An important skill I teach my biology students is how to make relevant observations of their surroundings, not only in the classroom/laboratory but also in the field. If we embark on a walking trip around Northwestern's nature trail, for example, we start by tilting eyes skyward to reckon the weather conditions.

Before even setting foot into the woods, we jot down notes about time of day and year, percentage and type of cloud cover, wind speed and direction, precipitation, and ambient temperature. Many people take such non-living environmental factors for granted, but all are exceedingly important to organisms they affect on a day-to-day basis.

Even casual observers may sense a relationship between temperature and degree of activity at bird feeders, or between time of year and the appearance of the first wild dogwood blooms, but it takes a deliberate observer to be able to actually predict when some of these happenings will occur. Many backyard naturalists delight in discovering environmental influences on living things, and there's even a name for such study: "phenology."

The word "phenology" comes from the same Greek root that gives us "phenomenon," an appearance or occurence, and "-ology" means "the study of" something. Phenology, then, is a branch of science that mainly studies cyclic
phenomena of living things in relation to seasonal changes, climate, and other ecological factors.

(By the way, don't confuse "phenology" with "phrenology," which is the study of the bumps on peoples' skulls, or with "penology," the science of prison management!)

In my classroom, we have started a "Northwestern Phenology" that is really just a big calendar on which we record various observable changes in the natural world around us. On it we've noted an early date (3 April) for this year's first Eastern Bluebird egg, and the season's first male Ruby-throated Hummingbird that I banded on on 2 April at Hilton Pond near York. In 1985, I saw my first hummingbird on 5 April, so perhaps this year's arrival was a little early because of our warm Easter week. Maybe the bluebirds are a bit ahead of schedule for the same reason.

Obviously, without phenological records from year to year, we'd have no way of knowing when to expect hungry hummingbirds and when to put up the nectar feeders (always by the 21 of March), nor would we know to have the bluebird boxes cleaned out and hung by 1 March at the latest. Next year, an April Fool's frost may slow down the first hummingbirds, but at least we'll have a sugar source available to supplement the diets of any early arrivals.

As an ornithologist, I'm especially interested in what birds migrate when in the Carolina piedmont. Purple Finches that loaded up on sunflower seeds all winter are about gone from my York feeders by mid-April, but Pine Siskins are still present in good numbers; both are northern species that breed in New England and Canada. The first White-eyed Vireo was singing locally on 31 March, and a Chuck-will's-widow was calling from open fields around my house five days before that; both these species have just returned from wintering grounds in Central America. On 2 April, I was excited to see two Ospreys flying over my property, stopping off to dive for fish in Hilton Pond before wandering on toward their breeding territory, probably on the South Carolina coast.

Some other phenomena worth writing in a phenology might include first dates of chorus frogs calling from ponds or puddles, snowfall and hailstorm occurrences, early redbud tree blossoms, the first edible wild blackberry, and so forth. Making and recording observations like these serve to make anyone a better observer, and better observation develops interest, understanding, and a much better appreciation for the natural world of which we are a part.

If there's space on your kitchen calendar you might start your own "backyard phenology," or perhaps you'd like to help compile one for York County or South Carolina by sharing observations through the Nature Study Network.

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