Low resource ·High resource How might FID change with changing (a) predation ris
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Low resource ·High resource How might FID change with changing (a) predation risk (For example, if the predator could run faster or there were multiple predators) (b) distance to cover? (For example, if both the distance from the predator to the prey, and the distance from the prey to the safe zone, were different. Consider both scenarios independently). Be sure to relate your answers in terms of effects on foraging efficiency and predation rates, both of which affect survival (10 pts). 3. ur own words, describe optimal foraging theory (OFT) and provide two different examples from the literature. Briefly describe how OFT applies in each example. Make sure you provide appropriate citations for your examples. (10 pts) 4. In yoExplanation / Answer
3)
a)FID changes due to many factors, of which, predation risk plays a large role inboth the decisions of the predator and prey. In a study of incubating birds andvariable predation risk, it was discovered that male birds could detect increasedpredation and would visit its incubating nest less frequently as a result(Ghalambor, 2002). In our study, we were unable to precisely determine the effectof predation risk in regards to FID due to lack of variables, however, a generaltrend was observed during the study. The instance the predator would take off, theprey would attempt to grab food while deciding to initiate running withoutlooking at the predator, observe predators closing distance and begin runningonce, and increased vigilance throughout foraging resulting in several starvedprey. Similar observations were seen in the FID of different prey and theirresponses; immediate flight or cost benefit of staying and fleeing seems to be arecurring trend (Blumstein, 2005). Increased predator speeds or experience wouldresult in less efficient foraging for both populations. In some studies, the speed ofthe predator would only increase the FID when the starting distance was increased– a formula for which was derived where the FID was affected by approach speedand starting distance (Cooper, 2008). Foraging decisions such as when and whatto eat would result in less time spent foraging leading to less acquired resources.The predation rate which is the proportion of prey killed by predation would havealso been affected had the risk of predation been a variable (Vucetich, 2011). Hada certain distance been set as a constant where most prey would notice thepresence of a predator and not flee immediately, the mean FID would have beenlarger as a result of increased speeds.
b)Distance to cover is another important aspect of predation in terms of the preyforaging for resources. The results of one study indicate that the FID is related tothe benefit of flight value in relation to the cost of flight – the greater value of thetwo resulting in a response of fleeing or staying (Dill, 1989). In this study, had thedistance to cover been larger than 15 meters, the result would most likely be anincrease in the mean FID of the prey that due to starvation or predation due to thehigh cost of staying versus the cost benefit of fleeing and the distance needed tocover being a larger value. Just as this was seen in our study, had the prey not collected sufficient food, they would stay the extra time resulting in their death by the predator. In our study only 3 samples died as a result of starvation compared to the other 10 that died due to predation. Had the distance to cover been shorter, the FID would've been smaller as a result of this. Instead of the distance to cover being altered, if the distance of the predator to prey was changed, a much more clear distinction would be made as to the decisions of the prey. When the distance of predator to prey is decreased, the reactions mostly result in an immediate fleeing response by the prey and a relatively high FID, similar to the study of the yellow bellied marmot (Blumstein, 2005). When the risk of predation and cost of staying outweigh the cost benefit of fleeing, most prey would flee but in the case of scarce resource supply, I believe that the mean FID would either be a larger value resulting in many starvation or a small value resulting in the deaths of many of the birds. Alternatively, if the distance of the predator to the prey was increased, a lower predation rate would be observed and cenain trade-offs such as vigilance, activity time and level, and resource supply versus predation risk which affect the FID of the prey can be made. If the cost of staying is low, resource supply is high, and low predation rate, most prey would exhibit a low FID due to the ability to effectively forage without having to worry about vigilance or activity time and level.
4)Optimal foraging theory is a model that is used to quantify the behaviors of an animal when in search of food. Variables such as prey size, search time, and response to food density are measured along with other factors which allow for researches to better understand how animals decide the optimal approach to foraging which would essentially maximizing their fitness. In cases such as Perm fluviatilis, OFT is more clearly seen in aspects such as its diet and feeding location. In a study where the sample areas where divided to determine what were some of the choices made by the perch in order to forge at an optimal rate. The perch demonstrated several positive correlations in respect to its diet and feeding habits; observations reported when only one resource was available to the perch, the perch would go for the larger pelagic fish in their habitat and a longer search rate was noted (Persson, 1990). However, when in the presence of another prey, the optimal foraging for the fish was scattered and it was obvious that the best foraging was situational. The perch normally would be expected to feed on the benthic prey due to the decrease in available pelagic fish, but still, at all times of the experiment pelagic feeding was still considered. This indicated lack of correlation between growth rate and predicted return rate for predation of the benthic prey. Although the predicted return rate was extremely
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