The ecological role of Temminck’s pangolins in a dryland ecosystem

Abstract

Conservation practices prioritising the preservation of species, along with the ecosystem services that they provide, are crucial as threats to global biodiversity escalate. Rare species are often assumed to have a limited contribution to overall ecosystem functionality, yet these species are often the most in need of conservation efforts. However, the extent to which rare species contribute to ecosystem processes remains poorly understood. One such species is Temminck’s pangolin (Smutsia temminckii), which has been speculated to impact ecosystem functionality through contributions to soil turnover, increases in local biodiversity and nutrient cycling. The International Union for the Conservation of Nature (IUCN) has classified Temminck’s pangolins as Vulnerable due to their decreasing population trend, largely as a result of their exploitation in the illegal wildlife trade. Temminck’s pangolins are recognised globally as a threatened mammal requiring urgent protection. Despite their threatened status, the consequences of their loss in terms of ecosystem services are poorly understood, and empirical data on their ecological role is limited. Therefore, the aim of my study was to gain an understanding of Temminck’s pangolin foraging behaviour and patterns (foraging frequency and distance foraged) and evaluate the ecosystem services these pangolins provide through their foraging activities. I opportunistically located four Temminck’s pangolins at Tswalu Kalahari Reserve, Northern Cape, South Africa, and tagged each with a Very High Frequency (VHF) tracking transmitter. I observed pangolins during their foraging activities, and recorded data for the seasonal frequency of foraging sites created, the distance travelled while foraging, and how foraging frequency and distance foraged may be affected by prey abundance. I took measurements of seasonal soil turnover, accumulated organic matter and soil nutrient concentration at foraging digs, with repeat samples being taken for biodiversity accumulation and nutrient concentration to assess changes over time. The mean foraging frequency of pangolins was 12.5 ± 7.3 sites per hour iii and varied seasonally, with peaks in summer (17.9 ± 4.4 sites per hour) and winter (14.4 ± 9.7 sites per hour) as compared to lower values in autumn (11.3 ± 6.3 sites per hour) and spring (8.5 ± 3.9 sites per hour). The mean distance foraged per hour, 0.2 ± 0.1 km, did not differ seasonally. Prey abundance showed seasonal variation, increasing in summer (28.7 ± 23.2 ants per trap) and autumn (27.0 ± 28.1 ants per trap) and decreasing in winter (13.7 ± 17.3 ants per trap) and spring (13.4 ± 13.1 ants per trap). Prey abundance was 115 % higher in summer as compared to in spring. Foraging frequency was not linked to prey abundance, however, the distance foraged was positively associated with prey abundance. The results of my study provide support for seasonal variability in pangolin foraging behaviour, and its potential link to prey abundance. I estimated that a single pangolin uses 29 855 ± 8281 foraging sites each year, turning over 15.6 ± 10.8 metric tonnes of soil (15 619 ± 10 788 kg), and that their foraging digs accumulate 66.1 ± 62.8 kg of organic matter each year. Pangolin foraging had no effect on the nitrogen concentration of soil throughout the year, with mean concentrations of 0.03 ± 0.01 % in both dig sites and control sites. In contrast, the total carbon concentration was 10.4 % (relative difference) higher in the soil of pangolin dig sites (0.20 ± 0.07 %) as compared to the surrounding undisturbed soils (0.19 ± 0.05 %). The ecosystem services of Temminck’s pangolins, quantified in my study, are comparable to those of Chinese pangolins (Manis pentadactyla), however Temminck’s pangolins may provide additional services, such as burrow maintenance and altering plant community structure. Soil turnover estimate for Temminck’s pangolins, when expressed relative to body mass (2.6 tonnes of soil individual-1 kg body mass-1 year-1), align with estimates for fossorial animals in general (1.8 to 3.6 tonnes of soil individual-1 kg body mass-1 year-1). Overall, my study demonstrates that pangolins contribute to their environment through the ecosystem services that they provide. By quantifying the ecosystem services of Temminck’s pangolins, iv my study may allow for better alignment of conservation efforts to protect this vulnerable species and preserve their unique and vital role within the ecosystem.