It's a skunk-eat-pelican-eat-trout world out there
Each spring, on the shores of Nevada's Pyramid Lake, fishermen in waders stand 50 feet out in the water, on stepladders, casting long, narrow loops for huge Lahontan trout. They look a little like Kodiak bears lined up on an Alaskan river. But, these men aren't the only fishers around. American white pelicans glide long, slow stretches over the lake, skimming above their coal-and-ivory reflections.
Pelicans are charismatic, and stirring to watch. So a recent dispatch from Idaho caught my attention: the state's Department of Fish and Game just released three badgers and two skunks on Gull Island in the Blackfoot Reservoir, which, like Pyramid Lake, hosts one of the 13 to 15 major breeding colonies of white pelicans in the West. These mustelids are charged with just one thing: devouring pelican eggs. The department wants to reduce the colony's populations from 2,400 birds to 700, because they apparently threaten the native Yellowstone cutthroat trout that live in the reservoir and spawn in the Blackfoot River. They also scarf up stocked rainbow trout, to the aggravation of anglers.
Admittedly, the thought of fewer white pelicans in this world pains me. With their ungainly bills tucked to their necks, pelicans seem so aloof, so guileless. But they devour plenty of fish: In 2007, nine of 27 Yellowstone cutthroat tagged in a radio telemetry study on the Blackfoot reservoir-river system turned up in pelican nests. Meanwhile, trout counts in the river dropped from 4,700 in 2001 to less than 100 in 2007. The count rebounded to 500 fish in 2008, a five-fold increase that may be correlated with a drop in pelicans that year. But that's nowhere close to the 10,000 to 15,000 fish the department hopes to see spawning regularly in the river.
Others argue that the trout are in trouble not because of pelicans, but because of us — agricultural diversions, subsequent runoff, increased water temperatures, algal blooms, and selenium from upstream mines. Lower water levels might make it easier for pelicans to snatch trout as they head from the reservoir to the river. But some scientists, such as David Delehanty, an Idaho State University biology professor, say the evidence that pelicans are responsible for the crash in the trout population is far from clear.
Fortunately, white pelicans aren't endangered: though their numbers took a dive in the middle of this century, the U.S. population has climbed to over 45,000 birds since then. Still, they are protected under the Migratory Bird Treaty Act of 1918 and, last year, the U.S. Fish and Wildlife Department criticized the Idaho agency's management plan (see the PDF link on the left side of their Web site) to "take" pelicans, and spray eggs with vegetable oil (which would suffocate the embryos), calling the proposal an "eradication program." So the Idaho department is being a tad sneaky and taking advantage of a loophole: releasing skunks and badgers almost certainly will impact the pelican's nesting success, but it won't violate the Migratory Bird Treaty. Who knows how much it will help the Yellowstone cutthroat, however, or what will become of those skunks and badgers when the pelicans fly off this fall.
It may be that the pelicans should be managed. (Ironically, badgers existed on Gull Island as late as 1992, when the department removed the population; 200 pelicans immediately colonized the place.) They're agile predators. At Pyramid Lake one evening, I watched a flock of ten or 12 float in a zigzag toward the shore, when, all at once, they plunged their heads into the water, making a terrific, synchronized splash. When they shook their faces free of the lake, one had a two-foot-plus trout roiling in its stretched, diaphanous pouch; they had been herding or stalking the fish as a group. Instantly, the lucky pelican was attacked by some of the others, who stabbed viciously at its pouch with their bills. But it broke away and paddled toward the middle of the lake, tossing its heavy load, trying to figure out a way to swallow its monstrous catch.
A two-foot fish — I almost choked.