WLF 315 Wildlife Ecology I Lab Fall 2012 Sampling Methods for the Study of Animal Behavioral Ecology

Transcription

1 WLF 315 Wildlife Ecology I Lab Fall 2012 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 animals, selecting the appropriate method(s) for 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, behaviors can be classified as 1 of 2 types: 1) Behavioral states (Table 1) describe what an animal is doing at any specific time (e.g., lying, standing, walking). The categories should be mutually exclusive, such that you could place an animal s behavior into only 1 category at any specific time. Behavioral states are often timed and reported as proportions of an animal s time spent exhibiting each behavior (e.g., 90% standing, 10% walking). 2) Behavioral events (Table 2) tend to be infrequent behaviors that are relatively short in duration (e.g., grooming, nursing, fighting). Behavioral events are counted when they happen and reported as a rate (# of occurrences per unit time). Some behaviors might fit into both categories (e.g., nursing) because we might be interested in both how long and how frequently such behaviors are exhibited. Table 1. Example behavioral states (general categories of activity). These are often measured as amount of time in each state. Note that each behavior must be mutually exclusive. Behavioral state Code Description Standing S Animal is standing, not moving forward, and not feeding Walking/running W Animal is moving forward or backward Feeding F Animal is feeding (browsing or grazing). May be moving or stationary. Lying L Body is in contact with the ground. Animal is not feeding. Interacting I Includes any direct interactions between 2 or more individuals, excluding playing. Animal may be standing, lying, moving, or feeding. Playing P Usually exhibited by young animals and defined relative to the species being studied. Playing supersedes other behavioral states. Table 2. Example behavioral events (specific, short-duration behaviors). These are usually counted, rather than timed. Behaviors may or may not be mutually exclusive. Individual behavioral events Behavioral events between >2 individuals Vocalizing Courtship/copulating Urinating/defecating Sparring/fighting Grooming/scratching Allogrooming Flehmen (lip-curl) Nursing Pawing/scraping Approaching/retreating

2 Behavioral sampling methods: 1. Ad-libitum Sampling: The researcher records the behaviors of individuals or groups encountered, 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. During a set period of time, the researcher records either 1) all behaviors of that individual, or 2) all occurrences of specific behaviors of interest that the focal animal exhibits. Individuals may be chosen randomly from all members of the population, or may be chosen with some specific criteria in mind (e.g., 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. 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. Ungulate vigilance behavior and foraging efficiency: In this exercise, you will gather behavioral data from ungulates at the Bison Range and use those data to test a hypothesis about ungulate vigilance. Vigilance is defined as being alert to danger, specifically with regard to potential predators (although animals may be vigilant to potential competitors, as well). Vigilance for predators may be affected by several factors, including group size, social position (e.g., sex or age) within a group, season, group composition (adults vs. young), etc. Different species might be more or less vulnerable to predators depending on their body size, group dynamics, etc. Why would these factors affect the vigilance of an individual? Which individuals would you expect to be more or less vigilant? Individuals that are vigilant are likely to spend less time feeding because they are spending more time looking around for predators. Consequently, 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) is spent feeding versus being vigilant. We will discuss the utility of measuring active time before you begin the field observations,

3 but why might it be appropriate to measure? Assigned reading (available on the lab website): Childress, M. J. and M. A. Lung Predation risk, gender and the group-size effect: does elk vigilance depend on the behaviour of conspecifics? Animal Behaviour 66: Methods (before going to the Bison Range): 1. Understand how each behavioral sampling method works, the differences between the methods, and the advantages and disadvantages of each method. 2. Read the assigned reading by Childress and Lung (2003). It will help you develop a hypothesis for #3, below. 3. Develop 1 hypothesis and 1-3 predictions about ungulate vigilance that you will test (see below for examples). Write them down and bring them to the Bison Range. These do not need to be perfect because we will discuss them before starting data collection. Your hypothesis may suggest differences between sexes, between species, between different group sizes, between groups of differing compositions (e.g., groups with young vs. groups without young), etc. At the Bison Range, you should be able to observe elk, bison, pronghorn, mule deer, white-tailed deer, and possibly bighorn sheep (no guarantee on the sheep, though, so avoid hypotheses that are specific to that species). You are encouraged to come up with a second hypothesis and predictions, in case the first one does not prove testable. Your second hypothesis may be about vigilance or some other behavior. What are the differences between hypotheses and predictions? Hypotheses are broad statements and cannot be directly tested. Predictions are quantifiable statements that can be tested by experimentation or observation. If the predictions are false, then the hypothesis is rejected. If the predictions are true, then we fail to reject the hypothesis. Unfortunately, it is generally impossible to determine if a hypothesis is completely true because there may be other explanations for predictions that are true. Consequently, hypotheses are not generally accepted as true. They are either rejected or they fail to be rejected. If we fail to reject a hypothesis, we are, in essence accepting it as true, but we never really know for sure. Examples: 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 will be negatively correlated with group size for a given species. Prediction 2: Group size will be positively correlated with active time spent feeding.

