Carolina Wren Thryothorus ludovicianus

Carolina Wrens have been spreading northward through the Great Lakes and New England regions since the 19th century (DeVos 1964). Within Ohio, however, their status has not appreciably changed since the late 1800s. Wheaton (1882) and Jones (1903) listed similar distributions for these wrens, describ- ing them as abundant in the southern counties, common in central Ohio, and rare in the north. Jones (1903) claimed they were still spreading northward at the turn of the century. In the mid–1930s, Hicks (1935) cited breeding records from every county and described them as common to abundant in the southern two– thirds of the state, becoming uncommon to rare and often very locally distributed in the northern counties. He further noted they were absent from portions of northeastern Ohio. Similar distribution patterns are expected within Ohio during years with normal winter weather conditions. However, these wrens are susceptible to excessive mortality during unusually severe winter weather, particularly seasons with prolonged periods of sub–zero temperatures and deep snow cover. Their statewide distribution patterns can be very different following these harsh winters. For example, the severe winters of 1976– 1977 and 1977–1978 decimated Carolina Wren populations throughout Ohio, reducing their numbers by more than 90% and Alvin E. Staffan eliminating them from many counties. Following these two winters, Carolina Wrens were virtually absent from the northern half of the state and rare to uncommon elsewhere. Their numbers The majority of Atlas Project records pertained to probable slowly recovered during subsequent years, producing noticeably breeders, primarily territorial males and pairs in suitable expanding populations during the Atlas Project. Despite a habitats. Breeding was confirmed in 111 blocks, with active substantial increase in numbers between 1982 and 1987, these nests in 31 blocks, recently fledged young in 16 blocks, and wren populations were smaller than the peak numbers recorded adults carrying food for young in 10 blocks. The “30” code was from Ohio following the relatively mild winters experienced in used to confirm this species in 43 blocks, primarily in the the state between 1971 and 1975. Unglaciated Plateau region (28 blocks). The remaining con- The Atlas Project produced records from 414 priority blocks firmed records were scattered among the other codes. Reports of representing 54.2% of the statewide total. Carolina Wrens were possible breeders were largely confined to the central and most widespread in the southern one–third of Ohio, especially in northern counties and many of these individuals were believed to the southwestern counties where they were found in 100% of the be unmated. Illinoian Till Plain blocks. In the Unglaciated Plateau region, Carolina Wrens are occupants of brushy edge habitats, there were records from 84.9% of the priority blocks although abandoned fields with numerous brushy thickets, and young these wrens became somewhat locally distributed along the woods with fairly dense undergrowth. They regularly inhabit northern margin of the plateau. Considerably fewer Carolina upland sites and riparian corridors but tend to avoid wetlands and Wrens were recorded in the other regions. The Till Plain region swamp forests. These wrens are frequently found near rural had records in 43.9% of its blocks. These records were concen- residences but tend to be fairly scarce in densely populated urban trated within the southern half of the region with only widely areas. Their nests may be located in dense tangles, the roots of scattered sightings elsewhere. Carolina Wrens were found in fallen trees, natural cavities, various undisturbed objects, trash 36.4% of the blocks in the Glaciated Plateau region, primarily piles within buildings, and occasionally in bird houses. Most adjacent to the unglaciated counties. They became very rare in the nests are placed at heights of 2–5 feet. Breeding pairs may raise extreme northeastern counties where no wrens were found in two or three broods annually. Nest construction has been reported Geauga County. Carolina Wrens were scarcest in the Lake Plain between the second half of March and early July. Most clutches region with widely scattered sightings from 19.0% of the priority have been found between April 7 and July 23, although late blocks and no records from Williams, Defiance, and Paulding March clutches are possible in southern Ohio. A nest with eggs in counties. Brown County on December 8, 1988 was exceptionally late The relative abundance of Carolina Wrens on Ohio Breeding (Peterjohn 1989c). Nests with young have been reported by April Bird Surveys exhibits a similar pattern. They are most numerous 12 and fledging dates extend between April 27 and Sept. 3. in the Illinoian Till Plain region, more than three times as abundant as in the Unglaciated Plateau region. They are scarce on BBS routes in the other physiographic regions. 222 Blocks Special Areas Other Observations Confirmed Probable Possible

Analysis of Block Data by Physiographic Region Summary of Total Blocks % Regional Ave. # Individ Breeding Status Physiographic Blocks with with % per BBS Route No. of Blocks in Which Region Surveyed Data Data for Ohio (1982–1987) Species Recorded Lake Plain 95 18 19.0 4.4 <0.1 Till Plain 271 119 43.9 28.7 0.3 Total 414 54.2% Ill. Till Plain 46 46 100.0 11.1 12.7 Confirmed 111 26.8% Glaciated Plateau 140 51 36.4 12.3 – Probable 241 58.2% Unglaciated Plateau 212 180 84.9 43.5 3.7 Possible 62 15.0%

223 Carolina Wren