A colony of Humboldt penguins Spheniscus humboldti in central Chile was monitored from August 1995 to July 2000 to determine patterns of breeding and colony attendance and how these were affected by climatic (rainfall) and oceanographic (El Niño) factors. Nests were periodically checked for contents and roosting birds were counted from vantage points. Two main breeding events were observed: between August and January (spring event) and between April and June (autumn event). Whereas the spring event regularly produced offspring, the autumn event was systematically affected by rains, causing considerable nest desertion. Adults were present in the colony from August to May, abandoning the colony during winter after the nests were flooded. Juveniles occurred only between November and March. Adults moulted mainly in February, while juveniles moulted in January. During the 1997/98 El Niño episode, the number of breeding pairs was 55 to 85% lower than the mean, the onset of nesting was delayed, and abnormally heavy rainfall flooded nests. While the number of breeding pairs was significantly related to sea surface temperature anomalies (SSTA), breeding success was not. The attendance of adults and juveniles at the colony during El Niño was 25 and 73% lower, respectively, than the mean attendance. This 2-peak breeding strategy of Humboldt penguins appears to have evolved in response to the more favourable oceanographic and climatic conditions of Perú, where breeding is continuous and not interrupted by rains. Although less productive, the species probably maintains its autumnal breeding in central Chile because this provides additional offspring to supplement those regularly produced during the spring event.KEY WORDS: Humboldt penguin · Spheniscus humboldti · El Niño · Nest desertion · Breeding · Colony attendance Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 227: [43][44][45][46][47][48][49][50] 2002 with the tropics where little, if any, seasonal environmental fluctuation occurs and bird breeding may extend over a longer period (Lack 1954, 1967, Furness & Monaghan 1987. Nearly all marine birds follow this synchrous breeding strategy (Lack 1967).The Humboldt penguin Spheniscus humboldti breeds over 4500 km along the Pacific coast of Perú and Chile between 5°and 42°S (Williams 1995). Over this extensive distribution area the species faces considerable latitudinal gradients in oceanographic and climatic factors, including marine productivity, El Niño events, sea surface temperatures and rainfall (see Hunt & Schneider 1987). This situation is likely to expose the species to differential selective pressures over its breeding range.In their northernmost breeding areas along the subtropical Peruvian coast, Humboldt penguins nest throughout the year with well-defined breeding events in autumn and spring (Murphy 1936, Zavalaga & Paredes 1997. Whereas adults remain permanently near the colonies, juveniles are absent for several months after fledging (Zavalaga & Pared...

To establish baseline hematologic and plasma biochemistry values in free‐ranging Humboldt penguins (Spheniscus humboldti), heparinized blood samples were collected from 51 apparently healthy, adult Humboldt penguins residing at two colonies off the Chilean coast. Thirty samples were collected in April, 1992, from penguins inhabiting the Ex‐islote de los Pájaros Niños in Algarrobo, Chile. In September, 1992, 21 samples were collected from birds inhabiting Isla de Cachagua, Chile. Hematologic values measured include packed cell volume, leucocyte count, leucocyte differential, and the presence of blood parasites. Plasma biochemistry values measured include glucose, blood urea nitrogen, creatinine, uric acid, calcium, inorganic phosphorous, sodium, potassium, chloride, total protein, albumin, globulin, aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, total bilirubin, and creatine kinase. Only the mean values for chloride and for the number of eosinophils differed significantly between the two sample groups. No blood parasites were seen. © 1995 Wiley‐Liss, Inc.

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Plasma retinol and α‐tocopherol concentrations were measured in heparinized blood samples collected from 51 free‐ranging adult Humboldt penguins (Sphenicus humboldti) residing at two colonies off the Chilean coast. Thirty samples were collected in April 1992 from penguins inhabiting the Ex‐islote de los Pájaros Niños in Algarrobo, Chile. In September 1992, 21 samples were collected from birds inhabiting Isla de Cachagua, Chile. Samples were assayed for retinol, retinyl palmitate, α‐tocopherol, γ‐tocopherol, lutein, β‐cryptoxanthin, lycopene, α‐carotene, and β‐carotene. Retinol, α‐tocopherol, and lutein were detected in all samples, while lycopene and γ‐tocopherol were not detected in any. A significantly higher percentage of samples had detectable levels of retinyl palmitate and α‐carotene in April (P < 0.001): for β‐cryptoxanthin the percentage was higher in September (P < 0.001). Plasma concentrations of α‐tocopherol and lutein were higher in September. Alpha‐tocopherol concentrations were 1,877.1 ± 99.0 (SEM) μg/dl in April compared to 2.289 ± 122.3 μg/dl in September (P < 0.05); lutein concentrations were 4.16 ± 0.43 μg/dl in April vs. 10.68 ± 1.02 μg/dl in September (P < 0.001). Retinol concentrations were not significantly different (117 ± 8.0 μg/dl in April vs. 105.3 ± 7.6 μg/dl in September). Both physiologic changes associated with season, and the change in locale may have contributed to the differences seen in the assay means and the number of samples with detectable levels. © 1996 Wiley‐Liss, Inc.

Gender was determined by laparoscopic visualization of the gonads for 38 adult American flamingos (Phoenicopterus ruber ruber L.) and 36 adult Chilean flamingos (P. chilensis L.). Concomitant body weight (kg) and linear measurements (mm) of the culmen (bill), tarsus (tarsometatarsus), middle toe, and wing were taken. Statistical comparisons of body weight and linear measurements for male vs. female were made for each species. Also, the same-sex statistical comparisons were made between these two species, and between each of these two species and with data for greater flamingos (P. r. roseas L.) from a previous publication. As previously published for greater flamingos, an overlap between sexes existed in all measurements with males on average larger than females for both American and Chilean flamingos. However, Students' t-test indicated a significant sexual difference for all measurements between males and females of each species except for culmen length in Chilean flamingos. Students' t-test also indicated a significant difference when species were compared (Chilean vs. greater, and American vs. Chilean) and subspecies (American vs. greater) were compared for most of the 5 measurements. Thus, despite limitations imposed by between-sex overlap, weights and linear measurements, especially tarsus, middle toe, and wing length, appear to be useful in determining an individual's gender when species or subspecies identification is considered.