Their techniques can unfortunately be quite damaging to other features in the garden. They really like digging into thick lawns. They also dig up recently planted cool season annuals and vegetables to replant in the freshly cultivated soil below, or perhaps because they think that they might find what someone else had buried earlier.

The squirrels and birds that cause this damage do not actually intend to plant forests of oaks and walnut trees. They are simply storing groceries for later in winter. It is only incidental that trees grow from the stash that they do not dig up later. A few acorns and nuts get left behind because they may be surplus, because whoever buried them forgot where they were, or perhaps because squirrels and birds really do plant for the future.

Birds (but not squirrels) dig also to find grubs that live in loose moist soil or under lawns. Like their planting techniques, their pest management techniques are not performed to directly benefit the garden, but because birds get hungry.

There does not seem to be any practical prevention for damage caused by squirrels and birds. Some birds are more or less repelled by flashes from reflective materials such as strips of silver Mylar (found in some garden centers) or CDs, but they eventually become accustomed to such devices. Trapping squirrels is only temporarily effective because other squirrels simply move in from surrounding areas.

Freshly planted annuals, vegetables or shallowly planted bulbs can be protected with chicken wire. This wire can be suspended by forked twigs and should be weighted or slightly buried around the edges so that squirrels cannot get underneath. Hopefully, these plants will be too mature to be bothered by birds or squirrels by the time the chicken wire must be removed to accommodate their growth.

Later on, it may be necessary to pull oaks or other seedlings from the garden. They generally appear where they are not wanted: in pots, planter boxes, lawns or cultivated flower or vegetable beds. If any appear where they are not immediately in the way, it is important to consider how big they will get before leaving them to mature.

It is unfortunate that birds and squirrels are not very interested in the annoying maces (fruit or seed capsules) that fall from sweetgum (liquidambar) trees. The only way to possibly limit their profusion that I know of is to have a licensed applicator spray a caustic substance known as Florel precisely during bloom, which singes the maces off before they develop.

Incidentally, a formerly mysterious bleeding of sap among many local sweetgum trees in early 2004 has been attributed to excessive application of fruit eliminator.

Greenery of the Week: Cotoneaster

Of the various cultivars (cloned varieties) of cotoneaster, several that are low and sprawling are useful as groundcover. The classic rock cotoneaster, Cotoneaster horizontalis, can spread to more than 10 feet wide without getting much deeper than two feet. Birds enjoy the profuse clusters of rust-red berries in winter. The round half-inch long leaves turn orange and red before falling off to be quickly replaced by bright green new foliage. The small white flowers are profuse in spring. The increasingly popular "Lowfast" cultivar is even shallower with slightly larger evergreen leaves.

Cotoneasters actually prefer neglect to regular maintenance and irrigation. They can be somewhat weak in rich and frequently irrigated soil. Pruning compromises their naturally appealing form of arching, limber branches. Ground cover types looks best if allowed to sprawl without defined boundaries where the edges get pruned.

Horticulturist Tony Tomeo can be contacted at 408.358.2574 or at LGHORTICULTURE@aol.com.