Western corella facts for kids
Quick facts for kids Western corella |
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| At Blackpool Zoo, England | |
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| Genus: |
Cacatua
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| Species: |
pastinator
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The western corella (Cacatua pastinator), also known as the western long-billed corella, is a type of white cockatoo. These birds are found only in south-western Australia.
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Understanding the Western Corella
Cockatoos are a special group of parrots. They are different from other parrots because they have a crest (feathers on their head that can be raised), and their feathers don't have a certain green color. They also have yellow down when they are born.
The western corella has two main types, called subspecies. These are Butler's corella (Cacatua pastinator butleri) and Muir's corella (Cacatua pastinator pastinator). They live in different areas and are separated from each other.
One group lives in the northern wheat-belt region of Southwest Australia. The other group, which has slightly larger birds, lives in the far southwest of Western Australia. The northern birds are generally smaller than the southern ones. This suggests that these two groups might have been connected a long time ago.
The common names for this bird are western corella and western long-billed corella. In the Noongar language, they are called manatj and manyte. The word manatj is sometimes used for the Western Australian Police. This is because the birds are known for being "noisy and inquisitive."
What Does a Western Corella Look Like?
The western corella is a white cockatoo. Its upper wings are completely white, and the underside of its wings is pale yellow. It has a white crest that can stand up. Around its eyes, the skin is blue-grey. Between its eyes and beak, there's a crimson-pink color, and a small pink patch is on its throat. It also has a long, pointed beak.
It's hard to tell male and female western corellas apart just by looking at them. Their eye color and feathers are similar. However, male birds are usually larger than females and have a deeper alarm call.
This cockatoo is a medium-sized, strong bird with wide, rounded wings and a short tail. Its crest is usually flat. Muir's Corella adults are about 43 to 48 centimeters (17-19 inches) long and weigh between 560 and 815 grams (20-29 ounces). Butler's Corella, the northern type, is smaller. Adults are 40 to 48 centimeters (16-19 inches) long and weigh up to 700 grams (25 ounces). Their beak is a dull grey-white, and their legs are dark grey. The tip of their upper beak is long. Their lower feathers often look dirty because they feed on the ground and dig for food.
Where Do Western Corellas Live?
The two groups of western corellas live in different parts of south-west Western Australia. The northern group, Butler's corella, lives in the northern and central wheatbelt. The southern group, Muir's corella, lives in the very southwest.
The northern population has about 5,000 to 10,000 birds. The southern population has fewer birds, around 1,000.
Long ago, when people first settled in Western Australia, these birds were very common. They were seen in large groups during the 1800s.
Western corellas live in rolling hills where most of the natural plants have been cleared for farming wheat and sheep. The remaining woodlands and shrubs are found in small, separate patches or along roads. Important places for them include large eucalyptus trees and other trees, whether alive or dead. These trees can be in forests, standing alone in fields, or along roadsides. They especially like trees like marri, jarrah, moitch, yate, and moonah.
Western corellas move around in the central wheatbelt of Western Australia. Their movements depend on their age. After young birds leave the nest in spring, family groups join up with other young birds. They then move to places where they can find food in the summer. The young birds are fed by their parents for about a month. Then, the parents go back to their breeding areas between January and March. The young birds don't return until May or June. Most birds like to return to the area where they were born, even if they've been away for a few years.
Challenges and Conservation Efforts
Sometimes, cockatoos form large groups and use resources that humans provide, like crops. This has caused problems with farmers. In the late 1800s and early 1900s, many western corellas were shot or poisoned because they ate cereal crops. This likely caused a fast drop in their numbers and where they lived.
By the 1920s, only two groups of western corellas were left. The southern group, Muir's corella, had very few birds, only about 100 in 1921. This group continued to shrink until the 1940s. However, the northern group has grown and spread eastward since the 1930s, especially as more land was used for farming.
Since the early 1900s, the number of both subspecies has slowly increased. In the last 50 years, farmers have stopped persecuting them as much. Also, these birds are good at adapting to new places. This has allowed them to spread into the Western Australia wheatbelt, where they find plenty of food and water.
Butler's corella is not currently a species of concern for conservation. However, Muir's corella is listed as a "Specially Protected Fauna – Schedule 4." It is also considered "Endangered" by the Western Australian Threatened Species Scientific Committee and "Vulnerable" under a national law called the Commonwealth Environment Protection and Biodiversity Conservation Act 1999.
Here are some things that threaten Muir's corella:
- Being illegally shot and poisoned.
- Losing their natural homes (habitat).
- Changes in how land is used.
- Not enough hollows in trees for nesting.
- Other animals, like wild honeybees, competing for nest hollows and sometimes killing the birds.
To help Muir's corella, here are some recovery actions:
- Find money to pay for future conservation work.
- Count the birds, find out where they live, and track their movements.
- Figure out what affects their breeding success and manage nest hollows to help more young birds survive.
- Map important feeding and breeding areas and create plans to manage them.
- Plant more trees that can provide hollows for nests.
