Dietmar Nill / Tengmalm's Owl (Aegolius funerus) pouncing on mouse, Germany

Markus Varesvuo / Tengmalm's Owl (Aegolius funereus) close-up of eye. Kuusamo Finland, May. Winner of the Birds Category in the Finnish Nature Photo of the Year Competition 2013

Wild Wonders of Europe / Lesniewski / Tengmalm's Owl (Aegolius funereus) nesting in an old beech tree. Bieszczady, Carpathian Mountains, Poland, May.

Wild Wonders of Europe / Cairns / Tengmalm's owl (Aegolius funereus) peering out of nestbox, Bergslagen, Sweden, June 2009

Konrad Wothe / Tengmalm's owl (Aegolius funereus) Bavarian Forest National Park, Germany, June. Captive.

Laurent Geslin / Naturalist ringing Tengmalm's / Boreal owl (Aegolius funereus) chick, Jura, Switzerland, April.

Laurent Geslin / Scientists examining mice left for chicks in Tengmalm's / Boreal owl (Aegolius funereus) nest by parents, Jura, Switzerland. May 2015.

Laurent Geslin / Naturalist ringing Tengmalm's / Boreal owl (Aegolius funereus) Jura, Switzerland. April 2015.

Laurent Geslin / Tengmalm's / Boreal owl (Aegolius funereus) chick in nestbox with mice prey, during bird ringing Jura, Switzerland. April.

Laurent Geslin / Naturalist ringing Tengmalm's / Boreal owl (Aegolius funereus) Jura, Switzerland.

Laurent Geslin / Naturalist removing Tengmalm's / Boreal owl (Aegolius funereus) from nest box to be ringed. Jura, Switzerland. April 2015.

Laurent Geslin / Tengmalm's / Boreal owl (Aegolius funereus) looking out of nest in tree hollow, Switzerland. May.