United States military bases provide habitat for a diverse suite of wildlife species despite intense anthropogenic disturbance inherent in training activities. Little research has examined how military activity affects wildlife reproduction. We compared parental investment, reproductive success, offspring and adult quality, and stress hormone concentrations of northern cardinals (Cardinalis cardinalis) breeding in areas that differed 10-fold in levels of on-ground military activity. We found no evidence of direct impacts of military activity on cardinals, nor did the reproductive success of several other passerine species appear to be affected. However, we observed American crows (Corvus brachyrhynchos) much less frequently in areas of high military activity, and cardinals nesting in those areas were less responsive to crow models. The apparent displacement of this nest predator suggests that military activity could indirectly benefit some wildlife. Although these results are promising for the conservation of birds that depend on military bases for breeding habitat, further assessment of direct and indirect effects of military training on a wider array of species is required before concluding that such activity is benign. © 2012 The Wildlife Society.