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Aerial insectivorous birds have experienced alarming population declines in eastern North America. Meanwhile, urbanization continues to increase rapidly, with urban land use comprising 69.4 million acres (1 acre = 0.40 ha), or 3.6% of total land area, in the contiguous United States. Multiple environmental changes are associated with urbanization, including alterations to local climate, changes in habitat structure, and potential shifts in both terrestrial and emergent aquatic flying insects on which aerial insectivorous birds rely. Here, we investigated the linkages between urbanization, water quality, and Tree Swallow (Tachycineta bicolor) reproductive success and body condition at seven river‐riparian sites representing urban and protected land use in Columbus, Ohio (USA) over five consecutive years (2014–2018). Tree Swallows at urban and protected sites relied on emergent aquatic insects for 37.4% and 30.8% (SD = 28.4% and 24.1%) of their nutritional subsidies, respectively. Despite the loss of environmental quality generally attributed to cities, Tree Swallows exhibited greater reproductive success in urban settings where climate was more amenable to egg and nestling survival, and the breeding season was longer. Urban‐nesting Tree Swallows initiated laying 7.9 d earlier and fledged 35% more young per nest than those at protected sites. Multiple characteristics of urban sites appeared to drive these patterns, including differences in mean and extreme air temperatures and measures of water quality (e.g., water temperature, nutrient concentrations, turbidity). However, chronic effects of elevated Hg concentrations, which were 482% greater in adult swallow blood at urban sites than at protected sites where swallows exhibited a 17.4% lower trophic position, may disadvantage individuals in other ways. Further, although Tree Swallows are a good model aerial insectivore bird species, characteristics of urban landscapes that benefit Tree Swallows may not advantage other aerial insectivorous birds owing to differences in life‐history and foraging strategies. These findings implicate urbanization, local climate, and water quality as important considerations in the conservation of aerial insectivorous birds.

Streams and their adjacent riparian zones are increasingly viewed as interdependent systems linked by reciprocal exchanges of energy, organisms, and materials. We assessed potential associations between the emerging aquatic insect flux and transitions between agricultural land and forest fragments to better understand these stream‐riparian linkages in managed landscapes. We sampled stream environmental conditions and emerging insects at 28 sites distributed along three streams flowing through agriculture‐forest‐agriculture transitions in central Ohio, USA, in the summer of 2012. Ephemeroptera and Trichoptera (ET) taxa had higher flux densities in forests (mean and 95% CI: 0.3 insects m⁻²d⁻¹[0.1, 0.8]) compared to agriculture (mean and 95% CI: 0 insect m⁻²d⁻¹[0, 0.1];p= .004), and ET taxa were found in 67% of forested sites compared to only 15% of agricultural sites. In contrast, Dolichopodidae were more strongly associated with agricultural land (mean and 95% CI: 0.6 insect m⁻²d⁻¹[0.3 to 1.2]) than forests (mean and 95% CI: 0.1 insects m⁻²d⁻¹[0.1, 0.2];p= .002). Although Chironomidae were the most numerically abundant, ET taxa were among the larger bodied insects and comprised >30% of the total biomass flux, illustrating the importance of taxonomic traits in mediating flux dynamics. Mechanisms driving emerging insect flux were related to substrate grain‐size distribution, channel width, and nutrient concentrations. Overall, our results demonstrate that small forest fragments are strongly related to the aquatic‐to‐terrestrial insect flux and thus have important implications for terrestrial biodiversity and food webs in agricultural landscapes.