
reproductive condition or health (Lindburg & FitchSnyder 1994). THE OBERVATIONAL METHOD AND REPRODUCTIVE ENERGETICS OF
10. Murray’s research team investigated the reproductive energetics of free living
female chimpanzees in Gombe National Park in Tanzania. Chimpanzees, mediumsized
primates that live in equatorial Africa, prefer to feed on calorierich, ripe fruit but will eat
a variety of foods.
11. Murray’s team found that the three types of adult females tended to differ in their
feeding behavior. The diets of both pregnant and lactating females included more fruit
(allowing more energy gain) than the diet of nonpregnant, nonlactating females (Figure
12. The research team concluded that pregnant and lactating females appear to alter
their diet to meet the increased energy demands of reproduction. This conclusion was
reached through research that relied solely on observations of animals, without any
THE EXPERIMENTAL METHOD
13. In the experimental method, scientists manipulate or change a variable to
examine how it affects the behavior of the animal. The variable that is changed is called
the independent variable, and it can be anything that we measure, control, or manipulate.
14. It can be abiotic (e.g., temperature, humidity, wind) or biotic (e.g., habitat, food
availability, social interactions). The researcher then measures changes in another
variable, the dependent variable, that occur in response to changes in the independent
15. The control group does not experience the manipulation but is treated similarly in
all other aspects. In the simplest experimental design, only one factor differs between the
experimental and control group. In essence, the control group represents the null
hypothesis, and the experimental group represents the alternate hypothesis. THE EXPERIMENTAL METHOD AND JUMPING TADPOLE
16. In the
the evolution of
Often, sets of
adaptations because their shared ancestor possessed the behavioral trait.
17. Ancestral traits (also called plesiomorphic traits) are found in a common ancestor
of two or more species, while a derived trait (or apomorphic trait) is found in a more
recently evolved species and was not present in the common ancestor.
18. Evolutionary relationships are provided by a phylogeny, a hypothesized
evolutionary history of a group of species. For any set of species, a phylogeny illustrates
our best understanding of the patterns of descent, showing ancestordescendant
relationships that reflect their evolutionary history.
THE COMPARATIVE METHOD AND THE EVOLUTION OF BURROWING
BEHAVIOUR IN MICE
19. These researchers were interested in understanding the evolution of burrowing
behavior of mice species in the genus Peromyscus. Species of these small mice exhibit a
wide range of burrowing behaviors.
20. They found much variation i