Santa Cruz Island Reserve

06 Apr, 03 AM - 18 Apr, 07 PM

California has the greatest biodiversity of any state in the U.S. with many taxa listed as endangered or threatened. One of the creatures found only in this global biodiversity hotspot is a rare subspecies of the Loggerhead Shrike, Lanius ludovicianus anthonyi; a scarcely viable population with only two pairs counted on Santa Cruz Island in 2005 (Walter 2005). Research on this subspecies is minimal, inconclusive, and does not provide a comprehensive understanding of the threats, which are needed to list it as endangered. This project aims to determine the total number of birds remaining and the mechanisms causing its decline. The known breeding pairs on Santa Cruz Island will be monitored, and an island-wide census of all potential shrike habitats will be completed. Threats to the small population of L. l. anthonyi will be evaluated by gathering data on diet, foraging techniques, breeding behavior, social interaction, and predation. Once this information is collected, a restoration project will be proposed to recover the declining island shrike population. This work will build the foundation for future conservation of birds endemic to the Channel Islands, and hopefully prevent the extinction of L. l. anthonyi, one of California?s rarest subspecies. The standard monitoring methods for land birds cannot be used with this species due to its rarity. Therefore, to obtain an accurate estimate of the remaining population, a systematic, canyon-by-canyon survey of the entire island must be conducted. Based on habitat analyses of Lanius Ludovicianus across North America, it has been shown that shrikes associate with open habitats and grasslands that are scattered with shrubs, snags, fence posts, and a low vegetation cover for foraging (Scott and Morrison 1990, Yosef 1992, Jobin et al 2003). Depending on availability, vegetation maps and satellite imagery will be used to determine the locations of potential habitat on the island. Habitat is defined as open grassland containing one or more shrubs with a height between 1.0 and 5.0 meters (Scott and Morrison 1990). Densely forested areas will not be surveyed because they have never contained shrikes (Walter, unpubl.). A map of the island will be compiled that designates these locations and a survey of each one will take place in the spring of 2006 both by vehicle and on foot where necessary. Habitat that is extremely remote will not be overlooked as it has been in the past. After surveying the habitats a distribution map showing the locations of L. l. anthonyi on Santa Cruz Island will be produced along with a total estimate of the remaining bird population.

Visit #9440 @Santa Cruz Island Reserve

Approved

Under Project # 6432 | Research

An Initial Census of the Island Loggerhead Shrike (Lanius ludovicianus anthonyi)

graduate_student - University of California, Los Angeles

Reservation Members(s)

Julia Hicks Apr 6 - 18, 2006 (13 days)
Julia Hicks Apr 6 - 18, 2006 (13 days)

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Jeep 2 Apr 6 - 18, 2006