Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New model helps explain how human-provided food resources promote or reduce wildlife disease

23.07.2014

Scientists have long known that providing supplemental food for wildlife, or resource provisioning, can sometimes cause more harm than good. University of Georgia ecologists have developed a new mathematical model to tease apart the processes that help explain why. Their research, which has implications for public health and wildlife conservation, appears in the Royal Society journal Biology Letters.

Wildlife of many kinds are increasingly finding their meals in human environments, gathering at places like backyard bird feeders, landfills or farms that offer an easily accessible year-round source of food. As with people, however, when large numbers of animals congregate they can face a higher risk of contracting disease.


A new study by UGA Odum School of Ecology researchers on providing supplemental food for wildlife, such as a feral cat feeding station, can promote or reduce disease. (Scott Granneman via Wikimedia Commons)

A number of studies have found large disease outbreaks following the introduction of supplemental food resources, as in the case of Hendra virus in flying foxes in Australia. Others have shown just the opposite, with disease transmission slowed or eliminated, as with gut parasites in macaques in Bali.

A desire to understand this puzzling disparity in disease outcomes motivated the study by Daniel Becker, a doctoral student in the Odum School of Ecology, and co-author Richard Hall, assistant research scientist in the Odum School and the College of Veterinary Medicine department of infectious diseases.

... more about:
»Ecology »animals »diseases »pathogens »species

"This activity is important for wildlife conservation and human health," said Becker. "There are more and more examples of provisioning affecting disease risk. By creating resource hot spots, we're essentially providing opportunities to bring together wildlife, domestic animals and humans, offering chances for pathogens to spread between species."

Providing food for wildlife-whether intentionally, as with bird feeders or feeding stations for feral cat colonies, or unintentionally as in the case of garbage dumps-can cause changes to an animal's breeding success, foraging behavior and body condition that in turn influence its risk of acquiring harmful infections.

A steady, easy-to-access source of nutrition can increase the size of a wildlife population by improving reproductive success and increasing animals' life spans. A larger pool of uninfected-and therefore susceptible-animals can fuel disease outbreaks and increase the chance that the population remains infected over longer timescales.

Furthermore, gathering around feeding stations leads to more contacts between animals, increasing the chances that sick individuals will pass on their infection to others.

Easy access to food also improves body condition, allowing animals to mount more effective immune defenses. This can reduce infection levels in wildlife by allowing animals to successfully fight off pathogens before they become infectious. Conversely, if improvements to immune defense cause sick animals to live longer, they may pass on infection to more individuals throughout their lifetime.

"You've got these opposing processes, with factors such as aggregation and larger population sizes potentially aiding disease spread, and improved ability of animals to resist infection making it harder for the disease to spread," said Hall.

"Figuring out how these all work together to influence population-level disease outcomes isn't really straightforward," added Becker. "It helps having a formal model to look at how these processes together all play out."

For their model, Becker and Hall used data from studies of feral cats with feline leukemia virus that visited supplemental feeding stations. They looked at how birth rate, death rate, contact rate and the strength and speed of immune system response were influenced by the amount of supplemental food the animals were able to access.

The model revealed that a key factor in predicting disease outbreaks in wildlife that access supplemental food was how that additional food influenced the strength and speed of the immune response. And more food wasn't necessarily better. Under some scenarios, even low levels of supplemental food could increase the risk of outbreaks compared with wild-feeding populations. In other cases, a small amount of supplemental food initially drove down infection levels, but too much led to the population size growing so large that the increased opportunities for infection to spread overcame the animals' immune defenses, with large outbreaks possible.

The authors said that their results point to the urgent need for more field and laboratory studies to explore the relationship between resource provisioning, immune defense and disease.

"As the planet becomes more urbanized, wildlife are increasingly coming into cities to use these resources, and then they can come into contact with domestic animals and humans, with potentially the risk of infections spilling over across species," Hall said. "For people who put out food for birds, wildlife or free-roaming feral cats, it's important to understand that supplemental feeding can have these unintended consequences of enhancing disease transmission."

He advised that if people notice sick animals at their feeding stations, the best course of action is to remove the food source to allow the uninfected animals to disperse, and to clean feeders regularly and thoroughly.

