Earth & Sky

THE FOLLOWING IS A TRANSCRIPT OF OUR INTERVIEW WITH:
Wesley M. Hochachka, Assistant Director of the BirDd Populations Studies Program at the Cornell Laboratory of Ornithology in Ithaca, New York

ES: Can you tell me a little bit about how Project FeederWatch works?

WH: The Laboratory of Ornithology has a number of different projects where we involve the general public in scientific research. The first of these is Project FeederWatch, which, as the name implies, is just having the general public watch their feeders, and not just watch, but actually count the birds, and count them at regular intervals throughout the winter to give us an idea, in several thousand locations across the continent, about whether, and which birds are at their feeders, and how abundant they are, how the abundance changes through the winter, and also from one winter to the next. This has been going on since the late 1980s. And we are ready, in the middle of November, to start the 17th season of Project FeederWatch. So, the data are sent in either as paper forms, or, entered directly into the Internet and placed directly into our database here at the Lab of Ornithology. Then, at the end of the season, or whenever the need calls, throughout the season, myself, or another one of the researchers, will be called upon to access the data, pull them out of the database, and look at the various pieces of information to answer various biological questions. In the last winter, where I think the story on West Nile Virus comes from, is that we had heard, first anecdotally, reports in the Chicago area, that there were essentially no birds. In the wintertime in some parts of Chicago. And, we wanted to take this from a less formal, or more anecdotal observation, to see whether this Project FeederWatch project that has been going on that’s had participants in the Chicago area as well as, basically where there are people in North America, to take this information and see whether that really was the case, and to what extant the birds really had disappeared from Chicago, or the birds come to people feeders – as well as how large the area was impacted. It’s easy to tell when birds might disappear from an area where there are lots of people, where you actually have a lot of people who are feeding there to one another, comparing notes. But, in areas where there are relatively few people, birds could also be disappearing – it’s just that there wouldn’t be that many people to notice whether something really major and unusual had happened. They might think that it’s just a problem with their own feeder, and not realize the entire region where there are fewer birds than in previous years.

[45]

ES: Why is it necessary to involve the public in scientific research?

I’ll answer the question a little bit obliquely. The general way that ecological research works, is that a researcher or a small team of people will wok in one particular area to study all of the birds, or to ask and answer various biological questions. But they are anchored very much to one, or at least a handful of separate locations that they’re working. Just like birds don’t really realize or human and political borders, understanding what’s happening to populations of birds sometimes requires knowing something about what’s happening over very broad areas – not just a single study site or a single county, in some cases, literally what’s happening across the continent as a whole. And, while it might be possible for the normal, formal, method of scientific research to have people going out to hundreds or thousands of different areas and collecting the same pieces of information to see what’s happening on such a large scale, it’s logistically prohibitive. It would be an organizational-logistic nightmare to try and coordinate that many researchers, all whom have their own interests and their own questions. ^^^ But if you were to pay technicians to do that, it literally would break the bank. There’s just no way of effectively funding the sort of data collection that would give you a broad brush picture of bird populations, and their status throughout North America, without volunteers. It would be, for all intents and purposes, impossible. ^^^

[72]

ES: Why did you choose the Chicago areas as the focus of the FeederWatch-WNV study?

WH: We knew that something happened in Chicago. That was learned from information informally gathered, we knew that there were definitely fewer birds being seen in Chicago in the fall of 2002 and then on into the winter. What we wanted to know was how restrictive that event was to Chicago. There was reasonable evidence that something had happened, a substantial outbreak of West Nile disease in Chicago in the summer of 2002. But we weren’t sure how extensive the disease outbreak was spreading outside of Chicago, and we weren’t sure how far away from the Chicago area we could find bird populations to be impacted by the disease, or by something. We more or less centered the area of interest that we were looking at, Chicago. But we basically looked at the status of bird populations throughout a larger percentage of the North American continent to see whether what was happening in Chicago was mirrored in other places. So there were reports from people in Chicago where there was a fairly active, routine monitoring of birds in various neighborhoods that suggested that there were declines in bird numbers, but we needed the data from Project FeederWatch to find out widespread outside of the Chicago area these declines were.

ES: Why did you choose to study American Crows and Blue Jays?

