ARBORETUM NEWS (NATURALISTSNOTES)

Animal Signs

SUNDAY, JANUARY 15, 2012

One of the most striking animal signs from Sunday’s tour was the one that WASN’T there – rabbit tracks! Grateful to at last have some snow to track in, I had scouted the probable tour route on Saturday, and was struck by the lack of evidence of bunnies.

On Saturday I did not find ONE rabbit track or trail; on Sunday afternoon we found a single short set of tracks near the Visitor Center building. Normally in January, in fresh snow, I would expect to see them crisscrossing the Longenecker Gardens, especially in the shrub areas.

Could I be overlooking them, I wondered, or confusing them with squirrel tracks? But there were no other signs of rabbits either – their characteristic small, spherical scat (forgive me, but Cocoa Puffs® always come to mind); twigs nibbled to sharp, precise points; or bark and cambium chewed from shrub trunks.

I didn’t have an explanation then, and I still don’t. Thinking perhaps the rabbits were temporarily inactive for some reason, I came back to the Arboretum four days later to see if the story had changed. It hadn’t. Lots of turkey and squirrel trails; much evidence of voles and mice, in the form of tiny tracks as well as the outlines of their subnivian tunnels; but still a marked lack of the typical Y-shaped foot plant of the cottontail rabbit.

“Why” does the track look like a Y? Because the rabbit’s hind feet get ahead of its front feet – literally. As the animal bounds, its rear feet move forward, beyond, and to either side of its front paws. Voila! The characteristic Y pattern.

Squirrels, by contrast, place all four feet in anatomical position (and land them all at the same time). So their track forms a square or rectangle. What’s similar between squirrel and rabbit tracks is the space between the prints.

Of course exceptions to this pattern do occur, and other clues may be helpful. For instance, tracks that go from tree to tree are probably squirrel, and tracks accompanied by small deposits of round brown scat (as above) are likely rabbit. As one veteran Arboretum naturalist puts it with regard to animal-sign interpretation, “If you didn’t see the critter do it, you’re guessin’!”

If there is a dearth of rabbits this winter (perhaps because the coyotes or hawks are eating especially well), it does not extend to my neighborhood, which is immediately adjacent to the Arboretum on the Monroe Street side. By the day following our snowfall, I saw the usual number of bunny tracks in my yard. The Arboretum ecologist reported the same thing when I asked for his opinion.

Time will tell, I suspect. Hopefully the naturalists on the next few Sunday tours will look for rabbit tracks and inform us about their observations.

But enough about what we DIDN’T see … on to what we did (which of course has now been covered by another snowfall, thus subsequent observers will have a fresh slate upon which to hatch their theories).

I stopped the group near the Native Plants Garden pergola/arbor to point out a raised, serpentine ridge in otherwise undisturbed snow. This was the tunnel of a mouse or vole who had scurried about above the soil surface, but screened from the view of predators. Sometimes, near these tunnels, you will see obvious entrance/exit holes and/or tiny tracks and tail prints on the snow; or the tunnel may have partially collapsed. On my return to the Arboretum on Thursday, I saw a great many more such passageways, especially along the east-west firelane of the Curtis Prairie.

Also within the Native Plants Garden area, there was an imprint I always find exciting: a body-and-wing print left by a bird of prey as it has swooped down and caught a meal. In this particular case, we could see the feather-marks on only one side of the impression of the bird’s body – but it still gave us a vivid measure of the creature’s wingspread. Odds are that this print was made by a red-tailed hawk.

We found tracks of much smaller birds as well – usually around the base of prairie plants and forbs, where juncos and tree sparrows had been foraging on the dried seed heads. Once I watched a tree sparrow who had a unique method of seed gathering: the bird would fly up from the ground abruptly, striking its head on the seed head and knocking off some seeds; it would then feed on the bounty it had released. If the grass or flower stalk is strong enough, the little birds will perch right upon it and chow down, but in this case the stem must have been too slender or weak, and the clever little bird had figured out another way. I know it was not accidental behavior, because the sparrow repeated it several times in succession. Good show!

The most plentiful tracks in the Arboretum right now are those of wild turkeys and deer. Deer tracks will show just two toes; turkeys have three toes pointing forward and one aimed back. We have been observing some intriguing “loop de loop” patterns of turkey trails recently; finally someone saw the behavior which produces it. It seems that two males (toms) were displaying to each other. One moved in a smaller circle, and the other in a larger circle around him. Both had their wings extended down, so their flight feathers scraped the ground. (Thanks to Research Gardener Ken Zuba and Native Plants Gardener Susan Carpenter for that report.)

But as fascinating as tracks are, they are by no means the only animal signs we can find in the wintertime. The abandoned nests of bald-faced hornets stand out on the landscape at this time of year. Gray, oval, and papery, they hang from tree branches like old balloons. Nobody’s home; the only member of the colony who will survive the cold season is the queen, safely underground.

One place you can currently see a bald-faced hornet’s nest is along the Arboretum drive between the West Curtis parking lot and the main parking area. It hangs above the road on the west side.

Keep looking up into the trees, and you are sure to spot a squirrel drey – the large, leafy nests in which these creatures overwinter. They are seldom built less than 25 feet from the ground, and are constructed by first-year juvenile squirrels more often than by older ones. Usually they are abandoned after one season and a new nest made.

Fun fact: I read in Hartley Jackson’s classic book Mammals of Wisconsin that in the years 1901 and 1902, gray squirrels became so scarce throughout most of the northeastern US that biologists were concerned the species might be exterminated! Given how plentiful they are now, that is hard to imagine. They surely aren’t “scarce” around my bird feeders!

Enjoy your search for animal signs … and do let me know if you find rabbit tracks.

Kathy miner, Naturalist

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.