Health brings the powerful interrelationship between human and wildlife health together with ecosystem health. The initial concept of One Health was formulated decades ago and focused on disease transfer from wildlife to human populations. More recently, the concept has been used to associate resilience to disease with the health of the ecosystem and resilience to environmental stressors. The need for a One Health approach is particularly evident in the plight of Old World vultures, which are facing a conservation crisis due to drastic reductions in populations across their entire range. Moreover, vulture conservation exemplifies many contemporary tenets of One Health; vultures are critical to a sustainable and resilient ecosystem, which in turn is essential for the socio-ecological health of human communities. In this review, we examine the complex factors contributing to the demise of Old World vulture populations, using the lens of One Health to conceptualize the primary drivers impacting the health and sustainability of these populations. The One Health concept provides the basis for the development of a framework that incorporates a multidimensional approach and includes human health, wildlife health, environmental and disease-related stressors, disease incidences, societal pressures, and environmental contaminants. Integrating societal needs with management aimed at maintaining healthy vulture populations is key for successfully using a One Health framework to optimize the health of human and wildlife populations and ensure ecosystem health.

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Elephant were previously widespread in savanna and coastal systems of KwaZulu-Natal (KZN), but were virtually extirpated by 1870. Over time, elephant have been reintroduced into their former range in KZN, but always onto small fenced systems (mean size 191.3 km2 ± 87.8 km2, median size 107.0 km2, range 14 km2 – 900 km2). These populations have increased rapidly (8.4% per annum), and although a number of populations are now being managed using contraception, the majority of the populations (66.7%, 14 out of 21) are stocked above the ‘preferred density’ as defined in their approved management plans, while others will soon exceed the preferred density. Vulture populations in KZN are small, declining and already at risk of extinction. In KZN, 94.2% of tree-nesting vulture nests occur in areas with elephant; this could increase to 99.5% in the near future if proposed land-use change takes place. Anthropogenic impacts in the broader landscape mean that there are limited opportunities for vultures to nest elsewhere, and we hypothesise that loss of suitable nesting habitat in existing areas, including through impact of elephant on large trees, could result in declines and even extirpation of these species as breeding residents. Given the demonstrated and potential impacts of elephants on large trees necessary for vulture nesting, it is essential that the role of protected areas and extensive wildlife systems for vultures be adequately taken into account when managing elephant populations. It is important that a precautionary and adaptive management approach is taken regarding management of elephant in areas important for vultures, at least until the ecological interactions between vultures, vegetation, elephant and other drivers are better understood, and until the willingness and ability to manage elephant numbers and impact according to the elephant management plans are demonstrated.

African wildlife face challenges from many stressors including current and emerging contaminants, habitat and resource loss, poaching, intentional and unintentional poisoning, and climate‐related environmental change. The plight of African vultures exemplifies these challenges due to environmental contaminants and other stressors acting on individuals and populations that are already threatened or endangered. Many of these threats emanate from increasing human population size and settlement density, habitat loss from changing land use for agriculture, residential areas, and industry, and climate‐related changes in resource availability. Environmental chemicals that are hazardous include legacy chemicals, emerging chemicals of concern, and high‐volume‐use chemicals that are employed as weed killers and in other agricultural applications. Furthermore, there are differences in risk for species living in close proximity to humans or in areas affected by habitat loss, climate, and industry. Monitoring programs are essential to track the status of nesting pairs, offspring survival, longevity, and lifetime productivity. This is important for long‐lived birds, such as vultures, that may be especially vulnerable to chronic exposure to chemicals as obligate scavengers. Furthermore, their position in the food web may increase risk due to biomagnification of chemicals. We review the primary chemical hazards to Old World vultures and the interacting stressors affecting these and other birds. Habitat is a major consideration for vultures, with tree‐nesters and cliff‐nesters potentially experiencing different risks of exposure to environmental chemicals. The present review provides information from long‐term monitoring programs and discusses a range of these threats and their effects on vulture populations. Environ Toxicol Chem 2022;41:1586–1603. © 2022 SETAC

Summary 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.