Methods for Studying Animal Behavior Abstract

To study animal behavior, scientists utilize proximate explanations which focuses understanding on immediate causes of behavior, and ultimate explanations which focuses on evolutionary causes.  Tinbergen posed four questions that focus on proximate and ultimate explanations: What mechanism caused the behavior?, How does the behavior develop?, What is the function of the behavior?, and How did the behavior develop?  Methods to study behavior include observational, experimental, and comparative methods.  Observational methods involve observing and recording behavior without manipulating the environment or animals.  Experimental method involves manipulating a variable to examine how it affects the behavior of the animal and utilizes independent variable, dependent variable, and a control group.  Comparative method compares behaviors between species to understand evolution of behaviors.  This method uses phylogeny, diagrams indicating evolutionary ancestor descendent relationships, and sister species.  In phylogeny, ancestral traits, found in a common ancestor, and derived traits, common in more recently evolved species, are observed by researchers.  Scientists used comparative psychology, the study of animal behavior in a comparative manner across a species, to understand human minds.  It includes behaviorism that studies behavior independent of animal consciousness.  Lastly ethical animal use revolves around replacement, reduction, and refinement.

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Chapter 3 Abstract

This chapter introduces methods of studying animal behavior and related concepts. There are two explanations that are important in understanding how and why behaviors evolve. One type of explanation is proximate, which focuses on the immediate causes of behavior. The other type of explanation is ultimate, which focuses on the evolutionary causes of behavior. Within these explanations, there are four questions that should be considered. Researchers use three different methods to study these behaviors, observation, experimental,and comparative. Observational research includes observation without manipulating the environment or animals. Experimental research includes manipulating a variable and the effects on the behavior of the animal. Comparative research examines similarities and differences between species to understand the evolution of the behavior. Studying animal behavior started as early as Darwin and continues today. Animal behavior is used even used to understand human behavior, through a comparative psychology approach. This topic incorporates other disciplines, such as evolutionary psychology, cognitive ethology, and behavioral ecology. Ethical animal use is important for studying animal behavior to ensure proper results because all types of research can affect animals. It’s important to remember the three R’s in conducting animal research: replacement, reduction, and refinement.

Methods for Studying Animal Behavior

There are three basic methods to study animal behavior; these methods include observational, experimental and comparative. Observational methods include observing the organism of its environment without any manipulation, experimental methods manipulate a variable for examination of how it affects the behavior, and comparative methods use phylogeny to show ancestral relationships. Studying animal behavior can be categorized into proximate and ultimate causes of behavior. The proximate mechanism is immediate behavior, or within a specific amount of time whereas the ultimate mechanism is over a long period of time. To identify if a behavior is proximate or ultimate, Niko Tinbergen developed four questions to identify different behaviors done by an organism. These four questions are: 1) What mechanism caused the behavior? 2) How does behavior develop? 3) What is the function of the behavior? 4) How did the behavior evolve? There are a variety of perspectives to analyze animal behavior. These perspectives are comparative psychology, behaviorism, classical ethology, and other interdisciplinary approaches. When conducting animal behavior research, ethical animal use is required. To decrease the effect on animals, researches are encouraged to follow the three R’s, which are replacement, reduction, and refinement.asia-india-photo-11-animal

Example of observation method in animal behavior.

Methods for Studying Animal Behavior

Scientists utilize three main methods for studying animal behavior; observational, experimental, and comparative. In the observational method, the researcher physically watches the subject in the study without manipulating any variables. In the experimental method, scientists manipulate a specific variable to see how it affects animal behavior. Finally, in the comparative method researchers utilize both the ancestral and derived traits of the subject species to study animal behavior. An extension of the comparative method is comparative psychology, where researchers study animal behavior in order to understand human behavior.

One way to study wild animals is through classical ethology, where the animals are studied in their natural habitat through observation and experimentation. Animal behavior research requires ethical animal use, where animals are treated with handling and care, no malicious intent, and there are benefits for science. Replacement (use of computer technology), reduction (limiting the number of animals), and refinement (improving procedures and techniques) are all necessary factors in ethical animal use.images-2

Methods for Studying Animal Behavior

Early comparative psychology studied animal behavior to understand human minds. The field of behaviorism was derived from comparative psychology, which studies behavior independent of animal consciousness. This ranged from the Classical or Pavlov conditioning, to classical ethology, or, studying wild animals in nature. To quantify and articulate animal behavior, scientists study proximate mechanisms and the ultimate reasons for any behavior. Proximate explanations focus on the immediate cause of the behavior, and answer the questions: what mechanism caused the behavior, and how does the behavior develop? The ultimate explanation focuses on the evolutionary cause, answering the questions: what is the function of the behavior and how did it evolve? Researchers use observational, experimental, and comparative studies to answer these questions. The comparative method uses phylogeny to represent ancestor-descendent relationships. The two most closely related species are considered “sister species.” In observational studies, the animal behavior is observed without any influence or manipulation. Experiments involve independent variables, dependent variables, and control groups to test the influence of a specific variable. Importantly, ethical behavior of the researcher needs to be considered for every situation, and there are many sources of ethical standards.

Chimpanzee Study

Elizabeth Urresda, Erin Longo, Alicia Twisselmann

1) Main animal behavior method

Observational

What is the influence of the reproductive state of East African chimpanzees females, how do they compensate for the energy demands of reproduction? This question was investigated through an observational study, where scientists analyzed data gathered over the course of 31 years. Particular attention was paid to the differences in travelling budgets, feeding times, diet quality, and sociality among the pregnant, lactating, non-pregnant, and non-lactating females.

2) Hypothesis

Scientist predicted that the behavior differences amongst female chimpanzees would be most pronounced for the lactating females, because lactation is the most energy costly part of the reproductive cycle.

