BirdWalk Newsletter

Transcription

1 BirdWalk Newsletter Walks Conducted by Perry Nugent Newsletter Written by Jayne J. Matney He clasps the crag with crooked hands; Close to the sun in lonely hands, Ringed with the azure world, he stands. The wrinkled sea beneath him crawls: He watches from his mountain walls, And like a thunderbolt he falls. Alfred, Lord Tennyson, The Eagle Photo courtesy of Guenter Weber Bald Eagle Haliaeetus leucocephalus Nickname: Sea Eagle or Fish Eagle Like most Latin names, the scientific name for Bald Eagles is very fitting. First, Halo means sea and aeetos means eagle. Leukos represents white while cephalus pertains to head. Therefore, the scientific name is Haliaaeetus leucocephalus. The Bald Eagle is the only eagle that is unique to North America, with a range throughout North America, and northern Mexico. Its stronghold is in the northwest. The abundance of salmon and the lack of habitat destruction have been noted as the primary reasons for the large population in that area. Previously, the Bald Eagles were subdivided into two groupings and were even distinguished as subspecies, mostly due to size differences: Northern Bald

2 Eagle and Southern Bald Eagle. The northern group is slightly larger than the southern group. However, since the migration patterns are so interconnected, webbed, and overlapping, this distinguishing tendency has been discontinued in more recent literature. Above photo by Angie Bridges The Bald Eagle was named as our national symbol in There was strong contention when this decision was being made. Some of our leadership were in strong support of naming the Wild Turkey as the symbol for its intelligence and survival abilities. A few years after the naming, Ben Franklin strongly stated, I wish the Bald Eagle had not been chosen the representative of our country. He is a bird of bad moral character does not get his living honestly.besides is a rank coward. He says this to point out that the Bald Eagles are opportunists and may steal from others, and they can be harassed by smaller birds and driven away (even though they do their own harassing as well). However, Benjamin Franklin did not take into account the other aspects of this bird which can be considered honorable and majestic. They are powerful fliers, which turkeys are not known to be. The size of these birds and the expertise used for

3 catching prey with talons is also very noteworthy. When looking at these birds, they seem to give off an air of royalty, majesty, and strength. They mate for life, and both sexes help with the feeding and raising of the young. Our Native Americans have celebrated the Bald Eagle as a spiritual animal long before the United States was formed. The Bald Eagle is a dark brown bird with distinguishing white head and tail when it is mature. The body is stout and long (the female actually being larger in weight and stature than the male). They have large heads, impressive yellow hooked beaks, yellow legs and feet, and yellowish eyes. However, the transition to maturity and plumage change takes approximately 5 years to obtain. The immature Bald Eagle is much like the Golden Eagle in that the entire body is brown, and has a darker beak and brown eyes. Over the years, the immature Bald Eagle changes in outward appearance and will look mottled in coloration until the distinction between the body and head/tail can be seen. The feathers, eyes, and beak will gradually change. Photo right: By Guenter Weber An immature Bald Eagle without white head and tail and with mottled overall coloration. One of this year s immature eagles presently on our property. A genetic trait recognized in the bald eagle, called leucism, can give an eagle a patchy look as well and it will keep this look. The Bald Eagle s greatest weapons are his beak and talons. Both can be used for food acquisition and territoriality/defense. Their magnificent wings and sharp eyesight help make them successful in both activities. The Bald Eagle can be seen perched up high above on a tree top watching for prospective prey.

4 They have also been seen flying along the waterways not far from the surface to surprise an unaware fish along the way. Fish is their primary choice of food source, but they also eat other animals that are accessible such as small birds, ducks, reptiles, amphibians, rabbits, and rodents. They will also scavenge for carcasses. Here at our Photo by Guenter Weber property, the American Coots tend to be a favorite meal. They will swoop over prey, and grasp it with their long talons and strong feet. It was previously thought that eagles cannot let go of prey once the talons sink in, however it is now known that they do have control of their grasping at will. Therefore, they will not drown if the prey is overweight and the eagle cannot lift it out of the water- unless the eagle refuses to relinquish the prey. Their lifting ability is around 4 pounds. Once caught, they tear and shred their food at a nearby tree. The edge of the upper beak is sharp enough to slice through tough skin of their prey and the upper beak also overlaps the lower beak for a scissoring effect. They have been known to gorge themselves after a kill or if they are scavenging. In addition to feeding, the talons are used for other activities. Both in battle or in a courtship dance, the Bald Eagles have a behavior called talon clasping or cartwheeling, where the birds fly high in the sky, lock onto each other s talons, and tumble down locked together until they come near to the ground. Photo by Guenter Weber Courtship and mating occur from September to early

