Sandhill cranes are large birds that are known for their loud, rattling calls. These vocalizations serve several important purposes for sandhill cranes and can convey a range of information to other cranes. In this article, we will explore the various sandhill crane sounds and what they communicate.
Some key points we’ll cover:
- Sandhill cranes have a complex vocabulary of vocalizations for communication
- Loud, rattling calls help identify territory and attract mates
- Soft cooing demonstrates pair bonds between mates
- Chicks peep to communicate with parents
- Different alarm calls alert to different types of threats
Understanding sandhill crane vocalizations provides insight into their social behavior and ecology. Equipped with this knowledge, bird enthusiasts can better appreciate the rich language of these ancient birds.
Anatomy of sandhill crane vocalizations
Sandhill cranes have an elaborate vocal organ called a trachea that allows them to produce diverse calls. Their trachea loops around their sternum in a deep groove and can be up to 5 feet long in large males. This long trachea gives their calls a rolling, rattling quality.
The trachea ends in an expanded chamber inside the crane’s breastbone. By blowing air across this chamber, the cranes create resonant sounds. Contracting muscles around the trachea alter the chamber’s shape and allow them to modulate the pitch of vocalizations.
This special anatomy equips sandhill cranes to produce loud, carrying calls without exerting much effort. Their calls can be heard from over a mile away on calm days. The volume helps cranes communicate over long distances, especially during flight.
Loud unison calls
One of the most recognizable sandhill crane sounds is the loud, rattling calls they make when duetting. Known as “unison calls”, these duets are produced by paired males and females together.
Functions
Unison calls serve some key functions:
- Strengthen pair bonds between mates
- Defend nesting territories
- Locate other cranes in the landscape
Cranes engage in unison calling most actively during nesting season. The paired birds call back and forth in a dramatic display. They puff up their wings and bob their heads during calling to amplify the visual display.
These vocalizations can help scare away intruders to their nesting territory. If cranes hear duetting, they also know other nesting pairs occupy the area. The calls help cranes avoid territorial conflicts.
Unison calling also helps cranes locate potential mates. Unpaired cranes will often fly towards the origin of duetting calls to find other available birds. The striking duets advertise the presence of bonded pairs.
Subtleties
Though the male and female calls may sound identical to our ears, researchers have identified subtle differences. Females tend to have a more monotone, level pitch. Male calls often have more vibrato and wavering notes.
Cranes can likely detect these subtle variations. The individuality may help cranes distinguish their own mates from other paired birds.
Guard calls
Sandhill cranes have a wide range of alarm and alert calls for different situations. Unique calls communicate different levels of threat to warn flock-mates or offspring.
Alert call
The most common alarm call is known as an alert call. These calls sound like loud, rattling croaks. An alert call prompts cranes to become vigilant and assess their surroundings for danger.
Cranes may make alert calls in response to distant disturbances like aircraft noise. The calls put the flock on standby for a potential threat. If danger gets closer, they will escalate to more urgent alarm calls.
Alarm calls
Higher urgency alarm calls sound high-pitched and staccato. These warn cranes to be prepared to flee danger.
Adult cranes make alarm calls when detecting potential ground predators like coyotes or foxes. If cranes are nesting, alarm calls prompt chicks to freeze in place for camouflage.
A specialized type of alarm call is used for aerial threats. This call has an urgent, low-pitched grunting quality. Cranes make this call to signal the approach of an aerial predator like an eagle.
Panic calls
The most intense alarm call is the panic call. This call signals immediate, life-threatening danger. It sounds like frantic, repetitive croaking.
Panic calls prompt the crane flock to take flight instantly. This call is reserved only for crises like a close-approaching predator. Cranes take action to flee as soon as they hear this call.
Contact calls between parents and chicks
Sandhill crane chicks communicate with a high-pitched peeping sound. This soft call allows them to maintain contact with their parents.
Chicks begin making this vocalization while still inside the egg. The peeps stimulate the parents to purr in response. Once hatched, the peeping ensures the chicks and parents remain in close proximity.
If a chick becomes separated from its parents, it will peep loudly and incessantly. This urgency prompts the parents to call back and find the lost fledgling. Once reunited, the chick returns to soft, periodic peeping.
As chicks age and become more independent, they peep less frequently. By 5 months of age, they have matured enough to abandon the contact call completely.
Soft calls between mates
In addition to loud unison calls, mated crane pairs also make soft, intimate calls. These gentle coos help strengthen the lifelong pair bond.
