ARBORETUM NEWS (NATURALISTSNOTES)

Phenology

SUNDAY, JANUARY 5, 2014

WARNING: These notes contain references to blood, guts, excrement, and death. Sensitive readers may wish to close this document now.

Still with me? Good. Temperature and wind putting us very close to the category where bare skin gets frostbitten within 30 minutes, we limited our time outside on Sunday afternoon, but we found some pretty interesting things anyway.

But first, we chatted a bit indoors about phenology – what it is, how it’s practiced, and some calendars and other tools for keeping track of it. Then I read “January Thaw” from Aldo Leopold’s A Sand County Almanac. To my mind that particular essay is a great introduction to phenology – “that ceaseless cycle of beginnings and endings which we call a year”.

Generally my first phenology notes in any given year have to do with birds singing – cardinals, chickadees, house finches. Given the frigid weather, I didn’t expect to hear any of those on Sunday, and I was right. The best we could do was find evidence of some seasonal animal activities.

Large three-toed tracks showed us where wild turkeys had walked. These birds often roost for the night in the tall white pine trees just north of the Visitor Center. A really crisp print will show the bird’s talons, one at the tip of each digit, fore and aft.

Reddish-orange stains on the snow were probably rabbit urine. The color is commonly seen, especially in winter, and may have to do with what the animal has eaten. One particular specimen seemed large for a rabbit, but I don’t know what else it would have been.

I’m going to invoke the words of retired Arboretum naturalist Jack Borders here. Referring to identifying tracks and scat, Jack would say, with a twinkle in his eye, “If you didn’t SEE the critter do it, YOU’RE GUESSING!” A generous dose of humility is a good thing; I’m always wary of people who sound overly sure of themselves when identifying animal sign.

Under and around the white pines, we searched for evidence of a coyote gathering. An Arboretum staffer had reported hearing lots of yipping from that area on Friday evening – possibly signaling a group kill and meal – so we hoped to find clustered tracks or other evidence, but that was not to be. Enough snow had blown in over the weekend that many prints were unclear.

Deer trails showed us where white-tails had wandered about in the yew collection. We carefully examined the snow fencing in one especially narrow passageway, hoping to find a snagged hair or two. No dice. Each hair in a deer’s winter coat is hollow; the air spaces provide insulation from cold winds as well as buoyancy in water, should the animal need to swim. Uncomfortable thought!

We did find a place where a deer had recently bedded down, next to one of the yews. (I made a “B & B” joke, since yews are a favorite winter food of white-tails, although the protective fence around the shrub seemed to have worked in this case.) What we saw was a deer-sized dent in the snow, with scat and urine just off to the side of it. Bedroom and latrine, conveniently located en suite.

My sharp-eyed tour guest saw a tiny animal – presumably a meadow vole—dash under another shrub. We watched for a while to see if the creature reappeared, but it was too wise (or perhaps too cold) to do that.

Vole tunnel-holes are easy to spot in the snow. The hole is about 1” in diameter; the tunnel proceeds down at an angle. In winter voles spend most of their time beneath the snow, moving about in the matted-down grass there and feeding on seeds they find along the way, but occasionally they come up above the snow surface, for example to gnaw on the bark of shrubs.

The most exciting find of the day actually came after the official tour was over. Hearing a reference to “a big pile of guts” near the bend in the service drive east of the Visitor Center, of course I had to go and investigate.

I found a place where a rabbit had met its doom. There was just enough fur, and part of a leg and foot, remaining that I could tell what kind of animal it had been.

The rest was innards: stomach, other internal organs, looped intestines of two different sizes. A small amount of blood spotted the snow.

Sometimes we know that a hawk or owl has been the killer, if there are clear wingfeather prints adjacent to the remains. Here I did see shallow parallel ridges in the snow off to the sides, but they were longer and more linear than I’ve seen before. Did the raptor struggle to take off? Or did something else entirely make those marks? Other tracks, including human, were in the area, confounding the story. It’s likely to remain a mystery.

One creature died and became food for another one; of that we can be certain. The lessons of Nature are not kind, but they are practical, and life endures in one form if not in another.

In the coming weeks, as temperatures rise and daylight hours lengthen, we are bound to begin observing bird songs, birch catkins opening to scatter their starlike seeds on the snow, and other signals that winter’s days are numbered. Keep that thought in your heart when the thermometer dips far below zero. Stay warm!

Naturalist: Kathy Miner

Located between Lake Wingra and the West Beltline Highway at 1207 Seminole Highway, the University of Wisconsin-Madison Arboretum features the restored prairies, forests and wetlands of pre-settlement Wisconsin. This 1,260-acre arboretum also houses flowering trees, shrubs and a world-famous lilac collection. Educational tours for groups and the general public, science and nature-based classes for all ages and abilities, and a wide variety of volunteer opportunities for groups, families and individuals are available.