Use Real-Time Mortality Alerts to Save Vultures

Abstract

Poisoning is the leading threat to vultures and other scavengers worldwide, and its scale has grown alarmingly in the past decades (Plaza et al. 2019). From January 2000, nearly 41,000 wildlife deaths from poisoning have been reported in Africa alone, almost half involving threatened vultures (The Endangered Wildlife Trust and the Peregrine Fund n.d.). Strikingly, more than 8000 wildlife mortalities have been reported since 2020 alone, with over 6600 vultures among them. The mass poisoning in Guinea–Bissau in 2020, which killed more than 2000 Critically Endangered hooded vultures (Necrosyrtes monachus; Henriques et al. 2020), was followed by many other incidents. These include the recent loss of over 100 vultures in Kruger National Park, South Africa (May 2025; Vulture Conservation Foundation 2025). Similar events across South America, Europe, and Asia show that few safe havens remain for these keystone species (Plaza et al. 2019). Without urgent, innovative action, we risk losing vultures—and the essential ecosystem services they provide (Santangeli et al. 2024). So far, we appear to be losing the battle against the perpetrators of this illicit and indiscriminate practice (Ogada et al. 2016; Margalida et al. 2019). While education, legislation, and community engagement are essential to addressing the root causes of vulture poisoning, these measures typically yield results only in the medium to long term. What is urgently needed are evidence-based, immediate interventions to reduce mortalities. Rapid response teams capable of decontaminating poisoning sites can save many vultures’ lives (Murn and Botha 2018). However, their effectiveness is limited to the few events that are timely detected. Tragically, most incidents go unnoticed or are discovered far too late, as exemplified by the Guinea–Bissau massacre of 2020.

Rapid advances in biologging offer a powerful tool to combat poisoning and other wildlife crimes. This is particularly operationalized by fitting animals with GPS units and following their movement and behavior, which can eventually indicate the where and when of a specific incidence type under focus. Death detector algorithms in GPS-tracked birds can now send near-live mortality alerts via GSM and/or satellite. Moreover, the falling cost of transmission, driven by newly developed and developing systems, such as ICARUS satellite transmission (to be launched in 2026), makes large-scale deployments feasible, affordable, and reliable, especially in the near future (Kays and Wikelski 2023). The ICARUS system will be particularly valuable in areas without GSM coverage, where poisoning events might otherwise go undetected due to phone-based transmission gaps. By enabling satellite-based data transfer, ICARUS can ensure that mortality alerts are received even from the most remote regions. A recent study in Namibia (Curk et al. 2025) provided compelling evidence of the cost-effectiveness of using vultures as sentinels. By tagging just 5% of the local population, efficiently identify poisoning events across the landscape and save a significant proportion of vultures. Crucially, the number of birds saved depends on the speed of response. The latter relies on how quickly loggers transmit alerts, and on how fast ground teams can reach the site. With current and emerging technology, alerts can already approach near-real time. Sentinel-based systems can complement existing approaches, such as the use of trained dogs. For example, GPS-tagged sentinel vultures have recently been shown to guide dog-led ground efforts by revealing poisoning events in near real time (Rodríguez-Pérez et al. 2025).

When vultures are poisoned, many other species, including mammals, other raptors, and even domestic animals, also die at these contaminated sites. The ecological and conservation impact of each poisoning incident is thus very wide. Because vultures are very efficient at locating carcasses and are disproportionately affected by poisoning, they have the potential to act as flagship early-warning species. Their movements can reveal poisoning events early enough to save not only other vultures, but the entire community of scavengers. Therefore, the conservation implications of using vultures as sentinels go well beyond this group, and may also allow to uncover illegal activities that would otherwise remain undetected. Moreover, while vultures are effective sentinels, the same real-time detection systems can be adapted for other species, by applying species-specific adjustments to the mortality detection algorithms. Extending this approach to other raptors, carnivores, large herbivores, or other scavengers would improve the detection of poisoning events or other wildlife crimes across ecosystems. For example, wolves, but also albatrosses, have proven effective in detecting possible infringements of environmental regulations (Weimerskirch et al. 2020; Mateo-Tomás et al. 2023). Jaguars have been used to uncover poisoning incidents (Csermak et al. 2023), and herbivores in fighting poaching (de Knegt et al. 2021).

A unified operational platform is urgently needed to translate animal GPS-tracking data into rapid, on-the-ground conservation action. EarthRanger (www.earthranger.com) already provides such an infrastructure, integrating data from most major tag providers and analyzing location and sensor (e.g., accelerometer) data in near real time to generate mortality alerts. These alerts can be delivered through the EarthRanger interface and shared via WhatsApp, SMS, or similar channels with all registered users near the incident, enabling rapid verification and response. Importantly, alerts can be disseminated irrespective of project ownership, allowing sentinel animals to function across their full movements, including dispersal and migration beyond study areas. This approach is already operational and continuously refined by major conservation organizations, including the Vulture Conservation Foundation in Europe and the Endangered Wildlife Trust in Africa, which together manage hundreds of sentinel vultures capable of triggering near-real-time alerts. The coordinated use of a single, interoperable system offers the greatest chance of effectively mitigating mortality events. When a poisoning incident occurs, response time is really crucial to save potentially affected wildlife, as recent evidence clearly demonstrates (Curk et al. 2025).

I encourage ecologists, conservation scientists, and field practitioners working with GPS-tracked wildlife, particularly scavengers and carnivores exposed to poisoning, to use real-time mortality alerts. Doing so would help safeguard vultures, other scavengers, and wildlife more broadly, and enable animal GPS-tracking data to fulfill their full conservation potential. Ultimately, many animal GPS-tracking projects are funded by public (i.e., taxpayer) resources. Thus, governments, public institutions, and conservation NGOs should actively require, support, and, where relevant, use near–real-time alert systems. They should also ensure that the necessary training and operational capacity are in place. These actions would ensure that GPS-tracking technology can genuinely help save vultures and other wildlife from poisoning and other threats.

The authors declare no conflicts of interest.

The poisoning incidence data are freely available at: www.africanwildlifepoisoning.org