Ecosystem-level Changes

We had built fox populations back up, and relocated the breeding population of golden eagles on the islands. But what if golden eagles found the islands again? Would they set up shop? Prey on our recovered island fox populations? Ecosystem-level actions taken by the National Park Service, The Nature Conservancy and the US Fish and Wildlife Service and others sought to ensure they wouldn’t.

For one, that non-native prey base needed to be removed. In an example of foresight, the NPS and TNC had planned on removing pigs from Santa Cruz Island, long before pigs were known to attract and support golden eagles. As a rule, the NPS strives to remove destructive non-native species from parks, and in the case of pigs on Santa Cruz, there was ample reason to do so. Pigs were like rototillers on the island, tearing up native habitat and causing almost a dozen island plant species to be listed as endangered. So, in a joint project, NPS and TNC fenced the island into sections which were hunted out, be helicopter and then by dog teams. In this manner over 6,000 pigs were removed from the island in about a year and a half. It may be one of the most significant recovery actions ever conducted on the islands. Once removed, those pigs ain’t coming back – no pigs are going to swim out to the islands. On neighboring Santa Rosa Island, the introduced mule deer were removed by the NPS and the former owners of the island, who in fact owned the mule deer. They’re not coming back either. Any golden eagle that finds the islands will not find enough prey to sustain breeding.

Visiting golden eagles also may not get a warm welcome from the bald eagles which have taken up residence on the islands. Bald eagles were reintroduced to the Channel Islands after an absence of over 60 years, by a project funded by the cleanup of the DDT poisoning of southern California waters.  Dozens of bald eagles now breed on the Channel Islands, and will likely not tolerate breeding by any golden which shows up. These actions have tipped the ecological balance away from non-native species to favoring the persistence of native species, like the island fox and native island plants.