Bald eagles continue to be one of the most abundantly found birds in North America. Despite a significant decrease in their population in 1972, the numbers have now increased from being endangered to threatened. Read on to find out their ways of survival in the natural habitat.
Did You Know?
Bald eagles build the largest nest among any of the other North American birds. The nest can be up to 2.5 meters wide, 4 meters deep, and may weigh up to 1.1 tons!
The bald eagle is the national bird of the United States of America, and makes a species pair with the White-tailed Eagle. These birds have an average lifespan of 20 to 30 years in the wild, but due to urbanization and chemical pollutants, such as DDT and mercury, their overall existence in the wild is threatened.
They live longer in captivity (up to 48 years in a zoo). In spite of their shrinking habitat, let's have a look at the different ways in which these migratory birds conduct themselves, owing to changes in weather and encroachment of the forests by humans.
» The bald eagle is a sea eagle having two subspecies: (1) The "southern" bald eagle (Haliaeetus leucocephalus leucocephalus) is found in the range from Texas and Baja California to South Carolina and Florida; and (2) The "northern" bald eagle (Haliaeetus leucocephalus alascanus) is seen at 40ºN latitude throughout the continent of North America.
» Studies done by the USDA forest services show that these birds prefer a habitat near water bodies with a circumference greater than 7 miles. The water bodies include areas near rivers, large lakes, oceans, and the like.
» Lakes having an area greater than 4 square miles is a prerequisite for breeding bald eagles.
» For the purpose of perching, nesting, and roosting, bald eagles prefer virgin forest hardwood, or coniferous trees. It is essential for the chosen trees to have good visibility and should be located closer to the prey.
» Bald eagles always build their nests away from human disturbance and near water bodies having abundant fish.
» Forests selected for nesting always have a canopy cover between 20% to 60% and are in proximity to water bodies.
» Bald eagles build nests prior to the egg-laying period. During this period and the brooding time, they do not tolerate human interference of any intensity, and may desolate that particular area.
» Islands within lakes, or larger water bodies are also favored by these birds for nesting, since these sites have minimum human interference, and usually have suitable trees for building nests.
» Naturally, bald eagles are found in all parts of the U.S., most parts of Canada and Alaska, and northern part of Mexico. Only the bald eagle is indigenous to North America.
» During winter, a large number of bald eagles migrate to Squamish river, British Columbia. From November to February, salmon spawning is observed in the river; hence, around two thousand birds flock there during these months.
» At times, bald eagles also venture into estuaries of cities, such as John Heinz National Wildlife Refuge at Tinicum.
» Being sensitive to human disturbance, these birds select sites that are 0.75 miles away from an area having low-density human disturbance and 1.1 miles away from the one having medium- to high-density interference.
» Eagles belong to the family Accipitridae and are broadly divided into 4 groups, depending on their physical attributes and behavior.
» The bald eagle is brownish-black in color, having a prominent white head and a long tail. The presence of white feathers that are required to cover its head had led to its name -- "bald" eagle. The beak is hooked and yellow in color, as are the feet and irises.
» With a body length of 28 to 40 inches, the bald eagle has a wingspan of 6 to 7.5 ft. The weight of the females is larger than that of males by roughly 25%. The average size of this bird varies with location -- the largest eagles are found in Alaska, whereas the smallest ones are from Florida.
» The adult bald eagle is easily distinguishable due to its brown body and white tail and head. The juvenile eagles do not attain their prominent color until the age of 4 or 5.
Behavior and Diet
» These birds are known for their powerful flights, reaching up to the speed of 35 to 43 mph. They migrate depending on their location. If they have easy access to water, they stay at a particular place for almost three years, but if the body of water freezes during winter, the birds migrate to warmer places to hunt for food.
» Often, bald eagles feed on fish, but their diet can also be opportunistic, sometimes surviving on carrion. They also feed on rabbits, beavers, raccoon, ducks, geese, and hares.
There are many wildlife organizations dedicated to the survival of these birds. What you can do is keep an open eye to note all observations with regard to their habitat and nesting areas, and report to the concerned organization about any disturbances that interfere in their natural life. With every person doing his/her bit for the environment, we can surely bring back many species from the brink of being extinct.