New diseases travel on bird wings in rapidly changing north – Ecotone

When polar bears encounter burgomaster gulls on the remains of a bowhead whale, they may share more than just a meal. As global warming brings animals together, parasites, viruses and bacteria may find opportunities to spread to new and naive hosts, sometimes moving from birds to mammals and from marine ecosystems to terrestrial ecosystems. Credit, USGS.

When wild birds make up a large portion of your diet, opening a freshly downed bird to find worms wriggling under the skin is a bewildering sight. This is exactly what Victoria Kotongan saw in October 2012, when she started cleaning two of the four spruce grouse (Falcipennis canadensis) that she had brought near her home in Unalakleet, on the northwest coast of Alaska. The next day, she shot down four grouse and all four sheltered the long grubs. In two birds, the worms appeared to come out of the meat.

Kotongan, worried about the grouse’s health and the potential risk to her community, reported parasites to the Local Environmental Observer Network, which arranged for the frozen bird carcasses to be sent to a laboratory for analysis. Laboratory results identified worms as the nematode Splendidofilaria pectoralis, a finely described parasite previously observed in the black grouse (Dendragapus obscurus pallidus) in the interior of British Columbia, Canada. The nematode had not been seen so far north and west before. Although S. pectoral is unlikely to be harmful to humans, other emerging diseases in northern regions are not so harmless.

Splendidofilaria pectoralis nematodes wriggle on the meat of a spruce grouse (Falcipennis canadensis).  One weekend in October 2012, Victoria Kotongan killed six spruce grouse near her home in Unalakleet, on Alaska's remote northwest coast.  Four harbored worms visible under their skin.  Filaroid nematodes have never been reported in the Alaskan Grouse before.  Credit, Victoria Kotongan, Local Environmental Observers Network, Alaska Native Tribal Health Consortium.

Adult female Splendidofilaria pectoralis nematodes wriggle on the flesh of a spruce grouse (Falcipennis canadensis). Victoria Kotongan killed six spruce grouse near her home in Unalakleet, on Alaska’s remote northwest coast, on a weekend in October 2012. Four harbored worms visible under their skin. Filaroid nematodes had not been previously reported in the Alaskan Grouse. Credit, Victoria Kotongan, Local Network of Environmental Observers, Alaska Native Tribal Health Consortium.

Animals are altering their seasonal movements and feeding habits to cope with climate change, bringing together species that were rarely seen in the past. Nowhere is this more apparent than in polar latitudes, where the warming has been fastest and most dramatic. Red foxes spread north into arctic fox territory. Hunger drives polar bears to land as sea ice shrinks. Many Arctic birds undertake long migratory journeys and have the mobility to fly well beyond their historic ranges or extend their stay at attractive feeding or nesting sites.

With close contact, there is a risk of infection by parasites and exotic microorganisms carried by new neighbors, and therefore the disease also finds new territory. Clement conditions prolong the life cycle of disease-carrying insects and pathogenic organisms. Migratory birds can carry infectious agents for long distance walks. In November 2013, Native Alaskan residents of St.Lawrence Island, in the Bering Sea, alerted wildlife managers to the deaths of hundreds of Crested Staries, Thick-billed Murres, Northern Fulmar and other seabirds, caused by a epidemic highly contagious avian cholera (Pasteurella multocida).

“This is the first time that avian cholera has appeared in Alaska,” said Caroline Van Hemert, wildlife biologist at the US Geological Survey in Anchorage, Alaska. “St. Lawrence Island is generally frozen over in November, but last year we had a warm fall and winter in Alaska. We don’t know for sure that open water, climate, and high bird densities contributed to the outbreak, but it coincided with unusual environmental conditions.

Circumstantial Xvideos Red"}” data-sheets-userformat=”{"2":513,"3":{"1":0},"12":0}”>Xvideos Red evidence gathered by researchers and local observers points to an upsurge in infectious diseases in northern latitudes, but sparse baseline data makes interpretation of current trends uncertain. Van Hemert and colleagues review the state of our knowledge of emerging diseases in northern birds and their effects on wildlife and human health, discussing cooperative program strategies to address information gaps in the December issue of Frontiers in ecology and environment.

Frontiers Cover December 2014Wildlife health in a rapidly changing North: focus on avian diseases. (2014) Caroline Van Hemert, John M Pearce and Colleen M Handel. Frontiers of ecology and the environment, 12 (10): 548-556, doi: 10.1890 / 130291

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