Biology 425. Mammalogy
NAME: _________________________
Caribou and Musk Ox Observations at LARS
Tuesday, 14 September 2010
A. Observing Behavior
Biologists use several techniques to observe behavior, choosing the one that is most appropriate
for the question they are addressing and the species they are observing. We can categorize
behaviors as either states or events:
State: a behavior in which an individual is engaged; an ongoing behavior that can be
timed from beginning to end; e.g., eating, sleeping. (boring to observe)
Event: a change in states, may occur instantaneously or quickly, e.g., eating to alert
posture; generally occurs too quickly to time. (sometimes very exciting to observe)
Here are a few of the common techniques for observing behavior:
Focal-animal sampling: one individual is the focus of observation during a particular time
period; if the animal is interacting with others, the observer records all of its interactions with
others, whether it is the actor or receiver; e.g., whether it is behaving aggressively to another
individual or that individual is behaving aggressively towards it.
Basically, you record everything you can about that individual while you are observing it,
preferably on a timeline so that you can then calculate how much time it has spent in various
behavioral states.
Note that unless the focal animal is inactive, it is generally very difficult to record everything
that 2 or more individuals are doing are doing at the same time; that is why a single animal is
chosen for observation.
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All-occurrences: one behavior, rather than one individual, is the focus of observation during a
particular time period; e.g., active fights within a group of males, or copulations in a rutting
group; this approach works well when you are interested in just one behavior, and it doesn’t
occur too frequently that you might miss observing one occurrence while recording another.
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Scan sampling: At pre-determined times, the observer records the behavioral states (e.g.,
feeding, sleeping, resting, walking) of all individuals in a group being observed. The idea is to
record simply and quickly, to record a “snapshot photo” of the behavioral states of all
individuals. Data recorded might include characteristics of the individuals (sex, age class) as well
as their behavioral state.
Note that you could literally take snapshot photos at predetermined times and then record the
behavioral states of each individual on each photograph, but that approach can end up being very
time consuming.
Scan samples are very useful if you are trying to determine general activity budgets of various
age-sex classes, e.g., during the rut, do males eat less than females, do larger-antlered males eat
less than smaller-antlered males or adult females?
General Approach
To collect data to address questions and successfully test hypotheses about behavior, researchers
often combine 2 or more approaches in their data collection. One common approach is to
alternate scans of a group with focal animal observations of an individual. We’ll use this
approach at LARS.
Question:
Are adult male caribou and adult female caribou feeding at the same rate during our
observations?
What is our working hypothesis? (that males and females are eating at similar rates? males are
eating at much higher rates? if so, why? males are eating at much lower rates? if so why?)
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Procedure: You and a partner will alternate between scans and focal animal sampling in your
observations today. First, briefly observe the individuals and note what they are doing (feeding,
standing, lying, ruminating: How would you define this in terms of what you actually can
observe?). Once you can identify and distinguish each major behavioral state from the others,
make your first scan.
1. On the data sheet for the scans, name or number each individual and, if possible, note its age
(or age class) and sex. Then conduct a scan, categorizing the behavioral state of each individual
you are observing.
2. Once you have completed your first scan, choose a either an adult male or an adult female to
observe for 5 minutes. Record all behaviors of that individual and all behaviors of other
individuals that may directed at that individual.
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Background:
How should you choose a particular individual? A researcher typically would assign numbers to
each individual and then use a “random numbers table” to randomly choose one of them. We’ll
skip this step today: you can just choose one arbitrarily. Why wouldn’t this be a good idea if you
were conducting a detailed, rigorous study? The answer is that perhaps something about that
individual’s behavior not only biases your decision to choose that individual but also is unusual
in its behavior in other ways, thus also biasing your results.
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3, 4. If you just observed an adult male, repeat the scan and focal animal procedures for an adult
female. If you just observed an adult female, then repeat the procedure for an adult male.
Once the 10 minutes is up, reverse recording/observing roles with your partner; repeat the
scan sample and then the focal animal sample.
Focal Animal Sampling:
Age, sex, ID if possible: record starting time and state and then time of each change in state and
the new state:
SCAN SAMPLING: record the behavioral state of the individual in the table below
OBSERVERS:
Scan
Individual Age Sex 1
2
3
4
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Questions and your answers:
1. Are caribou and reindeer classified as just 1 or 2 species, and why?
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2. What is the scientific name of caribou, of reindeer?
Caribou: _____________________
Reindeer: ____________________
3. When do reindeer females at LARS mate generally?
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4. When do caribou females at LARS mate generally?
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5. When do wild caribou in Alaska and wild reindeer in Siberia mate generally?
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6. What is polyestrous, and why is it important in understanding why or why not domestic
reindeer and wild caribou might mate successfully?
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7. When do reindeer females at LARS give birth generally?
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8. When do caribou females at LARS give birth generally?
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9. What is the average gestation (pregnancy) period of reindeer? _______ caribou? ________
10. How can you distinguish reindeer from caribou by sight?
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11. List the species of the deer family Cervidae in which females as well as males grow antlers:
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12. List the species of the deer family Cervidae in which calves (first-year young) grow antlers:
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13. WHY do female reindeer and caribou grow antlers and retain them throughout the winter?
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14. When does an adult male caribou usually lose his antlers?_____________________
15. When does a nonpregnant female caribou usually lose her antlers?__________________
16. When does a pregnant female caribou usually lose her antlers?________________
17. In muskoxen, how can you tell adult males and adult females apart?
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18. When do female muskox at LARS usually mate? ________________
19. When do female muskox at LARS usually give birth?_____________
20. What is the average gestation period of muskox? ____________
21. At what age do female muskox at LARS first give birth? _______
22. Once they are adults, how often do female muskox at LARS usually give birth?_______
23. At what age do female muskox in the Far North (High Arctic) first give birth?________
24. Once they are adults, how often do muskox living in the Far North usually give
birth?_______.
25. Is there a difference between LARS and the High Arctic in how often females give birth, and
if so, why?
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26. Do female muskox, reindeer, or caribou reduce or completely stop feeding at any time during
the rut? _____ Explain
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27. Do male muskox, reindeer, or caribou reduce or completely stop feeding during the rut?
_____ Explain ______________________________________________________________
28. In terms of being able to survive the rest of the winter, does the mating (rutting) season have
more of an adverse effect on adult males or adult females, and why?
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29. What are some differences between antlers and horns, which seems most significant to you,
and why?
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30. What about caribou, reindeer, muskoxen, and/or LARS was most interesting to you and why?
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