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Discover the Fascinating World of the Common Crane: From Behavior to Demography

The Auckland Islands Merganser, Mergus australis, is a species of sea duck that was once abundant throughout the Auckland Islands of New Zealand. Unfortunately, due to human exploitation and habitat degradation, this species was hunted to extinction in the 20th century.

Today, there is no known population of this bird in the wild, and it remains one of the rarest birds in the world. In this article, we will discuss the identification, plumage, and molts of this unique species to increase awareness of its importance and encourage conservation efforts.

Field Identification:

The Auckland Islands Merganser is a small, slender duck measuring around 40-50 cm in length and weighing only 500 grams. The males are slightly larger than females and have a distinct black head with a green sheen.

The upperparts are dark brown, and the underparts are a creamy-white color with black bars on the flanks. The bill is broad, flattened, and serrated, making it a useful tool for catching fish.

The males have a bright red eye, while the females have a duller reddish-brown eye. Similar Species:

The Auckland Islands Merganser is easily distinguishable from other sea ducks in New Zealand due to its unique bill shape.

However, it can be mistaken for the extinct Lyall’s Merganser, which was also found in the Auckland Islands. The Lyall’s Merganser had a similar body shape, plumage, and bill, but it had a longer crest on its head.

Unfortunately, the Lyall’s Merganser was last seen in 1902, and it is now presumed extinct. Plumages:

The Auckland Islands Merganser has two distinct plumages: breeding and non-breeding.

During the breeding season (September February), the males develop a striking black head with a green sheen, while the females’ head is brown with a white chin. The body plumage is also brighter and bolder during the breeding season.

The non-breeding plumage is duller and more grayish-brown in color, with less distinct markings. Molts:

The Auckland Islands Merganser has two molts per year; a breeding and a non-breeding molt.

During the breeding molt, males and females replace their flight feathers in June and July. This molt is essential for the birds to maintain their ability to fly, escape predators and find food.

During the non-breeding molt, which occurs in January and February, the birds replace their body feathers. This molt is essential to maintain the feather insulation, which keeps the birds warm in the cold waters of the Southern Ocean.


The Auckland Islands Merganser is one of the rarest birds in the world, and its extinction is a tragedy that we cannot afford to ignore. By increasing our knowledge of this species, we can raise awareness of its importance and encourage conservation efforts.

To learn more about this unique species and how you can contribute to its protection, visit the Department of Conservations website and other wildlife organizations. Together we can make a difference and ensure that future generations can appreciate the beauty of the Auckland Islands Merganser.

Systematics History:

The common crane, Grus grus, is a large bird in the crane family, Gruidae. Its systematics history dates back to the 18th century when it was first described by Linnaeus in his Systema Naturae.

Since then, many taxonomists have studied the species and its many subspecies, leading to some changes in its classification. Currently, the common crane is considered to have two subspecies; the Eurasian Grus grus grus and the Asian Grus grus lilfordi.

Geographic Variation:

The common crane has a wide geographical distribution, spanning from Europe to parts of Asia. Due to its large range, it shows substantial geographic variation.

For instance, the size of the birds varies, with those in northern Europe being larger than those in southern Europe. The coloration of the feathers also varies.

Birds in the eastern part of the range tend to be lighter, while those in the western part are darker. Subspecies:

The common crane has two recognized subspecies; the Eurasian Grus grus grus and the Asian Grus grus lilfordi.

Eurasian Grus grus grus: This subspecies is found in Europe, except in the northern and southern parts of the continent. Birds belonging to this subspecies have a brownish-grey head and neck, the upperparts are grey, and the underparts are lighter.

The bill is pink with a black tip. This subspecies is migratory, breeding in northern Europe and wintering in southern Europe and North Africa.

Asian Grus grus lilfordi: This subspecies is found in Asia, from the Ural Mountains to the Pacific Ocean. Birds belonging to this subspecies are slightly darker and smaller than the Eurasian subspecies.

The bill is also shorter and more slender. This subspecies is resident in its range, with some birds moving short distances in response to seasonal changes in food availability.

Related Species:

The common crane belongs to the family Gruidae, which includes 15 genera and 15 species. The closest relatives of the common crane are the sandhill crane (Antigone canadensis) and the demoiselle crane (Anthropoides virgo).

Historical Changes to Distribution:

The common crane has undergone significant changes in its distribution over the years, primarily due to human activities. In the past, the common crane was found in parts of North America, but it went extinct in the region in the 19th century due to habitat loss and hunting.

