Birds from central Europe initially migrate to the southwest, reorientating to the south or southeast once in Africa, although Scandinavian migrants may head south through the Alps and across the Mediterranean Sea. woodwardi" reaches Africa by a more easterly route, many birds passing through the Arabian Peninsula. When garden warblers cross the Sahara, they fly at night, resting motionless and without feeding in suitable shade during the day. During their journey, they can metabolise not only body fat but also up to 19% of their breast and leg muscles and 39% of their digestive tract. Many birds pause for a few days to feed after the desert crossing before continuing further south. The nominate subspecies occurs in the western and central parts of the winter range, although some birds occur as far east as Kenya. woodwardi" winters in eastern and southern Africa. Movements in Africa are poorly known, although at least some birds return to the same location in subsequent years. There are only a handful of records of birds recorded in Europe in winter, from Corsica, the UK and Ireland. Spring migration routes are poorly known, but appear to lie more directly across the Mediterranean. This warbler has occurred as a vagrant in Afghanistan, Djibouti, Iceland, São Tomé and Príncipe, Somalia, Yemen, Svalbard, Jan Mayen and Madeira. The breeding habitat of the garden warbler is open areas with dense bushes, including thickets and woodland edges. Shady areas and a bushy or herbaceous undergrowth are preferred, as are woods adjacent to rivers or reed beds; in Ireland it favours thickets on the shores of small lakes. A tolerance of willow, alder and birch allows it to breed farther north and at higher altitudes than any other European "Sylvia" warbler. Mature conifers and dense plantations are avoided, although young conifer plantations with thick undergrowth are suitable for nesting. Despite its name, it is not a bird of gardens. In Africa, a wide range of habitats with trees are used, although closed forests and arid areas are again avoided. This warbler occurs at altitudes of up to in suitable mountain woodland, although in East Africa it is usually found at a lower altitude than the blackcap, and in moister areas than the common whitethroat. Garden warblers first breed when they are one year old, and are mainly monogamous, although the male at least may sometimes deviate from this.