4 Methods (at the Bison Range): 1. Refine your hypothesis and prediction(s) about ungulate vigilance and discuss what data will be needed to test it. Your hypothesis and predictions will need to be approved by the instructor before collecting any data. We also will discuss specific sampling methods that you should use, based on your hypothesis and predictions. 2. Form groups of 3-4 students with a single hypothesis and predictions to test. 3. Conduct behavioral observations and collect data to test your hypothesis. a. Use scan-sampling methods to record activity (behavioral state) of groups of ungulates at 5-minute intervals. b. 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). c. You can combine all-occurrences sampling for a specific behavioral event (e.g., grooming or sparring) with scan-sampling for activity by watching the animals continuously between your 5-minute scans. These data can be used to support your ideas or to test a second hypothesis. d. Observe each group for at least 20 minutes and record data. You may want to have 1 person observe and dictate to a recorder. Be sure to switch roles for the next group observed. Cautions: i. Use well-defined behaviors that are mutually exclusive (behavioral states) or easily identified (behavioral events). The data will be more consistent and there is less chance for bias. ii. 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. iii. You may not be able to watch the same individual or group for the entire 20-minute period. For the purposes of this lab exercise, if your animal group goes out of sight, stop recording data. Methods (after returning from the Bison Range): 1. Enter your data. One person in your group should be assigned to this task. All group members will share equal credit when the data are ed to the instructor by the due date. There is a data entry template posted on the lab website. Please use it. 2. Share your data with the entire class. We will pool all data to maximize sample sizes and so that everyone in the class is working from the same dataset. I will post the entire dataset to the website when all data have been received and compiled. 3. Prepare a lab report using the pooled dataset (see below). This will be completed individually, even though you collected data with a group and are working from the same hypotheses and predictions as your other group members. See the website for manuscript guidelines and report writing tips. Also, see below for formatting and other details. Due dates: Data turned in (via to Bill): 9 October 2012 Pooled data provided to class: 15 October 2012 Draft lab report due: 30 October 2012 Final lab report due: 27 November 2012

5 Lab report assignment: Your lab report should be written following Journal of Wildlife Management manuscript guidelines (posted on the website) for text, figures, tables, and citations. It should include the following sections: title, introduction, study area, methods, results, discussion, and literature cited. See the WLF315 Lab Report Instructions (posted on the website) for descriptions of what to include in each section. See the Instructions for Analyzing Behavioral Activity Data (posted on the class website) for help with analyses. You must reference at least 1 table or figure that you created in the results section of your report. Include the table or figure on a separate page at the end of your report. Be concise and avoid describing/discussing things that are not relevant to your hypotheses and predictions. You should be able to write this report with just 2-3 pages of text, plus 1 page for a figure or table. There is no minimum number of pages or words, so if you can do a thorough job in fewer pages, feel free. The maximum page limit is 4 pages for text and literature cited, plus 1 page per figure or table. Do not include figures or tables within the text. Attach them at the end of the document on separate pages. You do not need to do a literature review for this lab report, but you should reference and cite at least 1 paper. References to other published sources will enhance your work. Be sure to do the writing individually, even though you are using shared data! You may confer with classmates regarding analysis and interpretation of results, but you must write your own report and generate your own tables and figures.