LDWF’s Latest Bald Eagle Nest Census Shows Continued Improvement Of Species
story by TREY ILES, LDWF Public Information
Though majestic and a source of pride for Americans, the bald eagle is a horrible house keeper. Their nests can get nastier than a collegiate freshman’s dorm room.
Rather than spruce, bald eagles may relocate to find other nesting accommodations.
“Nests may quickly fill with animal parts,’’ said Louisiana Department of Wildlife and Fisheries non-game ornithologist Michael Seymour. “Eagles bring fairly large prey items back to the nests and if chicks don’t eat it all, there can be a buildup of decaying food. Combine that with parasites and nests can become pretty disgusting. The idea is that the nesting pair uses that nest for a season or more, then move on to a previously built alternate nest, which they’ll refurbish.’’
The species continues to expand its range in Louisiana as Seymour, through aerial surveys, sees more and more nests, be they active or alternate.
It’s a sign of the significant recovery of the bald eagle throughout the nation and Louisiana.
The population was decimated in the 1950s and ‘60s primarily because of the use of the pesticide DDT. When DDT was banned in 1972, there was an immediate uptick in the bald eagle population.
That’s been the case in Louisiana. In the early 1970s, there were only five to seven active nests recorded in the state. Now that number likely far exceeds 350 active nests, a count from a recent aerial survey. Bald eagle sightings in the state have gone from rare to common place, especially in southeast Louisiana, west and south of the New Orleans metro area.
The bald eagle was removed from the federal Endangered Species List in August of 2007 though it remains federally protected by the Migratory Bird Treaty Act and the Bald and Golden Eagle Protection Act.
“The bald eagle and the (eastern) brown pelican are the poster children for successful endangered species recovery,’’ Seymour said. “The productivity and nesting success continues to be good in Louisiana. The most recent survey (in 2017-18) for eagles show the number of chicks to be very high. The productivity was close to 100 percent in both the maximum and minimum values of the survey.’’
In 2014-15, LDWF surveyed 647 nests, including 355 that were considered active. The survey showed a minimum of 331 successfully fledged bald eagles.
Another survey was conducted in 2017-18 by LDWF though on a much smaller scale. Though bald eagles have been spotted throughout Louisiana, the majority reside in southeast Louisiana. So that’s where the most recent survey was conducted.
“To get the most bang for our buck, we flew the area where they’ve concentrated,’’ Seymour said. “We basically surveyed around the New Orleans metro area through west of Morgan City. Terrebonne and St. Mary parishes have some of the highest densities of nests. Lake Palourde and Lake Verret have a lot of nests concentrated in small areas.’’
The results were impressive. A total of 264 active nests were noted.
“You’d say that’s almost 100 less than the last time we flew,’’ Seymour said. “But that’s a much reduced land area we covered. We surveyed 647 total nests back in 2014-15 in the statewide survey. This time we surveyed 599 nests in a smaller survey area.’’
THE BREEDING SEASON
Bald eagles are migratory and they generally move north out of Louisiana in the late spring. However, because the population has increased, they have been spotted more often in the summer in Louisiana.
In September, the species begins nesting in the southern United States. Bald eagle pairs will mate for life although they will re-pair if one dies.
They’ll return from their northern migration in the fall and start refurbishing the nest they used the previous year. In November and December, they’ll lay eggs, usually two or three. Typically, the chicks have hatched by February.
“Once those chicks reach about 10 weeks of age, they’re just about fully grown and there aren’t many predators that would attempt to take them,’’ Seymour said. “For us, once a bird reaches about 10 weeks we consider it a successful nest. At about 12 weeks they’re able to fly.’’
The surveys start in the late fall as biologists look to time it when the birds have eggs in the nest.
“The idea is we fly two sets of surveys, one early and one later in the nesting season,’’ Seymour said. “The nice thing about bald eagles is that they’re fall-winter-spring nesters, they have a protracted nesting season. So we’re able to go out before leaf out (in the spring) and see the nests fairly well.’’
Biologists return in February and March and survey a subset of nests to calculate productivity and nest success.
WHERE TO CALL HOME
The preferred nesting spot for bald eagles in Louisiana is the bald cypress tree where 91 percent of the nests can be found. They’ll also nest in pine and hardwood trees. But they can also be found nesting in man-made objects such as cell towers or large electrical pylons.
That can be a problem sometimes. One of the provisions under the Bald and Golden Eagle Protection Act is that nests are protected for at least five years past vacancy.
“With so many more birds, we are seeing them nest more frequently in these man-made objects,’’ Seymour said. “There can be issues with people and bird safety in some cases. Removal of such nests after the nesting season may be permitted should safety be an issue.’’
Though bald eagles are thriving in Louisiana there are still challenges. Storms during hurricane season can easily bring down trees hosting bald eagle nests. Another issue is salt water intrusion in coastal Louisiana. That can mean the death of trees, such as the bald cypress, that house the species.
“That is something that needs additional research,’’ Seymour said. “It could be that the birds are nesting in large trees, but not producing any young because storms can break these salt water-killed cypress right in the middle of the nesting season.
“But because the population appears to be growing, I don’t have any immediate concerns about a decline like we’ve seen in the past. But we must remain vigilant of emerging threats to these and other Louisiana birds.”
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