Rationale
This species has an relatively small area of occupancy (AOO) of 56 km2, but because it is found in at least two widely separated subpopulations, the extent of occurrence (EOO) is 785 km2 in the Eastern Cape Province, South Africa. The two subpopulations are mainly found within 100 m of the high water mark on the shore or along the river bank of the tidal reaches of the Kromme River. The two known subpopulations are approximately 80 km apart, and searches in the intervening area (e.g. Kini Bay, Maitland River mouth, Van Stadens River mouth, Gamtoos River mouth, Seekoei River mouth) have all been negative (Bates et al. 2014.). It is therefore considered severely fragmented, and is potentially susceptible to stochastic events due to its small range. In recent years, however, the species has expanded its range and is now found in urbanized areas inland from its original habitat. Given that its range has expanded from an AOO previously estimated as 4 km2 (Branch 2017) to 56 km2, this species has experienced a genuine amelioration in threat status and is no longer considered to be in decline. Despite this, it could still be susceptible to coastal development in the future, as well as stochastic events, and is therefore considered Near Threatened (it almost qualifies for a threatened listing under criteria B1ab(iii)+2ab(iii)).
Distribution
Endemic to the Eastern Cape Province, South Africa and known from only two small subpopulations. The first occurs along a 25 km of shoreline immediately west of Cape Recife to Kini Bay. The eastern subpopulation comprises three historical sites (Chelsea point, Willows and Schoenmakerskop) and a recently discovered colony at Kini Bay (Conradie and Hundermark pers. obs. July 2018). The second subpopulation occurs approximately 80 km to the west (following the coastline). The western subpopulation is near the mouth of the Kromme River at the village of St. Francis Bay, extending 7 km inland along the tidal reach of the river (Branch and Bauer 1994; subsequent records) and in habitats adjacent to the coast at Cape St Francis, 5 km south of the Kromme River Mouth. Recently a new subpopulation was found at Oysterbay, 15 km west from the Cape St. Francis locality (Conradie et al. pers obs. August 2018). Theses two new localities are the first major new records in 23 years. It was previously thought to occur within 100 m of the high water mark, but the species has recently expanded inland. It is primarily found in salt marsh and adjacent coastal habitats.
Decline
Two patches of habitat are separated by approximately 80km of coastline and could not be easily repopulated or colonised from the other patch.
Population trend
Trend
A population expansion for this species has been observed in the western habitat fragment near St. Francis Bay. The species formerly occurred only near or within the coastal marshes, but in recent years it has expanded several kilometres inland and is now utilizing man-made structures as shelter (W. Conradie pers. obs. 2017). The species is therefore considered stable, but given there are only two isolated subpopulations known, it is severely fragmented.
Threats
Occupies a restricted range in a naturally-fragmented, sensitive coastal habitat that is subject to coastal development pressures. It is unclear if this development has actually been the driver of species range expansion, so whether this is a threat or a benefit is not known. The species' primary habitat (coastal marshes) could become affected by stochastic events such as increasing storm sea flooding and sea level rise associated with climatic change. It occurs in one protected area, but this is a small fragment (<10 km2).
Uses and trade
Not known to be utilized in any way.
Conservation
Perform surveys to confirm the restricted distribution, the range expansion extent, and whether the subpopulations are isolated. The range expansion should be monitored to determine if this is a temporary expansion, or if the new larger distribution is stable. The ultimate reasons for the range expansion should be investigated.
