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10 Fascinating Facts About the Australasian Gannet

The Australasian Gannet, scientific name Morus serrator, is a large seabird that inhabits the oceanic waters of New Zealand and southern Australia. These birds are known for their unique appearance, intricate social life, and remarkable flying abilities.

In this article, we will delve into the identification, plumages, and molts of these magnificent birds.

Identification

The Australasian Gannet is a large seabird with a distinctive appearance that sets it apart from other species. These birds have a white head, neck, and body, while their wings are black.

Their eye color is a pale blue-grey, while their bill is a light blue-grey color with distinctive dark markings around its base. The wingspan of these birds is around six feet, making them incredibly agile in the air.

Field

Identification

One of the best ways to identify the Australasian Gannet in the field is to look for their plumage and bill. These birds have a white body, black wings, and a pale blue-grey eye color.

Their bill is also a unique feature, as it is light blue-grey with dark markings around the base.

Similar Species

To the untrained eye, the Australasian Gannet may be confused with other species of gannets such as the Cape Gannet or the Northern Gannet. However, the Cape Gannet is found in South Africa and has a black face instead of a white one.

The Northern Gannet has a yellow tinge to its head and neck and a stronger bill compared to the Australasian Gannet.

Plumages

The Australasian Gannet has several plumages that vary depending on age and gender. Juvenile birds are predominantly brown with pale head and neck feathers.

As they mature, their feathers become white, and their wings turn black. Once they reach adulthood, the gannets transition to a pure white color with black wings.

Molts

The Australasian Gannet undergoes a significant molt once a year, where they replace all their feathers in a period of three months. This process is crucial as it helps them maintain their waterproof feathers and remain aerodynamic in the air.

During the molting period, these birds are grounded and cannot fly, which makes them vulnerable to predators. In conclusion, the Australasian Gannet is an amazing seabird found in New Zealand and southern Australia, known for its distinctive appearance, social life, and remarkable flying abilities.

Their unique plumages and molts make them easily identifiable while making them susceptible to predators during molting periods. Understanding their identity, plumages, and molts can help birders identify these birds while also appreciating their beauty.

Systematics History

The Australasian Gannet, scientific name Morus serrator, has a rich history in terms of its classification under the animal kingdom. It was initially classified as a member of the genus Diomedea in 1789 but was later moved into the genus Sula in 1829.

It was finally classified as a member of the genus Morus in 1840. The genus name Morus translates to ‘fool’ in Latin, which is a reference to their clumsiness on land.

Geographic Variation

The Australasian Gannet is found in the oceanic waters of New Zealand and southern Australia. The species exhibits some geographic variation based on location, with differences in size, coloration, and bill size being the key parameters.

Birds from New Zealand are generally larger and have a more extended bill than those from Victoria, Australia.

Subspecies

The Australasian Gannet has two subspecies – the Eastern Australasian Gannet (Morus serrator suttoni) and the Northern Australasian Gannet (Morus serrator tasmani). The Eastern Australasian Gannet is found on islands off the eastern coast of Australia, while the Northern Australasian Gannet is found in the Tasman Sea between Australia and New Zealand.

The Eastern Australasian Gannet has darker markings on the bill and face, while the Northern Australasian Gannet has more extensive black markings on its bill and a shorter neck. There are also differences in terms of vocalizations and breeding habits between the two subspecies.

Related Species

The Australasian Gannet belongs to the family Sulidae, which comprises the gannets and boobies. There are ten species in this family, with the Australasian Gannet being the most widespread and one of the largest members of the family.

Other members include the Cape Gannet, the Northern Gannet, the Brown Booby and the Red-footed Booby.

Historical Changes to Distribution

Historically, the Australasian Gannet’s range extended from the eastern coast of Australia to the Chatham Islands and out to the Tasman Sea. However, as human impact on the environment increased, the species faced a decline in population due to hunting, egg harvesting, and the introduction of non-native predators.

During the late 19th century, hunting for gannet feathers that were used to decorate ladies’ hats, led to a significant decline in population. Fortunately, the conservation efforts in the early 20th century helped protect these birds, leading to an increase in their population.

