(How) Are Birds Affected by Volcanic Ash?

tags: Eyjafjallajökull, volcanic particulate material, ash clouds, airborne-particle deposition, respiratory physiology, respiratory toxicology, medicine, veterinary medicine, birds, avian health, bioassay, anatomy, researchblogging.org,peer-reviewed research, journal club

April is the peak month of spring migration for millions of birds, so the ongoing eruption of the Icelandic volcano, Eyjafjallajökull, presents hundreds of millions of birds with an unusually challenging set of circumstances as they fly to their northerly breeding grounds. But when a reader asked me how volcanic ash affects birds, I had no ready answer. The best I can do is to say that the ash is affecting birds, but I cannot say precisely how -- so I decided to investigate this issue in more depth and share the studies I found.

The volcanic ash from Eyjafjallajökull's latest eruption is widespread throughout all of Europe. This eruption began on 14 April 2010, grounding EU-bound aircraft around the world due to fears that the tiny particles of rock, glass and sand contained in these clouds will damage their engines.

This is a valid concern. In a terrifying event now known as "The Jakarta Incident," a British Airways (BA) 747 aircraft that was flying near the island of Java on 24 June 1982 and flew into a high ash plume that was produced by Indonesia's Mount Gulanggung. One by one, all four engines failed. The aircraft lost roughly 23,000 feet in altitude, but after it glided clear of the ash cloud, all four engines were restarted. On 13 July, almost three weeks after the BA incident, three of the four engines shut down on a Singapore Airlines 747 when it flew over the same area.

It has been reported that great billowing clouds of Eyjafjallajökull's ash have been sent 6,000-7,000 meters (20,000-30,000 feet) into the atmosphere. The Norwegian Institute for Air Research in the Department of Atmospheric and Climate Research has shown these ash clouds are being blown all across northern Europe (Figure 2);

When the path of the ash plume is compared to the major flyways for migratory birds, there is considerable overlap (Figure 3):

Even though no one currently knows the exact composition of the Eyjafjallajökull plume, The gaseous volcanic toxins that pose the greatest concern to human health include sulphur dioxide gas (SO₂ -- which was used to track the ash in the above animation in Figure 2), fluoridic acids and hydrochloric acid.

Volcanic ash is light grey to black in color and contains particles of pulverized rock -- primarily basalt, which is comprised of silicates -- that can be as fine as diatomaceous earth or talcum powder. Researchers have found that the Eyjafjallajökull ash plume is composed of 57-58% silicon dioxide by weight -- fine glassy ash. To see what these particles look like, a British man, Ian Russell, collected a small sample of the light gray ash coating his car, placed it on a slide under his microscope and photographed it (Figure 4):

As you can see, the above micrograph clearly shows the presence of tiny glass-like silicates. It is known that even without any gaseous toxins, these microscopic particles can make volcanic ash dangerous. When inhaled, these tiny particles enter the lungs, become embedded deep within, and cause irritation even in healthy people.

"We're very concerned about it," said Daniel Epstein, spokesman for the World Health Organization (WHO). "These particles when inhaled can reach the peripheral regions of ... the lungs and can cause problems -- especially for people with asthma or respiratory problems."

But what about birds? Despite the fact that birds are common research subjects, a quick Google literature search reveals no studies of the effects of volcanic ash or other airborne particulates on either captive or wild birds or on wild bird populations.

Comparisons between avian and mammalian (excluding bats) lungs reveal that avian lungs have twice as much tissue devoted to gas exchange. Further, avian tissues are thinner than mammalian tissues, thus allowing birds to take up twice as much gas as mammals under the same circumstances [DOI: 10.2307/3433242]. So birds are more sensitive than mammals to airborne toxins due to their comparatively larger and demonstrably more efficient respiratory systems, as well as their smaller body size.

You'll probably recall that these physiological characters were quite useful in days past when coal miners brought caged canaries with them into the mines as biological indicators for toxic levels of methane and carbon monoxide. More recently, scientists have investigated the usefulness of wild English sparrows, Passer domesticus, as biological indicators for atmospheric pollutants that might have health significance to humans [PMID: 4373586].