Providing supplementary food is also a frequent management action as part of recovery plans for rare and threatened wildlife, but Becker and Hall urged caution before applying this strategy in species vulnerable to diseases causing high mortality, such as rabies.

"We really need to do more research to figure out how immune response depends on supplementation," Hall added. "The modeling study illuminates where we should be focusing experimental efforts."

The full research article is available at http://rsbl.royalsocietypublishing.org/lookup/doi/10.1098/rsbl.2014.0309. A UGA Graduate Research Assistantship and a National Science Foundation Graduate Research Fellowship supported this study.

UGA Odum School of Ecology
The UGA Odum School of Ecology, the world's first stand-alone school dedicated to ecology, is creating the future of ecological discovery through innovative research about the rapidly changing planet, educating the next generation of ecologists and applying knowledge in service to the broader public. For more information, see www.ecology.uga.edu.

Daniel Becker | Eurek Alert!
Further information:
http://news.uga.edu/releases/article/model-wildlife-disease/

Further reports about: Ecology animals diseases pathogens species

More articles from Ecology, The Environment and Conservation:

nachricht Northern bald ibises fit for their journey to Tuscany
21.08.2015 | Veterinärmedizinische Universität Wien

nachricht Boreal forests challenged by global change
21.08.2015 | International Institute for Applied Systems Analysis (IIASA)

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: OU astrophysicist and collaborators find supermassive black holes in quasar nearest Earth

A University of Oklahoma astrophysicist and his Chinese collaborator have found two supermassive black holes in Markarian 231, the nearest quasar to Earth, using observations from NASA's Hubble Space Telescope.

The discovery of two supermassive black holes--one larger one and a second, smaller one--are evidence of a binary black hole and suggests that supermassive...

Im Focus: What would a tsunami in the Mediterranean look like?

A team of European researchers have developed a model to simulate the impact of tsunamis generated by earthquakes and applied it to the Eastern Mediterranean. The results show how tsunami waves could hit and inundate coastal areas in southern Italy and Greece. The study is published today (27 August) in Ocean Science, an open access journal of the European Geosciences Union (EGU).

Though not as frequent as in the Pacific and Indian oceans, tsunamis also occur in the Mediterranean, mainly due to earthquakes generated when the African...

Im Focus: Self-healing landscape: landslides after earthquake

In mountainous regions earthquakes often cause strong landslides, which can be exacerbated by heavy rain. However, after an initial increase, the frequency of these mass wasting events, often enormous and dangerous, declines, in fact independently of meteorological events and aftershocks.

These new findings are presented by a German-Franco-Japanese team of geoscientists in the current issue of the journal Geology, under the lead of the GFZ...

Im Focus: FIC Proteins Send Bacteria Into Hibernation

Bacteria do not cease to amaze us with their survival strategies. A research team from the University of Basel's Biozentrum has now discovered how bacteria enter a sleep mode using a so-called FIC toxin. In the current issue of “Cell Reports”, the scientists describe the mechanism of action and also explain why their discovery provides new insights into the evolution of pathogens.

For many poisons there are antidotes which neutralize their toxic effect. Toxin-antitoxin systems in bacteria work in a similar manner: As long as a cell...

Im Focus: Fraunhofer IPA develops prototype of intelligent care cart

It comes when called, bringing care utensils with it and recording how they are used: Fraunhofer IPA is developing an intelligent care cart that provides care staff with physical and informational support in their day-to-day work. The scientists at Fraunhofer IPA have now completed a first prototype. In doing so, they are continuing in their efforts to improve working conditions in the care sector and are developing solutions designed to address the challenges of demographic change.

Technical assistance systems can improve the difficult working conditions in residential nursing homes and hospitals by helping the staff in their work and...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Networking conference in Heidelberg for outstanding mathematicians and computer scientists

20.08.2015 | Event News

Scientists meet in Münster for the world’s largest Chitin und Chitosan Conference

20.08.2015 | Event News

Large agribusiness management strategies

19.08.2015 | Event News

 
Latest News

Interstellar seeds could create oases of life

28.08.2015 | Physics and Astronomy

An ounce of prevention: Research advances on 'scourge' of transplant wards

28.08.2015 | Health and Medicine

Fish Oil-Diet Benefits May be Mediated by Gut Microbes

28.08.2015 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>