Conservation Bio: Emerging threat of avian influenza to the world's vultures

[Michael Coston]

Conservation Bio: Emerging threat of avian influenza to the world's vultures​

Black Vulture - Credit Wikipedia


#19,307

Of the 19,631 entries in the USDA's Detections of Highly Pathogenic Avian Influenza in Wild Birds - which has only been intermittently updated in 2026 - 1215 (6.2%) are listed as vultures.

Other raptors and scavenger birds on the list include eagles (n=990), hawks (n=1010), Owls (n=764) and California Condors (n=22). But these lists are far from complete

Three and a half years ago, (Apr 8th, 2023) the U.S. Fish & Wildlife Service issued a statement stating that HPAI Was Confirmed As Cause Of Death For 3 California Condorsfound in Northern Arizona.

Considered a critically endangered species with a population of ≈ 560 birds today - the California Condor nearly went the way of of the dodo in the early 1980s, when its population declined to just over 20 (in the wild) due to the combined effects of DDT, lead poisoning and a loss of habitat.

As scavengers, Condors feed almost exclusively on carrion, which increasingly runs the risk of being infected with HPAI H5 (see USDA Mammalian HPAI Infection List). Within days, the number of Condor deaths rose sharply.

HPAI UPDATE

(Excerpt)

As of April 17, 2023, 20 condors have died in the Arizona-Utah flock; HPAI has been confirmed for 10 of those condors. Eight birds were captured and brought in for supportive care. Four of those condors died shortly thereafter and are included in the total of 20 deceased birds. Four condors are still receiving supportive care and have shown improvement. Learn more about HPAI.

While an emergency vaccination program was initiated in the fall of 2023, and more than 200 birds were eventually vaccinated, the carnage visited upon scavenger birds by H5N1 has continued.

While not every bird that gets infected dies (see Preprint: Exposure & Survival of Wild Raptors During the 2022-2023 Highly Pathogenic Influenza A Virus Outbreak), the virus's toll on avian populations around the world has been enormous.

Over the past few years we've looked at a number of papers from the tag-team of Pablo Plaza & Sergio A. Lambertucci (often in collaboration with Andrea Santangeli), including:

ISIRV: Update on H5N1 Panzootic: Infected Mammal Species Increase by Almost 50% in Just Over a Year

Travel Medicine & Inf. Dis.: Differences Between Influenza H5N1, A/H1N1 2009, and SARS-CoV-2 in a Pandemic Risk Scenario

Nature Reviews: The Threat of Avian Influenza H5N1 Looms Over Global Biodiversity

Travel Med. & Inf. Dis.: Pacific and Atlantic Sea Lion Mortality Caused by HPAI A(H5N1) in South America

EID Journal: Recent Changes in Patterns of Mammal Infection with Highly Pathogenic Avian Influenza A(H5N1) Virus Worldwide

Last week they published the following letter (excerpts below) in Conservation Biology. Follow the link to read it in its entirety.

Emerging threat of avian influenza to the world's vultures

Jon Morant, Andrea Santangeli, Pablo Plaza, Sergio A. Lambertucci
First published: 19 August 2026
https://doi.org/10.1111/cobi.70372Digital Object Identifier (DOI)
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Article impact statement: Five action areas need to be implemented across continents to address the potential impact of H5N1 on world's vulture populations.

Vultures are among the most threatened bird groups globally (Buechley & Şekercioğlu, 2016), yet they provide invaluable ecosystem services that support human well-being (Santangeli et al., 2024). At least 16 of 23 vulture species are of conservation concern worldwide, largely owing to toxicosis and other anthropogenic threats (Buechley & Şekercioğlu, 2016). The current panzootic caused by highly pathogenic avian influenza virus (H5N1) (hereafter H5N1) (Lambertucci et al., 2025) could represent a catastrophic addition to this threat mix, magnifying already steep population declines. In fact, globally, several important vulture hotspots are under threat from the intensive spread of this pathogen (Figure 1).

(SNIP)

We call upon conservationists and wildlife managers to adopt a comprehensive, multilayered approach to mitigating H5N1 risks in vultures, prioritizing five key action areas that balance immediate fieldwork situations with broader population resilience.

First, there is an urgent need for intensive medium- to long-term population monitoring in geographic regions impacted by the current H5N1 panzootic (Figure 1); this monitoring should be coupled with targeted epidemiological surveillance and seroprevalence studies in vulture communities to evaluate immunological status and improve knowledge of how H5N1 affects their populations beyond acute mortality events. This action is especially relevant for sites where information on vulture mortality due to H5N1 remains limited. Second, we advocate for the continuous evaluation of the potential need for vaccination campaigns for specific and emerging cases where populations face severe risk and logistical conditions allow (Katzner et al., 2025; Larson 2026).

Third, carcass management must be carefully adapted to local socioeconomic contexts; managers should prioritize preventing the use of suspected or H5N1-infected carcasses at feeding stations, mirroring existing safe carcass protocols used to exclude toxic pharmaceuticals in vulture safe zones (VSZs). Ensuring the provision of H5N1-free carcasses from both domestic and wild sources is crucial to reducing viral transmission at supplementary feeding stations (i.e., vulture restaurants) (Santangeli et al., 2025), which often attract large aggregations of obligate and facultative scavengers (Brink et al., 2020; Cortés-Avizanda et al., 2016). Rapid molecular testing protocols (such as rRT-PCR using freeze-dried reagents; Takekawa et al., 2011) and the systematic removal of infected carcasses (Gold et al., 2026) could be valuable interventions, although we recognize that their availability, cost, and sensitivity may represent important barriers to their implementation in many regions.

Fourth, we recommend strictly following handling protocols for vultures during fieldwork (e.g., tagging, morphometry, and health surveys) in accordance with H5N1 biosecurity guidelines to minimize transmission risk among individuals and species. Finally, given the diversity of socioeconomic and governance contexts in the countries across the vulture's range, we urge regional conservation and health bodies, such as the International Union for Conservation of Nature (IUCN) and the World Organisation for Animal Health (WOAH), to develop and promote context-specific action plans that prioritize these feasible, locally adapted interventions.

This pathogen could represent the final threat to some vulture populations; therefore, tackling the five action areas outlined above is urgent. Crucially, these measures must not be pursued in isolation; their integration into coordinated, transboundary frameworks is essential to address the full geographic and ecological scope of the crisis.

The current H5N1 panzootic is occurring across all continents where vultures occur, concomitantly with other threats affecting these species. Coordinated and transboundary plans that embed these actions into shared governance structures are urgently needed to address this dangerous epidemiological scenario, which could decimate vulture populations, as has occurred with other avian groups globally.

(Continue . . . )

In early 2025, in Nature Reviews: The Threat of Avian Influenza H5N1 Looms Over Global Biodiversity, we looked at the massive, and often underappreciated, impact of HPAI H5 on both avian and mammalian wildlife around the globe.

While I can't tell you precisely what negative impacts the loss of a Billion+ wild and captive birds, hundreds of thousands of marine mammals - or unfathomable numbers of peridomestic mammals - might have on our human society, one thing is certain.

We are well on our way towards finding out.

https://afludiary.blogspot.com/2026/08/conservation-bio-emerging-threat-of.html