San Clemente Island plants, bird succeed despite obstacles

How do the foxes get there ?

they didnt talk at all about biggest threat: for flora its goat, for fauna its cat and rat,
i can understand goat/sheep are volontary put for keep exercice field clean without forest and food. but cat and rat can are often unwelcome and destroy all small lives like birds. lizardn, slowing pollen etc..
note also that isolated military island are perfect for terraforming, full control, no civilian, ascencion island was totally reshaped by darwin, idea was to bring 400plant species for bring ecoystem and fresh water for british navy,..that mean if us navy want they cant stay like this, or create forest or let goat keep it clean.