Coastal development and disturbance on breeding islands is likely the greatest threat to the species, with detrimental effects in the past, present and future (BirdLife International 2010). Frequent human disturbance flushes parenting birds from nests, resulting in widespread egg and chick predation by gulls Larus spp. (Gallagher et al. 1984, Symens et al. 1993, Aspinall 1996). Total colony abandonment also occurs, and is not always followed by successful relocation elsewhere (Gallagher et al. 1984, Symens et al. 1993, Aspinall 1996). The extinction of 12 colonies since the 1960s is attributed to encroachment by development and prolonged human disturbance (H. King in litt. 2005). A current proposal to build a large multi-use project on Siniya Island (at present supporting a stable colony of c. 25,000 breeding pairs) including a bridge to the mainland, is likely to see the loss of this colony as a result of disturbance and subsequent access of terrestrial predators (S. Muzaffar in litt. 2016). Parent cormorants tend to respond to threats by departing from the nest rather than defensive aggression, leaving the chicks vulnerable to predation. In 2011, reports suggests that three Feral Cats Felis catus and three Red Foxes Vulpes vulpes were alone responsible for the death of c. 2,000 birds. The island has the capacity to sustain far larger predator populations, and there is potential for future increases in predation pressures. Simulated population models under these predation levels predict declines to near-extinction levels (a few hundred individuals) within 30 years (Muzaffar et al. 2013). As a ground-nesting species, Socotra Cormorant is vulnerable to the effects of storms, such as the flooding of nests during heavy rains, as took place on Suwad in November 1997. Similarly, in April 2003, an isolated thunderstorm with strong winds resulted in sudden termination of breeding and mass abandonment of chicks (H. King in litt. 2005). The species is highly vulnerable to marine oil spills (Gallagher et al. 1984, Symens and Suhaibani 1993). For instance, in August 1980 an oil spill of about 20,000 barrels off the coast of Bahrain killed up to 1,000 birds, most of which were Socotra Cormorants (Baha El Din 1991). Apart from direct mortality, effects include reduced immune function and reduced breeding success from oiling and ingestion, and depletion of prey fish stocks (Baha El Din 1991). As a piscivore, the species is susceptible to other marine pollutants such as heavy metals and PCBs (Polychlorinated biphenyls) as well as neurotoxins (Baha El Din 1991). The species suffers minor effects from competition with fisheries, including non-targeted capture of prey species or their use as baitfish (Muzaffar et al. 2017b). The diet of chicks varied significantly between years, suggesting that the species is a generalist and feeds opportunistically on abundant fish species (Muzaffar et al. 2017b). Persecution, as well as chick and egg collection at remaining breeding sites, poses a threat of unknown severity (Aspinall 1996, Environment Agency - Abu Dhabi 2016, Muzaffar et al. 2017a).