As the current biodiversity crisis approaches levels comparable to the rates of the five historical mass extinctions, increasing attention has focused on how to stop or slow species loss and preserve ecosystem function. The impact of the loss of an individual species on communities and ecosystems is heterogeneous, however. Removing some species has negligible effects while the removal of others can be catastrophic. Metaphorically, the scenario can be likened to Jenga, a popular block‐balancing game in which players build a tower of wooden pieces, analogous to a dynamic ecosystem (DeRuiter et al. 2005). Players remove pieces (individual species extinctions), which can have no effect or cause partial or total collapse (of communities or ecosystems). Species that are invariably important to their communities and ecosystems include keystone species, umbrella species, and ecosystem engineers (Caro 2010). Ecosystem engineers are species whose traits have significant impacts on the physical structures of their habitats and the organisms that live in those habitats (Jones et al. 1994). Reptiles rarely feature as ecosystem engineers (e.g., review by Coggan et al. 2018), but monitor lizards excavate foraging burrows that trap leaf litter, viable seeds, and fruits (Whitford 1998), and these burrows have higher levels of labile carbon and mineralizable nitrogen than surface soils (James and Eldridge 2007, James et al. 2009). Herein we reveal that two species of large monitor lizards can serve a significant role as ecosystem engineers via their unique nesting behavior and remarkable communal nesting warrens.