November 18, 2011

In the Spotlight - Past Wildlife Disease Investigation from USGS National Wildlife Health Center

From the Latest USGS National Wildlife Health Center Quarterly Wildlife Mortality Report - April 2011 to June 2011

Field investigation at Poplar Island Environmental Restoration Site (Maryland)

Photo courtesy of U.S. Fish & Wildlife Service
Wildlife disease specialists and biologists from the US Geological Survey’s National Wildlife Health Center, Maryland Department of Natural Resources, and the U.S. Fish & Wildlife Service teamed up to investigate double-crested cormorant mortality at a rookery site on Poplar Island in Talbot County, Maryland (Map It ), in June 2011.

During the summer 2010, virulent Newcastle disease (vND) and concurrent salmonellosis were detected in young of the year cormorants at this rookery resulting in the death of approximately 84 birds. While juvenile cormorant mortality had not yet exceeded that observed during the previous summer, baseline mortality for this population of 816 active nests was uncertain.

Given the high density of domestic poultry in Maryland, resource managers wished to investigate the possibility of vND recurrence in this population. Fresh dead carcasses, as well as several 3-6 week old birds exhibiting lethargy, incoordination, and wing dragging were collected for diagnostic evaluation. In addition, serum and paired oropharyngeal and cloacal swabs were collected non-lethally from a subset of asymptomatic 4-6 week old juveniles for future analysis.

No evidence of vND or closely related avian paramyxovirus-1 was detected in the affected birds. Aspergillosis was diagnosed in the cormorants found dead while no infectious diseases were identified among the clinically affected juveniles.

Collaborative studies with USDA Wildlife Services and the Minnesota Department of Natural Resources have been initiated this summer (2011) to better understand vND disease ecology in double-crested cormorant populations.

Source: USGS National Wildlife Health Center, Quarterly Mortality Reports