Title
Using geometric probability to compare the random and actual mating success of the African
Elephant
Author
Yared Armstrong
Abstract
“Observations on the breeding of the behaviors of the African Elephant (loxodonta Africana) in
Uganda show that some wild females begin to breed are approximately 7 years and all females
breed by approximately 11 years of age. A declining population and lower annual increment of
elephants south of the Victoria River in Murchison Falls National Park are associated with an
average postpartum preconception interval more than three times longer than the 24.1- month
(sic) period reported 1953 by Perry. The change in length in interval is possibly a function of
self- regulation in population members. At least in some parts of its range the wild African
elephant breeds throughout the year with no distinct seasonal acceleration. Corpora lutea present
during early pregnancy are not replaced during the subsequent stage of pregnancy but are
maintained throughout gestation for about 2 month after parturition. Old or degraded Corpal
lutea persist for at least 45 years postpartum. Apparently in some animals copra lutea develop
before conception, whereas in others, conception apparently occurs when corpa are established.
At least two graafian follicles may ovulate and develop in to corpa lutea within a short time.
Cows have multiple mates, there is no prolonged male-female relationship, and frequently there
are no fighting bulls over females.” (Buss & Smith, 1966)
Introduction
The African Elephant is one of the largest animals in the world with one of the most
elusive mating rituals (Moss, 1988). The male African Elephant reproduces by first courting a
female and then mounting on her back for intercourse. Elephants actually have a very low
reproductive rate due to the difficulty of intercourse and the in some species the age at which
reproduction begins has an effect on it as well. Elephants mate when the male has found a
willing female through the act of courting, or attracting a mate; who he then mounts. The male
places his front feet on the females back, just so, that she supports herself and his weight. This
renders the female immobile because if she moved his weight could seriously hurt her. Once
mounted, he then attempts penetration. This can be a slow process due to the size and distance of
the target the male must hit. Once, and of, penetration is successful the sperm then goes in to the
vagina and fertilizes the egg.
Method
Random mating refers to the probability of a hitting the female elephants bulls eye out of
100 attempts. This is found through a geometric equation dividing the surface area of the target
and then dividing by the area of the actual target. The lines surrounding the elephant are the
surface area of the elephant. And the circle is the middle of the rectangle shows where the male
elephant has to penetrate to successfully mate and reproduce.
Figure 1: I found this image using Google, the website is at http://www.researchlive.com/features/elephant?-what-elephant?/4007246.article, the area of the rectangle, which is
the area of the back of the female which the male elephant approaches and mounts. The circle
represents the bull’s eye, or vagina, and is divided by the area to find the random probability of
mating success.
Results
Target surface area (Circle): 3.14x 1.52 = 3.14 x 2.25= 7.06cm2
Target surface Area (square): 17x5= 85
Total Target Surface Area: 7.06cm2 +85= 92.06 cm2
Random probability of mating success: 7.06/92.06= .0766 x 100 = 7.6%
According to my calculation the target surface area is only 7.7% of the total surface area of the
female elephant, which is very small considering their size. Therefore, by chance alone, only 7
darts out of 100 would hit the bull’s eye.
Discussion
African Elephants mate in a random fashion, not waiting for any particular season,
because they just roam around and look for a mate not only is witnessing this challenging but the
chances that randomly an elephant will be successful at mating is only about 7%. The Elephant
has a unique problem with mating because of the low productivity of this species, the term only
the strong Survive applies strongly here. The elephants also face the challenge of their weight
when in the mating stance. Once the male has mounted the female, she cannot move until the
male either penetrates and can deliver the sperm or until he gives up and gets off. From the video
we watched in class, elephants court before mating by doing what is best described as kissing
with their trunks and feeling up the other elephant (Brown, J. L., Olson, D., Keele, M., &
Freeman, E. W., 2004). Elephants do not keep the same partners, one male will mate and then
leave the female with the baby and go mate with another.
References
Brown, J. L., Olson, D., Keele, M., & Freeman, E. W. (2004). Survey of the reproductive
cyclicity status of Asian and African elephants in North America. Zoo Biology, 23(4),
309-321.
doi: 10.1002/zoo.20006
Buss, I. O., & Smith, N. S. (1966). Observations on reproduction and breeding behavior of the
African elephant. The Journal of Wildlife Management, 30(2), 375-388.
doi: 10.2307/3797826
Moss, C. J. (1983). Oestrous behavior and female choice in the African elephant. Behaviour,
86(3/4), 167-196.
Plotka, E. D., Seal, U. S., Zarembka, F. R., Simmons, L. G., Teare, A., Phillips, L. G., Hinshaw,
K. C., & Wood, D. G. (1988). Ovarian function in the elephant: luteinizing hormone and
progesterone cycles in African and Asian elephants. BIOLOGY of REPRODUCTION,
38(2), 309-314.
doi: 10.1095/biolreprod38.2.309