Abstract Whereas Engeström has suggested that Cultural-Historical Activity Theory (CHAT) approach bird identification as an unusual type of dispersed “wildfire” activity, we argue that bird identification represents a durable family of cultural practices that have been shaped by multiple sociohistoric motives and that share key mediating artifacts (e.g., field guides, specialized optical equipment, scientific classifications). In this article, we sketch a genealogy of three distinct, yet linked forms of bird identification: birdwatching, birding, and twitching, each of which crystallizes and weaves together a somewhat different set of historically produced priorities, dispositions, and practices. We argue that analyzing bird identification as wildfire activity indexes a tendency in CHAT to focus on “vertical” institutions (schools, workplace, government) at the expense of “horizontal” forms of human association (friendship, recreation, kinship). A richer understanding of horizontal families of activity may obtain if activity is addressed through the lens of Latour's notion of actor-network associations that are characterized as: flat, spatially and historically dispersed, varyingly hardened in artifacts, assembled and reassembled for use. We argue that such assemblages produce complexly laminated families, as diverse historical types and streams of activity are knotted together in particularly situated encounters.