With the approach of Valentine's Day, the thoughts of many people turn to romance. With apologies to my wife, my thoughts also turn to turkey vultures.

With the approach of Valentine's Day, the thoughts of many people turn to romance. With apologies to my wife, my thoughts also turn to turkey vultures.

If you are attentive, you can find the first signs of spring in September. It's a game I play to stretch out the season I enjoy the most. It all begins with the fall rains. As the rains moisten the soil that has been baked under a relentless sun since June, the seeds of countless annual plants germinate. A carpet of seedling stork's bill, poison hemlock, bulbous bluegrass, draba and a host of others bask in the autumn sun, putting down roots, getting ready. They must pause as the cold weather sets in, but they will be ready for late February and March to bolt and flower and seed before the soils dry once again. We live in an area where most of the precipitation falls in the winter months. The warmth needed for unbridled photosynthesis comes later. Because of this, there is a rush to grow in that brief period when warmth and adequate soil moisture intersect.

Birds aren't quite so ambitious. The first sign of spring each year are the courting great horned owls. Duets of hooting begin about Thanksgiving. Incubation begins in February in our area. Our resident red-tailed hawks start repairing nests in December. A warm sunny day with a slight breeze will have them courting at New Year's, and incubation begins in late March.

The real spring show begins in the waning days of January. The first tree swallows return from Southern California and Mexico about this time. It's always a bit of a question, because a hardy few attempt to winter in the valley — usually along the Rogue River, where there always seems to be a few insects in the air. Still, the small flocks that appear, usually near Denman Wildlife Refuge near White City, are the vanguard of spring. Studies have shown that these explorers pay a high price for their eagerness. Mortality is high if hard freezes occur.

Vultures are the second bird to scale the Siskiyous and drop into the valley. Three years running I saw my first rather miserable-looking flock huddled in a grove of trees on Valentine's Day. They have become my Valentine's Vultures and always bring a smile to my face.

Spring is coming for sure. Now, before we establish a Valentine's Vulture Day in the valley, I should acknowledge they don't always arrive on this date. The day, with much variation, has been nudging earlier in recent years. I can't say whether this is due to climate change or more observers.

Still, vultures depend on flight conditions and time their migration accordingly. The thermals they rely on to cruise the valley are produced by the sun warming the surface of the earth. The invisible bubbles of rising warm air are the secret to their effortless flight. They don't migrate because there is a shortage of roadkill opossums in winter. Food is plentiful year round.

As Valentine's Day approaches, check out the skies as you shop for chocolates and flowers. Spring is coming, and so are the vultures.

Stewart Janes is a biology professor at Southern Oregon University. He can be reached at janes@sou.edu.