Because the vast majority of migratory birds fly at altitudes of 7,000 meters or less where the ash cloud is drifting around, there is no doubt that they also are being exposed to the ash. Since birds are more sensitive than humans to airborne toxins and lung disfunction, there should be little doubt that many birds are being negatively impacted. Additionally, there is anecdotal evidence that wild migratory birds are suffering and possibly dying due to the effects of Eyjafjallajökull ash:

One of the most terrible consequences of an eruption like this is the effect on animals. Most domestic animals are still in house, but the birds have no shelter. They fly into the dark cloud, flap their wings like they have lost their bearings and then fall down and die. Our reporters saw a flock of geese fly straight into the deadly ash. Farmers have told of the desparate [sic] sound coming from the birds battling death. [Iceland Review Online]

I realize that at least a few of my readers, like me, live with captive birds in the path of the ash cloud that is rampaging across Europe, and are concerned about their long-term health in the face of this volcanic eruption. From what I've learned during my investigations, unless you live downwind (and close) to the volcano and dust is actually falling around you, volcanic ash poses less of a health threat to indoor birds than does either cigarette smoke or even a long-term accumulation of bird dander.

That said, volcanic ash does present a minor health risk that might make your birds uncomfortable, so here are a few things that all bird keepers can and should do to protect their birds' health and to prevent them from suffering:

1. clean your birds' environment daily by removing uneaten food, feces, feathers and by mopping or vacuuming dust and bird dander.
2. keep a fan or air filter running near your birds' enclosures to ensure adequate ventilation. If you opt to use an air filter (especially useful for bird keepers with allergies or asthma or when they and their birds are living in very small or windowless spaces), the best one to choose is a HEPA (high efficiency particle arresting) filter, which will remove dander and dust that is as small as 0.3 microns in diameter.
3. if your birds live outdoors, either bring them indoors while the ash cloud persists or cover their aviaries with clear plastic sheets to reduce their exposure to dust while still allowing ambient light to penetrate.

If you are one of the unlucky people out there who also suffers from allergies, asthma or other respiratory problems, the above listed precautions will help alleviate your suffering as well.

In addition to my avicultural and bird keeping activities, I am a bird watcher and a scientist, so I am curious to learn the answers to some questions that occurred to me whilst researching this piece (questions that will likely never be answered, unfortunately):

1. Is there a noticeable (statistically significant) decrease in wild and migratory bird populations from 2009 and 2011? How do these data compare to 2010?
2. Is there a noticeable (statistically significant) decrease in wild and migratory bird breeding success from 2009 and 2011? Did many birds breed in 2010? If so, what was their breeding success (percentage of eggs hatched and numbers of chicks fledged)?
3. Is there a noticeable (statistically significant) increase in wild and migratory bird health problems from 2009 and 2011? If so, what sorts of health problems are these birds experiencing? Do certain types of health problems occur more commonly in bird species with particular life histories (sedentary versus migratory, for example)? (A comparison of waterfowl and other birds that are commonly hunted throughout Europe could be used to obtain data for some species of migratory birds, at least)

If anyone out there knows of studies that have investigated any of these questions, I'd be interested to read them.

Sources:

Brown, R., Brain, J., & Wang, N. (1997). The Avian Respiratory System: A Unique Model for Studies of Respiratory Toxicosis and for Monitoring Air Quality. Environmental Health Perspectives, 105 (2) DOI: 10.2307/3433242

Llacuna S, Gorriz A, Riera M, & Nadal J (1996). Effects of air pollution on hematological parameters in passerine birds. Archives of environmental contamination and toxicology, 31 (1), 148-52 PMID: 8688002

McArn GE, Boardman ML, Munn R, & Wellings SR (1974). Relationship of pulmonary particulates in English sparrows to gross air pollution. Journal of wildlife diseases, 10 (4), 335-40 PMID: 4373586

Clark, L. (1998). Contribution of particulates and pH on cowbirds' (Molothrus ater) avoidance of grain treated with agricultural lime. Applied Animal Behaviour Science, 57 (1-2), 133-144 DOI: 10.1016/S0168-1591(97)00121-4

The Jakarta Incident.

Chemical composition of ash and scoria from the eruption in Eyjafjallajökull (15 April report) Nordic Volcanic Center Institute of Earth Sciences.

Eyjafjallajökull Gas Composition and Flux Report [PDF] Nordic Volcanic Center Institute of Earth Sciences.

Thanks to Bob O'Hara and Aranfoolcaytar for retrieving PDFs that would otherwise have been unattainable by me.