Invasive species. Introduced rats and feral cats prey on island foxes and compete with them for food, leading to population declines and even local extinctions.
Disease. Diseases carried by domestic dogs can easily spread to island foxes due to their small population size and close proximity to human settlements.
Hunting and persecution. In the past, island foxes were hunted for their fur. While this practice has declined, some islanders still view foxes as pests and will shoot them on sight.
Limited genetic diversity. Due to their small population sizes and geographic isolation, island foxes may be more vulnerable to negative genetic effects and less able to adapt to rapid environmental changes.