3) Methods

Field assistants and researchers conducted full-day follows on community members. This means tracking an individual from night-nest to night-nest and recording party composition and location every 15 minutes. Feeding data was recorded continuously as well as dominance interactions. Behavior was compared between non-pregnant and non-lactating (NPNL) females, pregnant females, and lactating females. Only females in the reproductive state were studied. the amount of time spent traveling or feeding was compared between the three groups, as was the quality of the diet consumed.

4) Major Findings

The differences in traveling time: pregnant chimpanzees spend the least percentage of time traveling around 34.5%, then NPNL at 37.7%, then lactating chimpanzees at 38.3%.  Differences in feeding time: Pregnant chimpanzees spend least percentage of time feeding 50.7%, then lactating at 54.3%, then NPNL at 58.6%.  The lactating and pregnant chimpanzees consumed more fruit than NPNL females.

5) Tinbergen’s question
What mechanism caused the behavior?
6) Did it support the hypothesis
The results did not support the hypothesis.  Pregnant females showed the largest difference from the norm in foraging and travel while lactating females showed the largest difference from the norm in diet.

Chimpanzees are ripe fruit specialists

These chimps are from Tanzania

Chimpanzees can live from 40-60 years

Chimpanzees can make and use simple tools

The evolution of burrowing behaviour in deer mice (genus Peromyscus)

Article by: Weber and Hoekstra (2009)

______________________________________________________________

(1) Method applied?

  • Comparative

(2) Hypothesis?

  • If there is a gradual accumulation of genetic change through time, then complex burrowing behavior may evolve in the Peromyscus species.  

(3) Methods?

    1. The mice were obtained from a Peromyscus Genetic Stock Center from 7 different species that descended from wild-caught ancestors and have not had exposure to natural environments.
    2. Four identical chambers were constructed and filled with sandy soil at 2 different elevations.
    3. Each mouse was placed in the chamber individually and was given 48 hours (2 full nights) to complete the burrowing activity. All alterations to the chamber were recorded.
    4. Each mouse went through 3 consecutive trials in each of the 4 identical chambers to measure repeatability of this behavior.
    5. Measured phenotypes: digging, some digging, or discrete burrows
    6. Calculated frequency of burrowing
    7. Injected tunnels with a foam, creating a “cast” of the tunnel
      1. measured the depth,  length of entrance, total length and angle of entrance
    8. Constructed a molecular phylogeny, among all seven species, using nuclear and mitochondrial DNA analysis.

(4) Major Findings?

There was no significant behavioral difference among mice in differing enclosures for all species.  Variation between  burrowing behavior occurred more often between differing species rather than  within a species. 2 groups of species closest to the ancestor species did not show any burrowing. 1 species exhibited little burrowing, but lack of depth/distance of the burrow. 2 species exhibited behaviors that formed 2 burrows in close proximation to one another.  1 species exhibited some burrowing with a lack of depth/distance. The final species furthest from the ancestral species exhibited extensive burrowing, including an escape tunnel.

Finally, complex burrowing exhibited by the species furthest from the ancestral species, P. Polionotus, is a derived trait.

(5) Tinbergen’s Four Questions:

    1. Proximate questions about behavior
      1. What mechanism caused the behavior?
        1. Not described by researchers.
        2. Mechanism appears to be unknown.
      2. How does the behavior develop?
        1. Local environments, over time, may have prompted response via burrow behavior (p. 603)
    2. Ultimate questions about behavior
      1. What is the function (purpose) of the behavior?
        1. Create space which provides:
          1. Protection from predators
          2. Thermoregulation
          3. Food storage
          4. Facility for social interaction and mating
      2. How did the behavior evolve?
        1. Going into the research, the scientists admit “we know almost nothing about how burrowing evolves within a clade” (p. 603)
        2. However, by using a phylogenetic analysis  of varying behaviors (as Weber and Hoekstra doing in this experiment), scientists can learn more about how these complex burrowing behaviors evolved independently in different species of deer mice!

(6) Results support hypothesis?

    1. Yes!
    2. “Overall, we document significant behavioural differences between Peromyscus species and find that ‘complex’ burrowing behaviour may evolve through the gradual accumulation of genetic change through time.” (p. 604)large

Odonate naiad influence on jumping behavior in Pseudopaludicola aff. falcipes tadpoles

pseudo frog   pseudo tadpole   naiad

Animal Method:  experimental

  • manipulated predator presence/absence in first experiment
  • coverings, screens as independent variable in second experiment

Hypothesis:

  • If predator present in tadpole environment, then tadpole jumping behavior elicited by that predator appearance
  • If tadpoles exhibit jumping behavior, then increase in chance of survival for long-term

Methods:

  • Absence of predator, presence of pseudo-predator, presence of real predator as independent variable in simulated environment as 3 different treatments
    • Reuse of predator species once, different tadpoles for each replication
  • Use of screening + non-screening enclosures as independent variable in simulated environment as 2 different treatments
    • Very tight enclosure with mosquito netting to prevent jumping
    • Completely open tub/container to allow jumping behavior

Findings:

  • More jumps in real predator treatment
  • No significant difference between control, predator-control (pseudo-predator) treatments
  • Predator treatment: most jumps after predator moved, other jumps indeterminable
  • Tadpole survival rate higher in non-screened treatments than screened enclosure
  • Predators prey on all tadpoles in screened treatment, very few prey in non-screened treatment

Questions:

  • Proximate:  What mechanism caused behavior? (presence/absence of predator, movement of predator)
  • Ultimate:  What was the function of behavior? (evade predation overall for survival)

Results:

  • Both hypotheses supported
    • Jumping behavior was elicited by predator presence
    • Jumping behavior increase chance of tadpole survival