Polar Bears - Data, Pictures and Videos

[sanjay]

Question: How much milk do polar bear cubs drink?

Answer(Dr. Thea Bechshoft) :

good question (and one that took me to new nooks and crannies of the polar bear literature!).

Healthy polar bear cubs increase massively in weight from the day they are born (500-800 gram) to the day they emerge with their mother from the maternity den (10-12 kg). This rapid weight gain comes from the cubs drinking their mother’s milk. Polar bear milk is the fattiest of any bears’. It contains about 40% fat when the cubs first start nursing, and decreases to around 20% as the cubs grow older. The fat percentage and the quality of the milk is of course also dependent on the mother’s body condition – the less body fat she has, the less fat she will be able to pass on to the cubs through her milk.

Although quite a few studies have looked into the quality and composition of polar bear milk, only one group of researchers have looked at the amount of milk consumed by polar bear cubs: in their study published in 1990, the researchers Arnould and Ramsay estimated that polar bear cubs in Western Hudson Bay during the ice-free period consumed 469 gram milk/day for cubs of the year (those under 1 year of age) and 131 gram milk/day for yearlings (those over one year old, but still with their mother and still nursing). Another way you could try to get this question answered would be to contact a zoo that has had to hand-raise a polar bear cub. Although the milk formula used for hand rearing the cubs has a somewhat different composition than actual polar bear mother’s milk, it should still give you an indication of how much the cubs consume.

I've found two videos for you: a polar bear nursing her single 2-3 month old cub (https://www.youtube.com/watch?v=MN2crSgz4PM) and a polar bear nursing her almost 2 year old twin cubs (https://www.youtube.com/watch?v=Ijq0qmH_Q9I). The cubs will often make a sound called trilling when nursing or simply well fed and happy - have a listen here: https://www.youtube.com/watch?v=FrPpj0MXB-s. Finally, for comparison: human babies drink about 750 ml (= approx. 750 gram) milk per day during their first 6 months (there is of course a huge variation - as mentioned, this is an average). However, human breast milk is only about 4% fat, meaning that human babies may drink more milk, but polar bear cubs have a much higher energy intake per serving. Reply