WH: When we were looking for evidence of bird decline, we chose to look at two fairly common species. Two of those were American crow and Blue jays, both of those we know are very sensitive to West Nile Disease and a large percentage, almost all that are exposed to the disease, die. So these seemed like likely candidates. If we were going to find declines for bird populations for anything, it would be crows or blues jays. So we examined data for those two species. We also looked at black cat chickadees. Because that was another bird that people said just was not showing up at their feeders in the fall of 2002. Although we still don’t have any evidence that chickadees tend to die when exposed to West Nile Disease. Crows, we know, in large part because they’re very large birds and they’re obvious. When you see a dead crow, especially just seeing dead crows lying around in on the ground in lawns and in parks, you know something strange is happening. Chickadees are very small birds. While they might be susceptible to West Nile disease, might die in large numbers, it’s very unlikely that we’d actually recover many, that we’d actually see any direct evidence of their death. We looked at chickadees as well, and a few other species of birds like cardinals, which is a common bird in the Western Unites States. ^^^ And, what we found is that, throughout the upper Mid-west, there were very substantial declines in the number of chickadees that people were reporting at their feeders, and to a lesser extant, there were declines in the number of bluejays and the number of crows that people have been reporting. And it wasn’t just restricted to the Chicago area where we essentially had the first inkling that something was happening. But, throughout a great part of the Midwest – or actually, if you look at a map wrapping around the bottom of the Great Lakes, from Southern Wisconsin roughly around Chicago and through Detroit, and into New York State – we were seeing several common feederbird species that were simply not being reported in the number that they had been in the previous years. And, in fact, in some cases, the lowest numbers ever seen or reported in the more than 15 years that Project FeederWatch has been run. So, it looks like there was something, or were some things, that caused declines in the number of bird species. And I will mention that there were other species of birds, like the Northern Cardinal, that were actually having a banner year – they were being reported normal, or higher than normal abundance, so whatever it was didn’t affect every single species of bird in the upper Midwest. Linking the disappearance of the bird to West Nile Virus is another issue entirely, and it’s something that we cannot do with any certainty. ^^^ Given that Bluejays and American Crows were two of the species that were in decline, and knowing that they are very susceptible to West Nile Virus disease, we had a reasonably good idea that West Nile Virus was implicated somehow, in some way. ^^^ As I said before, with Chickadees, we just don’t know whether they will die, or very commonly die, when exposed to the disease. But it would appear that it’s the case, on circumstantial evidence. That said, chickadees have been in lower than normal numbers in a very large part of North America, not just isolated in the upper Midwest, but along the Atlantic coast, and even as far west as the U.S. Pacific Northwest, the area around Seattle. Some of these areas, we’re almost certain that West Nile disease, while it might have been present – was not present to have caused the problems that we saw. That’s why I said earlier that we know that something or some things happened last winter. Our best guess is that West Nile disease was part of the story, particularly in the Midwestern states, but potentially something else happened in other areas, such as the Atlantic coast and the Eastern seaboard, where chickadees declined, but other birds like Bluejays, which we know to be susceptible and die when exposed to West Nile, were also having comebacks. ^^^ So it’s a little bit of a complicated picture, our best guess is that, at least in the upper Midwest, and in areas running around the bottom of the Great Lakes, everything seems to point to West Nile disease and West Nile virus being partially, if not largely responsible for these disappearances of birds. ^^^

ES: Dumb question – but why can’t we just do autopsies on a lot of these birds and firmly determine the cause of death?

WH: Well – as a personal anecdote, I think I’ve only found two birds that simply just died for no apparent reason. There was always a reason, you’d find birds, they’d run into windows, others might be killed by a cat, things like that, but you just don’t routinely see dead birds, in part because deaths don’t happen all that frequently, and part, especially with the smaller birds, they’re scavenge very quickly, anything from insects to mammals will just take a dead bird and disappear with it. So, birds like a chickadee, it’s nearly impossible to accumulate large samples of these birds to do autopsies on. That’s a little bit different for crows. ^^^ And what really, the initial reason why we knew something strange was happening, and that something turned out to be the arrival of West Nile virus in North America, was that there were dead crows showing up in New York City. And not just one or two – there were a lot of dead crows showing up. And what that meant is that – given the crows were big, they were common, and seeing them in numbers of such an unusual event – people were actually reporting these and bringing the dead animals into health agencies and having them tested. ^^^ And it was from these tests, as well as tests from the Bronx Zoo, that the presence of this novel virus in North America was confirmed. So yes, for a bird like crows, you can actually prove a link between West Nile disease, or the presence of disease, and death. For smaller birds, many of the common garden birds, you simply cannot find enough of them to even do the necessary tests.

