Long-term Breeding Bird Surveys of Three State Natural Areas in the Baraboo Hills, Wisconsin

摘要

The results of long-term breeding birdsurveys (26-36 years) for the period1971-2008 are reported herein for threeState Natural Areas—Honey Creek, Hem-lock Draw, and Pine Glen—in the BarabooHills of south-central Wisconsin. Mostspecies showed significant change, mainlynegative, in population levels. HemlockDraw had the most species with significantdecrease, while Pine Glen had the mostspecies with significant increase. Changewas shown for permanent residents, bothshort-distance and long-distance migrants,and for species of different feeding guilds.Fifty-three species were analyzed: only 7species showed no significant trend. Thenumber of species also changed over thecourse of these surveys: all three sites, espe-cially Hemlock Draw, had significant de-clines in number of species. Alteration ofthe natural landscape is occurring bothgradually and catastrophically. Naturalsuccession is ongoing, but major agents ofchange in the study sites during the periodof these surveys have also included sevenmajor floods since 1990, two major icestorms, an outbreak of the two-lined chest-nut borer from 1975-1978, fungal dis-eases of American elm and butternut, thecontinual spread of exotic plants and ani-mals, and increasing numbers of deer. Pos-sible problems for summer residents on theirmigration and on their wintering groundcompound the complex task of determiningcauses for changes in populations or num-bers of species, but natural forest succes-sion, coupled with local disturbance,especially flooding, may be the overridingfactor.