The Endangered Albany adder (Bitis albanica) is under serious threat of extinction, caused by continued habitat loss, and may have already become extinct in several historical locations, in the Eastern Cape, South Africa. Bitis albanica is an elusive and cryptic viper with only 43 confirmed sightings since 2016, including eight road mortalities, despite intensive surveys. The aim of this research was to assess methods of detection and capture, improve knowledge of occupancy and predictors of detection on roads, and assess the threat of road mortalities for this species.
A cross-sectional observation survey was conducted at a wind energy facility north of Algoa Bay, using a combination of drift fence surveys with pitfall and funnel traps, and road-cruise surveys by car and bicycle. During 23 days in October 2021, road-cruise surveys by car were the most effective (0.06 per hour) method to detect B. albanica (n = 6). Bicycle surveys detected more reptiles (0.56 per hour) and roadkill (1.64 per hour) than car surveys (0.45 live per hour and 0.18 roadkill per hour). Kernel estimates of intensity for invertebrate roadkill and live reptile detections showed similar hotspots in higher traffic and land-use areas. A single-season site occupancy model predicted increased detection probabilities on wider roads, in the late afternoon/evening, and on days without rain or cloud cover, but overall remained low, between < 0.01 and 0.03 (95% CI: 0, 0.18).
Detecting B. albanica required a high level of effort. However, using a range of methods informed future research and will help inform critical conservation recommendations. Roadkill hotspots across taxa were a useful proxy to target road mitigation and temporal changes in detection to direct times of traffic moderation. A bicycle is a promising method, for live reptile and roadkill surveys, however, in dense vegetation, trapping using less labour-intensive camera traps along drift fences may prove more efficient.