Long-distance migratory species often cross a range of human-modified landscapes. A key question is how animal populations are responding to these human-induced changes. Here, we use community science data to model the spring migration dynamics of 63 bird species in North America with the goal of understanding how migration is associated with variation in human population density (HPOP). We find that most migrating bird species demonstrate a negative navigational response to HPOP, yet nearly all bird species experience much greater HPOP during migration as compared to breeding. We show that species differ repeatably in their navigational response to HPOP, and that this variation can be explained by variation in breeding ecology and the pace of migration. These findings underscore how birds may be particularly vulnerable to the effects of HPOP during migration, as the average level of HPOP experienced during migration is 2.7-fold greater than that of breeding.