Thursday, March 22, 2007

You are what you eat

Photographer: Dave Herr

Mercury, a new threat for Osprey?

Researchers from the University of Montana and the Raptor View Research Institute took blood samples from Osprey nests in areas around Missoula, Montana expecting to find contaminants such as arsenic, cooper and lead left behind from the mines of Butte, home of one of the largest Superfund sites.

What they didn’t expect to find in the Osprey blood samples were “high-very high” levels of mercury along with large doses of selenium. Although the researchers aren’t sure why concentrations of these toxins are so high, they are sure that it spells trouble for other raptors.

Osprey are viewed as an indicator species for larger birds of prey, such as Bald and Golden Eagles.

Along with industrial pollution, raptors also risk lead poisoning caused by digesting fragments of lead ammunition left behind in carcasses after hunting season. Lead poisoning from hunters’ bullets was found to be responsible for the demise of California Condors.

In other bird dining news, reports the alarming decline in three South Asian Vulture populations. It appears these scavengers have been feasting on a veterinary drug called Diclofenac which was administered to livestock who are later scavenged by the vultures.

Researchers with the Peregrine Fund are offering diclofenac free donkey carcases at a “vulture restaurant” in Pakistan in an attempt to reduce exposure to the veterinary anti-inflammatory drug, but it is nearly impossible to control the vultures feeding off diclofenac laced carcasses elsewhere.

Educating livestock owners to bury or burn carcasses and avoiding use of diclofenac seem to be the answer. Otherwise, “extinction is inevitable in all populations foraging in areas where diclofenac is in veterinary use and treated carcasses become vulture food…””

No word yet if these vultures, like osprey, are an indicator species for smaller scavenging birds such as crows, jays, ravens and magpies.

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