Ask The Biologist

Were Having Triplets!

Were Having Triplets!

By Bob Humphrey

It’s pretty common to see a doe with two fawns, but how often do they have triplets, and can you predict what sex they’ll be?

QUESTION: I shot a white-tailed doe on Dec. 26 in Middle Tennessee. She had three button bucks with her, and I would guess they were hers by the way they acted traveling with her.

While field-dressing her, I discovered she was pregnant with three again. This was the first time I have seen triplets during hunting and was surprised to see she was pregnant with another three.

The embryos were very well developed, so she must have bred early. How unusual is this? — David R.

ANSWER: Research has shown that fecundity — a female’s ability to produce young — is directly related to nutrition. Under average conditions, does first breed as yearlings and often bear one fawn. Mature does most often give birth to two. Under highly favorable circumstances, doe fawns may breed, and adult does sometimes produce triplets. In one study on supplementally fed in a Michigan enclosure, 14 percent of mature does had triplets.

The fact that all three fawns you observed were button bucks is interesting. The odds of a fawn being either a buck or doe are about 50:50. But, like the flip of a coin, it’s always the same for each fawn; the fact that one fawn is a buck has little if any effect on the sex of its sibling.

However, there is some evidence, although it’s not confirmed, that the stress associated with dense populations can influence sex. The theory is that does produce more male fawns as a natural means of population control.

You wouldn’t expect triplets under those conditions, however.

In the case of your doe, it’s more likely that the coin came up heads instead of tails on three out of three flips.

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