Tuesday, July 28, 2015

Seabirds Decline Worldwide

Researchers in British Columbia, Canada report that monitored seabird populations have dropped 70% since the 1950's. The information came from a compilation of 500 seabird populations around the world representing 19% of the global population. The magnitude of the loss in the monitored population represents about 230 million birds have perished in the last 60 years. The lead author of the published study said seabirds are a good indicator of the health of marine ecosystems. Such a decline in bird numbers represents a serious imbalance in the ecosystem and an indicator of the adverse impact of humanity.

Laysan Albatross, credit Audubon
Albatrosses are particularly impacted. They live long lives and travel immense distances while encountering many dangers. A major threat to these beautiful birds is entanglement in longline fishing gear. The problem kills hundreds of thousands of seabirds evey year. Overfishing causes seabird mortality since they rely on fish for food. Pollution and introduced preditors also are major causes of mortality. One example of an introduced species causing seabird decline occurs on Johnston Atoll, the former site of US nuclear testing in the Pacific. There 14 species of seabirds are sometimes overwhelmed on their nests by yellow crazy ants. These ants are not native to the Pacific, but arrived from elsewhere aboard ships. They spray an acid that can blind or mame those birds that do not flee. Unable to nest in infested areas despite attempts at erradication by the US Fish & Wildlife Service, seabird populations have dropped, but some success has occurred. Tropic bird numbers in treated areas  have increased from 54 to 524.

The study by University of British Columbia researchers is the first to estimate the decline in available global seabird population data. It is an alarming discovery since seabirds play crucial roles in their ecosystem as prey and preditor and transport vital nutrients for entire food webs. Increased and effective seabird conservation is necessary on a global scale to prevent their collapse.