Paul Hobson / Wood warbler (Phylloscopus sibilatrix) singing whilst perched on branch, silhouetted at dawn. Sheffield, England, UK. May.

Paul Hobson / Wood warbler (Phylloscopus sibilatrix) male singing, perched on branch in morning light. Sheffield, England, UK. May.

Bruno D'Amicis / Wood warbler (Phylloscopus sibilatrix) singing on tree branch in old-growth Beech (Fagus sylvatica) forest. UNESCO World Heritage Site. Abruzzo, Lazio and Molise National Park, Italy. June

Jeff Foott / Yellow warbler (Dendroica petechia) at Yellow-Bellied Sapsucker site (Sphyrapicus varius) damage in tree to eat sap. Sapsuckers damages trees trunks to feed on sap. Teton National Park, Wyoming, USA....

Dave Bevan / Wood warbler (Phylloscopus sibilatrix) displaying and calling from the branches of an Oak tree (Quercus), Carmarthenshire, Wales, UK, May.

Dave Bevan / Wood warbler (Phylloscopus sibilatrix) displaying, Carmarthenshire, Wales, UK, May.

Nick Hawkins / Common yellow throat (Geothlypis trichas) male, singing, Anchorage Provincial Park, Grand Manan Island, New Brunswick, Canada, June.

Andres M. Dominguez / Wood warbler (Phylloscopus sibilatrix) with insect prey, Andalusia, Spain, August.

Fabrice Cahez / Wood warbler (Phylloscopus sibilatrix) singing, silhouetted, Vosges, France, May.

Fabrice Cahez / Wood warbler (Phylloscopus sibilatrix) Vosges, France, May.

Fabrice Cahez / Wood warbler (Phylloscopus sibilatrix) Vosges, France, May.

John Cancalosi / Common yellowthroat (Geothlypis trichas) singing, New York, USA, May.