Birds ‘branch-boarding’ on Isère- Grenoble, France.

Many among us love to hear the song of the wood thrush which has inspired many love poems through the history of our literature. But most of us don’t know a bird’s call from its song.

Bird song, "usually produced by the male, is an advertisement of territory and breeding availability, and, in most species, is limited to the breeding season …" It is mostly about territory or love songs, we can generally hear it only in spring and early summer, when the birds are nesting.

A few birds sing throughout the year. In some species, the bird is physically incapable of singing during the fall and winter.

"Bird calls tend to be unmusical, acoustically simpler, and less complex than the proclamatory songs, and they serve to communicate whereabouts between pairs or among members of a flock, warning sounds, sharp notes to intimidate or drive away enemies..."

When that same chickadee calls–"chick-a-dee-dee" or "chick-a-dee-dee-dee"–it may be saying literally, “Chickadee here! Here I am!” If there’s a fear; a predator nearby, more "dees" means more danger.

The common yellowthroat, is recognizable with its: "witchety-witchety-witchety."

We need to concentrate hear the difference between the "peter-peter-peter" of the tufted titmouse and the "TEACHer-TEACHer-TEACHer" of the ovenbird.

Sounds travel depends on the bird’s environment. Different sounds travel better in different environments. Some birds sound the way they do because of where they live.

Olive-sided flycatcher sings atop a tall tree and its whistled song carries half a mile through the open air.

One red-eyed vireo was heard to repeat its song over 22,000 times in ten hours!

Listen to wood thrush, robin, chickadee voices
Learn about chickadee codes
Or find answer to your many bird questions

Source:
http://awaytogarden.com/birdnote-qa-bird-songs-and-calls-demystified

To share your bird photos:
http://web1.audubon.org/imagePublic/cbc_form.php

Bird Nest Types
There are so many nest types built in various ways and techniques built every year for breeding but some are reused for many years. In most species, the female does most or all of the nest construction, though the male often helps. However not all species build nests. Some species lay their eggs directly on the ground or rocky ledges.

Some aquatic species such as grebes are very careful when approaching and leaving the nest so as not to reveal the location. Some species will use leaves to cover up the nest prior to leaving.

The smallest bird nests are tiny cups which can be a mere 2 cm (0.79 in) across and 2–3 cm (0.79–1.2 in) high. At the other extreme, some nest mounds measure more than 11 m (36 ft) in diameter and stand nearly 5 m (16 ft) tall.
http://en.wikipedia.org/wiki/Bird_nest

Adherent: Made of mud and built against a surface in a tree or cliff to form a nice shape.
Aquatic: Built up with sticks and debris; anchored, floating, in shallow or deep water.
Burrow: Built underground in a canal, to create a safe place for their eggs.
Cavity: Formed inside a tree using an existing cavity or create one.
Cup:  Made from grasses, twigs and mud, in a tree or on the ground.
Enclosed: Similar to a cup with a small entrance hole.
Mound: Heap of twigs and vegetation in form of a mound to protect and keep the eggs warm.
Pendant: Hanging nest, woven from fine grasses.
Plate: Shallow cup made of foliage or mud.
Platform: Huge nest, for larger eggs.
Scrape: Very shallow depression lined with grasses, feathers or moss.

http://www.handykam.com/Bird-hints-and-tips/bird-nest-types
http://www.stanford.edu/~petelat1

The distinction between birds songs and calls is based upon complexity, length, and context. In non-technical use, bird songs are the bird sounds that are melodious to the human ear. Songs are longer and more complex and are associated with courtship and mating, while calls tend to serve such functions as alarms or keeping members of a flock in contact.
Howell and Webb (1995) make the distinction based on function, so that short vocalizations such as those of pigeons and even non-vocal sounds such as the drumming of woodpeckers and the "winnowing" of snipes' wings in display flight are considered songs.
It is generally agreed upon in birding and ornithology which sounds are songs and which are calls, and a good field guide will differentiate between the two.The songs of different species of birds vary, and are more or less characteristic of the species.
In modern-day biology, bird song is typically analyzed using acoustic spectroscopy. Species vary greatly in the complexity of their songs and in the number of distinct kinds of song they sing (up to 3000 in the Brown Thrasher); in some species, individuals vary in the same way.The specificity of bird calls has been used extensively for species identification.
Some  musicologists believe that birdsong has had a large influence on the development of music. There seem to be three general ways musicians or composers can be affected by birdsong: they can be influenced or inspired (consciously or unconsciously) by birdsong, they can include intentional imitations of bird song in a composition, or they can incorporate recordings of birds into their works.
Bird song is a popular subject in poetry.
Source:
http://en.wikipedia.org/wiki/Bird_vocalization

Read more about birds:
http://www.stanford.edu/~kendric/birds/BirdSite.html
http://www.stanfordalumni.org/news/magazine/2001/marapr/features/cardinal.html
http://birds.audubon.org/faq/birds
http://birds.audubon.org/common-birds-decline
http://www.birds.cornell.edu/
http://imnh.isu.edu/digitalatlas/bio/birds/main/ident/bvk6sb.htm

Food is the primary motivation, for birds migration; some hummingbirds will not migrate if fed through the winter. As the days shorten in autumn, the birds return to warmer regions and enjoy the constant food supply.

The primary physiological cue for migration, are the changes in the day length. These changes are also related to hormonal changes in the birds. In the period before migration, many birds display higher activity as well as physiological changes such as increased fat deposition.

The routes taken on forward and return migration are often different. A common pattern in North America is clockwise migration. 

The specific routes may be genetically programmed or learned to varying degrees. Species that move short distances, however, may not need such a timing mechanism, and may move in response to local weather conditions.

Many, if not most, birds migrate in flocks. For larger birds, flying in flocks reduces the energy cost. Geese in a V-formation may conserve 12–20% of the energy they would need to fly alone. However, radar studies showed some birds; Red Knots and Dunlins, are able to fly 5 km per hour faster in flocks than when they were flying alone.