Evidence of the effectiveness of conservation interventions from long-term aerial monitoring of three crane species in KwaZulu-Natal, South Africa

Monitoring population trends is important for evaluating the effectiveness of conservation interventions. An annual aerial census of three crane species, the Grey Crowned Crane Balearica regulorum, Blue Crane Anthropoides paradiseus and Wattled Crane Bugeranus carunculatus, was performed in KwaZulu-Natal province, South Africa over the past 23 years. These crane species are listed as 'Endangered', 'Vulnerable', and 'Vulnerable', respectively, on the IUCN Red List. KwaZulu-Natal was chosen as a key site for monitoring as it covers an important region for cranes that has received concerted conservation effort since the 1980s. These annual surveys are conducted by Ezemvelo KwaZulu-Natal Wildlife, a provincial conservation agency, and the Endangered Wildlife Trust, a conservation non-profit organisation. We estimated crane population trends from data collected by means of standardised surveys conducted between 2003 and 2019. Results from the surveys show a steady and significant increase in the population size of all three crane species. Interventions including power line collision mitigation and engagement with landowners have been implemented in formal conservation programs to protect these cranes. Results from the annual census suggest that conservation interventions have been effective.