Cerulean Warbler & Golden Wing Warbler Status & Distribution in Kentucky

Managing for the habitat needs of nongame wildlife such as the cerulean warbler (Dendroica cerulea) and golden-winged warbler (Vermivora chrysoptera) is a challenge in light of changing land use patterns and human demographics in Kentucky. This study is designed to create the foundation for future studies and adaptive management for 2 species that have undergone dramatic distribution changes in the state and for which a paucity of autecological information exists. Projects 1) Correlates of Cerulean Warbler Habitat and Landscape - Influences on Distribution and Abundance The cerulean warbler is a neotropical migratory songbird that breeds in mature and older deciduous forests in the northeastern and central United States. It has exhibited one of the steepest declines of any warbler in North America (> 1.5% annually, U.S. Fish & Wildlife Service 2002; accessed website 16 December 2002; http://www.mbrpwrc. uSgs.gov/bbs/htm96/trn626/tr6580.html), and it has exhibited a particularly steep decline in Kentucky (>5.6% annually), the center of the species' breeding range (U.S. Fish & Wildlife Service 2002; accessed website 16 December 2002, http://www.mbrpwrc. usgs.gov/Infocenter/i6580id.html). Due to its habit of nesting high in mature trees and the difficulty in making direct behavioral observations (Monroe 1994)1, little is known about this species' natural history (Gough et al. 1998). Bird sampling using visual and ocular cues will be conducted following standard line transect and variable circular plot methodologies (Jarvinen and Vaisanen 1975, Ford and Hamel 1988). Bird locations will be recorded on site maps and will be recorded with a global positioning system. Vegetation at each site will be characterized by measuring the diameter at breast height of each tree >40 em dbh on 3 fixed plots of 0.1 ha. Canopy coverage will be measured following James and Shugart (1970). Other habitat variables as described by Robbins et al. (1988) will be measured at each 0.1 ha fixed plot. Locations of singing cerulean warblers and nests will be recorded as Universal Transverse Mercator (UTM) coordinates and entered into a data base for subsequent analysis in ArcView GIS (ESRI). These locations will be examined relative to their relation to the following landscape variables: forest patch size, distance to forest edge, height in forest profile, ratio of patch edge to area, basal area of patch, height of tallest tree, forest type, dominant tree species. These variables will be used in developing forward stepwise logistic and regression models that examine the relation between local and landscape attributes and cerulean warbler distribution and habitat use following the methodology of Bakker et al. (2002). Akaike's information criterion (AlC) (Burnham and Anderson 1998) will be used as the basis for model selection. The model with the smallest AlC value will be considered the best approximation for the information in the model. 2) Does Habitat Structure and Plant Species Diversity Influence Golden-winged Warbler Presence and the Likelihoodfor Hybridization with the Blue-winged Warbler? The golden-winged warbler is a neotropical migrant that breeds in the northeastern United States, at higher elevations of the southern Appalachians, and southern Canada. It nests in early successional habitat such as abandoned farmland and other areas maintained by fire, timber harvest, and power line maintenance (Hands et al. 1989). While the golden-winged warbler continues to increase in abundance in the northwestern portion of its range (i.e., Manitoba, Minnesota, Quebec and northern New York), it is declining in eastern and southern portions of its range (Sauer et al. 1997). Moreover, it has been extirpated from virtually all regions of New England that it occupied a century ago (Gill 1980, Hands et al. 1989, Confer 1992). The golden-winged warbler is considered as a "Species of Management Concern" by the U.S. Fish and Wildlife Service (Confer 1992) and is listed as a species of "Extreme Concern" on their "Watch List". The decline of the golden-winged warbler correlates with the succession of shrub habitat into forest (Confer and Knapp 1981, Will 1986, Confer 1992), hybridization and potential competition with the blue-winged warbler (Vermivora pinus) (Gill 1980), and brood parasitism from the brown-headed cowbird (Molothrus ater) (Brittingham ands Temple 1986, Confer et al. in review). Breeding Bird Survey data for the last 10 years show a major golden-winged warbler decline in all 3 U.S. Fish and Wildlife Service regions where it nests in perceptible abundance. Mengel (1965) noted the Golden-winged warbler as a very rare summer resident in Kentucky that was restricted to parts of the Cumberland Mountains, and possibly portions of the Cumberland Plateau. Recent observations of territorial male Goldenwinged warblers on a Harlan County reclaimed coal mine (1. Larkin, pers. obser.) warrants investigation of such areas as breeding sites and developing management plans if reproduction is occurring. Because vegetative growth tends to be slower on reclaimed coal mines (Vogel 1987), we hypothesize that these lands may offer large amounts of shrubland that will remain suitable for golden-winged warblers for longer periods than abandoned farmlands and clear-cuts. This could lead to the use ofthe golden-winged warbler as a featured species on reclaimed mine lands in Kentucky. We propose to 1) determine the extent to which golden-winged warblers breed in Kentucky; 2) quantify characteristics of golden-wing warbler breeding habitat and, in particular, the habitat that is most favorable for golden-wing warblers in excluding bluewing warblers; and 3) make recommendations for future experimental manipulation of reclaimed surface-mine lands for golden-winged warbler habitat. We will mist-net and mark resident golden-winged, blue-winged, Brewster's, and Lawrence's warblers in areas where both species and their hybrids are known to exist; and in areas where only goldenwings or blue-wings occur. Subsequent to determining the extent of territories, vegetation will be sampled following the methodology of Confer et al. 2003. We will then use multiple regression to compare sites occupied only by golden-winged warblers with sites occupied only by blue-winged warblers, and where the hybrid fonns are known to occur. The patterns revealed will then be used to develop recommendations that will assist land managers in promoting the golden-winged warbler as a featured species on early successional reclaimed surface mine land and other suitable landscapes in Kentucky.