Another significant change in the distribution of the Australasian Gannet was caused by the introduction of the Pacific rat (Rattus exulans) to New Zealand. The rat preys on the eggs and chicks of the gannets, leading to a significant decline in their population in areas where rats are present.

Human activity has also directly impacted the distribution of these birds. For example, the construction of a breakwater at Point Danger in Torquay, Victoria, led to the displacement of the local gannet colony in the 1950s.

This led to the formation of a new colony at nearby Bonney’s Coward, which still exists today. In conclusion, the Australasian Gannet has a rich history in the animal kingdom, with its classification undergoing several changes over the years.

The species exhibits some geographic variation based on location, and there are two subspecies. The conservation efforts in the early 20th century helped protect these birds, leading to an increase in their population.

Human activity has also impacted the distribution of these birds, where the introduction of non-native predators or the construction of infrastructure has caused changes in their habitat. Understanding the history of Australasian Gannet’s distribution can help with ongoing conservation efforts to protect these birds.

Habitat

The Australasian Gannet has a unique habitat that is restricted to offshore islands, rocky coastlines, and open ocean waters. These birds breed in large colonies on offshore islands around New Zealand and southern Australia.

They prefer nesting on tall cliffs and rocky outcrops, where their nests can be at a safe distance from potential predators. During the non-breeding season, the Australasian Gannet moves out to sea, where it feeds on schools of small fish.

These birds are known for their exceptional aerial abilities, and they feed by diving from heights of up to 30 meters to catch their prey. They mostly hunt fish such as pilchards, mackerel, and squid, which are abundant in the waters around New Zealand and southern Australia.

Movements and Migration

The Australasian Gannet is a non-migratory bird, and most of the population remains within their breeding territories throughout the year. After breeding, they move out to sea, where they feed on the abundant fish populations in the waters around New Zealand and southern Australia.

During the feeding season, the Australasian Gannet can cover vast distances, with some birds venturing as far as 1,200km from their breeding grounds in search of food. This species has a high level of site fidelity, ensuring that they return to the same breeding territory year after year.

Juvenile birds are known to disperse in search of new breeding grounds, but this movement is not a migratory one. They may fly long distances, but they are not leaving for a specific seasonal period.

Once these birds find a suitable breeding site, they tend to stay there for the remainder of their life. The only time that the Australasian Gannet undertakes a migratory journey is during the molting period.

They remain grounded for up to three months, while they replace their feathers. As they cannot hunt during this time, they undertake a short migration to areas with a more abundant food source to ensure that they remain healthy.

Some of these birds may migrate as far as Tasmania or the east coast of Australia during this period to access different food sources. Once the molting process is complete, they return to their breeding territories.

In conclusion, the Australasian Gannet has a unique habitat, which is restricted to offshore islands, rocky coastlines, and open ocean waters. They stay within their breeding territories throughout the year, with only juvenile birds dispersing in search of new breeding grounds.

During the non-breeding season, these birds move out to sea to feed on abundant fish populations. Their extensive foraging trips allow them to cover vast distances while remaining site faithful.

The only migratory journey these birds undertake is during the molting process, where they ensure that they have adequate food sources before the process. Understanding the movements and migration patterns of these birds can help with ongoing conservation efforts to protect these magnificent birds.

Diet and Foraging

Feeding

The Australasian Gannet is primarily a fish eater, catching its prey by diving from heights of up to 30 meters at high speeds of up to 160km per hour. They have a unique technique for hunting; they will swim and propel themselves to depths of up to 20 meters underwater to catch their prey.

These birds can also skim their prey from the ocean’s surface, which gives them the advantage of targeting smaller prey. They have an excellent binocular vision that allows them to locate prey from up to 30 meters above the water.

Diet

The diet of the Australasian Gannet varies depending on location and season. They feed mainly on fish that are abundant in the waters around New Zealand and southern Australia.

Their diet consists mainly of anchovies, pilchards, mackerel, and squid. However, they have been known to also eat cuttlefish and even smaller species of shark when opportunity presents.

The type of fish consumed depends on their location and season, with more variability in their diet during the non-breeding season, where they have to cover greater distances to find food.

Metabolism and Temperature Regulation

The gannet has unique adaptations that help them regulate their body temperature and metabolism during extended periods at sea. These birds have a large body mass that allows them excellent thermal inertia, meaning they can regulate their body temperature efficiently.