ES:

WH: Every year Project FeederWatch produces an annual summary. One of the things that we’re featuring this year is revisiting the article you saw on Project FeederWatch and disappearances of birds, and just kind of confirming that we actually had more data. Because with FeederWatch, the article that you saw, on about 60% of all of the participants information, were entering the sightings and observations on birds directly onto their computer and going directly into the database, so we can get it instantly. The other 40% fill out paper forms. The paper forms come in to the Lab of Ornithology, they are proofed and are scanned, and then the scanned information goes through a series of stages before they’re finally brought into a state where they can be added to the database. And, the annual report is based on this entire record. We doubted that we would see much difference, but it was reassuring to see that the same patterns were showing up. And to give you some idea of the effort of Project FeederWatch across North America – there were 92,000 individual bird lists – any single participant can send in from 1 to 20 of these observations. They’re done at either weekly or bi-weekly intervals, and roughly we were guessing that five million or more different birds have been observed by Project FeederWatchers over the course of the last winter. So in terms of using the data, what we actually have are not just presence and absence birds at feeders, but we have actual counts of the numbers of birds that people are seeing at their feeders. And we don’t just have it at one winter, as I said before, we have five or more, up to 20 different observations, usually on a weekend, from the middle of November to the end of March. And, in the upper Midwest, the area that seems to have the greatest decline in birds, what we found for birds like chickadees, in an area – Kentucky, Illinois, Indiana, Ohio – was that chickadee populations were about 32% lower than their average over the last 15 years. And what that roughly translates to is – a typical person will see roughly a flock of four chickadees at their feeder, and this last winter in that area, each individual participant in FeederWatch was only seeing maybe three birds at their feeder. So chickadees didn’t vanish off the face of the Earth, there were still chickadees showing up at feeders by and large, it’s just that people were seeing fewer of the birds at every single one of their feeders. So those are the sorts of impacts that we’ve found from the Project FeederWatch data.

ES:

WH: The Christmas Birds count is in a two week period, roughly the weekend before Christmas, and then two weekends subsequent to that. So the first part of December would be absolutely a good time to talk about the Christmas Bird Count.

The Christmas Bird Count is a little bit of a different beast than Project FeederWatch. In our view, FeederWatch and the Christmas Bird Count actually compliment each other very nicely. Each one has strengths, each one has weaknesses. In particular, in looking at the possible impacts of West Nile Disease on bird populations, we’ve been using both. Just because of the strengths of the two. And essentially we’re finding that one confirms what the other one is saying, which also gives it more certainty that what we’re seeing out there – the patterns are real. The Christmas Bird count, one of it’s strengths is its longevity. It’s been going on, in some parts of North America, for over a century now. So, what we really see from that is – we can step back much further than with FeederWatch and really get a broad, historical view of how populations of birds have changed in North America. You can watch some populations of birds expanding – birds like cardinals and tufted titmouse – their ranges northward into the northern parts of the state and into Canada. You can see other birds whose populations have declined in some regions – so this really is a very broad picture of what’s happening. It’s a way of nicely setting the stage – for example if we see a decline of chickadees like we did last winter, how large was that decline? Was that larger than the historical norm?

More Links:

http://www.cdc.gov/ncidod/dvbid/westnile/index.htm. Centers for Disease Control and Prevention West Nile Virus website

Milius, Susan. “After West Nile virus: What will it do to the birds and beasts of North America?” Science News, vol. 163, no. 13 (March 29, 2003).

http://www.audubonnaturalist.org/feature.htm Bialek, Janna. Bird Casualties and West Nile virus: Is the verdict still out? Audubon Naturalist News, March 2003.

“FeederWatchers” Help Track Decline of Crows and Chickadees
http://birds.cornell.edu/pr/FeederWatch03.html

Migratory Birds and Spread of West Nile Virus in the Western Hemisphere
http://www.cdc.gov/ncidod/eid/vol6no4/rappole.htm

Author’s notes:

