Life History and Reproduction

Reindeer sexually reproduce once a year during the rut (breeding season) which usually occurs around October.    During this time, males compete with one another for access to females by bellowing and clashing their antlers  together, which can lead to injury. To attract and mate with as many femalesMarzoa Alonzo,F. 2006. "TinyReindeer." (image) <>. Accessed 7 April 2009. as they can, they chase after them and thrash their antlers in the bushes to draw attention.5 Males usually control 5-15 females, and during the rut, they stop feeding and lose much weight.  They mate through polygamy (more than one mate throughout their lifetime).  Females (cows) are able to be impregnated at 16 months old, but it usually occurs around 28 months.  Good nutrition is a requirement to give birth each year; without it the female cannot support the pregnancy.  Calves can weigh 3-12 kg, and are born in May or June, which is about 228 days after impregnation. Thus, the average gestation period is 7.60 months.17


The calves are able to suckle from the mother immediately, but this only lasts for about a month and a half, and then they begin to forage.  After 45 days they rely exclusively upon foraging for their food.  For 6 months the calves follow their mothers wherever they go, and then they are weaned. Within an hour after their birth they are able to stand and walk, and can even outrun a human at one day old! 17


                   Nicolas,G. 2005. "Rangifer_tarandus_(Wroclaw_zoo)_-_young_-_body." (image) <>. Accessed 9 April 2009.


 It has been found that protein stored by mother reindeer during the winter is used for 96% of growth of the fetus.  This maternal body protein also comprises 91% of the protein given to the newborn via the milk over the calf's first month of life.  Large stores of fat in the winter months prevent body protein from being oxidized, and it is thought that their tolerance to varying food supplies contributes to both the timing of reproduction and how much protein is invested in it.1

                                                       Riebling, L. 2005. "800px-Rentiere." (image). <>. Accessed 7 April 2009.                                                 

 Females live longer than males, as males live to an average of 4.5 years, and females to 15 years. This is because the rut can leave males weakened from sparring injury or energy expenditure, which leaves them more vulnerable to predation.  An average lifespan of males and females in captivity however, can be up to  20 years.17 



Reindeer aren't the only organisms in the tundra and boreal forest.  Check out interactions with other species next!



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