I've often written about the wintering habits of chickadees, American toads, wood frogs and northern short-tailed shrews. This week I thought I'd find out how some of my other favorite animals make it through a Minnesota winter.
Crab spiders
Goldenrod crab spiders (Misumena vatia) like to spend summer days hunting from my peonies. These are the spiders that have pink thunderbolt markings on their abdomens and that can change their overall body color to match their surroundings. Their white, pale green or bright yellow camouflage gives them an advantage as they try to ambush prey.
Goldenrod crab spiders mate in early summer on whatever flower the female is hunting on, and the whole process is a bit tricky. Because the females are so much larger than the males, males "tie up" the females with a bit of spider silk before they try to mate, according to Larry Weber's "Spiders of the North Woods."
After mating, female goldenrod spiders attach their egg sacs to leaves and guard the sacs with their lives - literally. Females sometimes die before their spiderlings even hatch out.
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How much a spiderling matures before winter depends on food supply, but the new crop of goldenrod crab spiders spend winter on the ground as immature spiders, in one of several early stages, or instars. They pass the cold months in leaf litter under the snow.
Nevertheless, Larry Weber is frequently able to photograph spiders on the snow's surface, including transverse-banded crab spiders, so it is possible to observe spiders out and about in winter, at least on warm days.
Before I leave the subject of goldenrod crab spiders, let me also say that I once included in the column photos of what I thought were male and female goldenrod crab spiders. I was wrong. Both my photos featured female spiders - one was just larger than the other.
Not only are male goldenrod crab spiders teeny-tiny compared to females, but their carapaces (front section of the body) are also dark reddish-brown, distinguishing them from the all-white or all-yellow females.
Bats
We have seven different species of bats in the state, including little brown myotis, northern myotis, big brown bat, eastern pipistrelle, silver-haired, eastern red and hoary.
According to the Department of Natural Resources (DNR) Web site, all the species are found throughout the entire state, but Stan Tekiela's "Mammals of Minnesota Field Guide" gives range maps for each of the species that seem to indicate otherwise. For instance, according to Stan Tekiela, it seems pretty unlikely that we'll see an eastern pipistrelle in our neck of the woods.
The DNR Web site also states that the little brown and northern myotis, the big brown bat and eastern pipistrelle all hibernate in caves and mines during summer. However, I found a couple sources that indicate bats can make all kinds of choices as to where to spend the winter.
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For instance, Stan Tekiela said big brown bats "rarely winter in caves, preferring to roost alone or in small groups." A 1972 article by Harry Goehring stated that big brown bats sometimes overwintered in a storm sewer in St. Cloud. In a 1992 article, John Whitaker and Sherry Gummer reported that big brown bats overwintered in buildings, "even in the northern parts of their range."
During hibernation, bats reduce their heart rate from about 250 beats a minute to 20, and they lose one-quarter to one-half their body weight. According to Evan B. Hazard's "The Mammals of Minnesota," big brown bats can survive temperatures "well-below" freezing.
Bird news
Dick from Lake Emma Township has been seeing chickadees, nuthatches, downy and hairy woodpeckers, goldfinches and blue jays, as well as "occasional" redpolls and pine and evening grosbeaks. He also said a small bunch of juncos and one tree sparrow are "still around."
Take a break from wrapping presents and let me know what you're seeing in your neck of the woods. When sending your reports, be sure to give your name and a little information on where you made your sighting. Send to maureeng@unitelc.com .
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