Editing Common chiffchaff (section)

===Breeding===
[[File:Phylloscopus collybita MWNH 2266.JPG|thumb|Eggs, Collection [[Museum Wiesbaden, Germany]]]]
The male common chiffchaff returns to its breeding territory two or three weeks before the female and immediately starts singing to establish ownership and attract a female. When a female is located, the male will use a slow butterfly-like flight as part of the courtship ritual, but once a pair-bond has been established, other females will be driven from the territory. The male has little involvement in the nesting process other than defending the territory.{{sfn|Clement|1995|pp=84–88}} The female's nest is built on or near the ground in a concealed site in brambles, nettles or other dense low vegetation. The domed nest has a side entrance, and is constructed from coarse plant material such as dead leaves and grass, with finer material used on the interior before the addition of a lining of feathers. The typical nest is {{convert|12.5|cm|in|abbr=off}} high and {{convert|11|cm|in|abbr=off}} across.{{sfn|Clement|1995|pp=90–92}}

The clutch is two to seven (normally five or six) cream-coloured eggs which have tiny ruddy, purple or blackish spots and are about {{convert|1.5|cm|in|abbr=off}} long and {{convert|1.2|cm|in|abbr=off}} across. They are incubated by the female for 13–14 days before hatching as naked, blind [[altricial]] chicks.{{sfn|Clement|1995|pp=92–95}} The female broods and feeds the chicks for another 14–15 days until they fledge. The male rarely participates in feeding, although this sometimes occurs, especially when bad weather limits insect supplies or if the female disappears. After fledging, the young stay in the vicinity of the nest for three to four weeks, and are fed by and roost with the female, although these interactions reduce after approximately the first 14 days.{{sfn|Clement|1995|pp=95–100}} In the north of the range there is only time to raise one brood, due to the short summer, but a second brood is common in central and southern areas.{{sfn|Clement|1995|pp=102–103}}

Although pairs stay together during the breeding season and [[Animal sexual behaviour#Polygamy|polygamy]] is uncommon, even if the male and female return to the same site in the following year there is no apparent recognition or fidelity. Interbreeding with other species, other than those formerly considered as subspecies of ''P. collybita'', is rare, but a few examples are known of hybridisation with the willow warbler. Such hybrids give mixed songs, but the latter alone is not proof of interspecific breeding.{{sfn|Clement|1995|pp=100–102}}