5 April, depending upon the breeding region where they are found. For the plantation, we see them coming in and preparing now, and breeding early in that spectrum. Where do they choose to live and breed? In some southern places, the Bald Eagle remains a permanent A Favorite Look-out Point Photo by Perry Nugent resident. Many Bald Eagles migrate up to their northern range in spring and summer, then migrate south for fall and winter when they breed. They look for water which can deliver a reliable food source. Next on their agenda are isolated, woodland areas with tall, mature coniferous and deciduous trees that can provide look-outs to protect the nest and to scan for fish and rodents. They will also inhabit dry areas that are open and have cliff sides for resting and nesting- as long as there is a water source nearby. Even though they are becoming tolerant of human activity by utilizing opportunities at fish processing plants, dams, and dumps, they prefer wide open spaces without human disturbances. The immature Bald Eagles live as nomads traveling up and down the coastlines exploring many areas. Finally, they will start breeding at 4 to 5 years old. Once it is time to pick a lifetime mate and nest, they select a place that suits them and begin building their nest. The nest is built near the trunk of the tree for best stability and high up in the tallest trees but below the canopy crown of the tree. For obvious reasons, the Bald Eagle nest is quite large. Usually it ranges between 5 to 6 feet in diameter and at least 2 to 4 feet tall. However, Bald Eagles tend to come back and add on to the previous year s nest, causing these original nests to get even larger. They are. Our eagle in nest Photo by Perry Nugent 2015 typically cylindrical or cone shaped, but may be flat if located on cliff sides.

6 Sticks and branches are the primary materials, and the lining is usually made of feathers and soft plant material such as moss, lichen, grass, and corn stalks. It may take the pair up to 3 months of dedication to build their nest. While this is going on, the Bald Eagles are also establishing territory from other raptors and potential predators such as ravens, coyotes, raccoons, and foxes. One to three white eggs are laid 5 to 10 days after mating. Both parents incubate the eggs for about 34 to 36 days. The young are fed with pieces of prey brought to the nest by both parents and torn into pieces. As they get older the pieces get larger until finally the adults simply drop off prey into the nest. First flight occurs at Take-off Photo by Guenter Weber about weeks old. They gain their flying skills and strength over the months, and eventually start their migration in early spring. Living in solo or pairs, many of these eagles will live in communes of up to hundreds of birds during the summer months. These communities of birds can get quite noisy and pesky in these areas close to human communities. Bald Eagles, like the herons and egrets, are a part of a successful recovery program. In the early 1700 s their population was estimated to be somewhere between 300,000 to 500,000 strong. Due to shootings, DDT pesticide pollution, and trapping, by the 1900 s the Bald Eagle population took a dramatic turn for the worst with an estimated low of only 500 breeding pairs. By the mid-1900 s, conservation efforts placed them on the Endangered Species List in Since then, according to North American Breeding Bird Population Survey, the global breeding population is at 250,000 eagles- 88% of which live in the United States

7 at some time during the year. Now the nesting pair number is in the 5000 s. Thankfully, the Bald Eagles have been flourishing in recent years. However, many deaths and injuries are attributed to eagles being hit by vehicles or eagles flying into structures such as towers and high buildings with glass. Other contributing factors for deaths today are pesticides and lead poisoning due to a build-up of these chemicals in the tissues of prey which are eaten, and the destruction of habitat for these birds. Fun Facts: The oldest recorded Bald Eagle in the wild was at least 38 years old and was eventually hit by a car in New York. The usual live span is between 15 to 20 years. The Largest Bald Eagle nest recorded was located in St. Petersburg and measured over 18 feet in height and almost 9 feet across! Another one in Ohio was used for 34 years straight and weighed close to two metric tons when the tree it was built on blew over in a storm. Bald Eagles have been seen hunting cooperatively. One individual flushes the prey while the other captures it. In hard times, an Eagle can survive fasting for many days and even weeks. Great Horned Owls are notorious for taking over abandoned eagle nests. Like other birds, a Bald Eagle s bones are hollow. Therefore the skeleton only weighs about a half of a pound! The feathers weigh twice that much! The beaks, talons, and feathers are made of keratin- the same material our fingernails and hair are made of. The Bald Eagle s body temperature is about 106 degrees Fahrenheit or 41 degrees Celsius compared to our 98.7 degrees Fahrenheit. Their resting heart rate is between beats per minute while ours is beats per minute. You may see an eagle panting, or perching in the shade of a tree with its wings held out away from its body. This is because they have no sweat glands and need to cool off. Because an eagle s feet are comprised mostly of thick skin and tendons, their feet have a high tolerance for cold temperatures.

