Stone Soup for Thanksgiving: understanding bird disease through citizen science

Scientific American
Stone Soup for Thanksgiving: understanding bird disease through citizen science
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Windowkill. Photo: Susan Spear

When somebody opens their front door to pick up the morning newspaper and sees a dead bird below their hedge, they get curious for answers. As soon as they stoop down for a closer look, an Indiana Jones adventure unfolds within the confines of their backyard. Was it poison, disease, predation, starvation, old age? Is this a fluke or widespread plague? Perhaps dead birds like this one are widely scattered across a country. But, if so, what sort of scientific method could find answers to what happened to them all?

The stone soup method.

In my favorite version of the folk story "Stone Soup," a group of monks traveling through the war-torn countryside sit in the center of a quiet village and boil a stone in a large pot of water. Soon curiosity wins over the initial distrust and skepticism of impoverished villagers as each, in turn, are enticed to add a vegetable or spice. Through cooperation and sharing, the entire village feasts on delicious, nutritious soup.

When my colleagues and I carry out research using citizen science methods, we are like the monks boiling stone soup. Instead of a pot, we have a big blank spreadsheet and curious folk are enticed to each add their observations, ultimately creating a robust database with observations from across a continent.

Through citizen science I study healthy birds, but several of my colleagues focus on the sick and dying ones. This week in PLOS ONE, a research team led by Becki Lawson, a veterinarian and ecologist, reported a new strain of avian pox spreading in a common backyard bird in Great Britain. Citizen science participation was pivotal to tracking the outbreak, unraveling its mysteries, and informing localized studies.

The new strain of avian pox entered Great Britain and spread in one family of birds, the Paridae. The Paridae include chickadees in North America, their European counterparts are various types of tits, most notably the Great Tit. By piecing together reports from citizen science participants, the team was able to track the spread of pox, starting in southeast England, moving to central England, and then into Wales in less than five years.

Avian pox is not for the squeamish, so this study is a testament to what citizen scientists are willing to do. Birds with avian pox grow red, yellow, or gray wart-like lesions, particularly around the eyes, beak, and legs. The new strain makes really large lesions, so severe that they leave the bird unable to feed itself or look out for predators. The pox spreads from individual to individual through direct contact, indirect contact (like touching the same bird feeder), or through a vector that bites, like mosquitoes. There is no way to treat wild birds medically. When an outbreak occurs, people are advised to remove bird feeders to prevent birds from congregating. Also, the study is a reminder for people to periodically clean and sanitize wild bird feeders, just as you would with pets.

There are numerous causes of bird deaths in Great Britain. I get the shivers from the names, such as the bacteria like salmonellosis, colibacillosis, Suttonella ornithocola, and Chlamydia psittaci, viruses like pox and fringilla papilloma, and parasites, like trichomonosis, cnemidocoptiasis, and syngamiasis. People have found birds with all of these infectious diseases in over 60 species since 2005 because thousands of individuals have followed hygienic protocols to pick up, package, and submit over 2,500 dead birds to designated veterinary labs for post mortem exams.

The veterinary labs participate in the Garden Bird Health initiative (GBHi), a highly collaborative research project to investigate causes of sickness and death in British garden birds. Researchers at the Zoological Society of London collate information from two citizen science projects. First, they receive ad hoc reports, typically through the Royal Society for the Protection of Birds. Second, Garden BirdWatch, run by the British Trust for Ornithology, formed a systematic surveillance system in which participants provided information every week throughout the year (not just when sick or dead birds are found).

Over the past few year Brits were alert and tracking the spread of this pox virus. Two years ago they also followed an epidemic of parasitic finch trichomonosis that caused a significant decline in British greenfinch populations, in research also led by Becki Lawson. The parasitic epidemic spread from the UK to the rest of Europe. The current viral pox epidemic turned the tables: this epidemic is likely invading the UK from Europe. Great Tits don't migrate, so the new strain of pox had to arrive some other way.

Working in coordination with the national efforts, ornithologists from the University of Oxford confirmed that the Great Tit was more susceptible than other species. Although the avian pox has severe effects on individual birds, in particular lowering the odds of survival for chicks and juvenile birds, researchers do not anticipate population declines as occurred with the greenfinch.

In the US, citizen scientists are helping study disease and death in birds, too. The House Finch Disease Survey, which is a project by Andr? Dhondt, my colleague (and supervisor) at the Cornell Lab of Ornithology, has tracked an epidemic of conjunctivitis, spread by bacteria. Like pox, people can typically see the symptoms of conjunctivitis in house finches, mainly red swollen and crusty eyes, like pink eye in our children.

In the Pacific Northwest, hundreds of people help monitor marine health as they take long walks on the beach. They have counted thousands of dead (beached) sea birds each year and submitted their observations to my colleague Julia Parrish through the Coastal Observation and Seabird Survey Team (COASST). These baseline numbers are important. Unless people are paying attention, we won't notice if there is a sudden uptick in deaths, or be able to properly estimate the impact of a catastrophe, such as an oil spill.

There are plenty of misconceptions about citizen science, largely attributed to its dual achievements: public engagement and academic research. Is the purpose of making stone soup to teach people about cooperation or to produce a good meal? The intent doesn't matter because the stone soup method achieves both. Likewise, citizen science can woo everyday people into falling in love with science AND co-create knowledge that an individual scientist could not acquire alone.

References:

Lawson, B., Lachish S., Colvile, K.M., Durrant, C., Peck, K.M., Toms, M.P., Sheldon, B.C., Cunningham, A.A. Emergence of a novel avian pox disease in British tit species. PLoS ONE

Lachish, S., Bonsall, M.B., Lawson, B., Cunningham, A.A., Sheldon, B.C. Individual and population-level impacts of an emerging poxvirus disease in a wild population of great tits. PLoS ONE

Lachish, S., Lawson, B., Cunningham, A.A., Sheldon, B.C. Epidemiology of the emergent disease Paridae pox in an intensively studied wild bird population. PLoS ONE

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