As regular CFZ-watchers will know, for some time Corinna has been doing a column for Animals & Men and a regular segment on On The Track... particularly about out-of-place birds and rare vagrants. There seem to be more and more bird stories from all over the world hitting the news these days so, to make room for them all - and to give them all equal and worthy coverage - she has set up this new blog to cover all things feathery and Fortean.

Friday 23 November 2018

Cormorants’ rebound confounds wildlife managers


FRIDAY, NOVEMBER 16, 2018

By TIM ROWLAND
Thirty years ago, with increasing frequency, squadrons of black seabirds were spotted on Lake Champlain flying low and fast across the water as if on some sort of black-ops raiding mission. Their appearance was something of an environmental success that, in the eyes of many, quickly turned into an environmental catastrophe. 
The same scene was playing out on the Great Lakes and the Pacific, as the double-crested cormorant made a miraculous recovery after the ban on DDT, a pesticide that had once imperiled the bird’s existence. But while conservationists hailed the return of birds such as the bald eagle, they became increasingly wary of the collateral success represented by the cormorant. 
As the population surged, once-lush Lake Champlain islands were one-by-one commandeered and summarily defoliated by the cormorants, whose populations had exploded from a single nesting pair into a population that peaked at more than 20,000. Anglers fretted as well, as cormorants slurped down tons of fish, most notably the yellow perch that is an important part of the aquatic food chain and the star attraction at many a lakeside fish fry. 
 In 2003, the U.S. Fish and Wildlife Service, citing fears of cormorant overpopulation, allowed state conservation agencies to “take” cormorants without a permit (owners of private fish farms had been allowed to do so since 1998). Thus empowered, the state of Vermont began to oil eggs — spraying eggs with oil keeps out oxygen and stops their development — to prevent them from hatching, soon to be followed by conservation agencies in New York. The feds further allowed states to shoot excess birds by the thousands in an attempt to restore pre-cormorant equilibrium. What followed has been a case study in the successes, the failures, and most of all the unknowns and frustrations that arise when attempting to micromanage the environment. 


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