Wlf 315 Wildlife Ecology I Lab
Fall 2010
Sampling Methods for the Study of Animal Behavioral Ecology: Scavenger Ecology
Lab Objectives:
1.
Introduce field methods for sampling animal behavior.
2.
Facilitate 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. Whether you are interested in behavioral states (e.g., lying,
standing, walking) or behavioral events (e.g., grooming, nursing, fighting) also will affect the sampling
method you choose. See handouts for examples and illustrations of of behavioral states and events
frequently recorded for avian scavengers.
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 data is usually recorded as a frequency (number of times the event
occurred over the time that the animals were observed).
Examples of behavior sampling methods:
1. Ad-libitum Sampling: The researcher records the behaviors of individuals or groups s/he
encounters, with little or no reference to specific, well-defined 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.
2. 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.
3. All-Occurrences 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.
4. One-Zero 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.
Wlf 315 Wildlife Ecology I Lab
Fall 2010
5. 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.
Lab Exercise: Sampling Behavior of Avian Scavengers
In this exercise, you will gather behavioral data from 2 avian scavengers, Common Ravens (Corvus corax)
and Black-billed Magpies (Pica hudsonai), at carcasses. Research on scavenging behavior suggests that
many factors can influence the how efficiently (how much and how fast) food is obtained by scavengers
at a kill including the size and state of decomposition of the carcass, species and number of scavengers
present at the carcass, aggressive interactions within and among species, and habitat type (some
scavengers are more effective in wooded vs. open habitats). In this exercise, we will examine
relationships among feeding rates, vigilance, and group size for a smaller scavenger (Magpies), and also
ask whether the presence of a larger scavenger (Ravens) influences their behavior.
Exercise Expectations:
1. Understand how each selected sampling method works, the differences between the methods,
and the advantages & disadvantages of each method.
2. Plan a hypothesis and predictions that follow logically from the hypothesis, and discuss the ideas
with the TA or instructor before beginning your data collection.
3. Gather behavioral data, 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 students for the behavioral observations. The lab write-up must be completed
individually even though you may share data with others in the class!!
2. Develop one hypothesis and a couple of predictions that you will test.
Assigned reading:
McKinstry, M.C., and R.L. Knight. 1993. Foraging ecology of wintering Black-billed Magpies.
Auk 110:632-635.
Examples of hypotheses and predictions are provided in the reading (McKinstry and Knight 1993)
Be sure you are clear about the difference between hypotheses and predictions
Please talk with the instructor or TA about your hypothesis and prediction before you do the exercise.
Wlf 315 Wildlife Ecology I Lab
Fall 2010
3. Use appropriate behavioral sampling methods for the different behaviors:
- Select one Magpie (focal animal) that is within 1 m of the carcass – one observer will
observe vigilance and another will observing feeding and agonistic interactions; the 3rd
team member will record the data. Be sure to switch activities.
- Use scan-sampling methods to record vigilance (activity state) of the focal animal at 1min intervals and also record the number of Magpies at the carcass (within 1 m). These
data will be analyzed as proportion of time within 1-m of carcass spent feeding. Also,
record the number of Ravens around the carcass.
- Use all-occurrences sampling for feeding pecks and agonistic interactions (behavioral
events) per 1-minute interval between pecks. These data will be number of events per
time observed.
- When your animal is no longer at the carcass or active, then stop observations, and
record total time that the animal was observed. Then select another bird and continue.
- 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.
Written Assignment
Your lab report should include the following sections:
Draft Lab Report
Due Oct 5
Title
Final Version
Due Oct 19
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 12 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.