Black-bird die-off Investigation
David E. Green examining a Blackbird in necropsy
- The USGS National Wildlife Health Center works with Federal, state and other natural resource agencies throughout the United States to investigate, research and assist with wildlife health and disease issues.
- The National Wildlife Heath Center worked with the Arkansas Game and Fish Commission in the investigation of the death of approximately 4,500 red-winged blackbirds and some other species. National Wildlife Heath Center wildlife pathologists examined birds from the Arkansas event on January 4 and samples were submitted to our laboratories for further testing. Necropsy (autopsy) findings are consistent with “impact trauma”. This is compatible with the report issued by the Arkansas Game and Fish Commission. The initial screening tests for poisoning indicated that the birds had not been exposed to organophosphate or carbamate pesticides.
- The Center's final report stated that the cause of death in the submitted birds and the probable cause of the mortality event at this site is attributed to blunt (impact) trauma. Field observations provided by the submitter suggested that these birds were roosting for the night, were startled from their perches by loud noises in the area, and because of their very poor night-vision, the birds may have flown into stationary objects such as powerlines, telephone poles, houses, mailboxes, tree branches, etc. No significant underlying or predisposing conditions or diseases were found in these birds in numerous toxicological analyses, cultures and tests.
- The National Wildlife Heath Center also worked with the Louisiana Department of Wildlife and Fisheries to investigate the death of approximately 500 red-winged black birds, starlings, brown headed cowbirds and grackles found on Jan. 3 in New Roads. The necropsy findings from these birds were also consistent with “trauma”. Many of these birds appear to have collided with a power or fence line.
- We have no evidence of a link between the bird events in Beebe, Arkansas and Louisiana, or a concurrent drum fish die-off in Arkansas. National Wildlife Heath Center is not investigating the fish die-off.
- While large-scale bird die-offs are always a concern, they are not that unusual. Over the past 10 years there have been over 175 wild bird mortality events reported to the NWHC exceeding 1,000 birds. Infectious disease, weather, poisoning, trauma, starvation are just some of the causes for these large scale mortality events.
- It is not uncommon for large numbers of blackbirds to roost in a fairly small area. While we do not have any records of birds being startled by loud noise and subsequently dying, there are many reports of migrating birds becoming disoriented at night from fog and other weather related events, or lights on transmission towers, and colliding with trees, towers and other objects.
- People finding sick or dead birds should report this information to their state conservation agency.