Introduction to Behavioral Ecology: Quantifying Behavior ...



Behavior Field Laboratory, Ecol. 4960/5960 (Dave Gori)

Introduction to Behavioral Ecology: Quantifying Behavior Using Time Budgets and Focal Animal Observations.

Behavioral ecology is the study of how an organism’s environment, the physical environment, social and biological environment, shapes its behavior through the action of natural selection, kin selection, and sexual selection. [Kin selection is a special case of natural selection involving related individuals and the selection of genes that individuals share with their relatives through common descent. This form of selection is responsible for the evolution of altruistic behaviors where individual fitness is reduced by performing the behavior but close relatives benefit disproportionately.] Like morphological characteristics (i.e. finch beaks), behavior is tremendously variable between individuals in form and frequency. Ultimately, behavioral ecologists are interested in how this variability affects an individual’s survivorship and mating success as a way of understanding the evolution of behavior(s).

The objectives of this lab are to: 1) observe the behavior of a selected species and be able to identify/describe a series of its behaviors; (2) learn how to do a time budget on focal individuals to quantify the amount and frequency of different behaviors; (3) use your time budget observations to generate 5 questions about a selected behavior(s); and (4) take one of these questions and design a study to answer it.

To do this, you will first select a study species for this excercise. Some possible choices include: Galapagos sea lions, marine iguanas, foraging finches, reef fish or lava lizards at Loberia. Once you have done this, watch an individual or if possible several individuals for approximately ½ hour, identifying and describing as many behaviors that you possibly can. These may include calls, displays, movements made during food searching, interactions between individuals, etc. In this identification phase, clear your mind, open your eyes…..look and see. Ask yourself the following questions for each behavior that you identify:

Who is performing this behavior (sex, age, individual) and who is it directed to?

When was the behavior performed, e.g., time of day, after feeding or mating, and roughly how frequently was it performed relative to other behaviors?

What context is the behavior performed in (e.g. a fight between two males over food, a chase between females that arose when female A approached B) and what might determine the frequency and intensity of the behavior if this varies between individuals and for a single individual over time?

Why? This is the type of question that deals with how the behavior evolved and involves speculating about the advantage of the behavior in terms of increased survivorship, mating success and offspring production by the individual/performer.

After you have described a series of behaviors and have asked yourselves these questions (N.B., you don’t have to have answers to any of them in order to proceed), pick a focal animal and perform a time budget on that animal for ½ hour. You’ll need a watch with a second hand or display for this. The time budget involves marking the time when a change in behavior occurs. For example, when you start the time budget (time 00) a male bird is calling from a perch; you can keep track of the number of calls by making hatch marks on your time budget sheet. 2:50 minutes into the observation, another male flies up (his neighbor on the left); the focal male displays, stretching his neck over his left shoulder and does this 5 times, continuing to call. At 4:37 the male flies off the territory to forage, and returns at 9.05, perches and calls. At 12:22 a non-neighboring male flies up and your focal male continues perching and calling.

You might record the following sequence of events on your time budget sheet as follows:

00 P, C ////////////

2:50 N on left → NS, NS, NS, NS, NS ///////////////////////////////////////////

4:37 off T, F

9:05 Returns, P, C ////////////

12:22 NN arr., P, C //

From your exploratory observation, you’ve already identified P, C, NS, N, NN, off T and F as perching, calling, neck-stretch display, neighboring male, non-neighboring male, flies off territory and foraging, respectively. Be sure to make an abbreviation key so that when you analyze your data later, you’ll be able to decipher your time budget. Also, provide information at the top of the sheet about who the focal animal is, the time when the budget was initiated, and general notes on weather conditions which can have strong effects on behavior. In a population of banded birds, it is relatively straightforward to identify an individual. If individuals are not marked, you can identify sex, age, size, plumage characteristics, unique markings or any number of descriptors that will enable you to categorize and later distinguish the time budget of one individual or category of individuals from that of another. For territorial individuals you can produce a quick map showing the location of the focal animal relative to neighbors.

Since more data is always better than less in research, if behaviors are not coming fast and furiously, try watching 2 or more individuals during a single time budget. This will probably not be possible if you’re watching foraging finches or sea lions at dusk but will be possible if you’re watching a group of marine iguanas. If behavior is changing to fast to keep up with for a single individual, try breaking each minute into 10 or 15 second segments and at each 10 or 15 second break , record the behavior that is occurring precisely at that time break.

After completing your first time budget, switch to another focal animal(s) and perform another time budget (½ hour).

To summarize the time budgets for analysis, you can calculate the amount (percent) of time that the focal animal spent doing each identified behavior and the frequency or rate of a behavior per unit time (e.g., percent of time a male spent on territory, number of calls per minute on territory, etc.)

Once completed, reflect on your exploratory observations and two time budgets and then run through the who, when, what, and why questions, generating 5 of your own questions regarding behavior(s) that you’ve just observed. Pick one of these questions and design a simple study to answer it, perhaps using time budgets to do this. If needed, Katrina and I will help you with this step.

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