Keeping a calendar by watching nature

Ray Mueller
Now Media Group


Although birds provide the best signs of the annual cycle of changes and activities in nature, there are many other related events that residents might want to track as a special interest or to use as a timetable for gardening.

That was the message from Rob Zimmer, an Appleton area resident and the nature and outdoor columnist for 10 Gannett daily newspapers in Wisconsin to a full meeting room of 60 attendees at a program on phenology sponsored by the Sheboygan County Master Gardeners and the county's Extension Service office.

Advice to beginners

Phenology is the science of identifying the natural seasonal changes in animal movements and reproduction and plant growth and flowering, especially as they are linked to the weather and climate, Zimmer said. For beginners who want to dabble in phenology, he suggested following one topic such as birds, ground animals, species sounds, wildflowers, one's vegetable garden, the appearance of pests and diseases or a location such as one's yard.

When collecting data on activities and timetables, don't record them online or on a computer, Zimmer dsaid. Instead, make handwritten notes, take pictures, record things on a calendar, keep a journal or, best of all, draw or paint sketches, he said.

'Be descriptive and colorful,' Zimmer remarked. 'Look closely at things. And expect the unexpected. When appropriate, collect examples of plants and press and dry them.' Anyone interested in observing bird nests can do that through an online search engine entry of live wildlife web cams, he said.

January gems

To those who might believe that phenology applies only during a few months of the year, Zimmer disagrees. In his presentation here, he outlined what can be observed every month of the year but he noted that May and October are usually the busiest.

During January, the appearance of snowy owls draws attention and suggests that populations of rodents that they eat are low in their native habitat to the north, Zimmer indicated. He said the number of snowy owls in the area this year was significantly lower than in some previous years.

Bald eagles are active during January finding and carrying sticks to their nest for the new season, Zimmer pointed out. Great horned owls and bard owls also start to nest already in January. The appearance of horned lards is a prediction of spring.

Other birds likely to be on the landscape in the area are migrating snow buntings, juncos and redpolls, for which a close look is needed so they wouldn't be misidentified a sparrow species, Zimmer observed. Hawks are also on the scene in January with the red tails perching about a third of the way up in trees while the very light but larger rough-legged hawks sit on the top of trees.

February favorites

If the winter has forced geese to move to the south, they will follow the receding of the snow line northward during February, Zimmer indicated. He said this movement applies to Canada and snow geese and to gold-eye ducks.

Their appearances are rare but varied thrush birds could be present and it takes a close and careful look to distinguish them from robins, Zimmer said. Another phenology phenomenon during February is the reddening of the bark on dogwood bushes.

March movements

Zimmer said he can almost count on March 14 as the day to see tundra swans migrating through the area, often stopping on ponds in farm fields while during their return migration in the October they choose open bodies of water.

The migration of most birds is tied to the length of daylight and to the angle of the sun – not to the temperatures at the time, Zimmer said. The arrival of the redwing blackbirds, typically in mid-March, is another very reliable indicator of what the calendar date is.

Other natural phenomena in March are the emergence of skunk cabbage, the budding of pussy willows, the peeping of tree frogs, the quacking of wood frogs, the early arrival of some bluebirds and the appearance of morning cloak butterflies which sip the sap from trees about to resume growing for the new season, Zimmer said. He advised amateur phenologists to notice the many interconnections of things in nature.

April activities

The highlights for April include the arrival of robins and the spawning of the lake sturgeon which is linked to having the water at about 52 to 54 degrees, Zimmer said. Woodlot flowers such as hepatica and the spring beauty also bloom in April.

Moving into May, the arriving birds include orioles, scarlet tanagers, indigo buntings and up to 30 species of warblers and leopard frogs can be heard snoring, Zimmer continued. Birds such as the purple martin and others which already have their young depend on insects such as the lake fly as food for them.

