THERE are too many cormorants on the Columbia River between Washington State and Oregon, say US federal officials. Richard Collins says there's no need for a cull.
They want the army to shoot 11,000 of them and spray their nests with vegetable oil, smothering the embryos inside. The measures are deemed necessary to protect dwindling salmon and trout stocks. Opponents of the proposed cull, including the Portland branch of the Audubon Society, say that the decline in fish numbers is due to habitat destruction water pollution and over-fishing, not cormorants.
The species to be targeted is the double-crested cormorant, the most common of North America’s six species. As the name implies, it has two black and white tufts on the head during the breeding season, vaguely resembling the smaller of our two Irish cormorants, the shag. The American bird, however, lives both on the coast and along rivers, whereas shags don’t venture inland. The shag has only one head-crest and it’s all black.
The cormorant is ‘history’s most persecuted bird’, according to a caption in the current edition of New Scientist. Ornithologist Linda Wires, of the US Fish and Wildlife Service, claims that a cull authorised in 1998 led to the killing of 300,000 double-crested cormorants in 13 US states. That same year, an illegal slaughter took place at a breeding colony on Lake Ontario where 8,500 pairs nest. An order issued in 2003 had resulted in the deaths of 146,000 birds by the end of 2011.
The bird we in Ireland call ‘the cormorant’, known as ‘the great cormorant’ elsewhere, was deemed a threat to fish-stocks in 19th Century Europe and hunted to the verge of extinction. It was outlawed in Ireland up to 1976, with bounties paid for shooting it. This, the most widely distributed species of the 39-member cormorant family, is still persecuted in some parts of the world.
Despite the name, the great cormorant is not the biggest member of its tribe. That distinction goes to the Galapagos cormorant. Secure on an uninhabited archipelago, 1,000km from the Pacific coast of South America with few predators to worry about, it lost the ability to fly. This allowed it to grow larger, a useful heat-saving measure when the cool Humboldt and Peru currents bathe the Galapagos between May and December. With the arrival of people on the islands, the flightless cormorant suffered. It is classified as ‘Endangered’ by the IUCN.
The temptation to abandon flying was even greater in the cold waters of the far north. Pallas’s cormorant, which nested on Bering Island off Russia’s Kamchatka Peninsula, opted to become flightless, or nearly so. It was a fatal decision. Cormorant meat is so unpalatable that people don’t eat it. The flesh of Pallas’s cormorant, however, was said to be delicious. During the 1840’s, whalers and fur trappers converged on this remote part of the world and ate Pallas’s cormorant into extinction.
Some 40% of the world’s shags breed along the coasts of Britain and Ireland. According to the recently published Bird Atlas, shag numbers rose by 21% between 1968 and 1988. However by 2002, they had fallen by 27% and were down by a further 26% in 2011. The fortunes of our larger species, the great cormorant, are more difficult to assess. The numbers breeding inland have increased, particularly in the western half of the country, making comparison with older records difficult. Inland nesting may lead to pressure for culling from fishery interests.
Climate change is affecting our cormorants. Starving shags are driven ashore during prolonged bouts of extreme weather, which the climate forecasters say will become more frequent. As the sea around our coast warms, the sand-eels, on which shags depend, are moving northwards.
There is no good reason, Wires argues, to cull cormorants. Few of the fish species they take are eaten by people. “To date, no study has demonstrated that cormorants pose a threat to the survival of fish populations in natural systems’, she claims.
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