EFFECTS OF PAPER-MILL SLUDGE IN SPRUCE-FIR FORESTS ON WILDLIFE IN MAINE

The pulp and paper industry has spread waste sludges containing low le vels of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on forestland. We s tudied the effects of sludge in regenerating spruce-fir (Picea spp.-Ab ies balsamea) forest stands on habitat and populations of breeding bir ds, small mammals, and invertebrates in Maine. Sludge was applied to 1 randomly selected site from each of 4 pairs of sites in August-Septem ber 1990. We conducted population and habitat studies prior to treatme nt in May-August 1990 and on treatment and control sites in May-August 1991 and 1992. Thirty-four bird species established territories and 1 1 small mammal species occurred on study sites. White-throated sparrow s (Zonotrichia albicollis), common yellowthroats (Geothlypis trichas), magnolia warblers (Dendroica magnolia), alder flycatchers (Empidonax alnorum), masked shrews (Sorex cinereus), and southern red-backed vole s (Clethrionomys gapperi) occurred on all sites in all years. Breeding bird density did not differ among years (P = 0.14) and was not affect ed by sludge treatment (P = 0.26). Small mammal abundance differed amo ng years (P = 0.01) but was similar for treatment and control sites (P = 0.36). The number of territories of omnivorous ground-gleaning bird s, song sparrows (Melospiza melodia), and Lincoln's sparrows (M. linco lnii) increased (P < 0.10) on treated sites relative to control sites. Insectivorous ground-gleaning birds, Nashville warblers (Vermivora ru ficapilla), palm warblers (D. palmarum), and pygmy shrews (S. hoyi) de creased (P < 0.10) on treated sites relative to control sites. For bir ds, these changes appeared to be associated with an observed increase in the amount of vegetation < 1.0 m in height on sludge-treated sites. Invertebrate abundance did not differ (P > 0.10) between treated and control sites. Overall, we found no evidence that spreading sludge on regenerating spruce-fir clear-cuts affected breeding bird or small mam mal communities.