Walden Pond is a lake in Concord, Massachusetts in the United States. A famous example of a kettle hole, it was formed by retreating glaciers 10,000–12,000 years ago.[4] The pond is protected as part of Walden Pond State Reservation, a 335-acre (136 ha) state park and recreation site managed by the Massachusetts Department of Conservation and Recreation.[1] The reservation was designated a National Historic Landmark in 1962 for its association with the writer Henry David Thoreau (1817–1862), whose two years living in a cabin on its shore provided the foundation for his most famous work, Walden; or, Life in the Woods.

Bald eagles are not actually bald; the name derives from an older meaning of the word, "white headed". The adult is mainly brown with a white head and tail. The sexes are identical in plumage, but females are about 25 percent larger than males. The beak is large and hooked. The plumage of the immature is brown.The bald eagle is both the national bird and national animal of the United States of America. The bald eagle appears on its seal. In the late 20th century it was on the brink of extirpation in the contiguous United States. Populations have since recovered and the species was removed from the U.S. government's list of endangered species on July 12, 1995 and transferred to the list of threatened species. It was removed from the List of Endangered and Threatened Wildlife in the Lower 48 States on June 28, 2007.

The plumage of an adult bald eagle is evenly dark brown with a white head and tail. The tail is moderately long and slightly wedge-shaped. Males and females are identical in plumage coloration, but sexual dimorphism is evident in the species, in that females are 25% larger than males.[2] The beak, feet and irises are bright yellow. The legs are feather-free, and the toes are short and powerful with large talons. The highly developed talon of the hind toe is used to pierce the vital areas of prey while it is held immobile by the front toes.[3] The beak is large and hooked, with a yellow cere.[4] The adult bald eagle is unmistakable in its native range. The closely related African fish eagle (H. vocifer) (from far outside the bald eagle's range) also has a brown body, white head and tail, but differs from the bald in having a white chest and black tip to the bill.[5]

The plumage of an adult bald eagle is evenly dark brown with a white head and tail. The tail is moderately long and slightly wedge-shaped. Males and females are identical in plumage coloration, but sexual dimorphism is evident in the species, in that females are 25% larger than males.[2] The beak, feet and irises are bright yellow. The legs are feather-free, and the toes are short and powerful with large talons. The highly developed talon of the hind toe is used to pierce the vital areas of prey while it is held immobile by the front toes.[3] The beak is large and hooked, with a yellow cere.[4] The adult bald eagle is unmistakable in its native range. The closely related African fish eagle (H. vocifer) (from far outside the bald eagle's range) also has a brown body, white head and tail, but differs from the bald in having a white chest and black tip to the bill.[5]