- Find ways to remove wild honeybees from nesting hollows.
- Create information kits to help stop illegal killing and share them with the public.
- Stop other types of corellas from spreading into south-west Western Australia if they are not native to the area.
- Collect DNA samples to learn more about the different western corella subspecies.
Western Corella Behavior
Western corellas are well-known birds in Western Australia. In summer, you can often see them in large, noisy groups of up to 700 birds. These groups move around, staying in one place for days or weeks to feed. Young birds and breeding pairs can travel up to 10 kilometers (6 miles) from their nest trees to find food. Breeding pairs usually stay together, but about 15% of them do "divorce" and find new partners.
Corella groups are often very loud. You can hear their calls from far away. Their call is a high-pitched, wavering sound that can seem eerie or ghostly. They also make various shrieks and squeaky, chattering noises.
Reproduction and Life Cycle
Western corellas build their nests in hollows inside large eucalyptus trees. Sometimes, they use other trees like paperbarks. They prefer large, live or dead eucalyptus trees, especially Marri and Jarrah. These trees are found in remaining woodlands, forests, along roads, or as single trees in fields. Corellas like to nest in trees with open tops and some dead branches, but they will use dead trees if there's a healthy tree nearby for shelter. They often nest close to other pairs and might use the same nest hollow for up to six seasons.
Nesting hollows are usually 6 to 20 meters (20-66 feet) above the ground. Their entrances are 15 to 40 centimeters (6-16 inches) wide and face away from floods and strong winds during breeding season. The hollow itself is about 0.5 to 2 meters (1.6-6.6 feet) deep. The birds remove bark around the entrance. They lay their eggs on rotten wood or wood dust at the bottom of the hollow.
Western corellas start laying eggs in August and continue until October. Most eggs are laid in late August and early September. A female can lay one to four eggs, but usually lays three. The eggs are about 41.8 millimeters (1.6 inches) long and 30.5 millimeters (1.2 inches) wide. A fresh egg weighs about 21.6 grams (0.76 ounces). As the season goes on, females tend to lay fewer eggs. This suggests that some females are better at finding food, so they breed earlier and lay more eggs.
Western corellas form pairs that stay together to breed and raise their young. The male and female stay together during daily and seasonal movements, except when one partner is nesting. The nest tree is the center of their activities when they are in the breeding area. Incubation (keeping the eggs warm) starts when the second egg is laid. Both parents share this duty, and the eggs hatch in 22 to 23 days. It's common for the youngest chick to die within two weeks.
Western corellas have a good breeding success rate. About 67.2% of their eggs hatch. On average, they raise about 1.9 chicks per nest. The number of chicks that leave the nest and become independent increases with the number of eggs laid and chicks hatched.
Young birds stay in the nest for 53 to 67 days. For the first week, one parent spends almost all their time brooding (sitting on) the chicks. This quickly decreases and stops when the chicks are about 25 days old. The chicks become independent after about three months.
Western corellas have some of the highest survival rates among birds. About 77.4% of chicks survive to become independent at three months old. About 50.8% survive to one year. For females, about 23.2% survive to breed at three years old, 13.6% at four years, and only 9% at five years. Males also start breeding at five years old, by which time only about 9% of the original group are still alive.
Things that cause birds to die, especially young ones, include being hunted by falcons or other birds of prey, being hit by cars, or being shot or poisoned by humans. We don't know how long wild birds live, but corellas in zoos can live up to 26 years.
What Do Western Corellas Eat?
Western corellas have benefited a lot from the food available due to farming. However, using these food sources has also led to them being hunted, which has hurt their population. Like all parrots, corellas mostly eat seeds. But they can change their diet depending on where they live and what food is available.
From December to April, western corellas eat wheat grains and native seeds. From May to November, their main food is bulbs and corms, which they dig out of the ground with their long beaks. A common plant they eat is Romulea rosea (Onion Grass). In late winter and spring, insect larvae are an important part of their diet for both adults and young birds. They remove the hard outer shell and insides of the larvae before feeding them to their young. Most feeding happens in large open areas like pastures and crops. Corellas have also been seen feeding in cattle feedlots. They have been observed eating Marri seeds by holding the seed capsule and tipping the seed into their mouth. They also eat wheat by bending the seed heads down to pull out the grains.
Western Corellas as Pets
Western corellas can learn to mimic sounds clearly. Like other cockatoos, they form strong bonds with their owners. However, they might be aggressive towards other birds if kept in an aviary. They are not as common as pets as other corella types.
The Noongar people used the feathers of this bird to decorate headbands or put them in their hair. It is believed that the Indigenous people of Southwest Australia ate these birds. English settlers also reported that the birds were good to eat.
Status and Protection
Even though they are not very common, western corellas have spread to new areas in recent years. Because of this, BirdLife International lists them as a species of "least concern" for conservation.
However, the specific type called Muir's corella is quite rare, with only about 3,000 birds left. It is considered "Vulnerable" at a national level.
See also
In Spanish: Cacatúa cavadora para niños
