Pup survival in the Mediterranean monk seal (Monachus monachus) colony at Cabo Blanco Peninsula (Western Sahara-Mauritania)

We surveyed pup survival in Mediterranean monk seals (Monachus monachus), a t Cabo Blanco Peninsula (Western Sahara-Mauritania) colony from May 1993 to December 1997. This species breeds and hauls out on beaches inside two mai n caves. During the study period we detected a total of 93 pups that died o r disappeared. The survival rate of 84 pups through the age of first moult (approximately two months) was 0.47. This value is similar to those reporte d for other pinnipeds breeding in caves but lower than for those breeding o n open beaches. Mortality varied seasonally and appeared to increase as a r esult of storms, large ocean swells, and high tides. Mother-pup pair separa tion (and resulting pup starvation) and physical injury caused by impact ag ainst the rock walls of he cave and cliffs were established as the causes o f most deaths. Beach surface area inside the caves also appeared to be a me diating factor in the effects of sea conditions. High pup mortar;ty may be a limiting growth fact-or in this population, although cave dwelling protec ts the population from predators and human disturbance.