Naturespeak A naturalist's view of the world

June 12, 2009

Shedd’n to Red

Filed under: Uncategorized — wykes @ 8:53 pm

I have a love/hate relationship with my backyard Red Squirrels. Things were at their lowest point earlier in the year after these diminutive rodents destroyed my car’s air conditioning fan. Upon seeing the new brood of squirrelets this spring, however, my criticism meter shifted toward the positive side. I will never love these squirrels, but have to admit that seeing mom with one of her little ones provided a nice little natural moment (see above). It was at this point that I noticed that this female was still in the process of shedding her old winter coat and was shedd’n to summer red. You could clearly see patches of reddish orange shining through the coarser gray layer – especially on her shoulders.

The spring squirrel molt can begin anytime between late March and early July and it basically progresses from head to tail.  One study revealed that the sequence starts on the feet, then goes to the head, and moves down the body to the rump. The tail fur, oddly enough,  isn’t replaced until the autumn molt comes along in October.

All mammals have to go through an an annual molt in order to keep up with the changing seasons. This change normally involves a switchover from a long cold weather coat to a short warm weather covering along with a shift in fur color.  The Red Squirrel is an exception to this pattern. When they molt out of  thier winter grays they do not alter the density or length of their pelt, although they do make a color shift. Being small, the difference in heat retention is probably minimal. Larger mammals – at least the northern ones – have to go light in order to keep from sweating to death during the warm season.

One of those larger molting mammals, with whom I also share a love/hate affair, is the White-tailed Deer. This is an animal that undergoes a rather dramatic summer molt to a orange-red hue . I spotted a velvet buck (see above) earlier in the week that had already undergone his molt. This one was well into his antler growth cycle as well. Later on in the same day I spotted a doe feeding on waterlilies in the marsh shallows (see here). This female was in mid-molt and you could clearly see her old hair sluffing off to reveal a smooth orange layer beneath (see below).

Mammal molts are controlled by hormones which are, in turn, controlled by photo-period. The length of daylight, in other words, acts as a trigger to set off the chemical reactions necessary to start producing a new layer of fur. General health, diet, and temperature do have a slight effect as well. The hormonal cause and effect on White-tailed Deer results in a change from long to short hair. During the winter, the hairs are densely packed (over 2500 hairs per squre inch) and long (15-17 mm).  They are also hollow and underlain with a layer of woolly fur. The summer coat, initiated in May or early June, is actually denser than the winter garb ( 5,000 hairs per square inch) but is significantly shorter. Summer hairs are not hollow, so the body heat is quickly dissipated through the new crew cut.

I trust that the next time I spot this female, she will have attained her sleek red persona and will look, well, almost pretty. As long as she doesn’t make any attempt to store any walnuts in my car’s air conditioning fan, my “deer meter”  will drift away from disapproval for the time being.

3 Comments »

  1. I just love squirrels, especially the reds, which are rarer for me to see than the fox squirrels. Do fox squirrels molt as well? I see them almost every day and have never seen any color variation or sparse areas of fur. Thanks!

    Comment by Monica the Garden Faerie — June 14, 2009 @ 6:30 pm

  2. Monica:
    Yes, all mammals shed and I suspect that Fox Squirrels probably follow a similar pattern to the Red Squirrels. It certainly isn’t that noticable, but you will see that summer fox squirrels are a bit scrawnier looking than their winter persona. I think they become more organgish and the pelt is shorter.

    Comment by Gerry Wykes — June 15, 2009 @ 9:07 pm

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