World Migratory Bird Day 2023

Finding Winged Travelers and Ourselves in Troubled Waters


By Sarah Olson | October 14, 2023

Specialist of the Peruvian National Service of Agricultural Health (SENASA) inspecting the mass mortality of Peruvian pelicans (Pelecanus thagus) in a breeding colony in the beginning of the outbreak in Peru. Photo credit: P. Colchao © WCS. Thanks to SERNANP.

As we observe World Migratory Bird Day in 2023, the chosen theme — water — ripples with profound significance. Water, in its various forms, serves as both a barrier and a facilitator in birds’ extraordinary travels. Oceans, rivers, lakes, and wetlands are indispensable waypoints for these resilient travelers. But in helping to shape birds’ migratory routes, water also helps to create aerial superhighways for opportunistic, hitchhiking pathogens to travel the globe.

Historically these hitchhikers were predominantly low pathogenic avian influenza viruses, meaning they did not cause high mortality in wild birds. Then about two years ago, a highly pathogenic lineage of avian influenza took advantage of the flyways and became an unprecedented global pandemic. Likely millions of wild birds have been killed worldwide and the breadth of species impacts have been astounding:

Carcass of a common dolphin (Delphinus delphis) positive to HPAI found in the north of Peru. Photo credit P. Colchao © WCS.

As the virus traversed continents, it crossed species barriers:

For good reasons, scientists are advocating a watchful approach. Since 1900, avian influenza has caused five human pandemics, nearly all tracing back to an animal source — with the largest in 1918 killing an estimated 50 million people. In the last two decades there have been hundreds of isolated human fatalities of people exposed to sick animals.

Carcass of a Sanderling (Calidris alba) positive to HPAI. Before dying, this migratory shorebird was found signs of disorientation, ataxia and nystagmus. Photo credit: P. Colchao © WCS.

So far these spillover events have been self-limiting, and virologists point out that the ability to transmit among mammals is concerning but not yet reason to panic. The contemporary lineage that is wreaking havoc spent 25 years evolving in poultry, resulting in deaths of at least 400 million domestic animals and US$20 billion of economic losses. In recent years it was likely responsible for egg and turkey shortages and rationing in your local grocery store.

Beyond watchful waiting, efforts like Preventing ZOonotic Disease Emergence (PREZODE) are advocating salient steps to address the emergence of viruses at the source. The current avian influenza pandemic demands a reevaluation of our food systems and practices. Wild birds and mammals are the most current victims of our unsafe and unsustainable agricultural practices. If business as usual continues, there is a risk we could be next and victims of our own industrial food animal production.

It is clear that human intensification of poultry farming contributed to the emergence and spread of the virus. Prevention initiatives like PREZODE are needed to bring public, conservation and livestock sectors together so that better policies are informed by health risks and costs alongside the economic drivers and constraints of the industry. We need to consider a reorientation of our approach to food production and promote sustainable practices that prioritize the health of ecosystems, all animals, and the well-being of humans.

Specialist of the Peruvian National Service of Protected Areas (SERNANP) collecting samples from a south American sea lion (Otaria flavescens). Phot credit: P. Colchao, ©WCS. Thanks to SERNANP.

The challenge at hand is not one that any nation or community can face alone. World Migratory Bird Day is a yearly reminder of the need for both international collaboration and action. Yes, it is imperative that we all work to increase surveillance of avian influenza virus in animals to track the continuing evolution and impacts of the pathogen. Moreover, the mass mortalities and frequency of outbreaks of migratory birds and other animals from this virus are sending us an urgent message.

We need more than watchful waiting. Efforts like PREZODE that get to the source and help foster better poultry industry practices and policies will help our oceans, lakes and wetlands continue to provide a safe stopover point for birds on their long journeys. The deaths of these incredible migratory birds are a direct result of our actions, and it is time to change course. Governments, NGOs, scientists, and communities must come together to implement prevention strategies, reevaluate food systems, and safeguard the health of our shared environment for generations to come.

Dr. Sarah Olson is Director of Health Research at WCS (Wildlife Conservation Society).



Wildlife Conservation Society
One Planet, One Health, One Future

WCS saves wildlife and wild places worldwide through science, conservation action, education, and inspiring people to value nature.