The species was also nearly lost in Europe during the 19th and 20th centuries, primarily due to habitat loss and hunting. However, in the 20th century, conservation efforts led to the recovery of the common crane population in Europe.

The establishment of protected areas and efforts to restore degraded habitats has helped the species to recover. As a result, the breeding population in Europe has increased from only a few hundred pairs in the 1970s to over 70,000 pairs today.

In Asia, the common crane population has remained stable, despite pressure from habitat loss and hunting. This is thanks to the existence of large protected areas, such as the Yancheng Reserve in China, which provides critical habitat for the species.


The common crane is an iconic bird with a storied history dating back centuries. While its range has been impacted by human activities, conservation efforts have led to significant success in restoring its populations in Europe.

It is critical to continue to protect and restore habitats to ensure that the common crane and other crane species continue to thrive. Habitat:

The common crane is a species that has adapted to a variety of habitats, ranging from forests and grasslands to wetlands and agricultural areas.

However, wetlands are the most critical habitat for the species, which rely on these ecosystems for breeding, feeding, and resting. Breeding: Common cranes prefer wetlands such as bogs, swamps, and fens as breeding habitats.

These wetland habitats tend to support a variety of suitable vegetation types for nesting, including reeds, sedges, and grasses. In addition, wetlands provide ample access to prey such as frogs, insects, and small fish, which are essential for the growth and development of the crane’s young.

Foraging: During the non-breeding season, the common crane feeds on a wide variety of food sources, including grains, seeds, tubers, insects, and small vertebrates. The birds often forage in agricultural areas, such as fields or fallow lands, where they can find food more easily.

In Europe, they also feed on waste grain on farmland during the winter months. Movements and Migration:

The common crane is a migratory species that travels long distances to breed and feed throughout its range.

These movements are closely related to seasonal changes, as the birds seek out breeding and feeding grounds that offer the greatest food availability and access to suitable nesting sites. Breeding migration: In Europe, common cranes begin their northward migration in March and April, returning to their breeding grounds in northern Europe.

They typically use wind currents to aid their flight over long distances. Once they arrive at the breeding grounds, they establish their territories and begin to nest.

Non-breeding migration: After the breeding season is over, common cranes gather in large flocks and begin their southward migration in September and October. They travel in family groups or small flocks, navigating with the help of landmarks, patterns of the sun and stars, and other environmental cues.

The birds use a combination of soaring and flapping flight to travel long distances, resting at suitable stopover sites along the way. During the non-breeding season, common cranes can form large flocks, with up to 50,000 birds coming together in areas where food is abundant.


Conservation of the common crane is an important issue, as the species faces numerous threats related to habitat loss and degradation, hunting, and pollution. Habitat loss, in particular, poses a significant risk to the species, as wetlands continue to be drained, damaged, and transformed for human use.

Climate change, with its associated impacts on wetlands, also presents a significant challenge to the species’ survival. Efforts to conserve the common crane have been successful and ongoing.

Conservation measures include habitat restoration, creation of protected areas, and strict regulation of hunting. The European Union, for example, has implemented a range of conservation measures to protect the species, including the EU Birds Directive, which requires member states to protect habitats critical to bird populations, including wetlands.

Similarly, in China, the government has created many protected areas and wetland reserves to help protect the common crane and its habitat. Conclusion:

The common crane is a species of conservation concern, and it is important to ensure the protection of its habitats and breeding and foraging areas.

The species’ adaptable nature has allowed it to persist in a range of different environments, but ongoing conservation efforts are necessary to ensure its survival. Protecting wetlands, creating protected areas, and regulating hunting and other human activities are all necessary steps to help secure the future of the common crane and other wetland-dependent species.

Diet and Foraging:


The common crane is primarily herbivorous, feeding on a wide range of plants, particularly in the non-breeding season when they rely heavily on agricultural areas for their food. However, during the breeding season, they shift their diet to include a wider range of animal prey.


The common crane feeds on grains such as wheat, maize, and barley, as well as other plant materials like tubers, roots, and berries. In addition, they also forage opportunistically, feeding on insects, small fish, and other small vertebrates, depending on the availability of these food sources.

Metabolism and Temperature Regulation:

Given their large size, the common crane has an impressive metabolism, requiring a lot of energy to move, digest, and thermoregulate. To maintain body temperature, cranes generate heat through metabolic processes, such as shivering.

