NESTING BIRDS ON CONN ISLAND located in the Potomac River above Great Falls

Transcription

1 NESTING BIRDS ON CONN ISLAND located in the Potomac River above Great Falls American Bald Eagles, Great Blue Herons, Double-Crested Cormorants, and Black Crowned Night Herons

2 Prepared by Bud Cline, Ph.D. Master Ranger Corps This presentation contains information gathered from a variety of sources including personal observations and reports of visitors and volunteers in the C&O Canal National Historical Park It contains images taken by myself and others

3 The information is provided for use by C&O Canal NHP volunteers (and guests) to assist them in telling visitors to the Park about the eagles and other bird species that we observe on Conn Island and elsewhere in the Park 3

4 4

5 Immature Eagle 5

6 American Bald Eagles Became the National Emblem in 1782 Were placed on the ES List in 1967 DDT was banned in 1972 due to impact on eagles Was removed from the Endangered Species List in 2007 but still protected! It is estimated that there are currently more than 11,000 nesting pairs of eagles in the US now see over population pressures Alaska leads all states in eagle population 6

7 Colors & Feathers Both male & female adult bald eagles have a blackish-brown back and breast, white head, neck, and tail Bald eagles have a yellow bill and feet Juvenile bald eagles are a mottled mixture of brown and white it takes 4 5 years for them to achieve adult feather colors Bald eagles have about 7,000 feathers

8 Fact & Figures Members of the sea and fish eagle group Eagles have excellent eyesight Eagles feed mainly on fish and carrion Female bald eagles are inches long slightly larger than the male Eagles wingspan ranges from feet Eagles are strong swimmers - hypothermia Eagles can fly to 10,000 feet - at up to 35 mph

9 More Facts & Figures Eagles reach sexual maturity at 4-5 years of age in the wild they can live to 30 yrs Once paired, eagles remain together until one dies survivor takes a new mate Nests are built in large mature trees near rivers or coasts Eagles lay from one to three eggs The 35 days of incubation duties are shared by both the male and female eagle 9

10 Eagle Nest - What To Look For Nest Location Food fish slackwater above dam Warm water effluent from power plants Safety islands & high in trees Access high in trees Sycamore trees Territory 3-5 mile separation of nests Perch trees good place to look for eagles A mating pair will return to the same nest

11 Perch Tree 11

12 Eagle Nests When eagles reach adulthood, they return to the area where they were born to mate Eagle nests are built in mature large trees that have open access to hunting areas Eagle nests are the largest of any N. American bird and can reach 13 ft. deep by 8 feet wide and weigh over a ton Nests are used repeatedly over many years with new material added each year

13 Eagle Nests - Continued If a nest is damaged by weather or collapses due to its weight, a new nest is built close by Conn Island nests 1-3 Eagles are sensitive to human presence and when possible, built their nests in isolated locations Eagles are adaptable, however, and will build nests in location close to human presence Conn Island visitors and helicopters

14 Eagle on Nest Eagle on Nest

15 Adult with Nestling

16 Eaglets in Nest

17 Conn Island Eagle Nest There has been an eagle nest on Conn Island since The current nest is the third one on the Island. 17

18 Close Up View

19 January 2011 View

20 January 2011 View VA

21 Spring 2010 View

22 January 2011 View Old Nest

23 History of the Conn Island Nest Original Nest has been there since 1986 it was abandoned in 2008 after collapse due to a wind storm A new nest was established in 2008 about 500 yards downstream and to the West The second nest was blown down by wind in 2014 and then rebuilt later that season very close to the second nest The current nest may be seen from the deck near the Tavern and less well from the River Trail The current nest also can be clearly viewed from Great Falls NP on the VA side of the river 23

24 Nesting Cycle Eagles arrive in late November to early December and begin nest building or remodeling Mating occurs in January first egg is laid 5-10 days later, 2 nd in next couple days Eggs are laid from Jan. thru early Feb. Eggs hatch in about 35 days Both the male and female share in the incubating and hunting duties 24

25 Nesting Cycle - Continued One to three eaglets may hatch and will compete for food the adults may ignore all but the largest of the nestlings The largest nestling may attack the smaller nestling(s) the adults will not intervene and death of the eaglet(s) may result Nestlings reach nearly adult size by early June and fledge from the nest by mid-june

