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Fauna of Pacific Islands
JOrnitho: I'm making this new topic to discuss the animals living in the Pacific islands. Since there is so many islands in the world, I believe that discussing about them in only one topic would be confusing. So, for the sake of organization, I'll leave the other topic that I did to discuss only the fauna of Atlantic islands. To start this topic, I want to talk about the Easter Island. I believe that it would have an interesting fauna, with a combination of species introduced by the humans here and those from the close Eonesia. For example, the Chilean tinamou (Nothoprocta perdicaria) that was introduced here could have a flightless descendant in the Neocene of the island.
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Биолог: JOrnitho Great! The Easter Island could have interesting fauna due to its isolation from continents. A flightless large ratite-like bird is a good idea!
JOrnitho: I made the description of this bird. For the predator of Easter Island, I was thinking that it could be a large bird of prey, similar to the haast eagle, that came from South America. What do you think? False-nandu (Paranandu pumilus) During the Holocene, the man introduced many species to other continents. Those that were able to survive left descendants in the Neocene. The false-nandu is one of them. This species is a large and flightless descendant of the Chilean tinamou (Nothoprocta perdicaria) which were introduced by the humans in Easter Island. This species inhabits all areas of the Island, being the largest herbivorous animal living on it. As its name says, the false-nandu is similar to the extinct South American rhea. This species stands at 60 to 90 cm and has a length of 110 to 135 cm. The false-nandu is sexually dysmorphic. The males are brown above, barred with blackish colouration, and white below, with a long grey neck and head. Their breast and lower neck sides are chestnut and there is a pale brown wash to the back. They also have a black crest that is long, thin, and straight. The breast and neck of the female are buff, with brown and pale colouration over the rest of the plumage, also lacking the crests. Immature birds resemble females. Differently from many flightless birds, the false-nandu maintained its wings. However, they are small and can't be used to fly. Their wing feathers were also modified, with the males having fluffy pure white primaries and secondaries, while in the females they are pale grey. Such fluffy feathers aren’t useful to fly, being used by the males for courtship. The tail is very short. They have a gray and curved bill. The legs are pinkish red and strong, allowing them to run. The feet have long claws, which are used both to excavate the ground and to defend against a possible predator, or to be used in territorial fights. The false-nandu eats seeds, berries, leaves, fruits and small animals. Mostly of the elements in their diet are collected in low branches or in the ground. The fruits and seeds are usually those that fell from the trees. These birds are solitary during most of the year, but in the summer, when the mating season starts, they form pairs. The male will construct a rough nest in a semi-sheltered hollow on the ground in the center of his territory, using bark, grass, sticks and leaves to line it. Then, he will start to vocalize, as an invitation for the females. They will enter the male’s territory and follow his calls until reaching the place of the nest. Once he sees her, the male will flap his wings and sit on the nest with wings open, allowing the female to see his white feathers here. She will proceed to circle him and the nest, pulling her neck back while puffing out the feathers and flapping her wings. If she approves the male, the female will emit a low call to invite him to join her. Then, he will move closer, stretching his neck and erecting his feathers and will start to circle the nest with her. If another female appears, the incumbent female will try to repel them, usually by chasing and kicking. The pair mate every day or two, and every second or third day the female lays one of a clutch of 6 to 15 very large, thick-shelled, green eggs. The eggs are incubated only by the male. During this period he does not eat, drink, or defecate, and stands only to turn the eggs, which he does about ten times a day. The incubation period lasts 50 days, during this period the female stays and defends the nest. When the chicks start hatching, she returns to her territory. Newly hatched chicks are active and can leave the nest within a few days of hatching; they will stay with the father until 6 months, when they will disperse to find their own territory. The lifespan of the false-nandu is 28 years.
Биолог: JOrnitho Another "false" creature, ha-ha But a good one!
JOrnitho: Биолог пишет: Another "false" creature, ha-ha But a good one! Yes! Hahahaha I was going to name it as giant tinamou, but there is already a bird with this name, so I went to the second name that made sense.
Биолог: JOrnitho It's OK, don't worry
JOrnitho: I was thinking that the largest predator of the island could be a bird of prey, like the extinct haast eagle of New Zealand. Its ancestor could be a descendant of the cinereous harrier (Circus cinereus) that moved from South American to here. Finding a habitat lacking even owls, these birds could have originated two species: the large diurnal predator and one that was owl-like that hunts during the night.
Биолог: JOrnitho Good ideas! But two different descendants of the same ancestor on an island (a limited habitat) seem unlikely: it can hardly develop a population so rich that it can split in two on the same island.
JOrnitho: Биолог пишет: But two different descendants of the same ancestor on an island (a limited habitat) seem unlikely In this case, I think that the large predator could be a descendant of the buzzar-eagle that reached the island coming from South America. With the presence of such large predator, the harrier would be forced to adapt to other niche. In this case that of an owl, feeding during the night by hunting the descendants of Polynesian rats. Would bats be capable to reach the islands? If not, maybe a nocturnal species of passerine could have settled here, with the ancestor coming from South America or from Eonesia.