The West Nile virus first made headlines in North America in 1999, when it was determined to be the cause of both human and bird deaths in the New York City area. The virus has since spread to other parts of the continent; by the close of 2003, it had been detected in 44 U.S. states and 5 Canadian provinces. Mosquitoes are the key vector for this virus, which is related to the viruses that cause various kinds of encephalitis,or brain inflammation. When a mosquito takes a blood meal, she can pick up the virus from an infected human or animal. And then, when she bites a second victim, she leaves some of the virus behind. The U.S. Centers for Disease Control and Prevention (CDC) has also identified people who were infected by blood transfusions. It’s also possible that a baby was infected through its’ mother’s milk. Birds can contract the disease by rubbing bills with an infected bird or eating an infected mosquito. West Nile virus was first assigned a name in 1937, by scientists who found the virus in the blood of a woman living in the West Nile region of the African Nation of Uganda. Subsequently, the virus seems to have spread through the Middle East and southern Asia and Europe. The virus detected in New York is thought to be strain of West Nile known to be responsible for outbreaks in Israel in 1998. Scientists don’t know how it got to New York, but in this era of international travel, it’s possible that an infected mosquito arrived accidentally by plane or ship. Or perhaps an infected bird was brought into the country. Most humans infected with West Nile never even get sick?their immune systems fight off the infection. Some people develop flu-like symptoms. For a handful of people, the disease has been deadly. The CDC reported that in 2002, 284 deaths nationwide were attributed to West Nile virus (that’s 4 percent of the 2,300 people known to have been infected.) A wide variety of wildlife species are susceptible to the virus. Antibodies to West Nile have been detected in the blood of squirrels, wolves, dogs, black bears, deer . . . about 200 species in all. In fall of 2002, an outbreak of West Nile killed hundreds of alligators in Florida. Wild horses in France’s Camargue have also been felled by West Nile. Meanwhile, in lab tests, several very common and widespread bird species, including blue jays, common grackles, house finches and American crows, build up especially high concentrations of the virus in their blood after being bitten. Scientists worry that migrating birds could contribute to the spread of the virus in North America?although it’s not yet know whether this actually happens. Scientists have tried to use data from such nationwide bird surveys as the Christmas Bird Count and the Breeding Bird Survey to understand declines in bird populations?but without better systems in place to document that West Nile is actually present and killing birds, it’s hard to draw conclusions. Also, in some areas, pesticides are being sprayed to control mosquitoes because of concerns about human health, and it’s possible that this action is affecting birds, either through outright poisoning or by reducing food supplies. Though West Nile outbreaks seem to be geographically localized, and though populations of common species seem to be able to bounce back, experts worry that small and isolated populations, such as the endangered Bachman’s warbler and whooping crane, could be wiped out by West Nile. If the virus reaches Hawaii, where about one-third of the native species are already endangered, it could spell disaster.

Author’s notes:

The West Nile virus first made headlines in North America in 1999, when it was determined to be the cause of both human and bird deaths in the New York City area. The virus has since spread to other parts of the continent; by the close of 2003, it had been detected in 44 U.S. states and 5 Canadian provinces. Mosquitoes are the key vector for this virus, which is related to the viruses that cause various kinds of encephalitis,or brain inflammation. When a mosquito takes a blood meal, she can pick up the virus from an infected human or animal. And then, when she bites a second victim, she leaves some of the virus behind. The U.S. Centers for Disease Control and Prevention (CDC) has also identified people who were infected by blood transfusions. It’s also possible that a baby was infected through its’ mother’s milk. Birds can contract the disease by rubbing bills with an infected bird or eating an infected mosquito. West Nile virus was first assigned a name in 1937, by scientists who found the virus in the blood of a woman living in the West Nile region of the African Nation of Uganda. Subsequently, the virus seems to have spread through the Middle East and southern Asia and Europe. The virus detected in New York is thought to be strain of West Nile known to be responsible for outbreaks in Israel in 1998. Scientists don’t know how it got to New York, but in this era of international travel, it’s possible that an infected mosquito arrived accidentally by plane or ship. Or perhaps an infected bird was brought into the country. Most humans infected with West Nile never even get sick?their immune systems fight off the infection. Some people develop flu-like symptoms. For a handful of people, the disease has been deadly. The CDC reported that in 2002, 284 deaths nationwide were attributed to West Nile virus (that’s 4 percent of the 2,300 people known to have been infected.) A wide variety of wildlife species are susceptible to the virus. Antibodies to West Nile have been detected in the blood of squirrels, wolves, dogs, black bears, deer . . . about 200 species in all. In fall of 2002, an outbreak of West Nile killed hundreds of alligators in Florida. Wild horses in France’s Camargue have also been felled by West Nile. Meanwhile, in lab tests, several very common and widespread bird species, including blue jays, common grackles, house finches and American crows, build up especially high concentrations of the virus in their blood after being bitten. Scientists worry that migrating birds could contribute to the spread of the virus in North America?although it’s not yet know whether this actually happens. Scientists have tried to use data from such nationwide bird surveys as the Christmas Bird Count and the Breeding Bird Survey to understand declines in bird populations?but without better systems in place to document that West Nile is actually present and killing birds, it’s hard to draw conclusions. Also, in some areas, pesticides are being sprayed to control mosquitoes because of concerns about human health, and it’s possible that this action is affecting birds, either through outright poisoning or by reducing food supplies. Though West Nile outbreaks seem to be geographically localized, and though populations of common species seem to be able to bounce back, experts worry that small and isolated populations, such as the endangered Bachman’s warbler and whooping crane, could be wiped out by West Nile. If the virus reaches Hawaii, where about one-third of the native species are already endangered, it could spell disaster.

The following people were interviewed for today’s program. Our thanks to:

Wesley M. Hochachka [Huh chahch ka]
Assistant Director of the Bird Populations Studies Program
Cornell Laboratory of Ornithology
Cornell University

Dr. Peter Marra
Smithsonian Environmental Research Center