Masked Booby (Sula dactylatra) Science Article 4
abstract
Punta Suarez, Isla Espanola, Galapagos Islands, Masked Boobies (Sula dactylatra) nested at the edge of a cliff while Blue-footed Boobies (Sula nebouxiz) nested farther inland. Elsewhere in the Galapagos, Blue-footed Boobies nested near cliff edges at seven of eight sites where Masked Boobies were absent.
DAVID CAMERON DUFFY, The Condor 86:301-304