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Bird vomit reveals fish clues
Fledgling pelicans are seen Friday, June 9, 2006 at Canyon Ferry Wildlife Management Area near Townsend, Mont. The Canyon Ferry Wildlife Management Area encompasses 5,000 acres and includes a series of four ponds and about 350 artificial islands, which were developed by the Bureau of Reclamation. Biologists counted counted 486 cormorant nests and 2,394 pelican nests in the area this year.

TOWNSEND — It's as if a fraternity party went horribly awry. And even worse — the partygoers had attended a clambake beforehand.

The rain dampens the smell of regurgitated fish, but occasionally the wind shifts in just the right direction to wallop Eric Roberts in the nose with the distinct odor of partially decomposed sucker served with a clarified ammonia sauce.

"Sometimes that smell stays with me for three days," says Roberts, a fisheries biologist for Montana Fish, Wildlife and Parks.

Roberts and fisheries technicians Jerry Anderson and Ron Selden step out of their canoes and gingerly walk across a small island in Pond 3 of the Canyon Ferry Wildlife Management Unit near Townsend. The island is littered with broken eggshells. And on closer look, fledgling pelicans huddle in twos and threes in haphazard nests. Some eggs, about three times the size of chicken eggs, are still intact with beaks just starting to peck through.

Mass exodus

The adult pelicans complain loudly and then fly off in a mass exodus. The fledglings, still too young to walk but alert enough to notice something is amiss, squawk and bob their heads, maybe hoping the commotion might mean the catch of the day is about to be served.

What they get instead are the fisheries guys waving yardsticks over their heads. The young pelicans' heads sway with the movement of the yardstick, and after a few minutes … bleac-bleac-hoark. A chunk of scales, bones and a fish tail tumbles out of one of the pelican's beaks and lands just inches from Anderson's feet.

"I got some," Anderson yells to his colleagues.

Anderson picks up the heap of vomit with his yardstick and together the men poke through it to figure out just what type of fish the bird ate for breakfast.

"It's carp," Roberts says and then writes the observation in his log book.

The men examine several more vomit piles before paddling to another island in Pond 3. This island is covered in cormorant nests, which are more sophisticated structures than the scraped sand and gravel pelican nests.

Again, the adults fly off, leaving the fledglings alone to deal with the men and their waving yardsticks. It takes a little longer, but finally the young black birds become stressed enough to present a sample of their stomach contents.

Finding trout

"We definitely got some trout here," Peterson says, pointing to a pile of pink meat.

Roberts walks over to examine it. The regurgitated fish happens to have enough skin with it to indicate that it was a brook trout.

This is somewhat good news. Part of the reason for the diet study is to see whether the cormorants are eating a significant amount of the 150,000 rainbow trout stocked earlier this spring. And by the end of the morning after visiting five islands — one pelican island, three cormorant islands and one mixed, the answer is no.

"We had 52 cormorant samples," Roberts says. "Stonecats made up the largest portion of the diet, with 77 percent of the observed samples containing stonecats."

According to Roberts' data, the rest of the cormorant samples show longnose dace found in 27 percent of the samples, trout in 23 percent, suckers in 23 percent, crayfish in 13 percent and sculpins in 11 percent.

Few stocked fish

"From a fish management perspective, it was good to see the low frequency of occurrence of trout in the diet," Roberts says. "One trout sample was a brook trout, and a couple of samples were adult rainbows. So for the time being, there does not appear to be many stocked rainbows in the cormorant diet."

The average size of the rainbows stocked in May averaged 8 inches, and Roberts suspects that most of those have dispersed far enough into the reservoir to make them hard for cormorants to find.

The pelican samples showed mostly carp and crayfish, which is consistent with samples from the last couple of years, Roberts says.

"We do know that pelicans will eat stocked fish right after they come off the hatchery truck," Roberts says, "but pelicans are such opportunistic grazers, that I think that the fish are only vulnerable for a short period of time. Once the fish start to disperse, the pelicans just aren't that effective at catching them."

But while pelicans have less impact on the sports fishery at Canyon Ferry, they are having an impact on habitat at the WMA, said Tom Carlsen, an FWP wildlife biologist.

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Addressed dust problem

The Canyon Ferry WMA encompasses 5,000 acres and includes a series of four ponds and about 350 artificial islands, which were developed by the Bureau of Reclamation. The ponds were initially built to address a dust problem created when wind would hit exposed mud flats when the reservoir was low. The islands were built for waterfowl nesting. Construction was completed in 1978, and management of the area was turned over to state wildlife agency.

Cormorants started nesting at the wildlife management area in 1979, when FWP counted two nests. Pelicans came in 1990, when FWP counted 10 nests. This year FWP counted 486 cormorant nests and 2,394 pelican nests.

"We're concerned about the amount of pelican nests," Carlsen said. "This is turning into the largest colony of pelicans in the state."

Unlike the more traditional stick nests of the cormorants who will use the same nests year after year, pelicans abandon their nest each season and build new ones the next.

"After nesting season, the (pelicans' nesting) area is denuded," Carlsen said.

Because pelicans are considered a species of concern, there is little FWP can do to limit their numbers.

"It's a real management challenge," Carlsen said. "But I think it's great to have too many of a wildlife species. Look at the elk."

But back to the vomit.

"One interesting trend for both pelicans and cormorants is the absence of perch in the diet," Roberts said. "When we first did diet surveys in 2003, perch were present in 80 percent of the samples. Since perch numbers have crashed in the reservoir, perch are practically nonexistent in the diet samples."

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