Island loggerhead shrike surveyors, from left: Jimmy McMorran (PRBO), Allison Alvarado (UCLA), Robert McMorran (FWS), Douglass Cooper (FWS), Rachel Wolstenholme (TNC), Kirk Waln (FWS), Ashleigh Blackford (FWS), Nils Warnock (PRBO), Jeff Birek (IWS)- Christy's Ranch Santa Cruz Island (USFWS photo)

Nils Warnock (PRBO) searching for loggerhead shrikes on Santa Cruz Island west shore. (USFWS photo by Ashleigh Blackford)

Island loggerhead shrike perched on Santa Cruz Island. (Photo by Jimmy McMorran )

Ashleigh Blackford, Ventura FWO
A seven-member team comprised of staff from the Ventura Fish and Wildlife Office and PRBO Conservation Science, The Nature Conservancy and volunteers hiked the canyons and western shore of  Santa Cruz Island April 16-17 to survey the elusive loggerhead shrikes (Lanius ludovicianus anthonyi).

The survey effort was part of a pre-listing action for the island loggerhead shrike to help determine its abundance on Santa Cruz Island. The island loggerhead shrike is a subspecies of loggerhead shrike which occurs only on Santa Cruz, Santa Rosa, and Santa Catalina islands off the coast of California, and is believed to be in very low numbers.

In 2007, the U.S. Fish and Wildlife Service was petitioned to list the island loggerhead shrike as an endangered species on all three islands where it occurs; however, the petition was withdrawn due to lack of information on the species. In 2008, the Ventura Fish and Wildlife Office contracted PRBO Conservation Science to conduct an island-wide survey of Santa Cruz Island in hopes of assessing the number of birds present. Beginning in March, Jimmy McMorran, a biologist with PRBO Conservation Science, commenced surveys in search of the elusive birds. Despite daily survey efforts, only three birds had been located at the time of the survey. For the group survey, McMorran organized a seasoned assemblage of biologist, all avid birders, and most with previous experience searching for and working on loggerhead shrikes. The area selected for the survey looked to be potentially good shrike habitat, consisting of scattered shrubs and open spaces, with some trees for perching in shallow canyons. Perseverance paid off and survey efforts were successful.  Five pairs of island loggerhead shrikes were confirmed with three additional individuals detected which potentially could have been paired. 

The Ventura Fish and Wildlife Office was fortunate that several members of its staff had numerous years of experience observing shrikes which they were able to contribute to the survey effort. Partnering with the Nature Conservancy and PRBO Conservation Science provided an excellent opportunity to augment the results of the Santa Cruz Island survey effort which will provide the Service with valuable information on the status of the shrike. Loggerhead shrike surveys have been organized previously on Santa Rosa and Santa Catalina islands by the National Park Service and the Carlsbad Fish and Wildlife Office, respectively. 

The island loggerhead shrike is a medium size, gray, black and white bird, distinguished by its black mask and hooked bill. The loggerhead shrike is nicknamed the “butcher bird” because of its feeding habit of impaling or wedging its prey (i.e. lizards, large insects, or mice) on sharp objects including thorns, cactus spines, and bared wire. Loggerhead shrikes utilize open spaces between vegetation to spot their prey. Historically, grazers such as sheep, cows, and goats helped create these open spaces on the Channel Islands, and likely lead to the prosperity of this species. Changes in land management attempting to restore the native ecosystem have removed or reduced grazing animals from many of the Channel Islands, altering the vegetative landscape. It is unclear how the changing landscapes will affect the island loggerhead shrike. Therefore, continued survey efforts will enable the Service to identify where the birds have selected to live and document their numbers in a changing landscape.

The volunteers who contributed their time and expertise to the survey effort include: Jimmy McMorran and Nils Warnock (PRBO Conservation Science), Rachel Wolstenholme (The Nature Conservancy), Douglass Cooper, Robert McMorran, Ashleigh Blackford, Kirk Waln (U.S. Fish and Wildlife Service, Ventura), Allison Alvarado (University of California, Los Angeles), Jeff Birek (Institute for Wildlife Studies)