Charlie Summers / Greater sandhill crane (Grus canadensis tabida) just folding its wings after landing in a snow covered field, Bosque del Apache, New Mexico

Charlie Summers / Five Greater Sandhill Cranes (Grus canadensis tabida) in flight, coming in to land. Bosque del Apache, New Mexico, December.

Charlie Summers / Flock of Greater Sandhill Cranes (Grus canadensis tabida) against darkening sunset. New Mexico, December.

Charlie Summers / The silhouette of a Greater Sandhill Crane (Grus canadensis tabida) as it prepares to land. Bosque del Apache, New Mexico, USA, January.

Charlie Summers / Greater Sandhill Crane (Grus canadensis tabida) taking off from a frozen pond. Bosque del Apache, New Mexico, USA, February.

Charlie Summers / Four Greater Sandhill Cranes (Grus canadensis tabida) preparing to take off. Bosque del Apache, New Mexico, USA, February.

Charlie Summers / A small flock of Greater Sandhill Cranes (Grus canadensis tabida) in flight. Bosque del Apache, New Mexico, USA, January.

Charlie Summers / Two Greater Sandhill Cranes (Grus canadensis) silhouetted against a dusky sky. Bosque del Apache, New Mexico, USA, January.

Charlie Summers / Greater Sandhill Cranes (Grus canadensis tabida) flying in dusky light. Bosque del Apache, New Mexico, USA, January.

Charlie Summers / Greater Sandhill Cranes (Grus canadensis tabida) silhouetted in dusky light, standing in water. Bosque del Apache, New Mexico, USA, January.

Charlie Summers / Greater Sandhill Crane (Grus canadensis tabida) courting the bird on the left. Courtship displays include opening the wings, leaping into the air flapping the wings and picking up something. Bosque de...

Charlie Summers / Courting behaviour of the Greater Sandhill Crane (Grus canadensis tabida). Bosque del Apache, New Mexico, USA, January.

Charlie Summers / Greater Sandhill Crane (Grus canadensis tabida) left, standing by a Snow Goose (Chen / Anser caerulescens). Bosque del Apache, New Mexico, USA, January.

Charlie Summers / Greater Sandhill Crane (Grus canadensis tabida) walking through shallow water. Bosque del Apache, New Mexico, USA, January.

Charlie Summers / Greater Sandhill Cranes (Grus canadensis tabida) foraging in a steamy irrigation ditch. Bosque del Apache, New Mexico, USA, February.

LYNN M. STONE / Pair of Greater Sandhill Cranes (Grus canadensis tabida) calling / bugling in a wetland habitat, in early evening, southern Wisconsin, USA

LYNN M. STONE / Greater Sandhill Crane (Grus canadensis tabida)incubating eggs on mounded nest of reeds; southern Wisconsin, USA

LYNN M. STONE / Greater Sandhill Crane (Grus canadensis tabida) standing near its nest in wetland, southern Wisconsin, USA

LYNN M. STONE / Greater Sandhill Crane (Grus canadensis tabida) wading in pool near its nest in wetland, southern Wisconsin, USA

LYNN M. STONE / Greater Sandhill Crane (Grus canadensis tabida) incubating two eggs on mounded nest of reeds in wetland, southern Wisconsin, USA

LYNN M. STONE / Greater Sandhill Crane (Grus canadensis tabida) rolling two eggs for even incubation on mounded nest of reeds in wetland, southern Wisconsin, USA

LYNN M. STONE / Greater Sandhill Crane (Grus canadensis tabida) settling down to incubate two eggs on mounded nest of reeds in wetland, southern Wisconsin, USA

LYNN M. STONE / Greater Sandhill Crane (Grus canadensis tabida) standing over nest of two eggs, on mound of reeds in wetland, southern Wisconsin, USA

LYNN M. STONE / Greater Sandhill Crane (Grus canadensis tabida) settling down to incubate two eggs on mounded nest of reeds in wetland, southern Wisconsin, USA

Marie Read / Greater Sandhill Cranes (Grus canadensis) (Florida race) four walking across a road, Kissimmee, Florida, USA