Sandhill Cranes are large migratory birds, recognized by their gray plumage, long legs, and the distinctive red patch of skin on their forehead. Found across North America and parts of Siberia, many populations undertake long annual migrations. Their reproductive cycle is characterized by a high degree of parental investment over a long period. This strategy focuses on nurturing a small number of young each season.
Clutch Size and Egg Characteristics
Sandhill Cranes typically lay a small clutch, usually consisting of one or two eggs per nesting attempt. Two eggs are the most common number, though three are possible but rare. This small clutch size relates directly to the massive energy investment and extended parental care provided to each chick.
The eggs are oval-shaped and relatively large, measuring near 99 millimeters in length and 62 millimeters in breadth. Their coloration is pale brownish-yellow or olive, marked with irregular speckles of brown or gray. This natural camouflage helps them blend into the surrounding vegetation of the nest site, offering protection from predators.
Although two eggs are the norm, the crane pair seldom raises two surviving young, typically resulting in a single offspring. The second egg functions as an insurance policy against the failure of the first egg or the early death of the first chick. This strategy maximizes the pair’s chance of producing at least one survivor.
The Sandhill Crane Nesting Cycle
The timing of the nesting cycle varies geographically. For migratory populations, egg-laying begins in early spring, typically between April and May. Non-migratory populations, such as the Florida Sandhill Crane, may start as early as January or February. The breeding pair, which mates for life, builds a ground nest near water in marshes, bogs, or wet meadows.
The nest is constructed from surrounding plant material like cattails, sedges, or grasses, forming a mound 30 to 40 inches across. Both the male and female gather vegetation to create the structure. After the eggs are laid, both parents share the incubation duties, a process lasting approximately 29 to 32 days.
Shared incubation allows the pair to maintain constant vigilance over the nest before the chicks hatch. This period of intense focus is followed by a long duration of parental care for the young.
Raising the Colt
The newly hatched crane chick is called a “colt.” Colts are precocial, meaning they are covered in down feathers and can leave the nest within 24 hours. These young colts weigh around 114 grams at hatching and can walk and follow their parents immediately. Both parents are involved in feeding and protecting the young, a period of biparental care that extends for nearly a year.
The young crane achieves its first flight, or fledges, relatively late, typically 65 to 75 days after hatching. Even after they can fly, the colts remain with their parents, often staying as a family unit for nine to ten months. This prolonged association ensures protection and provides a long period of learning before they are driven off prior to the next nesting season.
When two chicks hatch, the high mortality rate of the second chick is often due to sibling rivalry. The older, more aggressive chick may outcompete or injure the younger sibling, resulting in only one colt being successfully raised to independence. This extended parental investment contributes to a higher survival rate once the colt reaches nearly a year old.