Tree Swallow Tachycineta bicolor During the first half of this century, breeding Tree Swallows Swallows were found in 41.0% of the priority blocks but proved were restricted to the northern half of Ohio. In the early 1900s, to be very locally distributed within the western and southern they were numerous only at Buckeye, Indian, and St. Mary’s counties. There were records for 35.9% of the blocks in the lakes while “small numbers” nested in the other northern counties Unglaciated Plateau region where this species was widespread in (Jones 1903, Trautman 1940, Clark and Sipe 1970). Their Tuscarawas, Guernsey, Carroll, Harrison, and Jefferson counties numbers were apparently declining at that time. Hicks (1935) along the northern portion of this region. Tree Swallows were cited breeding records from 28 counties south through Mercer, scarce throughout the Illinoian Till Plain region with records Shelby, Pickaway, Perry (Buckeye Lake), Guernsey, Stark, and from only 17.4% of the blocks. Columbiana. They were abundant at a few localities, especially The relative abundance of breeding Tree Swallows in Ohio along western Lake Erie, but became very scarce near the exhibits a similar pattern on the Ohio Breeding Bird Survey southern margin of this range. He also noted populations were routes. They are most numerous on surveys in the Glaciated declining at inland lakes, reflecting the loss of suitable nest sites. Plateau region. Considerably fewer swallows are noted in the This status was maintained into the 1950s. By the early 1960s, Lake Plain region, although these surveys do not accurately however, increased numbers of swallows were apparent indicate the size of the population breeding within the marshes thoughout their established range. Breeding pairs began to spread bordering western Lake Erie and Sandusky Bay (Peterjohn into the southern half of Ohio, a trend that was widely noted 1989a). Few Tree Swallows are found on Breeding Bird Surveys during the 1970s. By the early 1980s, Tree Swallows were well in the other regions where this species is very locally distributed. established summer residents throughout Ohio (Peterjohn 1989a), When breeding Tree Swallows were restricted to the northern although their numbers probably continued to increase during the half of Ohio, pairs primarily occupied natural cavities in dead years of the Atlas Project. snags standing in or along the margins of lakes and wetlands. These cavities were normally at heights of 5–20 feet, and they nested singly or in small colonies of 10 or fewer pairs. This species infrequently utilized nest boxes (Hicks 1935). The expansion of their breeding range was correlated with a change in their breeding biology. Tree Swallows began to regularly nest in artificial nest boxes, initially taking advantage of Wood Duck boxes placed over water. Breeding pairs eventually spread to upland habitats, primarily within large open fields, where they nested in boxes erected for Eastern Bluebirds. Today, these swallows are as likely to be found in upland habitats as near water. Within Ohio, Tree Swallows normally begin their nesting activities during late April or early May. Most published egg dates are between May 10 and June 10. Young swallows normally hatch during the first half of June and fledge between June 25 and July 10. Renesting efforts or attempts to raise second broods are responsible for reports of clutches into Mike Williams - ODNR Photographer early July and nests with young through late July (Peterjohn 1989a, Tuttle 1987). This species was confirmed in 155 priority blocks during the The Atlas Project produced Tree Swallow records from 337 Atlas Project, slightly less than one–half of the statewide total. priority blocks representing 44.1% of the statewide total. Active nests were reported in 119 blocks, reflecting the ease with Although there were records from every county except Athens, which they were found in nest boxes. Reports of adults carrying these swallows were not evenly distributed across the state. food for young and recently fledged young were noted in 16 and Summering pairs were most widespread within the Glaciated 14 blocks respectively. The “30” code was not accepted for this Plateau region with records from 64.3% of the blocks, primarily species. The remaining records were nearly equally divided in the northeastern counties south through Wayne, Stark, and between possible and probable breeders. Reports of possible Columbiana. They were detected in 54.7% of the Lake Plain breeders were only accepted between May 20 and July 15 to blocks, exhibiting a preference for localities near Lake Erie and preclude migrants. Sandusky Bay but becoming locally distributed within the interior counties of this region. In the Till Plain region, Tree 196 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 52 54.7 15.4 0.9 Till Plain 271 111 41.0 32.9 0.1 Total 337 44.1% Ill. Till Plain 46 8 17.4 2.4 – Confirmed 155 46.0% Glaciated Plateau 140 90 64.3 26.7 2.6 Probable 93 27.6% Unglaciated Plateau 212 76 35.9 22.6 0.3 Possible 89 26.4% 197 Tree Swallow.