Pelican powered

By Diane Tipton
Montana Fish, Wildlife and Parks
Statewide Information Officer

Idaho Fish and Game biologists monitoring
American white pelicans on the
Minidoka National Wildlife Refuge in
Idaho between Idaho Falls and Twin
Falls on the Snake River were surprised
in 2011 to find evidence of a brown
trout from Montana’s Big Hole River.

The biologists were busy tagging
pelicans to monitor their habits,
what they eat and where they are at
different times of the year, when
they noticed some fish tags in the
area. Called floy tags, these 1.5-
inch individually numbered tags are
inserted into a fish near their dorsal
fins so fisheries biologists can track
individual fish and their growth
and movement.

The fish tags found on “Bird Island”
within the refuge were apparently
expelled after pelicans consumed
some of the fish, which like the
birds, were tagged for research. The
Montana tag was found among some
50 other such tags on the island.
All the other fish tags were traced
to Idaho hatchery trout stocked
locally.

“The Big Hole drains into the Missouri,
and the Snake River drains into the
Columbia River on the other side of
the continental divide,” said Jim Olsen,
Montana Fish, Wildlife and Parks fisheries
biologist who originally tagged
the fish. “A pelican likely harvested the
fish on its way to Idaho where it finally
finished processing the 18-inch, two-pound
fish and expelled our fish tag.”

Olsen said he doesn’t know how long it
takes a pelican to digest a fish, but this
one was pretty sizable, so he could see
it taking a few days to move through
the pelican’s digestive tract.

“I think we figured the distance it must
have flown to be somewhere in the
neighborhood of 300 miles,” he said.

Pelicans are known to routinely travel in
the range of 150 miles a day to forage.
One of the Idaho Fish and Game folks
involved in gathering the fish tags
offered an alternative theory. “Pelicans
do keep stuff in their bill sacks
or pouches for a period of time so it is
possible something as small as a fish tag
remained in this pelican’s pouch for the
trip from Montana to Idaho,” said Rob
Longsinger, an Idaho Fish and Game
biologist.

The fish was tagged in the Big Hole on
April 5, 2011. FWP received the report
the tag had been found in Idaho on July
14, 2011.

“Pelicans are pisciverous, or fish
eating, and their impacts on local
fisheries can vary. As far as the
Big Hole goes, anglers often
complain about pelicans when
it comes to grayling recovery,
because in drought years large
flocks of more than 50 pelicans
can congregate in the
upper reaches of the river,”
Olsen said.

“It seems in better
water years like we
have had the past three
summers, these large
flocks of pelicans have
not been seen, but the
birds are still commonly
observed and based on
this report from Idaho
they are consuming
trout from rivers.

Pelicans in
Montana are
long-distance
migrants that
can be found in a
variety of aquatic and wetland habitat,
including rivers, lakes, reservoirs, bays
and marshes.

For more on pelicans, go to the
Montana Field Guide at fieldguide.
mt.gov and search for
“American White Pelican.”