The barred warbler has a highly complex and unusual method of breeding. From May to July, territorial males attract female mates with songs, wing-clapping in flight, and by building a loose nest platform, the quality of which is believed to indicate the male bird’s health. After a pair have bonded, the female uses the material from this platform to help build a more elaborate cup-shaped nest in a dense thorny bush. Once the pair have mated, the female lays a clutch of three to six eggs and the male bird may abandon the female to take-up a new territory, in attempt to mate with additional females. Some males, however, choose to stay with the original female and form a monogamous relationship. When this is the case, both birds share incubation duties for around 12 or 13 days, and both tend to the chicks while they are in the nest for a further 11 or 12 days. After fledging from the nest, the young birds remain with the adults for around three weeks. When the adult male bird has more than one mate, the female incubates the eggs and tends to the chicks alone. Sexual maturity is reached at around one year, although most barred warblers do not breed until their third year (2).
The barred warbler feeds largely on insects, which are usually plucked off leaves in bushes near the ground, or in the canopy of tall trees, on the ground or in flight (2). It is this dependency on insect prey that explains why the barred warbler must migrate southwards after breeding; during the winter at northern latitudes insects become scarce, but at this time insects are in abundance in the tropics. The barred warbler typically leaves its breeding grounds in July, arriving at the wintering grounds around December, where it remains until around March or April (2). Before the barred warbler embarks on its long journey, it accumulates substantial fat reserves which act as an energy store (3).