PACIFIC COOPERATIVE STUDIES UNIT UNIVERSITY OF HAWAI`I AT MĀNOA Dr. David C. Duffy, Unit Leader Department of Botany 3190 Maile Way, St. John #408 Honolulu, Hawai’i 96822 Technical Report 197 A report on the guano-producing birds of Peru [“Informe sobre Aves Guaneras”] July 2018* *Original manuscript completed1942 William Vogt1 with translation and notes by David Cameron Duffy2 1 Deceased Associate Director of the Division of Science and Education of the Office of the Coordinator in Inter-American Affairs. 2 Director, Pacific Cooperative Studies Unit, Department of Botany, University of Hawai‘i at Manoa Honolulu, Hawai‘i 96822, USA PCSU is a cooperative program between the University of Hawai`i and U.S. National Park Service, Cooperative Ecological Studies Unit. Organization Contact Information: Pacific Cooperative Studies Unit, Department of Botany, University of Hawai‘i at Manoa 3190 Maile Way, St. John 408, Honolulu, Hawai‘i 96822, USA Recommended Citation: Vogt, W. with translation and notes by D.C. Duffy. 2018. A report on the guano-producing birds of Peru. Pacific Cooperative Studies Unit Technical Report 197. University of Hawai‘i at Mānoa, Department of Botany. Honolulu, HI. 198 pages. Key words: El Niño, Peruvian Anchoveta (Engraulis ringens), Guanay Cormorant (Phalacrocorax bougainvillii), Peruvian Booby (Sula variegate), Peruvian Pelican (Pelecanus thagus), upwelling, bird ecology behavior nesting and breeding Place key words: Peru Translated from the surviving Spanish text: Vogt, W. 1942. Informe elevado a la Compañia Administradora del Guano par el ornitólogo americano, Señor William Vogt, a la terminación del contracto de tres años que con autorización del Supremo Gobierno celebrara con la Compañia, con el fin de que llevara a cabo estudios relativos a la mejor forma de protección de las aves guaneras y aumento de la produción de las aves guaneras. Boletín de la Compañia Administradora del Guano. 18 (3): 1-132. Editor: David C. Duffy, PCSU Unit Leader (Email: [email protected]) Series Editor: Clifford W. Morden, PCSU Deputy Director (Email: [email protected]) About this technical report series: This technical report series began in 1973 with the formation of the Cooperative National Park Resources Studies Unit at the University of Hawai'i at Mānoa. In 2000, it continued under the Pacific Cooperative Studies Unit (PCSU). The series currently is supported by the PCSU. The Pacific Cooperative Studies Unit at the University of Hawai'i at Mānoa works to protect cultural and natural biodiversity in the Pacific while encouraging a sustainable economy. PCSU works cooperatively with private, state and federal land management organizations, allowing them to pool and coordinate their efforts to address problems across the landscape. CONTENTS Abstract ……………………………………………………………………...1 A Note Concerning the Translation (including Acknowledgements) ………4 Introduction …………………………………………………………………7 Geography …………………………………………………………………10 The Birds and Time ……………………………………………….……….37 The Guanay Cormorant …………………………………………….……...46 The Peruvian Booby ……………………………………………….…......115 The Peruvian Pelican …………………………………………….…….....128 Synecology …………………………………………………….…………138 Management Recommendations ………………………………….……...155 Literature Cited …………………………………………………….….....171 Notes on the Translation (Footnotes) ……………………………….…...176 Literature Cited in the Footnotes …………………………………….......186 List of Figures ……………………………………………………….......196 List of Tables ………………………………………….…………….......197 List of Images …………………………………………...…………........198 Abstract.-- (Modified from the original) Vogt studied the Guanay Cormorant (Phalacrocorax bougainvillii), Peruvian Booby (Sula variegata), and Peruvian Pelican (Pelecanus thagus) for almost three years (1938 - 1940). The nesting range of these species extends from 04035'S to 380S, covering an area of considerable geographical diversity. The climate is briefly described. The report contains details of the oceanography and marine biology of a part of the nesting range of the birds, and a rejection of the theory that a warm southward-flowing surface current causes major changes on climate and breeding season for guano birds. The histories of past abnormal years and their effects on the birds are reported. The average density of Guanay Cormorant nests is 313.9 ± 3.76 per 100 m2. The ecological efficiency of the islands and their microclimates are linked. The Guanay Cormorant is limited to nesting on the windy parts of the island, which are the coolest, as there is an inverse relation between wind and temperature. A detailed description of the social behavior of the Guanay Cormorant, including its feeding and nesting, is given. Nesting is concentrated in spring and summer. The breeding season keeps the adults on the