Economic escape theory states that there exist several relationships between flight-initiation distance (FID, the distance between a predator and its prey when the prey begins to flee) and the cost of fleeing. However, the theory fails to explain why FID increases as starting distance (SD, the distance between predator and prey when the predator begins to approach) increases. A study published by Behavioral Ecology and conducted by William E. Cooper Jr. from Indiana University-Purdue University and Daniel T. Blumstein from University of California at Los Angeles proposes that this phenomenon is caused by costs involving the monitoring of the predator during predation.
The researchers collected data from 76 avian species and recorded changes in basal metabolic rate (BMR) when the prey first became aware of the predators. They measured differences in BMR in response to alert distance (AD, the distance at which the prey first becomes aware of its predator), as well as SD and FID. The proposed hypothesis was that when SD and AD were higher, the prey would need to spend more time monitoring the predator, and this physiological cost of heightened awareness would cause the prey to have an increased FID, since fleeing as soon as possible would minimize the amount of biological resources consumed.
The results were in accordance with the hypothesis. The researchers found that during instances of high SD and AD, the FID was also higher, and BMRs were relatively high. This led the researchers to conclude that monitoring costs negatively influenced the FID, but only when the FID was found to be large. In instances of low FID, they concluded that BMR and cost of monitoring could not have any substantial relationship, as BMR tends to fluctuate naturally.
These experiments support the original explanation that prey monitoring costs contribute to the apparent starting distance and flight-initiation correlation. More research is needed, however, to confirm that this is the only cause and that there are not any lurking variables. This study is an excellent example of how predator-prey relationships are influenced by a wide array of factors.
Citation:
Cooper, W. E., & Blumstein, D. T. (2014). Novel effects of monitoring predators on costs of fleeing and not fleeing explain flushing early in economic escape theory. Behavioral Ecology, 25(1), 44-52.
The researchers collected data from 76 avian species and recorded changes in basal metabolic rate (BMR) when the prey first became aware of the predators. They measured differences in BMR in response to alert distance (AD, the distance at which the prey first becomes aware of its predator), as well as SD and FID. The proposed hypothesis was that when SD and AD were higher, the prey would need to spend more time monitoring the predator, and this physiological cost of heightened awareness would cause the prey to have an increased FID, since fleeing as soon as possible would minimize the amount of biological resources consumed.
The results were in accordance with the hypothesis. The researchers found that during instances of high SD and AD, the FID was also higher, and BMRs were relatively high. This led the researchers to conclude that monitoring costs negatively influenced the FID, but only when the FID was found to be large. In instances of low FID, they concluded that BMR and cost of monitoring could not have any substantial relationship, as BMR tends to fluctuate naturally.
These experiments support the original explanation that prey monitoring costs contribute to the apparent starting distance and flight-initiation correlation. More research is needed, however, to confirm that this is the only cause and that there are not any lurking variables. This study is an excellent example of how predator-prey relationships are influenced by a wide array of factors.
Citation:
Cooper, W. E., & Blumstein, D. T. (2014). Novel effects of monitoring predators on costs of fleeing and not fleeing explain flushing early in economic escape theory. Behavioral Ecology, 25(1), 44-52.
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