Raptor predation on bats occurs globally across a range of raptor and bat species. Colonially roosting bats that emerge in abundance are particularly vulnerable to avian predators. This threat likely constitutes selective pressure for bat nocturnality and preference for day-roosts that are out of reach of vision-oriented predators. Bats remaining well within crevice day roosts are generally considered safe from avian predation. We document novel daytime predation of roosting bats by adult Cooper’s hawk (Accipiter cooperii) from a maternity colony of Mexican free-tailed bats (Tadarida brasiliensis mexicanus). We observed this behavior repeatedly over several weeks late in the hawk nesting effort, during the colony’s pupping season. Based on the observed attack success rate, we anticipate the potential for colony-level effects. We seek other observations of bat predation within day roosts to assess the extent of this predation pressure on crevice-roosting bats more broadly, and to consider potential management implications for anthropogenic roost structures. Continued observations of our study roost may shed light on magnitude of impact to local predator-prey populations, prey species response, whether hawk offspring learn to take advantage of this foraging resource, and other intricacies of this potentially new relationship between two urban-tolerant wildlife species.