island for four months every year. The average Guanay Cormorant clutch size is 3.13 ± 0.101 eggs and incubation lasts 27 days. Nesting in large colonies protects nests because fewer birds are at the edges in larger colonies. Various causes of mortality are described. The only significant predator of the Guanay Cormorant may be the Andean Condor (Vultur gryphus). Food is probably the most important limiting factor for the birds. There is a correlation between the abundance of food for birds and the abundance of diatoms. Each Guanay Cormorant eats approximately 215 g/day of food and no more than 316 g/day. 1 Annually, each Guanay Cormorant eats 78.4 to 115.4 kg/year of the Peruvian Anchoveta (Engraulis ringens) and produces approximately 15.8 kg of guano per year. The quantity of fish consumed by birds in the year prior to the guano harvest of 1940 was between 711,903 and 917,150 metric tons. Based on extensive data, this is much lower than previous estimates. Each ton of guano is the result of 4.95 - 7.3 tons of fish consumed, but the guano that the company removes from the islands is only a small proportion of the guano that the birds deposit at sea, where it may act as an important fertilizer for plankton. Preliminary studies suggest that anchoveta are migratory. I have rejected, because of a lack of supporting data, the theory that anchoveta are still present during food shortages, but at depths too great for them to be taken by birds. A preliminary study of 1,427 anchoveta indicated a marked reduction in the year-classes hatched in the spring and summer of 1939 and 1940, when the birds died of hunger. Anchoveta spawned in 1938 were the most abundant. The Peruvian Anchoveta appears similar in biology to the California Sardine (Sardinops sagax caerulea). The commercial anchoveta fishery should be carefully monitored as it represents one of the most serious potential threats to the guano industry. Various interactions of the birds and humans are discussed. I review the history of the guano birds, based on available data, from the pre-Columbian period to the present. The ecologies of the Peruvian Booby and Peruvian Pelican are discussed. Each species seems to occupy a distinct niche so that, within broad limits, the three do not compete with one another. Interactions or the synecology of plants and animals connected with the guano birds appear to be so complex that they require more thorough study. Various 2 management methods are suggested that might allow an increase in the numbers of birds and the proportion of guano harvested. Key words: E1 Niño, Peruvian Anchoveta Engraulis ringens, Guanay Cormorant Phalacrocorax bougainvillii, Peruvian Booby Sula variegata, Peruvian Pelican Pelecanus thagus, upwelling. 3 A NOTE CONCERNING THE TRANSLATION After I finished my own work in Peru on guano birds and had learned enough Spanish to begin to understand the importance of this paper, I spent more than a decade periodically trying to recover Vogt's original English-language manuscript, tracking down leads from four continents. Being unsuccessful, I decided instead to translate the surviving Spanish into English. A translator usually tries to achieve two things: accuracy and preservation of the author’s style. The latter is, in this case, almost impossible since I have had to translate back into English a document originally written in English but surviving only in Spanish. Enrique Avila, the Peruvian who originally translated the document into Spanish, apparently tried to keep the translation more or less literal, but as Spanish is a more loquacious language than English, there is the customary proliferation of introductory and parenthetical phrases which Vogt is unlikely to have used in the original. Avila at times had to invent Spanish equivalents for English scientific words and jargon. In some cases, the English originals followed in the Spanish text, but in others, recovery of the original sense was difficult. Additionally, some of the words and expressions are idiomatic, being peculiar to the Peruvian Spanish of the period. Finally, the typesetters and copyeditors have not been kind. Many of the numbered references were omitted and several phrases altered through omissions or “typos.” Two photographs, of an unidentified plankton and of Peruvian Boobies nesting on artificial ledges, have been included but at limited quality because of difficulties of reproduction. I have tried to make my translation as concise as possible without sacrificing the sense of the “original” Spanish. I have cut redundant sentences wherever possible and 4 reformed others, often pruning supplementary or reinforcing phrases. The translation is thus rather more “free” than literal. Emphasis has been on “readability” and context while respecting