The Galapagos Penguin (Spheniscus mendiculus) population probably has
always been small and largely restricted to the islands of Fernandina
and Isabela. Counts suggest the current population of Galapagos Pengui
ns is likely between 4,250 and 8,500, half of what it was in the early
1970s. Population size has varied and declined probably because of su
bstantial changes in oceanic conditions. Body condition as evidenced b
y weight is enhanced during cold surface water conditions, La Nina, an
d deteriorates when surface waters are warmed, El Nino, and under the
most severe conditions, penguins starve. Analysis of a long-term data
set from counts of the population suggests that the population has flu
ctuated, dropping precipitously after the 1982-1983 El Nino and has si
nce then been recovering very slowly. This parallels the overall warmi
ng in the Pacific during the last 20 years associated with the more fr
equent El Nino and less frequent La Nino events. These trends suggest
that long-term global climate warming is likely to threaten the Galapa
gos Penguin population particularly because the population is small an
d its distribution restricted. New threats from climatic warming and i
ncreasing human perturbations such as fishing, inadvertent discharge o
f petroleum products, and transport of potential predators and pathoge
ns to islands increase the risk of extinction.