The Common Raven in Cliff Habitat: Detectability and Occupancy

The common raven (Corvus corax) is a species of conservation concern in Kentucky and is listed as threatened (http://www.kdfwr.state.ky.us/). Fowler et al. (1985) provided the first post-decline observation of breeding ravens in Kentucky. Since then, ravens have been observed with relative consistency along the Pine Mountain thrust fault and at other locales in the Cumberland Mountains of southeastern Kentucky (B. Palmer-Ball, personal commun.). Larkin et al. (1999) and Cox et al. (2003) reported use of strip-mine high-walls by breeding ravens in Knott and Breathitt Counties, Kentucky. Hooper (1975) characterized 41 raven nests in the central Appalachian Mountains in terms of elevation, substrate (i.e., cliff or tree), local physiography (i.e., cliff height), and distance to human habitation. Thirty-eight of these nests were on cliffs (3 in trees) and all cliff-nests were sheltered by overhanging ledges; also, lower elevation and shorter distance to human habitation were associated with better productivity. Aside from these generalities, almost nothing is known about landscape-scale attributes of breeding locations, or about factors affecting nest-site establishment - particularly in regions where the raven had been extirpated as in Kentucky. Palmer-Ball (1996) noted that apparently suitable but unoccupied habitat is extensive in portions of eastern Kentucky, especially in the Cliff Section of the Cumberland Plateau. Cox and Larkin (2004) reviewed the history, status, and conservation needs of the raven in Kentucky. The problems we aim to address generally pertain to the lack of information on the status of the common raven in portions of its historic habitat. First, there is no information on factors that affect our ability to detect cliff nesting ravens, so reliably inferring absence in a region is problematic. Second, we need more information on specific habitat attributes that characterize their breeding habitat so we can apply this knowledge as part of future survey efforts in Kentucky. Third, the current number and location of nesting pairs of ravens in Kentucky is unknown. Lastly, there is no long-term monitoring plan in place for the species that focuses on key Kentucky historic habitats, so its status remains uncertain. From practical and aesthetic perspectives, it is important to develop a better understanding of the status of the common raven in its historic habitat because the longterm conservation implication of its recent use of human-constructed habitat is unknown.