Population size of Humboldt Penguins assessed by combined terrestrial and at-sea counts

The Humboldt Penguin (Spheniscus humboldti) has been reported as declining along its distributional range and has recently been classified as vulnerab le. The actual size of the Humboldt Penguin population is still unknown, an d a complete population assessment, is required. Here we present a study co mbining both counts of molting birds on land and counts of birds at sea dur ing the molting period. We conducted our study in me Coquimbo Region, North ern Chile, and round 7,619 birds on land and 2,700 at sea. adding up to a t otal of about 10,300 Humboldt Penguins during the molting season (February 1999). Since these numbers are much higher than all other recent estimates, we emphasize that assessment on land and at sea need to be combined to pro vide more reliable estimates.