The effects of Bobcat (Felis rufus) urine on the preference behavior of Mice (Mus spretus)
in a relatively familiar environment.
One of the frequently used learning tasks in rodents is the maze. During the experiment I used the Y-maze to characterize the role of the predatorís scent in preferences and memory. Specifically, stimuli free trials showed the randomness of mice and their preferences of choosing one of the sides to run. This strategy described in this control trial listed above prompted me to do more advanced testing of preference behavior. There will be a physiological disturbance from Bobcat Felis rufus odour on the walking pattern of Mice, that will lead to increase avoidance of a predisposed area. Furthermore, I was interested if experimental results before and after the introduction of potential, dangerous stimuli as might show gained memory and strategy.
To answer these questions, I used walking patterns of mice in several trials. I estimated the distance to the stimuli. Furthermore, I found significant relationships between observation and statistical analysis.
Animals can often gain information about the quality of mates and potential predators from the quality of their odour, allowing them to discriminate against individuals of low social class, poor health or potential danger for life. When defending territories that are large and structurally complex, scent marks alone are unlikely to be reliable signal of residentís dominance. Competitors should require initial proof through direct interaction. This was tested using freshly captured Mus spretus, which occupy large non-overlapping ranges in grassland, and are strongly attracted to substrate odors from unfamiliar competitors (Hurst, 1997). The presence or absence of fresh countermarks from competitors within an owner's territory or area marked by a dominant animal, provides a reliable indicator of the owner's ability to defend its territory or dominate competitors (Rich, 1998). All of these factors could have a significant effect on behavior of animals toward specific scent marks.
The experiment was designed to test how mice use odor cues. Bobcat urine is a powerful communicator. It attracts a bobcat to its mate. It warns potential prey like mice and other rodents away from the presence of the most dangerous territorial predator as a signal of his dominance (Knick, 1990). This leads to the prediction that placing territorial adour cues during the experiment will reduce the possibility of mice choosing one side of the maze. Removing odour cues that signal clear danger of one might thus increase the possibility of choosing the side where the scent mark had been placed. This way I also investigated the effect of providing mice with a sent mark that can easily be transferred in and out of the maze. This is a constant environment for the experiment and could show gnomic factors as evolutionary gained experience, phenotype memory, and a response to changes of environmental cue.
The subjects of this study were 10 adult mice obtained from Alverno college animal laboratory. Each of mice was housed in the same room in individual cages. Each mouse was given an identifying number. Prior to the experimental treatments preferences in all 10 mice were scored over a period of 9 hours following the procedure of the first trial with an odour free maze. Next, three trials were conducted with presence of odour and last trial without odour inside the maze. Each time the maze was cleaned by bleach solution. I used Bobcat urine average 5gr. Distributed by J&C marketing, Inc. The Y-maze (150 cm. Long) was made of Plexiglas so I can clean the experimental surface as needed.
I predicted that the physiological disturbance by the predator's odour would lead to increased avoidance of this area and support memory of recent presence of potential predator in the same environment Furthermore I examined the behavior disturbance before and after introduction of the scent and during the presence of predatorís odour. Urine was always placed on the right side of the maze. Introduction of bobcat urine appeared to have significant effect on their preference in first two trials.
The data consisted of the total trial investigations of reaction towards the predator's urine. I compared the five different trials total investigating preference behavior during each exposure, to determine whether mice had habituated to the right or left side of the maze.
I should point out that the measured behavior in this study was a response to natural stimuli, as I would expect to see in nature. No harm or abuse was done to the mice.
I had initial trials, which were free of sent. Trials without presents of odour in the maze represents that mice do not have any specific preferences in choosing right or left side of maze. The P= 0.28 control trial before introduction to the urine, P =. 05-control trial after removal of the urine also supports my conclusion that it is no preference in right or left side of the maze. (Fig.1)
Introduction to bobcatís urine in the maze in 2 &3 trials that mice went straight to the left side where no odour was present. This allowed me to assume that they do recognize possible danger. The data shown in the Figure 2 represents 100% refusal to go right where the urine was located. Finally, I investigated whether there is any change in the behavior on the third exposure. The #4 trial all female mice, went to the side where the urine was present (Fig. 2.)
Most mammals and reptiles, with the exception of crocodilians, aquatic mammals and some primates, have a functional vomeronasal organ that detects and perceives semi-volatile chemicals in the environment. This organ is used in detection of prey and is also important for recognition of conspecifics and potential predators (Miller, 1999). Prey often avoids predator chemical cues and may even appraise perdition risk via cues associated with the predator's diet (Murray, 1999).
Habituation occurred with the same individuals over five separate encounters due to increasing familiarity with an initially novel environment. This habituation is interpreted as resulting from the recognition of the same condition (Thor & Holloway, 1982). To support this behavior I had in my experiment the change in the female behavior. I would assume that females have less sense of territoriality in mice society. The house mice for example use urine marks on the substrate to assess the competitive ability of resident male and avoid potentially costly encounters. This supports the explanation of why after two trial female animals chose to go toward the urine. Removal of predator urine from the maze affect the preference behavior (Fig.1.) showed no significant change in the behavior compared to the first odour free trial. The finding that environmental context does not appear to influence recognition memory suggests that previous positive experience (without actual contact of predator) may lead to ignorance and adaptation to new environment.
In conclusion, clearly we need a better understanding of prey-predator behavioral mechanisms that effect many aspects of evolutionary processes. However, it is not realistic to expect that a full understanding of such mechanisms can be studied in several hours lab period. More research needs to be performed to allow further definition of the role that contextual cues might play in environmental recognition and memory in nonhuman animals.
Hurst, J.L., 1997, Social interaction alters attraction to competitorís odour in the mouse Mus speretus Lataste. Behavior and Ecology Research Group, Department of Life Science, University of Nottinham, Animal Behavior, 54, 941-953.
Knick, S. T., 1990. Ecology of bobcats relative to exploitation and a prey decline in southeastern Idaho. Wildlife
Miller, L. R. Gutzke, W. H. N. 1999. The role of the vomeronasal organ of crotalines (Reptilian: Serpents: Viperidae) in predator detection. Animal Behaviour , 58, pp. 53-57.
Murray, D.L., Jenkis, C. L. 1999. Perceived predation risk as a function of predator dietary cues in terrestrial salamanders. Animal Behaviour, 57, pp. 33-39
Rich T. J., Jane L. H.,1998. Scent marks as reliable signals of the competitive ability of mates. Animal Behaviour, 56, 727-735.
Thor, D. H. & Holloway, W. R. 1982. Social memory of the male laboratory rat. Jornal of Comparative Physiology and Psychology, 96, 1000-1006.