MARSH LAKE, Minn. — White pelicans nesting on Marsh Lake in the Upper Minnesota River watershed appear to be rebounding from a decline in numbers recorded between 2006 to 2010, but challenges remain.
High waters this spring could result in lowered nesting success, based on research that was conducted from 2003-2012 on the islands and peninsula where they nest in Marsh Lake. The research found that high water levels in April force the pelicans to nest on higher ground where they are more susceptible to predation.
Last April brought floodwaters to the lake. “The high water was probably the highest seen in our time,” said Jeff DiMatteo, formerly with North Dakota State University. DiMatteo and John Wollenberg, recently retired from the Minnesota Department of Natural Resources, and Mark Clark, NDSU, conducted the research that found the reduced success rate for nests located on higher ground.
On the flip side, DiMatteo and colleagues also conducted research that showed many pelicans will build new nests when high waters ruin their first nests. Surprisingly, that research showed that the second hatch of chicks mature at a faster rate, giving hope for a decent survival rate.
The Marsh Lake colony provides important information on the status of the white pelican in North America. The pelicans there have been banded and monitored since 1972, providing what is believed to be the longest-running record for any pelican colony in the country. The late Dr. Al Grewe, St. Cloud State University, began the project and DiMatteo, as a former graduate student of Grewe’s, has continued it.
DiMatteo said he is planning to return to band pelicans and count this year’s nests sometime in July. The banding was originally conducted on Father’s Day weekend in June, but for years now he’s had to wait until later in July to do it. He purposely waits until the chicks are at least eight weeks old and less susceptible to disruption caused by banding.
While fellow researchers tell him that climate change should bring about earlier nesting by pelicans, DiMatteo said he has seen the opposite at Marsh Lake. He does not know why.
He is hoping to count anywhere from 10,000 to 12,000 nesting pairs in the colony this year. At a peak, there were as many as 20,000 pairs.
Those numbers plummeted to about 8,000 pairs in the years 2006-2010. The birds are extremely susceptible to disruption on their nesting grounds and will abandon live chicks and eggs, said DiMatteo. During the decline, DiMatteo said there were researchers and even a photographer making visits to the nesting area, which is protected as a sanctuary.
In one case, a photographer set up a blind and is blamed by DiMatteo for the death of 400 chicks. The photographer’s presence led the adults to leave. The chicks are unable to regulate their body temperatures and died without the adults to shade them, he said.
Unfortunately, coyotes also targeted the nesting colony during those years. They first targeted birds on the peninsula, but also began swimming to the more protected islands where nesting success is the best. The coyotes killed a lot of birds, said DiMatteo, and did what apex predators will do. They killed for fun, sometimes just taking a bite out of individual birds, he said.
Predation problems have subsided since 2010, said DiMatteo. He doesn’t know why, but believes that it is possible that hunters have reduced coyote numbers in the area.
Thanks to the reduced disturbance by humans and coyotes, the colony has seen nesting numbers slowly rebound. While pelican colonies can quickly crash, they have a slow reproduction output. It can take years for a population to come back, according to DiMatteo.
Thanks to the banding project, it’s known that the Marsh Lake pelicans will migrate straight to the Gulf of Mexico for the winter where they disperse widely both east and west. Most prefer to stay with freshwater, and winter in lakes and river systems all the way to Florida to the east and into Mexico and the Yucatan Peninsula. Some bands have been returned from Cuba.
Some of the pelicans winter in the estuaries and salt water of the Gulf. Oil from the 2011 British Petroleum Gulf Oil Spill and the dispersant used to clean it up have been found in them.
Overall, pelican numbers in the U.S. and Canada are doing well, according to DiMatteo. The Marsh Lake colony is not only one of the better known colonies, it’s also one of the larger. There are also colonies at Bitter Lake in South Dakota, Chase Lake in North Dakota, and Lake of the Woods. Western Minnesota, eastern South Dakota and eastern North Dakota offer the shallow lakes and habitat favored by the birds.
Nesting pelicans were hard to find in Minnesota from 1878 to 1968, largely due to human disturbance. Settlers harvested their eggs and shot the birds for sport, the researcher explained.
A variety of factors are credited for their comeback, but DiMatteo said there remain those who do not appreciate the birds. Some anglers believe they compete for game fish.
His experience at Marsh Lake has shown him that pelicans rely mainly on the fish we do not consider table fare. “They can feed only as deep as their necks are long,” said DiMatteo. Game fish like walleye and northern pike tend to stay much deeper, leaving the pelicans to target baitfish and rough fish like carp, he explained.
Their nesting depends on protection from disturbance, more so than proximity to food. The birds will fly as much as 100 to 200 miles if necessary in search of food for their young, he said. When eggs are incubated, the parents will take turns on the nest for 48-hour periods while one of the pair ventures for food. When the chicks are present, the male and female will take turns on a one-day schedule.
Contrary to belief, they do not store their catch in the pouch on their bills. Their catch is kept in the stomach and regurgitated at the nest.
All this researcher asks is that people respect their need for seclusion.
The birds are not sexually mature until ages three to five. Consequently, birds that you may see staying for extended periods of time on a lake or river at this time of year are likely younger birds.