I've already seen two incidents this month where occupied bird nests interrupted tree work. First, when a dying tree, with a deep cavity in the upper trunk was taken down, a little nest with a few blue eggs popped out. Second, in a hedgerow of evergreens being pruned for shaping, one plant held a nest with a single white egg in it.

The fallen nest and eggs were taken to the Silverado Pet Hospital and forwarded to a specialist for incubation. The evergreen was left unpruned until the egg hatches and the chick flies away. It's not convenient but it's the right and legal thing to do.

These are common occurrences when the flurry of human activity, at the onset of nice weather, moves into parts of the garden that have been undisturbed for several months.

I've noticed a certain seasonality, not only in the life cycle of birds, but in the way people regard and plan tree work. There seems to be an annual lull in December and another in early spring as tax time approaches. While we are preoccupied with the holidays, the tax man, or stymied by cold, wet weather in early spring, life goes on outside.

The December lull is a wasted opportunity, since that is a safe month to prune pines and elms, while their associated pests, bark beetles that are attracted to wounded trees, are not active. Not only that, but it's also a safe time in terms of avoiding active bird nests. In a better world, everyone would schedule tree work months in advance and tree workers would all have effective bird nest detectors.

Without exception, I have found that homeowners' hearts are in the right place with regard to bird nests. Even tree workers, who are sometimes regarded as, shall we say, a none-too-delicate bunch, seem to have a soft spot for wildlife. But in their case they must, since there may be serious penalties under the Migratory Bird Act, for disturbing nests.

But even with good planning and due care, nests are occasionally disturbed, and young birds will be left homeless.

We are fortunate in Napa to have an active group of volunteers who are trained, certified and legally permitted to care for injured and orphaned wildlife, the Wildlife Rescue Center of Napa County.

When I last wrote on this subject, one year ago, the center was just about to open its new songbird facility. I'm happy to report that it is open and doing well.

This week I spoke with active volunteer and longtime friend, Rae Sheffer, and got an update on the center. Rae's work is focused on squirrels and jackrabbits, but she spoke about the center in general.

Most notably, and sadly, she mentioned the passing, just this week, of Gayle Thompson. Gayle worked tirelessly for Wildlife Rescue, particularly the baby bird center, and was instrumental in promoting its success. I'm sure the loss of her presence will be keenly felt by those who now carry on her work.

Wildlife rescue is specialized work, and volunteers are trained to meet the needs of the various species that are brought in. Rae helps Pam Condos in working with the furry orphans. Owls go to a separate place for care, and baby birds go to the songbird facility also known as the baby bird clinic.

Unhatched eggs go to another volunteer outside of the Wildlife Rescue Center system. They present a challenge for proper incubation. In some cases it's better to put the fallen nest and eggs in a nearby tree at about the same height and watch for the parents. If they start tending it again within four hours, consider it a successful rescue.

You may find it surprising that one of the common nests found in local trees are those of squirrels. They are often mistaken for bird nests. When I asked Rae what squirrel eggs look like, she laughed and said to tell everybody "Squirrels don't lay eggs."

Rae said that gray squirrels nest in trees, even without babies. They commonly build two nests fairly close by so the mother can easily move the babies if need be. When baby squirrels fall out of the nest accidentally, the mother will retrieve them, but occasionally the mother will push babies from the nest for reasons we may never know. She said that if baby squirrels run up to you, they probably have lost their mother and would be good candidates for the Rescue Center.

The Wildlife Rescue Center is operated by volunteers. But even with unpaid help, the cost is about $10 to $15 per day per bird. If you are interested in volunteering or making a donation, call Pam Condos, 226-5573. To reach the center, call 224-HAWK.

Bill Pramuk is a registered consulting arborist. Please e-mail questions to bpramuk@pacbell.net