Studies by the ICBP have identified a number of factors that may have contributed to the recent decline of the species on Fregate island. The quality and quantity of both feeding and breeding habitats has declined on the island primarily due to commercial production of bananas and coconuts. Lack of abundant food supplies close to breeding sites limit the time parents can spend on the nest and hence limit incubation time and nest defense against predators. Magpie robins produce only one clutch of eggs per year. Finally, recent investigations have implicated pesticides used to control cockroaches and ants in homes and the hotel may be contributing to reduced breeding success.
Insecticides are potentially harmful to the magpie robin for several reasons.
Unlike many rare species, the magpie robin is often found feeding close to human habitation and indeed at times is found feeding inside the hotel. The birds show a propensity for feeding on cockroaches, including dead specimens, so it seem likely that the birds are receiving some dose of pesticides on an almost daily basis. Although there was no incontrovertible evidence that any insecticide was directly implicated in the plight of the magpie robin, the critically low population levels of this rare bird persuaded the ICBP to eliminate all possible threats to the bird's recovery. These techniques have resulted in the commercial development of the insect juvenile hormone analogue methoprene for use against the Pharaoh's ant and hydroprene for use against cockroach infestations. They are unstable in ultra-violet light and in water.