Wlf 315 Wildlife Ecology I Lab

Fall 2010

Sampling Methods for the Study of Animal Behavioral Ecology

Lab Objectives:

1.Introduce field methods for sampling animal behavior.

2.Gain an understanding of how behavioral research is conducted.

3.Gather behavioral data in the field to test hypotheses and associated predictions.

In any study of behavior that involves watching the animals, selecting the appropriate method(s) of sampling behavior is important. In most field studies of animal behavior, it is impossible to observe and record every behavior of every animal in the group. Therefore, you need to make decisions about which animals to observe and which behaviors are of interest. Those decisions will form the basis for selection of specific behavioral sampling methods. In general, behavior falls into two types: 1) behavioral states (e.g., lying, standing, walking), which describe what an animal is doing at any time (the categories should be such that you could place an animal’s behavior into one category or another at any time); or 2) behavioral events (e.g., grooming, nursing, fighting), which tend to be infrequent behaviors that are relatively short in duration. Behavioral events are counted when they happen and reported as a rate (# of occurrences per unit of time).

Table 1: Example Behaviors

Behavioral States (General Categories of Activity – often measured as amount of time in each state):

Standing / S / Animal is standing, not moving forward, and not feeding
Walking/running / W / Animal is moving forward
Feeding / F / Animal is feeding (browsing or grazing)
Lying / L / Body is in contact with the ground
Interacting / I / Includes any interactions between 2 or more individuals
Playing / P / Behavior usually exhibited by young animals, and usually defined relative to the species being studied

Behavioral Events (Behaviors that are shorter duration and usually counted rather than timed):

Examples of Behavioral Events between 2 or more individuals:

Allo-grooming

Sparring/fighting

Nursing (or attempting to suckle)

Approaching/retreating

Courtship behaviors/copulating

Examples of Individual Behavioral Events:

Vocalizing

Urinating/defecating

Scratching (grooming)

Flehmen (lip-curl)

Pawing/scraping

For behavioral state data, we are often interested in the amount of time that an animal spends doing different activities. So, data are usually collected and analyzed to represent the proportion of time during which animals were observed that they were doing a particular activity (e.g, feeding, walking, etc.). In contrast, behavioral event dataare usually recorded as a frequency (number of times the event occurred over the time that the animals were observed). Some behaviors might fit in both categories (e.g., nursing) because we might be interested in both how long and how frequently such behaviors are performed.
Sampling methods for behaviors:

  1. Adlibitum Sampling: The researcher records the behaviors of individuals or groups s/he encounters, with little or no reference to specific, welldefined methods. This is a good method for initial observations and question formation for later research, but is limited in the quantity and quality of data produced.
  1. Focal Animal Sampling: The researcher selects one individual to be the primary focus of observation. The researcher records either 1) all behaviors of that individual, or 2) all occurrences of specific behaviors of interest that the focal animal exhibits, during a set period of time. Individuals may be chosen randomly from all members of the population, or may be chosen with some specific criteria in mind (by age, sex, or reproductive status). This technique is useful for providing data on specific behaviors and is more reproducible than ad-libitum sampling.
  1. AllOccurrences Sampling: The researcher selects one or a few specific behavioral events and records every occurrence of that (those) behavior(s) within the animal group (every occurrence of grooming, chasing, etc.). This technique is especially useful in determining the rate, frequency, or synchrony of occurrence of specific behaviors.
  1. OneZero Sampling: The researcher records whether specific behaviors did (1) or did not (0) occur during a given time interval. It does not matter whether the behavior occurred once or several times during the time interval. Either individuals or groups can be observed with this method. The time interval is usually short (15 seconds) and samples are usually taken frequently. This method is somewhat limited in its usefulness because information is lost by categorizing the occurrence of behaviors so rigidly. However, this method may have less observer bias.
  1. Scan Sampling: The researcher records the instantaneous activity or behavioral state of all animals in the group at predetermined time intervals (e.g., once per minute). It is impossible to record the behavior of all individuals instantaneously, but the researcher attempts to do so in as short a time period as possible. The behaviors should be well defined so that scanning is made easier. This method is useful for understanding the frequency with which all animals in the group display certain behaviors or behavioral states.

