BI 441 – Animal Behavior
We tested whether male adult house mice (Mus musculus) would successfully find the food at the end of a Y-maze faster than female adult house mice. We placed all the mice at the end of the Y-maze and timed how long it took for the mice to find the sunflower seeds at the end of the left arm of the maze. We found that there was no significant difference between the male and female mice.
In this experiment we thought that by giving the mice some time to habituate they would be more comfortable in a environment with the least complexity, such as barriers, a lot of turns, or long to complete. Previous studies also suggest that the physical structure of a habitat has intense effects on competition among small mammals (Gray et al 2000). This is why we chose to conduct the experiment using a Y-maze because the maze was not complex and was a simple structure for each mouse to do its experimental testing. We also found that, high testosterone levels in male house mice, Mus musculus, increase aggressive behavior and lead to a greater overall survival sense when compared to mice with low testosterone levels (Zielinski et al 1993). Furthermore, Zielinski states the “testosterone level leads to a variation in dominant behavior and competitive ability of the male and female house mice” (Zielinski et al 1993). Therefore, because a male mouse has more testosterone than the female mouse, we think it is possible that the male will do better in an experiment that provides competition among the male and female mice. Although the males and females complete the maze separately, we thinks it is possible for the males to complete the maze in a faster time due to higher testosterone levels than the female mice. For this reason we proposed that when given a reward, male house mice will successfully complete the Y-maze in a faster time than female house mice.
On February 27, 2002 at Alverno College, we took 10 mice that were housed in cages and brought them into a classroom setting to test them in a Y-maze. The Y-maze, which is shaped like a “Y,” is made of plastic and has nine walls (Figure 1). We tested 5 male and 5 female mice over a span of 2 and one-half weeks. Sunflower seeds were placed at the end of the left arm of the Y-maze. Each mouse was placed at the beginning of the maze and timed with a stopwatch until they reached the sunflower seeds. The stopwatch was stopped when the mice either ate a seed or sniffed the seeds. After each mouse was tested the maze was wiped clean with water and new sunflower seeds were added. The tests were started on Wednesday at 1300 hours and ran every Monday and Wednesday for the next 2 weeks at 1300 hours. The mice always ran the maze in the same order with the female mice running first. The data was then analyzed using Microsoft Excel, version 7.0.
Fig. 1. Y-maze, the environment that each mouse conducted the experiment.
There was no significant difference between the amount of time it took the female mice and the male mice to reach the end of the maze, Figure 2 (P = 0.16). The mean time for the female mice to complete the Y-maze was 20.5 seconds and the mean time for the male mice was 17.25. The standard deviations were 12.19 for the female and 11.33 for the males.
Fig. 2. Average response time for male and female house mice to complete a Y-maze when given a reward.
The male house mice in this study did not significantly complete the Y-maze in a faster time then the female house mice. These findings are not consistent with the hypothesis that when given a reward male house mice will successfully complete the Y-maze in a faster time than the female house mice. This may coincide with research that claims mice may not develop quick response strategies when given small tasks (Valsecchi et al 2000). Therefore, the male mice may not have utilized a strategy in order to complete the maze in a faster time than the female mice. Another factor for which the male mice may not have completed the maze in a faster time than the female mice may be due scent markings. Although we cleaned and washed the mazes, the mice may still have picked up the scent from another mice. One study suggests that odors or scent markings represent individuals among many rodents (Hurst et al 2001). This suggests that a mouse can distinguish its own odor from another rodent’s odor. For this reason we think it is possible that the mice in this experiment were distracted by each other’s scent and therefore did not complete the maze in a faster time. We were also shocked to see that the testosterone levels in the male mice seemed to have no effect on the mice completing the maze in a faster time then the female mice. If we were to re-do this experiment we would include different mazes for each mouse in order to eliminate interference among rodents.
Gray, S.J., S. Pelsner-Jensen, J.L. Hurst. 2000. Structural complexity of territories: preference, use of space and defence in commensal house mice, Mus domesticus. Animal Behaviour 60: 765-772.
Hurst, J.L., C.E. Payne, C.M. Nevison, A.D. Marie, R.E. Humphries, D.H. Robertson, A. Cavaggioni, R.J. Beynon. 2001. Individual recognition in mice mediated by major urinary proteins. Nature 414: 631-634.
Valsecchi, P., A. Bartolomucci, M. Aversano, E. Visalberghi. 2000. Learning to cope with two different food distributions: the performance of house mice, Mus musculus. Journal of Comparative Psychology 114: 272-279.
Zielinski, W.J., J.G. Vandenbergh. 1993. Testosterone and competitive ability in male house mice, Mus musculus: laboratory and field studies. Animal Behaviour 45: 873-892.