Abstract Manager

Between 2013 and 2016, the Ministry of Transportation of Ontario constructed the Highway 407 East Phase 1 Extension, resulting in the loss of 55 buildings that had supported 501 Barn Swallow nests. At least 30 Barn Swallows were known to be active in the Study Area during pre-construction surveys (2008-2009). As Barn Swallow were listed as Threatened provincially in 2012, an ESA Overall Benefit Permit was granted to the project. In June 2013, 24 artificial Barn Swallow nesting structures containing a total of 750 nest cups were placed across 13 sites to mitigate the loss of nesting habitat and prevent further decline of the species. Foraging habitat was also enhanced or created within the 13 sites. As Barn Swallows choose to construct their nests in particular locations for a variety of reasons, different treatments were applied to the structure to enhance availability of site selection: 11 structures were "large" with 48, 50, or 64 nest cups each, and 13 were "small" with 11 or 12 nest cups each; and 13 structures had dividers visually isolating nest cups from each other (6 large and 7 small). Monitoring surveys were conducted within the Barn Swallow breeding season (May 1st and August 31st) annually from 2014 to 2018. Six to nine monitoring surveys were carried out at each of the Barn Swallow Sites, with surveys spaced 7 to 17 days apart depending on the year of study. Surveys included nesting structure inspections, inspections of all nest cups within individual structures to determine breeding status (e.g., mating, egg presence/egg incubation, fledged chicks) and counts, and general observations of Barn Swallow behaviour. Between 2014 - 2018, Barn Swallows nested at 17 nesting structures across 11 sites. The number of nest cups used across all years (159) remained relatively consistent with the 30 Barn Swallow occurrence records identified pre-construction. A total of 465 eggs produced a total of 266 successfully fledged young across the five-year monitoring period. The number of nest cups used, eggs laid, and young fledged increased year over year from 2016 to 2018, suggesting that Barn Swallows do accept artificial structures as viable habitat options. Our study provided sufficient data relative to Barn Swallow use of nesting structures, success of Barn Swallow Site restoration, and effectiveness of mitigation efforts, to suggest that the Barn Swallows have benefited from the artificial nesting structures since disturbed by highway construction.