- Your assignment is to design and execute a study examining the influence of predation risk on other activities.
- Your study can be either experimental or observational, but it must examine the influence of one or more variables on behaviour.
- The following project suggestions include e-periments that can be done using an aquarium or a terrarium, in your backyard, a nearby park, a woodlot, a stream, or, if you are lucky enough to live near it, the seashore.
- Each suggestion includes a brief e-planation of a tradeoff between avoiding predators and performing other activities, such as foraging, courtship, etc. Possible experimental manipulations and study organisms are suggested, and e-emplary studies are referenced.
- Feel free to modify any of these project suggestions or to devise your own experiments.
- Your study should be written as if it were a paper to be published in a journal-look at any of the papers you have read in this course for examples.
- Your paper will be evaluated according to the "Project Write-up Guide" that follows the "Project Suggestions" below. You should also refer back to the criteria that you used when you critiqued other papers to help yourself write a good paper.
Project Suggestions
- The effect of energy requirements on where to forage with respect to cover. The further an animal ranges from cover during feeding activities, the higher the predation risk it encounters. The animal should be willing to incur higher risks (by foraging at greater distances) when it has higher energy demands, such as when it is hungry. A possible e-perimental design would involve comparing how far birds (e.g., chickadees, towhees, juncos), rodents, or squirrels forage from cover (from trees or brush piles) after cold nights versus warm nights.
Grubb Jr., T. C., & Greenwald, L. (1982). Sparrows and a brush pile: Foraging responses to different combinations of predation risk and energy cost. Animal Behaviour, 30, 637-64.
- Vigilance (scanning for predators) before and after the appearance of a predator. Time spent watching for predators (being vigilant) increases an animal's safety but decreases the time it has available for other activities. After a predator appears, animals should become more vigilant. A potential experimental design involves comparing the vigilance of animals at a feeder before and after introducing a predator (a human sitting nearby, or a cat or dog tethered nearby). (Note: Group size must be accounted for because vigilance will vary with group size.)
Gluck, E. (1987). An experimental study of feeding, vigilance and predator avoidance in a single bird. Oecologia, 71, 268-272.
- The effect of distance to safety on how close an animal allows an attacking predator to approach before feeding.
Fleeing sooner from an approaching predator increases the safety of an animal because it is more likely to reach a refuge before being captured.
However, the earlier the animal flees, the more time it loses for other activities (e.g., foraging). Various factors can influence this trade-off. For example, an animal should flee sooner when it is farther from cover.
Other factors that would influence this trade-off include quality of the food source, hunger level, and group size (for the dilution effect, see
Alcock). A potential e-perimental design would involve comparing chipmunks, tree squirrels, or birds fleeing to trees from a high- or low-quality food source in response to an approaching human.
Dill, L. M., & Houtman, R. (1989). The influence of distance to refuge on flight-initiation distance in the grey squirrel (Sciurus carolinensis).
Canadian Journal of Zoology, 67, 232-235.
- Effect of foraging requirements on time to return to a food patch after fleeing a predator.
Animals often flee from predators to hiding places where they lose sight of the predator and cannot determine whether it has left or is waiting in ambush near the food patch. The cost of returning early is a high predation risk, because the predator is less likely to have left.
The benefit of returning early is less time lost for foraging-this benefit will increase with increasing hunger.
Potential experimental designs include:
a) Frightening birds from a feeder (e.g., by making a loud noise) and comparing their time to return after cold and warm nights;
b) Frightening squirrels from a food patch of high or low quality and comparing their times to return; and
c) Frightening hungry and well-fed fish from a drip-feeder to a refuge at the far end of an aquarium and comparing their return times.
Godin, J., & Sproul, C. D. (1988). Risk taking in parasitized sticklebacks under threat of predation: Effects of energetic need and food availability. Canadian Journal of Zoology, 66, 2360-2367.