Fig. 6. Sketch illustrating the general phylogenetic relationships among the procellariiforms (see Kennedy and Page, 2002). DP indicates diving petrels. We have proposed that the procellariiforms may have arisen from a burrow-nesting lineage, with surface nesting arising independently in two groups (shown in red) as a derived condition. In the context of foraging, this change could have lessened the degree to which surface nesters rely on olfactory tracking to locate ephemeral prey patches (DMS–), while at the same time promoting a cascade of changes that ultimately led to a multi-modal foraging strategy, and the exploitation of distant and more consistently productive areas (Van Buskirk and Nevitt, 2008).