WHITWORTH, D.L., CARTER, H.R., YOUNG, R.J., KOEPKE, J.S., GRESS, F. & FANGMAN, S. 2005. Initial recovery of Xantus’s Murrelets following rat eradication on Anacapa Island, California. Marine Ornithology 33: 131-137.

At Anacapa Island, California, breeding effort, hatching success, and nesting distribution of Xantus’s Murrelets Synthliboramphus hypoleucus increased in the years (2003-05) following the eradication of Black Rats Rattus rattus compared to pre-eradication years (2000-02). Within sea cave study areas, nest-site occupancy increased from 36% to 51%, nesting attempts increased 42%, hatching success increased from 42% to 80%, and nest depredation decreased from 52% (by rats) to 7% (by endemic Deer Mice Peromyscus maniculatus anacapae. Post-eradication, murrelets and Cassin’s Auklets Pytychoramphus aleuticus began nesting in habitats previously occupied by rats, including Cat Rock where murrelet breeding was last reported in 1927. Initial post-eradication signs of recovery of Xantus’s Murrelets at Anacapa Island are encouraging for eventual restoration of this important colony, but additional monitoring is needed to better document the rate and process of recovery.

Keywords: Anacapa Island, Black Rat, breeding, eradication, introduced predator, Rattus rattus, recovery, restoration, Synthliboramphus hypoleucus, Xantus’s Murrelet