Cheryl Ann Mack! age 10  of Wichita, Kansas,, for her question;

Will an ermine turn white in warm winter weather?

The ermine is really a weasel in a white winter coat, Under either name he is cousin to the mink, the marten the otter and the sable, Surely this must be the most expensively dressed family in the animal kingdoms The weasel changes from summer to winter wear by shedding his fur, He grows an entire new coat for spring and fall, In summer his soft fur is always a fine blend of toast color and taffy brown with a black tip to the tail. The winter coat is always thicker. If he lives in the southland where little or no snow falls his winter coat is also tan, But if he lives in regions of winter snows his winter coat is white ‑ with a black tip to his tail:

Of course the furry little hunters color helps him to blend in with his background, He can sneak up on countless. rats and mice without being seen. He can hide from his enemies ‑ the owls the eagles and the snakes, For he matches either the white snow or the brown earth which ever is in season,

Let’s take a weasel from Wisconsin for a vacation in. Florida, And let's take a Louisiana weasel up for winter sports in Oregon. We would expect the northern weasel to change into a winter coat of brown this season, And surely the southerner would know enough to don a white coat for sliding in the snow, Not at all.

The northern weasel will not wear a coat of tan in the Florida sunshine, He will change his coat as usual to snowy white. The native son of the south will don his winter coat of brown according to his custom. Naturally neither little fellow belong in such surroundings, The brown weasel will soon be seen  by his enemies against the white snow. And the white weasel will show up like a beacon in the browns and greens of Florida*

How a weasel changes to an ermine is no longer a mystery say the experts, His tan colors are made by certain glands in his body which cause pigments to color the fur. These glands are stirred up by the sunlight as it strikes the little fellows' bright eyes, In fall, the daylight. hours are short. He doesn’t see enough sunlight to stir up his color‑making glands so his fall coat is made without color. It is white and luckily matches the snow,

In spring the days grow longer, More light shines in the ermine’s eyes, His color‑making glands are stirred up His body makes enough pigment to color his spring coat brown.

Surely this should also work for our visiting weasels, The reason why it doesn’t may be due to habit. Northern and southern weasels have been wearing their winter colors for countless generations. Part of the tendency to change or not to change is inherited. Part is due to the effect of sunlight or lack of sunlight;, In any cases when it comes to weasels a northerner is a northerner and a southern a southerner.