Some migratory species, such as the marsh warbler, have an international repertoire. These birds nest in Europe but migrate to Africa in winter. Although the marsh warbler imitates some European species, most of its songs are those of African birds, which it hears on the wintering grounds. The warbler may mimic the calls of over 70 bird species. Warblers are telling females where they spend the winter. A female may find it advantageous to pair with a male adapted to wintering in the same part of Africa as she does.
Although it is generally the male that sings to attract mates or defend territories, in some species the female joins in too. The female alpine accentor sings to attract males, because for her it is an advantage to mate with as many males as possible - each one will then help in caring for her young.
The red-winged blackbird female sings two distinct song types throughout the breeding season. Song A is a form of communication directed at her partner. She sings Song B when other females appear; it seems to be an aggressive signal. Male European robins sing all year round. They have two songs, a longer more complex one to attract females in the breeding season, and a shorter simpler one to defend the territory in the winter. However, in winter, both sexes sing, because both male and female defend separate territories. They need these territories to ensure that each will have enough food to survive the winter.
The female black-headed grosbeak seems to use song to give her man a scare. Grosbeak parents take turns in incubating the eggs. But if the male is late returning to relieve the female from her duty, she sings a complex song imitating a male grosbeak. This may be to trick her mate into returning by giving the impression that a rival male is on his territory.
Ravens do a similar thing. Members of a pair learn each other's calls. When one partner is away or out of sight, the other will often call with it's mate's individual calls to relocate it and prompt it to return. In some species, the female may join the male in singing to defend their mutual territory. Both sexes will sing a duet in alternation. Duetting is particularly common in birds that maintain year-round territories and it helps in maintaining contact between members of a pair, in the dense and noisy environment of a tropical forest.
African shrikes are famous for their musical, repetitive duets, sounding something between a bell and a horn. Each pair develops a unique duet "part", which they use to keep track of each other in dense vegetation, to maintain their territory and to synchronize their breeding cycles. The two birds are so well synchronized in their duetting, you would think it was one bird singing, not two.
Magpie larks sing a duet to defend their territory in the Australian bush. One bird utters a loud metallic "tee-hee" that is immediately followed by the other's "pee-o-wee, pee-o-wit". The pair is so co-ordinated that the whole thing sounds like one song.
In some species, an entire group of birds may join in a chorus song to defend the territory. Groups of Australian magpies produce a remarkable chorus, varying from quiet warbling to loud caroling. The white-crested laughing thrush also sings a group chorus. Each individual has its own phrase to contribute to the song: the result is like one bird singing. One of the most amazing performances comes from the lyretailed honeyguide.
In the forests of Central Africa it flies above the tree canopy, sings and then spirals down like a roller-coaster from hundreds of feet up in the air. As it does so, it vibrates its tail and the rush of wind through its spiky feathers makes a loud drumming sound, audible throughout the forest. Whooper and Bewick's swans perform a noteable love duet. Nearly every day they confirm and strengthen their bond by a mutual greeting and courtship ceremony. Both partners join in a resonant duet that rings across the lake. The two stately birds swim to face each other and with beaks raised and wings uplifted launch into a wild clangor, the female replying to the quick honking of the male with repeated notes half a tone lower.
Song is certainly a way for a young man to get on. Consider the D'Arnaud's barbet, an African species, master of the art of singing in harmony. Barbets live in groups of 3-6 birds, with one dominant male and female. The male and female sing an intricately synchronized duet. The other members of the group are forbidden to join in.
But should the male be away for too long, one of the other males quickly moves in. He immediately begins singing the song that had been reserved for the dominant bird. The female sings her part and the two begin to form a new pair, synchronizing their duet more precisely. But should the former male reappear, the new bird becomes a subordinate member of the group once more. White-browed sparrow weavers sing group choruses, which they use to defend their territories.
Remarkably, each bird is an expert sound mixer. It can also produce the whole chorus on its own. The sound produced by one individual will sound as complex as that produced by nine. Bird song is a deep and complex subject as well as a gloriously uplifting one. There is much scientists still do not understand about it. In the meantime -- enjoy.
In this riveting book, Jack Sacco tells the realistic, harrowing, at times horrifying, and ultimately triumphant tale of an American GI in World War II as seen through the eyes of his father, Joe Sacco -- a farm boy from Alabama who was flung into the chaos of Normandy and survived the terrors of the Bulge.
As part of the 92nd Signal Battalion and Patton's famed Third Army, Joe and his buddies found themselves at the forefront of the Allied push through France and Germany. After more than a year of fighting, but still only twenty years old, Joe had become a hardened veteran. Yet nothing could have prepared him and his unit for the horrors behind the walls of Germany's infamous Dachau concentration camp. They were among the first 250 American troops into the camp, and it was there that they finally grasped the significance of the Allied mission. Surrounded by death and destruction, the men not only found the courage and will to fight, but they also discovered the meaning of friendship and came to understand the value and fragility of life.