New localities for Hyperolius pickersgilli

Overall, only a relatively small number of localities visited during the ground-truthing (Appendix D) appeared suitable for H. pickersgilli, and of these, the species was present at only six (one of which was a rediscovery): the St Lucia Estuary (iSimangaliso World Heritage Site; -28.37183º, 32.40335, altitude 4 m.a.s.l.), Port Durnford (-28.90521°, 31.85801°, altitude 21 m.a.s.l.), Nonoti (-29.29718º, 31.41226º; altitude 29 m.a.s.l.), Umkomaas (-30.217183°, 30.795353°, altitude 13 m.a.s.l.) and Sezela (-30.40670°, 30.66145°, altitude 21 m.a.s.l.). Although the wetland at Prospecton (-29.97837°, 30.93617°;

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altitude 6 m.a.s.l.), was not predicted by the model it is included as a new site which was discovered during the period of ground-truthing (December 2010). This wetland occurs in the industrial zone of Durban south and is described in Chapter 3.

The St Lucia Estuary location (rediscovered on 3 February 2011) is a tall, thick Phragmites australis reed-bed, straddling both sides of the main tar road into St Lucia, and is protected as part of the iSimangaliso World Heritage Site (Bishop 2004b) (Figure 4.5). Although the wetland is bisected by the road, the ability of H. pickergilli to disperse to the north and south, still remains.

Figure 4.5: Habitat at the St Lucia Estuary area at which a population of Hyperolius pickersgilli was found on 3 February 2011. Photograph by Adrian Armstrong.

The population near Port Durnford was discovered on 12 October 2011. The large perennial wetland comprised of P. australis and Cyperus latifolius with deep (50 cm in parts), stagnant water (Fig. 4.6). Numerous males were heard calling and visual confirmation was made though observation of both males and females (Fig. 4.7). Preliminary call records indicate that this site may host one of the largest known populations of H. pickersgilli. This land

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belongs to a timber company, Mondi-SiyaQhubeka, and is bordered by pine plantations and rural habitation. A 40 ha compartment of trees has already been removed from the area opposite the wetland and the timber company is planning to rehabilitate this area back to wetland, which could possibly provide a re-introduction site for rescued or captive-bred individuals of H. pickersgilli.

Figure 4.6: Habitat at the Port Durnford wetland at which a new population of Hyperolius pickersgilli was found on 12 October 2011.

Figure 4.7: (A) Male and (B) female Hyperolius pickersgilli at Port Durnford, 12 October 2011.

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A population on the south coast near Umkomaas was discovered on 6 January 2012. A few males were heard calling (and one visually detected) on either side of the coastal R102 road in a densely vegetated wetland comprised largely of P. australis, Persicaria attenuata and C.

dives. This small wetland is surrounded on all sides by transformed landscapes (urbanisation and roads) (Figure 4.8). The site is currently facing pressure from a housing development plan. Furthermore, the area upstream of the catchment has been ear-marked for further urban development (R. Boon, pers. comm.). The wetland is also heavily infested with alien vegetation including Brazilian pepper (Schinus terebinthifolius), Syringa (Melia azadarach), Wild canna (Canna indica) and Lantana (Lantana camara) (J. Vermuelen pers. comm.).

Calling was very intermittent and ceased altogether within 15 minutes, emphasising how easy it is to overlook this species. Although other species, including Hyperolius tuberilinguis, were calling strongly, the environmental temperature of 24.2 °C at 22:00 and extremely high humidity may have inhibited calling of H. pickersgilli. After searching the wetland, it became apparent that only a small portion of the area seems to host H. pickersgilli.

Figure 4.8: Site for the new population of Hyperolius pickersgilli discovered on 6 January 2012 near Umkomaas, on the KwaZulu-Natal south coast. The wetland area is indicated by the red line.

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Another new population was located near Zinkwazi Beach at Nonoti Sugar Estate on 10 January 2012. This is a medium-sized, densely vegetated perennial wetland that appears highly suited to H. pickersgilli. Although no calling males were detected at the time of the survey, many juveniles resembling H. pickersgilli (Fig. 4.9) were present on the wetland periphery. Three of these were collected for rearing at the Johannesburg Zoological Gardens to verify their identity and for inclusion in the ex situ captive breeding program (Visser 2011). All three have survived in captivity to date and appear to be H. pickersgilli. The wetland at Nonoti appears to be highly suitable for the species and is in good condition, but is surrounded by sugarcane.

Figure 4.9: Juvenile Hyperolius pickersgilli from the locality discovered on 10 January 2012 at Nonoti Farm, Zinkwazi Beach.

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On 19 January 2012, a further population on the south coast was discovered in the Sezela area. A number of males were heard calling from a very dense reed-bed of C. dives, P.

australis and P. attenuata with ~ 60 cm deep stagnant water. Other species present included H. tuberilinguis and Afrixalus fornasinii. This medium-sized wetland is surrounded by extensive sugar-cane fields. This population at Sezela is now the southernmost known site of this species, approximately 40 km south of the now extinct Warner Beach site, and is also completely surrounded by sugar cane and in the vicinity of industrial operations including an electrical substation and large sugar mill. On 20 January 2012 numerous males were heard calling in a relatively extensive P. australis reed-bed immediately adjacent to the busy N2 highway in the Prospecton area (-29.97837°, 30.93617°). This system is an extension of the Prospecton population discovered in December 2010.

Both the probabilities of occurrence at the ground-truthing locations where H. pickersgilli was present and the probabilities of occurrence of the locations at which H. pickersgilli was not detected followed a Normal distribution (Shapiro-Wilks W=0.93, p>0.05, W=0.95, p>0.05, respectively). The mean probability of occurrence for H. pickersgilli at the ground-truthed sites where it was present (0.5373) was greater than the mean probability of occurrence for H. pickersgilli at the ground-truthed sites where it was not detected (0.4177; t

= 1.506185, df = 31, p = 0.071; one-tailed test).