Martin Willis / Victoria's Riflebird (Ptiloris victoriae) male in courtship display, Atherton Tableland, Queensland, Australia. Sequence 2 of 3

Stefan Christmann / Emperor penguin (Aptenodytes forsteri), two chicks aged six to eight weeks brooding on parents' feet, one vocalising. Atka Bay, Antarctica. September.

Guy Edwardes / Marsh Frog (Pelophylax ridibundus) vocalising with bokeh effect in the background, Danube Wetlands, Bulgaria

Guy Edwardes / Marsh Frog (Pelophylax ridibundus) vocalising with bokeh effect in the background, Danube Wetlands, Bulgaria

Donald M. Jones / Yellow-headed Blackbird (Xanthocephalus xanthocephalus) male calling, Montana

Donald M. Jones / Western Meadowlark (Sturnella neglecta) male calling, Montana

Donald M. Jones / Elk (Cervus elaphus) bull bugling, Alberta, Canada

Tomasz Zawadzki/ BIA / Blue-headed Wagtail (Motacilla flava) calling, Poland

Tomasz Zawadzki/ BIA / Great Reed-Warbler (Acrocephalus arundinaceus) calling, Poland

Glenn Bartley/ BIA / Chestnut-bellied Cuckoo (Hyetornis pluvialis) calling, Jamaica

Glenn Bartley/ BIA / Patagonian Sierra-Finch (Phrygilus patagonicus) male calling, Andes, Chile

Guy Edwardes / Little bee-eater (Merops pusillus) vocalising whilst perched on branch, Khwai, Botswana.