Do birds return to the same nest year after year? All winter, when the deciduous trees are bare, I look at clots of debris high in their branches and try to pick out which are just clumps of leaves and which are nests. The obstacle to solving this puzzle is that the old nests are obscured by leaves by the time birds might come back. The trees leaf out before most birds begin nesting. It’s hard to tell if the nests are used again.

Only occasional observations have presented themselves over the past years of bird watching. Chickadees nested in one of our nest boxes two years in a row. A spotted towhee has nested in the hedge across the street for five or more years. And the herons down by the ponds start their nesting season long before the cottonwoods leaf out. The East Delta Pond rookery broke up 15 years ago when a pair of bald eagles started marauding their young. The number of active nests plummeted, probably fledging no young heron in some years. There has been resurgence this spring: Six nests are being tended. Four are old ones, two are new or dramatically refurbished. It will be interesting to see how they fare through the season.

Extra warm, sunny days, the ones that approach record highs, bring out everybody to stretch their wings. Literally in the case of birds, figuratively in the case of quiescent snakes and dozing turtles. And, of course, me too!

David Wagner is a botanist who has lived in Eugene for more than 30 years. He teaches moss classes and leads nature walks. He may be reached at fernzenmosses@me.com.