Figure 3.

Schematic representation of interspecific dynamics on Santa Cruz Island (A): fox (blue), skunk (green), pig (orange), and their predator the golden eagle (red); corresponding set of equations (B), and resulting simulations (C and D). (C) Foxes and skunks together without pigs are not sufficient to sustain an eagle population; any dispersing eagle disappears without colonizing, leaving the dominant foxes to outcompete skunks. (D) When pigs are present, they provide enough prey for dispersing eagles to colonize and breed. The growing eagle population drives the endemic fox toward extinction, which releases skunks from fox competition. The time scale is 15 years.