Woman in doorway of a 200 year old beehive house in the desert, Ebla area, Syria, Middle East

European Hoopoe (Upupa epops) perched at entrance to nest with food, Bulgaria

Syrian Woodpecker (Dendrocopos syriacus) female with food,perched at entrance to nest hole, Bulgaria

Syrian Woodpecker (Dendrocopos syriacus) female perched at entrance to nest, Bulgaria

Syrian Woodpecker (Dendrocopos syriacus) perched on tree by entrance to nest, Bulgaria

Cameraman, Mike Pitts, holding Komodo dragon hatchling. Scene behind showing entrance in the megapode mound to film the underground nest.

European hornets (Vespa crabro), workers on the entrance to the nest, former nesting hole of a great spotted woodpecker, Thuringia, Germany, Europe

Black woodpecker (Dryocopus martius), male sitting at the entrance of its nesting hole, Neunkirchen, Siegerland, North Rhine-Westphalia, Germany, Europe

Green Woodpecker (Picus viridis), male at the entrance to nisting hole, Neunkirchen, Siegerland, North Rhine-Westphalia, Germany, Europe

Little owl (Athene noctua), young bird looking out of the entrance of the nest box, Muensterland, North Rhine-Westphalia, Germany, Europe

Hoopoe (Upupa epops), adult feeding nestling at the entrance of the nest cavity with the larva of a snake, St. Margarethen, Tyrol, Austria, Europe

Blue tit (Cyanistes caeruleus) looking out of the entrance hole of the breeding cavity, Moenchbruch nature reserve, Moerfelden, Hesse, Germany, Europe

Common kestrel (Falco tinnunculus) female and young bird in front of nest entrance, Muensterland, North Rhine-Westphalia, Germany, Europe

Ural Owl (Strix uralensis). Adult at entrance of nest in hole of a tree. Enclosure in the National Park Bavarian Forest, Europe, Germany, Bavaria

Two Exotic Birds, Mountain Parakeets (Psilopsiagon Aurifrons), At The Entrance Of Their Nest, Mendoza, Argentina

Masked weaver (Ploceus velatus) bird perched at nest entrance, Serengeti National Park, Tanzania

leaf-cutter bee insects bees wild bees head of bee in nest entrance