Big snow made squirrel population smaller

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By Sylvia Brockner

With not much to do during the four-day power outage caused by the big snow, I had some time for squirrel watching.

Under deep snow conditions, most of the tree squirrels stay in their treetop penthouses, sleeping away the time. However, when they become hungry, they are forced to venture out to obtain food. When the snow is light and fluffy, they sometimes just plow through it, but when it is heavy, wet snow and 3 to 4 feet deep, that is an impossibility.

During the recent snow, it was warm enough that the snow settled and compacted during the day but then froze over the surface during the night. During the early-morning hours, they could scamper over the frozen surface to find their hidden caches of seeds or other food, but as soon as the sun was up, the surface would soften, and they would sink into the snow. I watched a fox squirrel run across the surface in a shady place and then come to a sunny spot, where he immediately sank into a couple of feet of wet, soggy snow. He could not touch ground but somehow managed to slowly “swim” through the snow to the nearest tree trunk. He finally reached safety and quickly scampered up to aerial pathways where there was less snow. As I watched this squirrel floundering through the deep snow, the thought occurred to me that it was lucky there was no hawk in the area at that particular moment. If there had been, it would have had an easy catch and a delicious squirrel dinner.

Shortly after that, Karel Buckley called to tell me that she witnessed a red fox take a fox squirrel in almost identical conditions in her yard. A bit later she saw another fox trotting down the road carrying what appeared to be another squirrel. Such wet spring snows certainly presented an opportunity for predators and a decline in squirrels.

The longer legs of fox make it possible for them to go through the snow and take advantage of the struggling squirrels. Foxes almost certainly have kits in their den by this time, and with multiple mouths to fill, the large fox squirrels must supply much more food than they could ever obtain from mice, which are safely hidden beneath the snow. Thus, the snow probably decreased the squirrel population for a time and increased the fox and mouse population. All things in nature are interrelated, and the tangled web sometimes produces interesting results.

Squirrels also are either breeding or already have young by now. The little pine squirrel, also known as the western red squirrel or chickaree, usually has two litters per year. Young are born in April or May and again in August or September. Their gestation period is 38 days. Males have been chasing females through the treetops since early April in this neighborhood, so they should have young by mid- to late May.

The big fox squirrels mate a bit earlier. They also have two litters a year. They have two to five young in each litter and therefore can soon replace any that the wily fox has eaten. Fox squirrels are not native to Colorado, coming originally from the eastern states. There are two theories as to how they got here. One is that they were illegally released in City Park by “someone” who missed having squirrels in the park. The second is that they simply moved westward along the plains watercourses and arrived here naturally. When we arrived here in 1965, they were all well established in Denver and as far west as Morrison. We did not have any in our area, but they soon appeared and have steadily increased ever since.

As the fox squirrels have increased, the native tassel-eared squirrels have declined. Today we have none in our yard, but I rarely see one in the more remote areas of Bell Park. They are beautiful squirrels, with big, bushy tails and tasseled ears, and they come in a variety of colors. They can be brown, black or gray and occasionally a pale tan, almost honey-colored. The gray color phase, which has a white belly and silver tips to the tail hairs, is the most beautiful.

The Kaibab squirrel found on the north rim of the Grand Canyon is a color phase of the tassel-eared that is believed to have developed by being isolated on the north rim for many years. Tassel-eared squirrels have also declined because they have no genetic fear of automobiles and are among the most common animals found killed along the highways.

Recently, Kris Laubis of Conifer sent me a photograph of an all-white squirrel that is in their yard. It is not a true albino, for it does have black eyes; otherwise, it is snow-white. I cannot be sure from the photograph what species it is. It is reported to be rather shy and cannot be approached closely, so the picture is not a close-up. There is little to relate to in the picture to judge its size, and it does not appear to have tasseled ears. So, my guess is that it is probably not a western red squirrel, as it appears too large and has too large a tail. It is either a tassel-eared or a fox squirrel, as it has a large fluffy tail. Laubis also said it did not make any sound. Tassel-eared squirrels are quite silent unless really annoyed. If it were a red squirrel, she would have heard its explosive chatter. Tassel-eared squirrels often lose their tassels when molting, so I lean toward that. If that is the case, it should grow new tassels with its next new coat. They also are a bit smaller than a fox squirrel and daintier; the fox squirrel is heavier, and the one in the photograph appears to have big feet, so I lean toward the Albert’s or tassel-eared squirrel. Whichever it is, it is a beautiful creature. It is great to learn about our native squirrels, as they are frequent companions when hiking forest trails.