Alaska Sandhill Crane 2021


THREAT & ATTACK DISPLAYS


Cranes are large birds and can be formidable adversaries when they are aroused. Their leaps, jumps, body slams, and bill stabs are spectacular and effective against predators and against other cranes competing for nest territories, food sources, or mates.

But usually, cranes in conflict don't savage one another. In fact, cranes are quite social: migrating, foraging, and roosting in flocks. Within such aggregations, body language maintains personal space and establishes dominance.

The displays depicted below are signals of conflict. As cranes become stressed, other social or dance displays (like Gapes, Run-flaps, and Jump-rakes) can be employed as threats.

For some representative scientific papers describing crane displays, see Masatomi & Kitagawa, Voss and Ellis & coworkers.

Crown contracted

Display: The skin of the crown (forehead) is reddish and coated with tiny sparse black feathers that are barely visible. When the crane is calm and relaxed, the forehead is small and the red skin ends just behind the eye.

Function: Contracted crown indicates the crane is relaxed and not stressed.

Bare-skin contracted

Crown expanded

Display: Aroused cranes flash bright red crowns. Superficial facial muscles pull the red skin backward along the top of the head and increased blood flow make it redder.

Function: An expanded crown is like a signal flag that announces arousal or excitement.


Bare-skin-expanded

Horizontal-walk-threat

Display:The displaying crane lowers its head and walks back and forth repeatedly in front of an intruder crane. The red skin of the crown is expanded and the tertiary feathers are raised.

Function: Encourages intruder to leave nest territory.

Horizontal-walk-threat

Bustle-up

Display:With the wings held close to the body, the innermost flight feathers are raised, giving the impression of a fluffy bustle at the rear.

Function: Reflects arousal. A component of Strut and Unison-call.

Bustle-up

Feather-tuft-sleeked

Display: When the crane is relaxed, the feathers on the top of the head (behind the bare red skin) and those on neck are slightly fluffed and the crown contracted.

As the crane gradually becomes aroused, the feathers on the top of the head are sleeked.

Function: Sleeking indicates mild arousal.


Feather-tuft sleeked

Pre-Strut & Strut

Display: Crane is stiff with feathers sleeked & crown expanded. In Pre-Strut, crane stands still while in Strut, it turns sideways to another crane and walks with slow measured steps.

Function: Threat display and dance.

Pre-Strut & Strut

Bow

Display: Crane lowers its head, points bill sharply down and arches the neck. Wings can be held close or spread.

Function: Bowing is used during chasing (left photo shows Charging Bow) or for threat, such as when alighting in a group of cranes (right photo).

Ellis calls this display a "Hoover" because of its resemblance to an old-fashioned vacuum cleaner.

Bow

Crouch Threat

Display: The crane lowers briefly to the lie position, sleeks the neck feathers, and partially spreads drooping wings as they touch the ground.

Function: This is a rare high intensity aggressive display, usually by a female.

Crouch Threat

In video opened with the button below, two pairs are competing for a nest territory in early May.

Ruffle-shake/Ruffle-bow

Display: Ruffling with red skin of eh crown expanded reveals arousal in threat or in dancing. Threat Ruffles often include walking with head held low, bowing, and gyrating from side to side. Some observers have reported that this display may be accompanied by a soft moan, almost inaudible in a field situation.

Function: Moderate to high intensity threat.

Ruffle-shake/Ruffle Bow

Bill Spar

Display: Two cranes stand tall, crowns-expanded, face-to-face, vocalizing and stabbing toward each other as did these two bachelors. The display may escalate into mutual Jump-rakes, with feet tearing at the opposing crane.

Function: Bill-sparring may be used for the establishment of a dominance hierarchy in small flocks.

Bill Spar

Bill Down

Function: The crane lowers its head until the bill touches or nearly touches the ground. The crown is expanded and tertiary feathers raised. The posture is held for several seconds.

Cranes may emit a growl/purr during this threat display.

Function: Threatening other cranes.

Bill Down Display

Cower

Display: The crane lowers its head and retracts its neck and may stand still or walk slowly with neck curved down, head held low, and often with feathers of the head and neck fluffed. In the extreme form of Cower, the crane lowers back on its heels to a sit or lie position.

Function: Cowering is a defensive display characteristic of defeated or ill cranes.

Cower                            Drawing from Ellis.

Droop-wing Threat

Display: The crane faces an intruder, spreads its wings wide, lowers them so that the primary feathers almost touch the ground, and advances on a predator. The crown is maximally expanded, showing a prominent flash of red skin.

Function: Chasing intruder from nest territory.

Droop-wing threat

Bill Stab

Display: Neck is coiled tightly back wrists held out. Roy (left) with neck thrust forward, peers up at his target with wings partly spread. Millie (right) is poised to stab. Roy and Millie are shielding twin colts from an attacking Mew Gull.

Function: Defense from predators.
Bill Stab

Running-charge-threat

Display: Th crane stands tall and runs forward with wings flapping and in stabbing posture. In this case, the crane was chasing a mallard duck which was a competitor for grain on the ground.

Function: Chasing other species from personal space.


Running Charge Threat


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We live on 40 acres of permafrost near Fairbanks, Alaska.

For 24 years, Christy Yuncker Happ has faithfully recorded the passing of the seasons in her written journals, still images, and videos.

George Happ is responsible for this website and the Alaska Sandhill Crane Blog.


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Christy Yuncker Happ
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