Биолог: JOrnitho a descendant of the buzzar-eagle Looks good, but note that the Haast's eagle had large prey - the moa. Your eagle has two ways: first is to become conspicuously smaller, while the second is to provide it with large prey. The second one needs a much larger island (near the size of New Zealand or at least New Caledonia). The size of the island (determining the limits of habitat and resources) is crucial here. Would bats be capable to reach the islands? Why not? They are present on New Zealand, which is not so far. But the new island for them must prodvide a diet, either vegetarian or predatory, sufficient for a constant population.
JOrnitho: Биолог пишет: but note that the Haast's eagle had large prey - the moa. Their main prey would be the false-nandu, which is a large bird. Of course, this eagle would not have same size of a haast-eagle, but would be strong enough to kill the false-nandu.
JOrnitho: Биолог пишет: But the new island for them must prodvide a diet, either vegetarian or predatory, sufficient for a constant population. I think that after the extinction of the humans, Easter Island would be able to recover some forests and there would insects and fruits to feed the bats. I also think that passerines that appear on this island would be close related to Eonesia.
Биолог: JOrnitho Their main prey would be the false-nandu, which is a large bird. Of course, this eagle would not have same size of a haast-eagle, but would be strong enough to kill the false-nandu. OK. after the extinction of the humans, Easter Island would be able to recover some forests Insectivorous or small predatory bats seem the most likely.
JOrnitho: Биолог пишет: Insectivorous or small predatory bats seem the most likely. I agree. I think that they would be close related to those of South America rather than of Asia. The fruits and nectar in the island would be consumed by birds. Would be interesting if one of these birds is a descendant of a South American tanager (Thraupidae)? This ancestor could generate a frugivorous and nectarivorous genera.
Биолог: JOrnitho they would be close related to those of South America rather than of Asia OK. The fruits and nectar in the island would be consumed by birds. Would be interesting if one of these birds is a descendant of a South American tanager (Thraupidae) Quite plausible, why not? Tanagers are beautiful!
JOrnitho: Биолог пишет: Tanagers are beautiful! Yes! They are my favourite group of Neotropical birds. I hope to be able to work with them when I do my Master degree some day.
Биолог: JOrnitho when I do my Master degree some day I'm sure you will! Good luck!
JOrnitho: I finished the description for the largest predator of Easter Island, with some alterations from the original idea. Rapa Nui caracara (Sociophalco insularis) The human actions during the Holocene caused the collapse of many ecosystems. Easter Island was one of these cases. This place was completely deforested and many of its endemic species perished. However, with the arrival of the Neocene it was able to recover, developing a new endemic fauna. One of the species living here is the Rapa Nui caracara, a descendant of the chimango caracara (Mivalgo chimango) that arrived in the island coming from South America and evolved here to this new species. The Rapa Nui caracara is larger than their ancestor, having a total length of 65 cm and a wingspan of 132 cm. The female is larger than the male. This species has a mantle and back with cinnamon brown feathers. Neck, chest, abdomen and belly are dark brown, while the head is pale. The tail is light brown with a white terminal band. The legs are orange in the male and light yellow in the female and hatchlings. Their claws are long and sharp, being capable of inflicting deep wounds. The wings are quite broad, an adaptation that increases maneuverability in forested areas of their habitat. Their shoulders are chestnut and dark grey primaries and secondaries, with white tips. This species is the largest predator of Easter Island, hunting even the false-nandu. While most raptors are solitary, only coming together for breeding and migration, the Rapa Nui caracara will hunt in cooperative groups of two to six. When hunting, all the caracaras spread around the prey and one bird starts chasing it out. To bring the false-nandu down, these birds will take turns to attack the prey, causing several wounds until the false-nandu bleeds to death. These birds will often chase prey on foot, and are quite fast on the ground and their long legs are adapted for this. These birds are monogamous, forming pairs that remain together for the rest of their lives. They nest in the top of trees. It’s made of sticks, plant roots, and stems, and are often lined with leaves, moss, bark and plant roots. They are built mainly by the female. There are usually two white to blueish white eggs sometimes with a speckling of pale brown or gray. The nestlings start out light buff, but in five to six days turn a rich brown. The incubation lasts for 36 days. The young begin to explore outside the nest at 38 days, and fledge at 45 to 50 days. The female sometimes breeds two or three times in a year. Young stay with their parents for up to three years, helping to raise later broods. They reach sexual maturity with 5 years and have a lifespan of 27 years.
Биолог: JOrnitho Good one!
Биолог: JOrnitho, we've made a record of your idea about the Easter Island for a future potential chapter. It can be seen in our Collection of Potential Chapter Ideas topic, #53 in the starting post of the topic.
медведь: Good one, but I see a bit of controversy in that its claws are sharp yet it runs pretty much on the ground. Won´t the claws become blunt from running?
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