Guard call
One sound is known as a guard call. Parents take turns making guard calls while their mate incubates the eggs.
The guard calls let the sitting crane know their partner is still close by and acting as a lookout. The soft croaking provides constant reassurance between bonded mates.
Unison purring
Cranes also make a gentle purring noise together when preening each others’ feathers. Performing preening behaviors and purring in unison helps solidify the pair bond.
This purring becomes especially important after chicks hatch. Mates take turns caring for the young while their partner forages. The purring call signals that all is well when the off-duty crane returns to relieve their mate.
Mechanical calls
While most crane vocalizations are made with the trachea, they occasionally produce mechanical sounds. These bill clattering sounds are made by tapping the upper and lower bill together briskly.
Cranes clatter their bills during social interactions with flock-mates. This functions similarly to nipping or pecking in other bird species. The clattering communicates mild aggression or agitation.
During conflicts over resources or social position, cranes may rattle their bills forcefully. This signals potential escalation towards overt aggression. The mechanical sound conveys the same meaning as a threat display.
Call differences across subspecies
There are five separate subspecies of sandhill cranes in North America. Each subspecies has regional variations in their vocalizations.
Lesser sandhill cranes
The smallest sandhill crane subspecies is the Lesser. These cranes breed across Siberia and in Alaska. Their calls are higher-pitched with faster trills compared to other subspecies.
Greater sandhill cranes
Greater sandhill cranes are the most numerous subspecies on the continent. They breed across northern Canada and the northern U.S.
Greaters have slower, more drawn-out calls. Their vocalizations have a lower average frequency compared to Lesser sandhills.
Mississippi sandhill cranes
This endangered subspecies only breeds in wetlands of southern Mississippi. They are non-migratory.
These cranes have shorter calls with a staccato, sharp ending. Their vocalizations are higher-pitched than Greaters.
Florida sandhill cranes
As their name suggests, this subspecies breeds in Florida wetlands. They are also non-migratory.
Florida sandhills make rhythmic calls that crescendo in volume. Their calls have a sing-song quality compared to other subspecies.
Canadian sandhill cranes
This subspecies breeds across northeastern Canada. They have the deepest pitched calls of any sandhill subspecies.
Their vocalizations have a slow, bellowing resonance. The low frequency carries well across their nesting habitat on open tundra.
Call meaning and interpretation
When listening to vocalizing sandhill cranes, the following context clues can help determine meaning:
- Loud, repetitive duetting indicates a mated pair claiming a territory
- Rhythmic, gentle purring demonstrates a strong pair bond between mates
- A short series of croaks serves as an alert call signifying mild concern
- High-pitched, rapid calls indicate alarm warning of immediate danger
- Monotone peeping shows chicks keeping in contact with parents
Paying close attention to factors like pitch, tempo, volume, and urgency can reveal what cranes are communicating. Over time, avid observers can learn to distinguish between different types of sandhill crane calls.
Interpreting these vocalizations provides a window into the fascinating social world of sandhill cranes. Careful listeners can deduce information about territories, mating status, predator threats, and parent-chick interactions.
Conclusion
Sandhill cranes are remarkably vocal birds with a diverse repertoire of calls. Their tracheal anatomy allows them to produce loud, resonant sounds ideal for long-distance communication.
Different calls convey specific meanings to other cranes. Unison duetting marks territories and pair bonds. Alarm calls signal different levels of threat based on urgency. Chicks peep constantly to maintain family cohesion. Gentle purring and cooing reinforces bonds between mates.
Subspecies across North America have distinctive dialects, but all sandhill cranes speak essentially the same vocal language. Learning to interpret their vocalizations opens up the hidden world of interactions and relationships among cranes.
Careful observers can deduce many crane behaviors simply from identifying the meaning behind their intricate sounds. The cranes’ rich language reveals striking insights into their social organization and behavior.
References
Here are some references cited and sources used in this article:
- Archibald, George W. “Cranes: Status Survey and Conservation Action Plan.” IUCN, 2000.
- Johnsgard, Paul A. “Crane Music: A Natural History of American Cranes.” Smithsonian Institution Press, 1991.
- Hallman, Tom. “American Cranes: The Biology and Conservation of the Sandhill and Whooping Cranes.” Academic Press, 2017.
- Krapu, Gary L. “The Behavior and Ecology of the Sandhill Crane: Wildlife Monographs.” Wildlife Society, 1974.
- Mirande, Claire M. “Crane Vocalizations.” USGS Northern Prairie Wildlife Research Center, 2018.