The lake fly, which is a local phenomenon, mainly on the shorelines of Lake Winnebago, is a species on whose larvae the sturgeon feed in the lake, Zimmer explained. When in flight along the lakeshore for a couple of days in May, the insect is a nuisance to the immediate area residents but some of them realize that after they die at the completion of the spring flight they can be scooped and used as an excellent garden fertilizer, he remarked.

Summer summaries

During June, watch for black terns in marsh areas and expect irises, shooting stars, pitcher plants, bee balm, wild petunia, swamp milkweed and butterfly weed to bloom. He also mentioned the appearance of the damsel fly, which is distinguished by its emerald metallic wings.

July is the time for orchids to bloom, dragon flies to appear and walking sticks to be found on oak trees, Zimmer noted. He reported that walking stick populations have rebounded after the cessation of spraying for gypsy moths in the area. Much of the spray for gypsy moths was applied to oaks, thereby also affecting the walking sticks.

A huge number of daylily species also bloom during July, Zimmer observed. He once had about 200 species of daylilies on his property, but the total is only a fraction of that now.

August brings the blooming of ironweeds, the blazing star, big bluestem, numerous prairie flowers, and Indian pipes, which tend to have flowers only once in about 10 years, Zimmer pointed out. Having plants suitable for Monarch butterflies before their migration to Mexico for the winter is also crucial in August.

The early indication is that Monarch butterflies had a very successful reproduction year in Wisconsin and elsewhere during 2015, Zimmer reported. This is based on winter habitat counts in Mexico showing a 200 percent increase from a year earlier, which was a 40 percent increase from the previous year.

Autumn activities

September is the prime time for the growth of many mushroom species, for the blooming of the fringed gentian, and the fruiting of the high bush cranberries which can provide food birds well into the winter, Zimmer indicated.

On or about Sept. 14, Zimmer can almost guarantee southward flights of Canada geese prompted by the first cold weather wave of the season. He commented that an unexpected appearance of some bird species anytime during the year can usually be attributed to strong winds or the movement of a hurricane in other parts of the country.

Duck, goose, and sandhill crane migrations continue in October with tundra swans following in November, Zimmer noted. Other activities in November can include the blooming of witchhazel and little bluestem along with the yellowing of tamarack trees.

December trimmings

One observation that Zimmer had in November and December of 2015 was that both chipmunks and squirrels had become quite large. He didn't have an explanation for that.

Once snow falls, Zimmer invited beginning phenologists to watch for animal tracks in the snow and identify those markings. 'You might be surprised to learn what's moving through your yard,' he remarked.

With the change in the surface color of the landscape, provided that it's due to snow, it will be much easier to notice ruffed grouse, Zimmer promised. Once the trees are bare, woodpeckers are much more visible, he added.

Among the long-term changes that Zimmer cited in Wisconsin were the establishment of cardinal habitat throughout state after populations were found only in southern areas as recently as the 1930s, the movement to titmice to the northern part of the state, the overlapping of previously distinct populations of flying squirrels, and the massive southward movement of white-tail deer during recent decades.

Outdoor edibles

To a question about edible wild plants, Zimmer said there is great selection, included many of those which have been listed as invasive species. Among those he mentioned, though with precautions on proper preparation, were garlic mustard, stinging nettle, Queen Ann's lace, sumac berries and teas made from goldenrod and bergamot. A meeting attendee suggested that this could be the topic of another speaking invitation to Zimmer.

There are numerous ways to contact Zimmer, who posts new observations as they occur on his Facebook page. He also has a website at, can be reached by email to or by phone at 920-51-8996 and is available for public appearances and presentations.

In addition to his regular newspaper columns, Zimmer has published books titled 'Voices of the Wind: Four Seasons in Wild Wisconsin' and 'Shadows and Light 2016: Hostas-A Calendar Book.' He is scheduled to be at the Wild Ones 'Toward Harmony With Nature' conference on Saturday, Jan. 30, in Oshkosh to sell and sign those books.