Ungulates: Vigilance Behavior and Foraging Efficiency

In this exercise, you will gather behavioral data from wildlife species at the Bison Range and use those data to test a hypothesis about vigilance by ungulates. Vigilance for predators potentially is affected by several factors, including group size (why would this be so?), position within a group, sex and age, season, group composition (adults or young), etc. Also, different species might be more or less vulnerable to predators. Individuals that are vigilant are likely to spend less time feeding as a result of spending more time looking around for predators. So, it is logical to conclude that factors that increase vigilance behavior might also reduce foraging efficiency. One measure of foraging efficiency is to examine how much active time (i.e., time when an animal is active and not lying down) that is spent feeding versus vigilant. The reason for considering active time will be discussed before you begin the field observations (but can you think about why?).

Assigned reading: (available on the lab web-site)

Childress, M.J. and M.A. Lung. 2003. Predation risk, gender and the group-size effect: does elk vigilance depend on the behaviour of conspecifics? Animal Behaviour. 66:389-398.
Exercise Expectations:

  1. Understand how each selected sampling method works, the differences between the methods, and the advantages & disadvantages of each method.
  2. Plan an hypothesis and predictions about vigilance. You will need to turn this in by Sept. 17. We will discuss this in class. Make sure that your hypothesis is approved by the TA or instructor. We’ll ask you to come up with a second hypothesis – it can be another one about vigilance or some other behavior. We’ll discuss these at the Bison Range.
  3. Gather behavioral data at the Bison Range, and share your data with the class.
  4. Complete a lab report using the shared class data to evaluate predictions and test the hypothesis of your choice.

Methods:

  1. Form groups of 3-4 students for the behavioral observations. The lab write-up must be completed individually(even though you will collect data with your group and share data with others in the class)!!
  2. Develop one hypothesis and prediction about vigilance that you will test. You can make hypotheses about the differences between males and females, or species, or group size or composition (groups with vs. those without calves or fawns). You should be able to observe bison, pronghorn, elk, mule deer, white-tailed deer, and maybe big horn sheep (but no guarantee on the sheep).

Examples: (What is the difference between hypotheses and predictions?) Think about this.

Hypothesis: Bison are less vulnerable to predators than pronghorn because of their larger body size.

Prediction 1: Bison will spend less active time vigilant than pronghorn.

Prediction 2: Bison will spend more active time feeding than pronghorn.

Hypothesis: Animals in larger groups will be less vulnerable to predators.

Prediction 1: Vigilance behavior will be negatively correlated with group size for a given species.

Prediction 2: Group size will be positively associated with proportion of active time spent feeding.

  1. Use scan-sampling methods to record activity (state) of groups of ungulates at 5-min intervals.
  2. You can combine all-occurrences sampling for a specific behavioral event (like grooming or sparring) with scan-sampling for activity by watching the animals continuously between your 5-min. scans. These data can be used to support your ideas or to test a second hypothesis.
  3. Agree with your team members on which individual animals to observe (the whole group, a subset of the whole group, or a particular individual). Before beginning observations, spend some time watching your study animals. Make sure all members of the group agree on the definitions of the behavioral states/activities (examples are listed in Table 1).
  4. Observe each group for at least 20 minutes, and record data. You may want to have one person observe and dictate to a recorder. Be sure to switch roles for the next group observed.

Cautions:

  1. Use well-defined behaviors. The data will be more consistent and there is less chance of bias.
  2. You may need to select a sub-group of all the animals in a group if the group size is too large to complete a scan sample in a short period of time. Talk this over with your group members before you start.
  3. You may not be able to watch the same individual or group for the entire period planned. For the purposes of the lab exercise, if your group goes out of sight, stop recording data.

Written Assignment

Your lab report should include the following sections:

Title

Introduction

Hypothesis & Predictions

Methods

Results (include at least 1 figure or table with your data). Do not repeat information in the text if it is provided in the figure or table. Also, note that figures should have a figure legend and tables should have a table caption that explains the data presented in the figure/table). You should be able to calculate mean values and 95% confidence intervals (or standard error values) to evaluate predictions. We will not expect a statistical treatment of the data for this lab.

Discussion (Did you support your hypothesis or not? What assumptions did you make? What other factors might also influence your results? What problems did you encounter?)

Some more information …

  • Use 11 point font, and double space the lab report. Max. page limit = 4-5 pages for text and 1 or 2 pages for your figure(s) and/or table(s).
  • See information on the lab web-site about how to write the different sections of a paper/lab report. There are short (few pages each) chapters from:

Robert A. Day. 1998. How to Write and Publish a Scientific Paper, 5th edition.

  • You will not need to do a literature review for this lab report, so you might have only a few references. If you do reference any published literature (like published papers, field guides, your text, etc.), you should include the citations in a References section.
  • Be sure to list the other members of your observation team on your lab report.
  • Be sure to do the writing individually, even though you shared data!