MEPS 227:43-50 (2002)  -  doi:10.3354/meps227043

Oceanographic and climatic factors influencing breeding and colony attendance patterns of Humboldt penguins Spheniscus humboldti in central Chile

Alejandro Simeone1,*, Braulio Araya2, Mariano Bernal3, Edward N. Diebold4, Karen Grzybowski5, Margaret Michaels5, J. Andrew Teare6, Roberta S. Wallace5, Mary Jo Willis7

1Institut für Meereskunde, Düsternbrooker Weg 20, 24105 Kiel, Germany
2Anakena 2311, Departamento 208, Viña del Mar, Chile
3Instituto de Oceanología, Universidad de Valparaíso, Casilla 13-D, Viña del Mar, Chile
4Riverbanks Zoological Park and Botanical Garden, PO Box 1060, Columbia, South Carolina 29202, USA
5Milwaukee County Zoo, 10001 West Bluemound Road, Milwaukee, Wisconsin 53226, USA
6Jacksonville Zoo, 8605 Zoo Parkway, Jacksonville, Florida 32218, USA
7Denver Zoological Foundation, 2900 E. 23rd Avenue, Denver, Colorado 80205, USA

ABSTRACT: 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

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