153848 Chiffchaff Phylloscopus collybita L 11cm. Tiny warbler, best known for its onomatopoeic song. Sexes are similar. Adult and juvenile have grey-brown upperparts and pale, greyish underparts suffused with yellow-buff on throat and breast. Bill is needle-like and legs are black; latter feature helps separate silent individuals from similar Willow Warbler. Voice Call is a soft hueet. Song is continually repeated chiff-chaff or tsip-tsap. Status Common summer visitor to mature deciduous woodland with a dense understorey of shrubs. Most migrate south to Mediterranean region in autumn but several hundred overwinter in S Britain.