Ingo Arndt / Weaver bird nest (Ploceus sp.) detail from Africa in collection at Uebersee-Museum, Bremen, Germany.

Ingo Arndt / Fan Coral (Echinogorgia sp) from Indo-Pacific, in collection at Senckenberg Museum, Frankfurt, Germany.

Ingo Arndt / Common Moorhen (Gallinula chloropus) nest from Germany in collection at Uebersee-Museum, Bremen, Germany.

Ingo Arndt / Common Moorhen (Gallinula chloropus) nest from Germany in collection at Uebersee-Museum, Bremen, Germany.

Ingo Arndt / Harvest Mouse (Micromys minutus) nest, Germany.

Ingo Arndt / Bower of Vogelkop bowerbird (Amblyornis inornatus) front entrance of bower decorated with red fruit and acorns, Arfak Mountains, West Papua, Indonesia.

Ingo Arndt / Baya weaver (Ploceus philippinus) subadult birds practising building 'play nest', Singapore.

Ingo Arndt / Baya weaver (Ploceus philippinus) male flying to nest entrance, Singapore

Ingo Arndt / Male Vogelkop Bowerbird (Amblyornis inornatus) constructing bower roof. Arfak Mountains, West Papua, Indonesia.

Ingo Arndt / European Red Wood Ant (Formica polyctena) nests in pine forest, Hessen, Germany, July.

Ingo Arndt / Green tree ant (Oecophylla smaragdina) group on entrance from nest, built from woven leaves, Northern Territory, Kakadu National Park, Australia.

Ingo Arndt / Grizzly bear (Ursus arctos horribilis) portrait, Lake Clark National Park, Alaska, USA, September.