Avian influenza in wild birds – Why climate change can increase irevalence

birdClimate change has been thought to affect migratory patterns of different species. To find out how this change has affected a species of shorebirds in relation to horseshoe crabs, two population ecologists set out to find the answers using a mathematical model. The two experts Pejman Rohani and Victoria Brown indeed discovered a few things. This quest was at the Delaware Bay owing to its strategic migratory positioning that makes it a hot spot.

Ruddy turnstone shorebirds stop over at the Delaware Bay as they migrate to the north. They feed on horseshoe crabs which are an awesome delicacy. The ecologists found that this sensitive relationship between the birds and their food can be greatly affected by change in climate. The bay is an estuary which is bordered by Delaware and New Jersey. The annual migration of the birds in relation to avian influenza is discussed as follows.

According to the researchers, an alteration in migratory patterns owing to climate change could lead to the increase and prevalence of avian influenza viruses not just among the ruddy turnstone shorebirds but in the resident duck population at the Delaware Bay as well. The fact that the bay plays host to wild birds as they migrate to various continents; different viruses are spread causing more and more avian influenza cases. These findings were published online at the Journal Biology Letters.

However, Rohani insisted that this does not necessarily mean an increased risk in humans. This researcher is a professor of ecology and evolution biology. Additionally, Rohani is also a professor of complex systems and epidemiology at the School of Public Health. This expert indicated that it was crucial to study different avian flu viruses that can pose danger in a bid to understand the risks as they are from an informed perspective. Type A viruses that are found in wild aquatic birds are many and some will cause avian influenza or bird flu. Many domestic birds may be infected after interaction with wild birds.

It is good to note that normally, these avian flu viruses do not affect humans. However, in some occasions, infections have been reported and more close to our memories is the 2003 outbreak of the avian influenza A H5N1. Worldwide, more than 600 cases were reported and half of those resulted in death. This is according to the World Health Organization. The experts found this virus to be notorious and very pathogenic.

Back at the migratory hot spot of wild birds; Delaware Bay, the researchers found that the avian influenza levels among the ruddy turnstone shorebirds would be very high when there was a climate change alteration. As the birds feed on the horseshoe crabs, they infect local ducks as well as other birds as they make way to the Arctic. These birds spend winter at the warm South America and head to the Arctic for breeding at around May of every month.

In this light, Brown and Rohani set out to find out what would happen if the availability of crabs to feed on by the birds was altered owing to change in climate. The ruddy turnstones have always followed a pattern with a perfect timing. These researchers therefore used their mathematical system which sort to find out what would happen if the ruddy turnstone birds arrived at the bay weeks earlier or weeks later. This model was also used on the resident ducks and specifically; two species were studied. They are the mallards which spend winter at the Delaware Bay and the America black ducks which reside at the bay all year round.

The results were that the prevalence of infection by avian influenza went up. This means that all these birds recorded more infections or a higher level of infection as a result of the changes. According to Brown who is a postdoctoral research fellow at the Center for Study and Complex Systems, if the birds get to the Bay earlier or later, they will encounter higher levels of avian influenza prevalence in the resident ducks. Brown is also a postdoctoral research fellow at the Department of Ecology and Evolutionary Biology.

According to Brown, this works both ways in that, when there is high level of avian flu infections in ruddy turnstone shorebirds, the resident ducks will also see a higher prevalence. The research found that if climate change was to affect the spawning of the horseshoe crabs, the population of birds will decrease at the Delaware Bay owing to lack of food. Consequently, the prevalence of avian flu infection in the birds will also decrease.

The Western Hemisphere Shorebird Network declared Delaware Bay a vital hemispheric site in the mid 1980s. This is because the bay is a potent breeding and nesting ground for over half a million shorebirds every year.

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