In other regions. – Sapsuckers cannot be dismissed lightly because the tree species damaged here do not exist, or are of minor importance, in other regions. One thing appears quite certain: If sapsuckers spend much time in an area, they probably are feeding on live, woody vegetation of some kind.

The feeding patterns observed here might be similar elsewhere in the northern nesting range – wherever the tree species are similar and nesting occurs. Elsewhere, differences probably occur in the tree species used and the feeding dates – especially in the wintering ranges.

Should damaged trees be cut? – We do not know how sapsuckers would react if their favorite feeding trees were removed for stand improvement. in this region, when sapsuckers kill their own favorite feeding trees, they simply move to other trees and continue their feeding. I have seen that repeatedly. in those areas where timber cutting has removed sapsucker-damaged trees, the birds began drilling undamaged trees. In other areas, heavy cutting has forced the birds to concentrate in adjacent woodlands, where abnormally severe sapsucker damage then occurred.

Cutting sapsucker-damaged trees to improve timber stands might be more likely to discourage migrant birds if they had another source of food within reasonable distance. But nesting sapsuckers would still need feeding trees. I believe local sapsuckers would simply turn to the available trees left in the stand – and these might be the best trees left after timber stand improvement.

Healthy trees also damaged. – Prior wounds on a tree are not necessary to attract sapsuckers. If sapsuckers occupy a nesting territory in this region, they will readily start new wounds on undamaged healthy trees. Among the 535 trees used for this study, only 5 had sapsucker drilling above earlier wounds made by an agent other than sapsuckers: 3 were above cankers or conks, 1 was above a partial porcupine girdle, and 1 was above a dead area that probably resulted from sapsucker drilling about 6 years earlier.

However, old sapsucker wounds on trees are highly attractive to sapsuckers. These wounds provide the basis for much future intensive sapsucker feeding in this region, and I believe the same should apply in any region. These trees may – or may not – be used first. It is common, in stands where there are many trees to choose from, for sapsuckers to begin feeding on undamaged trees, even though old feeding wounds occur on other trees nearby. For example, among a different group of 557 sapsucker-damaged trees I found in 1964, 49 percent had only damage that had been done prior to 1964, 25 percent had old and 1964 damage, and 26 percent had only 1964 damage. There were 116 conifers and 441 hardwoods.

Sapsuckers kill trees. – Can sapsuckers kill trees? That question has been asked often. They are known to kill at least 32 species of trees, shrubs and vines (4). For over 50 years persons reporting sapsucker damage have said that sapsuckers can kill trees of some species (1, 4, 5, 6). Occasionally it has been hinted that some other virulent organism also may be involved, but evidence has not been presented to support it.

In the course of this study I watched 22 trees gradually die during a period in which they sustained severe sapsucker damage: 16 were paper birch, 1 was gray birch, 1 yellow birch, and 4 red maple. The same birds and trees were observed repeatedly from the time damage began until the trees died. No other kind of animal damage appeared on these trees. When the band of holes became large enough, and occurred below all branches, the entire tree died. If one or more branches – of any size – occurred below the holes, they remained alive, but the tree above the holes was killed. The latter condition is common; it occurred on 112 hardwoods of the 557 sapsucker-damaged trees I found in 1964.

Hemlock a key species. – Hemlocks may be an important link in the life history of sapsuckers. It is an important early spring food in Maine for local and migrating birds. The evidence indicates that the same applies in the Adirondack Mountains of New York, and on the Allegheny National Forest in northern Pennsylvania. Feeding occurs on eastern hemlock in Vermont and West Virginia, and on Carolina hemlock in South Carolina and Georgia (4).

A western race of sapsucker damages western hemlock (2, 4, 11).

I believe that future observations will reveal similar use of hemlock over a much larger area. If you wish to make a quick check for evidence of sapsuckers, look at the hemlocks. If nesting does not occur in a region, migrants probably made the holes.

Apple a key species. – Sapsucker damage can be found in many apple orchards. But the impact of that damage on fruit trees has not been studied intensively in the Northeast (4). Current evidence suggests that trees of the apple family may form an important link in the life history of sapsuckers. These trees provide an abundant, easily located source of food during fall migration – and may thus sustain the birds on their movement to their wintering grounds among southern forests.

Migrants add to damage. – Migrating sapsuckers add to the damage caused by local nesting birds. Both spring and fall migrants normally used the same trees damaged earlier the same year, or in preceding years. Migrants pass through our local sapsucker territories in several waves. Individual migrants stay and feed for several hours to a week or longer. Later migrants may use the same trees.

I believe this habit also might prevail farther south, between the summer and winter ranges. But there only waves of migrants would be involved, not nesting or wintering birds.