Woodpeckers and the Southern Pine Beetle

James C. Kroll - Associate Professor of Forest Wildlife, Stephen F. Austin State University, Nacogdoches, Tex.
Richard N. Connor - Research Wildlife Biologist, Forest Service, U.S. Department of Agriculture, Southern Forest Experiment Station, Wildlife Habitat and Silviculture Labratory, Nacogdoches.
Robert R. Fleet - Research Associate in Forest Wildlife, Stephen F. Austin State University.

U.S.D.A.
Combined Forest Pest Research and Development Program
Agriculture Handbook No. 564

In 1974 the U.S. Department of Agriculture initiated the Combined Forest Pest Research and Development Program, an interagency effort that concentrated on the Douglas-fir tussock moth in the West, on the southern pine beetle in the South, and on the gypsy moth in the Northeast. The work reported in this publication was funded in part by the Program. This handbook is one in a series on the southern pine beetle.

Woodpecker Responses to SPB Infestations

From 1967-1976 numbers of woodpeckers and of SPB infestations increased substantially in East Texas (Fig. 4). Woodpeckers may have been responding to increasing SPB infestations or to increasing acreage in older, denser stands. They may be an oversimplification, however, since woodpeckers eat both hard and soft mast and other insects.
Figure 4. - Growth of woodpecker populations and SPB poplulations in East Texas, 1967-1976.	Figure 5. - Densities of downy, hairy, and pileated woodpeckers on SPB-infested (open bars) and noninfested stands (shaded bars).

A recent study (Table 1) comparing woodpecker population densities in SPB-infested and nonifested stands showed that woodpecker feeding concentrated on pines within infestations. Woodpeckers probably flew from nearby stands to feed on the beetles. Downy, hairy, and pileated woodpeckers, the primary SPB predators, were 8 to 58 times more abundant within infestations than in noninfested areas (Fig. 5). Densities of red-bellied woodpeckers also increased, but to a lesser extent (3-20 times). The three primary predators increased their activity on pine trees within beetle infestations and reduced their use of hardwood species; red-bellied woodpeckers showed little change in feeding activity on pine and hardwood trees.

Table 1. - Percent of activity by four commonly occurring woodpeckers within pine and hardwood stands in SPB-infested and noninfested East Texas forests during 1975-76. (Sample sizes are given in parentheses.)

Woodpecker Species	Percent of Observation
	Noninfested Stands	Infested Stands
Downy woodpecker
Pines	41 (20)	88 (79)
Hardwoods	59 (29)	12 (11)
Hairy woodpecker
Pines	72 (18)	98 (80)
Hardwoods	28 (7)	2 (2)
Pileated woodpecker
Pines	60 (33)	90 (69)
Hardwoods	40 (22)	10 (8)
Red-bellied woodpecker
Pines	66 (70)	60 (25)
Hardwoods	34 (36)	40 (17)

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