José Alfredo Castillo-Guerrero

Patterns of occurrence and abundance of land birds on Espíritu Santo Island, Gulf of California, México

Abstract Land-bird density on Espíritu Santo Island, lower Gulf of California, Mexico, was determined bimonthly from November 1998 to October 1999. Bird density was quantified in 4 habitats on the island using the line transect sampling method. Fiftyeight species were recorded, of which 44 were detected in the transects and the other 14 in adjacent sites. The highest bird densities were observed in March and June, coincident with the lowest rainfall months in the neighboring peninsular mainland. Average density (birds/ha) was highest in alluvial fans (18.14) and lowest in mesas (8.08). Migratory bird density on the island was relatively low and commonly less than 10% of the observed total density. The average land-bird density on the island (13.29/ha) was greater than that previously recorded.

Population Status of American Oystercatchers (Haematopus palliatus frazari) Breeding in Northwest Mexico

Abstract. The western race of the American Oystercatcher (Haematopus palliatus frazari) is a resident and endangered shorebird of western Mexico. Its breeding population and conservation concerns are poorly known, but recent information indicates extremely low numbers and a discrete breeding distribution. Because of loss and degradation of sandy beaches by coastal development and disturbance from human recreational activities, the American Oystercatcher is a priority species in the Shorebird Conservation Plans of the United States and Mexico. Research on its distribution and abundance during the 2009 breeding season resulted in the identification of 2,286 adults in northwest Mexico. Although the population is higher than previous estimates, its distribution is more restricted than expected. It is distributed almost exclusively in northwest Mexico, and 80% of the total breeding population is found on the islands of Sinaloa and Baja California Sur. Based on these results, this species was officially federally listed on the Mexican List of Protected Species in 2010. This legal mechanism will promote the management and protection of this priority subspecies as well as other waterbirds occupying the same habitats.

Correction: High quality diet improves lipid metabolic profile and breeding performance in the blue-footed booby, a long-lived seabird

Understanding the role of diet in the physiological condition of adults during reproduction and hence its effect on reproductive performance is fundamental to understand reproductive strategies in long-lived animals. In birds, little is known about the influence of the quality of food consumed at the beginning of the reproductive period and its short-term effects on reproductive performance. To assess the role of diet in the physiological condition of female blue-footed booby, Sula nebouxii (BFBO), during reproduction we evaluated whether individual differences in diet (assessed by using δ13C and δ15N values of whole blood from female birds and muscle tissue of the principal prey species) prior to egg laying and during incubation influenced their lipid metabolic profile (measured as triglyceride levels and C:N ratio) and their reproductive performance (defined by laying date, clutch size and hatching success). Females with higher δ15N values in their blood during the courtship and incubation periods had a higher lipid metabolic profile, earlier laying date, greater clutch size (2–3 eggs) and higher hatching success. Females that laid earlier and more eggs (2–3 eggs) consumed more Pacific anchoveta (Cetengraulis mysticetus) and Pacific thread herring (Opisthonema libertate) than did other females. These two prey species also had high amounts of lipids (C:N ratio) and caloric content (Kcal/g fresh weight). The quality of food consumed by females at the beginning of reproduction affected their physiological condition, as well as their short-term reproductive performance. Our work emphasizes the importance of determining the influence of food quality during reproduction to understand the reproductive decisions and consequences in long-lived animals.

Non-Breeding Distribution, Abundance, and Roosting Habitat Use of the American Oystercatcher (Haematopus palliatus frazari) in Sinaloa, Mexico

Abstract. The American Oystercatcher (Haematopus palliatus frazari) is federally listed as endangered in Mexico due to habitat loss and small population size. Recent surveys indicate that the State of Sinaloa supports about half of the breeding population in Mexico. However, no information is available about the non-breeding ecology in Mexico. To assess American Oystercatcher distribution, abundance, and roosting habitat use during the nonbreeding season (3 August 2014-23 January 2015), six bays were surveyed in Sinaloa. A total of 1,351 American Oystercatchers were detected using this area based on maximum count per roosting site at or near high tide. American Oystercatchers roosted in flocks of variable size (3–253 individuals per flock) with Bahía Santa María hosting the main roosting sites in Sinaloa. Mangrove islands and mudflats had larger numbers of individuals than expected relative to the availability of those habitats. The non-breeding Sinaloa population comprised approximately 45.0% of the total H. p. frazari population estimate (n = 3,000 individuals). Bahía Santa María represented 74.6% of the non-breeding population observed in Sinaloa. Thus, Sinaloa, and particularly Bahía Santa María, stand out as critical sites for the conservation of this subspecies. Hypothesized threats to American Oystercatchers were predators, livestock, and human activities.

Current Distribution Status of the White-Faced Ibis, Plegadis chihi, in the Peninsula of Baja California, Mexico, with Special Reference to the Region of La Paz

Departamento de Biologia Marina, Universidad Aut6noma de Baja California Sur, Apartado Postal 19-B, La Paz, Baja California Sur, 23000, Mixico (RC, JACG, and MZO) Facultad de Ciencias, Universidad Aut6noma de Baja California, Apartado Postal 1653, Ensenada, Baja California 22800, Mixico (GRC-United States mailing address = PMB 064, RO0. Box 189003-064, Coronado, CA 92178) * Correspondent: beauty@uabcs. mx