They also have a specialized gland above their eyes that excretes excess salt intake, which is important for maintaining their osmotic balance.

Sounds and Vocal Behavior

Vocalization

Australasian Gannets are generally silent at breeding colonies, except for occasional vocalizations during courtship or from chicks begging for food. They have a range of vocalizations, including honks, booms, and cackles, which they use for communication.

Their honking calls are used to locate their mate or offspring, while booms are used as part of courtship displays. The cackles, which are high-pitched calls, are used as contact calls between mated pairs.

The vocalizations of these birds are critical to their social structure and communication, particularly during courtship and when re-establishing bonds after long periods at sea. In conclusion, the Australasian Gannet has a unique feeding strategy and diet, specializing in fish such as mackerel, anchovies, pilchards, and squid, which are abundant in the waters around New Zealand and southern Australia.

Adaptations in metabolism and temperature regulation allow them to thrive during long periods at sea, while their vocalizations play a critical role in their social structure and communication. Understanding the feeding behavior, diet, and vocalizations of Australasian Gannets can help with ongoing conservation efforts to protect these magnificent birds.

Behavior

Locomotion

The Australasian Gannet is an excellent flier, utilizing a combination of flapping and gliding to navigate the air currents. They have a wingspan of up to six feet, which gives them excellent aerodynamic efficiency.

These birds are also powerful swimmers and divers, using their wings to swim and propel themselves underwater in search of prey.

Self-Maintenance

Australasian Gannets exhibit a unique behavior called “piping,” where they rub their bills together to clean and maintain their feathers. They do this to remove any debris or dirt that may have accumulated on their feathers during feeding or molting.

They also preen their feathers to ensure that they are correctly aligned, waterproofed and clean.

Agonictic Behavior

Agonistic behavior is common among gannets, particularly during the breeding season. These birds are fiercely territorial and will aggressively defend their nests from other gannets.

They use a range of behaviors to defend their territory, including loud vocalizations, aggressive posturing, and physical aggression.

Sexual Behavior

The Australasian Gannet has a complex social structure during the breeding season. These birds form monogamous pairs at the beginning of the breeding season, with the male gifting the female with twigs and feathers as part of the courtship display.

Once paired, these birds engage in courtship displays that include head-bobbing, stretches, and bill-snapping. During the breeding season, males defend their territory while the female is responsible for incubating the eggs and caring for the chicks.

Both parents are responsible for feeding the chicks, which rely on a regurgitated fish for nourishment.

Breeding

The breeding season for the Australasian Gannet occurs between September and May. They breed in large colonies on offshore islands around New Zealand and southern Australia, where they prefer nesting on tall cliffs and rocky outcrops.

The female gannet lays one egg per year, which is incubated for approximately 45 days. Once hatched, the chick is fed regurgitated fish by both parents for a period of approximately 90 days until it fledges.

During this time, the parents remain on their breeding territories, tending to the chick and protecting their nest.

Demography and Populations

The Australasian Gannet was once at risk of extinction due to hunting and habitat destruction. However, conservation efforts in the early 20th century helped protect these birds, leading to an increase in their population.

The population of the Australasian gannet is currently healthy and stable, with an estimated population of approximately 100,000 birds. The population trends are monitored by the Department of Conservation in New Zealand and the Australian Government to ensure that they remain protected.

In conclusion, the Australasian Gannet exhibits unique behaviors, including excellent flying, diving, and swimming abilities, as well as complex social behaviors during the breeding season. Conservation efforts have helped protect the population of this bird, and they remain stable and healthy.

Understanding the behavior and breeding patterns of the Australasian Gannet can help guide ongoing conservation efforts to ensure that these birds remain protected. The Australasian Gannet is a remarkable seabird, with its unique physical and behavioral qualities.

This article has covered several aspects of the bird, from its identification and habitat to behavior, breeding, and population. Understanding the feeding behavior, diet, and vocalizations of Australasian Gannets can help with ongoing conservation efforts to protect these magnificent birds.

The significance of understanding their behavior and ecology is in ensuring that conservation practices are carried out, which strive to achieve a sustainable balance between the activities of humans, the environment, and the well-being of these amazing seabirds.

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