8 Size-wise, the Bald Eagle s eye is almost the same size as the human eye, but their vision is at least four times sharper than ours even if we have perfect vision. An average weight for an eagle is pounds. Their lifting strength for a food source is 4 pounds. Both statistics emphasize the power of their wings. Bald Eagles are playful with objects and each other. They have been seen playing with water bottles and tossing sticks back and forth to a partner in mid-air. Information for this article came from: Bald Eagle, All About Birds, The Cornell Lab of Ornithology; Kaufman, Kenn, Bald Eagle, Audubon Field Guide; Basic Facts About Bald Eagles, Defenders of Wildlife; Bald Eagles, American Bald Eagle Information. When thou seest an eagle, thou seest a portion of genius; lift up thy head! William Blake

9 Sunday, September 17 th, 2017 What a glorious day! The humidity was very low and the breezes were pleasurable. Ray Swagerty took 10 bird watchers on their walk. The ducks and wading/water birds located this past week Wood Ducks, Pied-billed Grebe, Anhinga, Great Blue Heron, Great Egret, Snowy Egret, Little Blue Heron, Tricolored Heron, Green Heron, White Ibis, and Common Moorhen were found either in Ravenswood Pond, The Audubon Swamp, or the large impoundment. An Osprey was also seen at the large impoundment flying with his freshly caught prey. The Bald Eagle and Red-tailed Hawk were not seen until the group sat down at the end of the walk to tally their observations. In addition, two Redshouldered Hawk were seen near the Audubon Swamp and exit road. Many Black Vulture and Turkey Vulture were seen in the area. During the week, Black Vultures were taking turns at a carcass in the field beside the pony pasture. A local Bald Eagle decided to steal the food by swooping down, grasping it, and flying away. A couple of crow decided the eagle in the area was unwanted, so they attacked the eagle, and the eagle dropped the carcass. The eagle circled a few times, landed in a tall pine tree nearby and proceeded to watch as the vultures pulled the small meal under an oak tree into the shadows. This is a perfect illustration of eagles scavenging and also being run off by smaller birds as the preceding article suggests. Twenty-five Laughing Gulls were seen as flyovers from the river. These birds are progressing into their fall and winter plumage by becoming more predominately grey. Two Yellow-billed Cuckoo were seen together on the dry side of Ravenswood Dike- one was eating a frog! Also at Ravenswood and the large impoundment, Belted Kingfisher were seen darting from tree to tree with their very identifiable flight. A Prairie Warbler was seen between the Audubon Swamp and Ravenswood which was an unusual location for the sighting of these birds. A female Black-and-white Warbler was also seen near Ravenswood. In The Audubon Swamp, one male and one female Common Yellowthroat were seen together, while a single female was seen in a different area in the swamp. Noisy Red-winged Blackbirds were flyovers. One Northern Parula was spotted at Ravenswood and another was seen among the trees in the median between the entrance and exit roads. A Blue-gray Gnatcatcher was located near the Audubon Swamp and exit road. Near the Pavillion area and the oak tree row, Great-crested Flycatcher, Eastern Bluebirds, and a Southern Tanager showed up. Near the cabins, Red-eyed Vireo, and Pine

10 Warbler made appearances. Pine Warbler were also seen in a few other scattered locations. Also scattered about were the Carolina Chickadee, Whiteeyed Vireo, and Northern Cardinal. Pileated Woodpeckers are being heard earliest in the day during the walk. The Red-bellied and Downy Woodpeckers were noticed in the wooded areas. The remaining birds seen that day: Mourning Dove, Blue Jay, American Crow, Fish Crow, Tufted Titmouse, Carolina Wren, Northern Mockingbird, and Common Grackle. The total species count was 45. Two birds that were not counted in this total, but were considered likely identified were a Blue-headed Vireo and the Sharp-shinned Hawk (which have been spotted by other avid bird watchers during the last few weeks).