Surveys by Louisiana Department of Wildlife and Fisheries' biologists have detected declines in the state's brown pelican population during the last two years.
"Environmental effects caused by an oil spill, hurricane activity and high tides associated with tropical storm activity are taking their toll on brown pelican populations," said Tom Hess, LDWF biologist manager in the Fur and Refuge Division.
Department biologists conducted two brown pelican nesting surveys in 2006. On June 3, there were nine active nesting colonies with 7,630 nests containing eggs and hatched young up to seven weeks old. Four colonies with 5,425 nests west of the Mississippi River were observed with no major habitat problems and a majority of young in the four to seven weeks age category. The 2,205 nests east of the Mississippi River, however, were flooded by high tides in late April and early May. These totals represent a decline of nearly 10,000 nests based on survey results from 2005.
"Hurricanes and tropical storms during 2005 degraded brown pelican habitat and reduced production," Hess added.
The brown pelican, Louisiana's state bird, was first documented nesting on the Chandeleur Islands in 1918. Large numbers were present from North Island at the Chandeleurs to Raccoon Island west of the Mississippi River until the mid 1950s. The species ceased nesting in Louisiana in 1961 and disappeared from the Louisiana coast in 1963 as a result of exposure to pesticides that were contaminating the environment; the brown pelican was listed as endangered in 1970.
The brown pelican was reintroduced into Louisiana from Florida between 1968 and 1980. The population has increased steadily with 318,215 young produced between 1971 and 2005. In 2004, 16,501 nesting pairs produced an all time high of 39,021 fledglings. Production decreased 35.2 percent in 2005 to 25,289 fledglings as a result of an oil spill at the West Breton Island colony caused by tropical storm Arlene, and the cumulative effects of Hurricanes Cindy, Dennis, Emily, Katrina and Rita. Ninety-five percent of production occurred west of the Mississippi River as a result of early nesting and no colony flooding from Tropical Storm Arlene. Colonies east of the Mississippi River were repeatedly flooded by the tropical storm and hurricanes causing fledgling mortality.
Young brown pelicans west of the Mississippi River had reached flight stage at the time of Hurricane Katrina with no direct mortality at colonies. Conversely, brown pelicans incubating eggs and caring for five-to-six-week-old young east of the Mississippi River, when Katrina struck were impacted as eggs and young were washed away. In addition, this storm reduced the size of the Chandeleur Islands by 90 percent and completely washed away West Breton Island, Mitchell Island and Grassy Island.
Nesting habitat has been declining since 1998 when Hurricane Georges made landfall, which degraded brown pelican nesting habitat on barrier islands along Louisiana's coast. Hurricane Ivan in 2004, and Hurricanes Katrina and Rita in 2005, caused catastrophic destruction of barrier islands and brown pelican nesting colonies.
The Louisiana Department of Wildlife and Fisheries will continue intensive brown pelican population monitoring to determine 2006 nesting success, production, and also evaluate the long term impacts of habitat loss from Hurricanes Katrina and Rita.
For additional information, contact Tom Hess at 337-538-2276 or firstname.lastname@example.org .