Life-history traits related to pace of life, such as foraging strategies and activity levels, influence daily energy expenditure and can affect fitness. Lifestyles supported by high-energy aerobic activity result in daily energy expenditure and basal and maximal metabolic rates in some endotherms. Maximal capacities for exercise and thermogenesis are both functions of aerobic muscle output, so high activity-lifestyles might be expected to produce high thermogenic capacities as a by-product. We tested whether the high-energy aerial insectivore lifestyle in swallows is correlated with elevated basal and maximal thermogenic metabolic rates. We measured basal (BMR) and summit (Msum = maximum cold-induced metabolic rate) metabolic rates in six species of swallows and combined these data with literature data to address the hypothesis that swallows have higher BMR and Msum than non-aerial insectivore birds. BMR in swallows was significantly higher than for non-aerial insectivores for both conventional and phylogenetically adjusted analyses after correcting for body mass and region of origin (tropical vs. temperate). In contrast, Msum did not differ significantly between swallows and non-aerial insectivores. Thermogenic scope (Msum – BMR), however, was elevated in swallows relative to non-aerial insectivore birds. This latter result was driven mostly by elevated scope in tropical swallows relative to tropical non-aerial insectivores, suggesting that the aerial insectivore lifestyle limits reductions in thermogenic scope typical of tropical birds. Thus, swallows maintain a higher BMR than non-aerial insectivore birds, but maximum thermogenic capacities are not similarly upregulated, suggesting that the high-energy aerial insectivore lifestyle does not produce strong thermogenic side effects in this taxon.