They also have adaptations to reduce heat loss, such as insulating feathers, which trap warm air close to the body, and the ability to change blood flow to their feet, keeping them warm in cold environments. Sounds and Vocal Behavior:


The common crane is famous for its distinctive bugling call, often heard during migration and the breeding season.

The call is a loud, trumpeting sound, which can be heard over long distances. However, this call is not the only vocalization made by the species; they have a wide range of calls used in different contexts.

Breeding vocalizations: During the breeding season, common cranes use a range of vocalizations to communicate with their mates and defend their territory. These calls include trumpeting, throaty grunts, and other guttural noises.

Alarm calls: Common cranes make alarm calls when they perceive a threat, such as the presence of a predator. Typically, these calls are loud and harsh, and they may be made as a warning to other birds in the area.

Contact calls: When travelling or searching for food, the common crane makes contact calls to stay in touch with other members of the flock. These calls are quieter than the breeding or alarm calls and often involve trills and chirps.


The common crane is a remarkable bird, known not only for its striking appearance but also for its vocalizations, diet, and foraging behavior. As a species with a complex social structure and sophisticated vocal behavior, common cranes have a rich and varied communication system, which they use to navigate their environment, find mates, and protect their young.

Dense wetlands with a variety of plant and animal life are critical habitats for common cranes and must be protected to ensure their continued survival. Behavior:


The common crane is a tall, sleek bird that can move with surprising grace and speed.

They are strong fliers, capable of travelling long distances during migration. On the ground, their long legs allow them to wade through shallow water or run quickly across open fields.

Self Maintenance:

Common cranes are fastidious birds, spending considerable time preening their feathers to keep them in good condition. The birds also take regular baths, often using shallow ponds or puddles to clean their feathers.

Preening and bathing are essential behaviors that help the birds maintain the structural integrity of their feathers over time. Agonistic Behavior:

Common cranes can be aggressive towards other birds, particularly during the breeding season when they are defending their territory.

This agonistic behavior can include threatening postures, vocalizations, and even physical duels. Such conflicts can be dangerous and may result in injury or death.

Sexual Behavior:

During the breeding season, common cranes engage in a variety of courtship behaviors to find a mate. Males will frequently dance, jumping, and flapping their wings.

The dance might also involve a bowing display, with the male bowing his head and bending his legs in front of the female. Breeding:

Common cranes breed once a year, with breeding taking place in the spring and summer months.

These birds are monogamous, meaning that they typically mate for life, although individuals may find new mates if their partners die or disappear. Nesting: Common cranes nest on the ground in wetland habitats, building large, shallow scrapes in the vegetation and lining them with reeds and other plant material.

The female will typically lay two eggs, which are incubated for around 30 days. After hatching, the chicks are cared for by both parents and are fed a diet of insects and other small prey.

Young: The chicks grow quickly, gaining weight at a rate of up to 80 grams a day. They fledge around 60-90 days of age, at which point they can fly and are capable of foraging on their own.

Demography and Populations:

The common crane has varying population sizes across its range. In the western Palearctic, the bird’s population has shown a consistent increase over the past few decades due to extensive conservation measures.

Elsewhere, populations are considered stable, especially in Asia, where the birds have large protected wetlands. In North America, the species was driven to extinction due to habitat loss and hunting.

In the 1970s and 1980s, attempts were made to reintroduce the species, but these were not successful. Due to habitat loss and other threats, such as illegal hunting, the common crane’s population is considered vulnerable, and conservation efforts are ongoing to protect them.


The common crane is a fascinating species with complex behaviors associated with its feeding, breeding, and demography. Their grace in movement, self-maintenance, and display behaviors is a delight to see.

However, the bird remains vulnerable to human-caused impacts, emphasizing the importance of continuing conservation efforts to protect its critical habitats and ensure the survival of this iconic species. The common crane, Grus grus, is a remarkable species that has adapted to a wide range of habitats and environments.

From its feeding and locomotion to its vocalization and agonistic behaviors, the common crane has a complex set of actions that allow it to survive in often hostile circumstances. While the species has faced significant challenges over the years, including habitat loss, hunting, and climate change, there are many ongoing conservation measures that have been implemented to protect the common crane.

Our understanding of this species, including its systematics, movements and migration, diet, and behavior, is critical for protecting it and ensuring its survival. Ultimately, our efforts to conserve this species, protect its habitats, and reduce the threats it faces will have broader implications for the health and safety of our environment and wildlife.

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