Sandhill cranes are a fascinating bird species best known for their long migrations and long-term pair bonding. Many sandhill cranes do mate for life, but a few exceptions exist. Plus, not all pairs are truly monogamous.
Pairs of sandhill cranes are considered socially monogamous, which means that mated birds will form long-term bonds and share the responsibility of caring for their young. Mating and egg fertilization outside of the bonded pair does occasionally occur.
Most pair formations last until the loss of a mate. However, divorce does occur in pairs that lose a nest or are not able to reproduce. Reproduction appears to strengthen pair bonds, which makes sense evolutionarily. A crane would prefer to remain with a mate that will produce strong, successful colts.
Throughout this article, we will discuss sandhill crane mating and pair formation in greater detail. Read on to discover more!
Sandhill Cranes are classified as monogamous, and form long-term bonds with their mates
Sandhill Crane's likely mate for life to ensure the success of their offspring. Crane colts are running around and following their parents off to forage mere hours after hatching. They also remain with their parents for 9 to 10 months, joining them in the fall migration.
Both parents sticking together offers their young a greater safety net. Newly hatched colts are vulnerable running about outside of the nest.
Additionally, because they remain in a family unit for so long, it is far easier for both parents to share the responsibility of caring for and protecting their young.
Breeding pair of Sandhill Cranes
Pair formation in sandhill cranes generally occurs during spring migration. Males perform a courtship dance to attract a female's attention. Once a bonded pair forms, separation is unlikely unless one mate dies.
We will discuss courtship and pair bonding in more detail below.
As previously mentioned, males attract the attention of females by performing a courtship dance. Eight courtship displays occur between potential or bonded pairs. Three of the displays only occur between paired adults, including non-aggressive calls, bill up, and copulation. These serve to strengthen pair bonds and ensure reproduction.
The other five displays are performed by all sandhill cranes, paired or not. Three of these are meant to attract attention. They include the horizontal head pump, vertical toss, and upright wing stretch. Males generally use the wing stretch to attract the attention of the female, while both sexes will utilize the horizontal head pump. The vertical toss is thought to precede courtship dancing.
Dancing makes up the final two courtship displays. It includes the bow and vertical leap. Once the male attracts the attention of a female, both will begin a courtship dance. It is important to note, however, that dancing also occurs outside of courtship. Sandhill cranes will dance year-round and sometimes an entire flock will join in.
Sandhill Cranes performing the courtship dance
Pair formation amongst sandhill cranes can occur as early as 2 to 3 years of age. However, most cranes do not mate and begin producing successive nests until they reach 5 or 6. By age 8, nearly all birds are paired.
A bonded pair generally mates for life. Adult sandhill cranes rarely separate, unless a nest is lost or reproduction is unsuccessful. The majority of mated pairs remain together after the loss of one nest.
Young sandhill cranes (before the age of 5 or 6) that are beginning to take part in courtship behaviors and nesting occasionally separate and find new partners. However, separation without notable cause is extremely rare in mature adults.
Sandhill Cranes displaying and dancing to form a pair
Sandhill cranes only mate and produce a clutch once a year. If the first nest is unsuccessful and it is still early in the breeding season, a pair will re-nest and try to raise another clutch.
Sandhill cranes do not produce more than one successful clutch in a year because time does not allow it. Crane colts remain with their parents for 9 to 10 months, following them to their winter migration grounds.
A family of Sandhill Cranes with the chick inbetween the parents
When a sandhill crane mate dies, the surviving crane will seek out a new partner. If the loss occurs early enough in the breeding season, the crane may form a new pair bond and breed in the same season. If the loss occurs later in the year, the surviving mate may not pair up again until spring migration - when most new pairs are formed.
Little is known about whether or not sandhill cranes mourn the loss of a mate. However, it is not unlikely that they do mourn. Studies have shown that mated pairs mourn and perform rituals around the loss of their young. We also know that other bird species, including other species of cranes, mourn when a mate dies.
Mating pair of Sandhill Cranes at the nest
Female sandhill cranes do not mate with each other or appear to form pair bonds. However, it is possible for two females to perform courtship displays toward one another, perhaps in preparation for finding a mate. More research would need to be done in this area.
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