26 Mating Behavior Flying together in formation Locking talons and whirling toward the ground - a real treat to watch! Sitting side by side on a tree limb near the nest courtship behavior Copulation occurs on a tree limb or on the ground not in the air (red-tailed hawks) An eagle pair may not mate each year seems to depend on nest availability, food availability, and weather 26

27 Romance in the Air! 27

28 Fledging - Fly or Die The adult eagle pair will stop feeding the nestling(s) in early June The young eagle(s) will be forced to fledge (fly from the nest) or it/they will starve to death About 40% of nestlings do not survive their first flight! Fledglings must learn to fly and hunt for themselves they do this by trial and error with some help from the parents as they are learning Fledglings will continue to return to the nest until they migrate away from our area in the Fall They will return to the area where they were raised in the following year(s) 28

29 Feeding Behavior Eagles are at the top of the food chain Eagles hunt for fish both alive and dead Eagles are notorious for stealing fish from other eagles or osprey who are better at catching fish than eagles are Eagles will feed on carrion Eagles will take small mammal and birds Eagles use a shallow glide over the water to hunt they do not dive like an osprey

30 Migration Bald eagles that reside in the southern US are resident and do not migrate Eagles that live in colder areas of the lower 48 states may leave the area of their nests when waterways begin to freeze over that is what our eagles do When our eagles leave the area, they move to where fish are readily available My guess is they go to Conowengo Dam

31 Locked Talons

32 On the Hunt - Gliding Along 32

33 Population Issues In the early 1700 s it is estimated that there were 300,00 500,000 bald eagles in what is now the lower 48 states By the 1950 s there were only 412 nesting pairs of bald eagles in the same area Illegal shooting was the major cause of population decline DDT - lead Loss of habitat, power-line electrocutions, collisions with vehicles, and other hazards 33

34 Population Issues Continued More than 100,000 bald eagles were killed in Alaska from Declared an Endangered Species in 1967 DDT use banned in US in 1972 Population rebounded and is continuing to grow (half of US population is in Alaska) Delisted as an Endangered Species in now over 11,000 breeding pairs

35 Population Issues Continued The Potomac River Habitat is saturated with eagle nests so now seeing territorial battles leading to injuries and death Eagles are now establishing nests on tributaries and along other area rivers such as the Anacostia A new nest was established last year in the National Arboretum the first in 70 years (protected zone & eagle cam)

36 Survival Not all eggs that are laid result in living chicks being hatched weather one factor Not all nestlings survive to leave the nest About 40% of fledglings do not survive their first flight from the nest A significant number of juvenile eagles do not survive their first winter starvation Many other factors confront juvenile and adult eagles in their daily lives loss of habitat, power lines, lead, hunting, wind turbines, auto traffic, air traffic, other 36

37 That s my story & I m sticking to it! Photo taken by Ralph Wright in Homer, Alaska 37

38 GBH, Cormorant and Black Crowned Night Heron Nests Conn Island is a major rookery for great blue herons, doublecrested cormorants, and black crowned night herons.

39 Great Blue Heron (GBH) 39

40 Double-Crested Cormorant

41 Black Crowned Night Heron

42 Other Large Birds of the Park (in addition to hawks & owls) Canada Goose Vultures Turkey and Black Great Egret Green Heron (Little Blue & Tricolor Herons) Anhinga Osprey Tundra Swan (Muted Swan) Wild Turkey Common Raven

43 Canada Geese

44 Black Vulture

45 Great Egret

46 Green Heron 46

47 Anhinga 47

48 Osprey at Lock 16

49 Tundra Swan

50 Mute Swan

51 Wild Turkey

52 Common Raven

53 Raven s Nest on Devil s Eyebrow at mile on the Towpath

54 Hawks & Owls of the Park Red-tailed Hawk Red-shouldered Hawk Broad-winged Hawk Sharp-shinned Hawk Barred Owl Eastern Screech Owl Great Horned Owl Barn Owl 54

55 That s all Folks hope you enjoyed the presentation!