Anacapa Island-Rat Removal Boosts Seabird Populations

Photo showing west and east Anacapa Islands

Photo of west and east Anacapa Islands.

This year marks ten years since a team of experts removed rats from Anacapa Island, part of the Channel Islands National Park.  Biologists from the Montrose Settlements Restoration Program (MSRP) are observing growth of seabird populations after confirming the first breeding of Ashy Storm-Petrels nine years after rats were removed from Anacapa Island. The non-native rats likely populated the island during a ship grounding in the late 1800’s. The removal of rats was carried out by the non-profit group Island Conservation and funded by the American Trader Trustee Council with funds from the settlement following the 1990 oil spill near Huntington Beach, California (watch a video).

Removal of non-native species from islands is critical for the survival of native plants and animals. Islands are unique ecosystems and often contain plants and animals that are found nowhere else. Seabirds nest on islands and offshore rocks because of the lack of land predators.  Rats in particular are responsible for about half of all bird and reptile extinctions on islands. They can reproduce rapidly with a single pair producing over 5,000 offspring in just one year. Rats are also found on roughly 80% of the world’s islands.

Although, MSRP did not fund the rat removal project, we have been monitoring seabird populations on Anacapa Island and plan to enhance nesting habitat on this island in the near future. MSRP activities to help nesting Ashy Storm-Petrels may include installing social attraction devices and artificial nesting boxes. We will also continue to monitor seabird populations annually.

Photo showing an adult Ashy Storm-Petrel in an artificial nest habitat

Photo of an adult Ashy Storm-Petrel in an artificial nest habitat on Santa Cruz Island.

It is very costly and challenging to remove non-native animals from islands. These projects can take years of planning and include special techniques to protect native animals from potentially harmful removal methods. The good news is that once the non-native animals are removed from these islands, ecosystems can bounce back and thrive as they are on Anacapa Island.



-Gabrielle Dorr, MSRP Outreach Coordinator