We investigated a link between facultative semelparity (“male die-off”) in a small, endangered marsupial, Parantechinus apicalis (the dibbler), and the availability of resources on two small islands in Western Australia. Post-mating survival of male dibblers differed between the two islands, and the input of nutrients from nesting seabirds was a possible factor affecting available resources and therefore survival of male dibblers. Seabirds can increase significantly the concentration of nutrients in the soil and can ultimately lead to an increase in abundance of primary consumers and predators. We compared concentrations of soil nutrients, body condition, and post-mating survival of male dibblers on both islands. The body condition and post-breeding survival were significantly better on the island with many seabirds, where soil nutrients were up to 18 times higher, than on the adjacent island with fewer seabirds. Our results indicate a potential link between male die-off and resource availability. We suggest that marine-derived nutrients transported onto islands by nesting seabirds can alter the productivity as well as the life history traits of species in an island ecosystem.