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Fears over viability of dwindling beach herd

September 21, 2010

Fears are growing over the genetic viability of a dwindling herd of horses descended from 16th-century colonial Spanish mustangs that inhabit the Currituck Outer Banks of North Carolina.


Wild horses on the Currituck Outer Banks of North Carolina.


© Corolla Wild Horse Fund

The horses are a tourist attraction but the current herd count is 86 - around 40 short of the minimum needed to maintain the genetic diversity and physical health of the animals.

They have survived nearly 500 years in the area and can be seen wandering along the beach and grazing among beach homes.

The Corolla Wild Horse Fund, which exists to protect and preserve the last remaining herd of Spanish Mustangs on the northern Outer Banks, has been pushing to change a federal law which stipulates a maximum herd size of 60.

The organisation says its "ray of hope" is a bill from United States Congressman Walter Jones which mandates a herd size of no fewer than 110.

"DNA testing has shown that the herd is teetering on the brink of extinction, having dwindled to 86 with only one maternal line of mitochondrial DNA," the group says.

"Attempts by the Corolla Wild Horse Fund to have the management plan changed to the target population of 120-130, as recommended by the renowned equine geneticist Dr Gus Cothran, have been met with strong resistance by the United States Fish and Wildlife Service," it says.

The service contends that the horses are "nuisance animals" and may have a negative impact on the refuge in which they live, particularly in respect of bird life.

However, the group believes the impact of wild hogs, deer, and humans has a far greater impact on refuge wildlife than the horses.

The fund's executive director, Karen McCalpin, travelled to Washington DC in July to testify before a subcommittee of the House Committee on Natural Resources.

She noted that the protected herd on the Shackleford Banks had been managed by the federal government at a target population of 120-130 on half the land available to the Corolla horses for 12 years with no documented impact.

She said that as long as the Corolla fund managed the herd, there would be little or no additional cost to the government to raise the herd size.

"The wild horses of Corolla are at a genetic bottleneck and face an imminent genetic collapse if mares from Shackleford cannot be introduced into the herd to breathe new genes into the dying gene pool," McCalpin said.

The organisation says the management level was set at 60 (the US Fish and Wildlife Service had requested zero) not because of any existing scientific data, but merely because it was a number upon which all parties were able to agree.

"DNA testing completed in 1992 and again in 2008, by Dr Cothran ... showed that the Corolla horses have less genetic diversity than any other group of horses and that the horses had now reached a 'genetic bottleneck'," the group noted on its blog.

 

 

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