The fluttering shearwater (Puffinus gavia ) is a species of seabird in the family Procellariidae. It is endemic to New Zealand and migrates to Australia and the Solomon Islands. Its natural habitats are open seas and rocky shores. It has been known as Forster's shearwater in the past.
A piscivore is a carnivorous animal that eats primarily fish. Piscivorous is equivalent to the Greek-derived word ichthyophagous. Fish were the die...
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TerrestrialTerrestrial animals are animals that live predominantly or entirely on land (e.g., cats, ants, snails), as compared with aquatic animals, which liv...
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CongregatoryCongregatory animals tend to gather in large numbers in specific areas as breeding colonies, for feeding, or for resting.
Oviparous animals are female animals that lay their eggs, with little or no other embryonic development within the mother. This is the reproductive...
Precocial species are those in which the young are relatively mature and mobile from the moment of birth or hatching. Precocial species are normall...
Soaring birds can maintain flight without wing flapping, using rising air currents. Many gliding birds are able to "lock" their extended wings by m...
Seabirds (also known as marine birds) are birds that are adapted to life within the marine environment. While seabirds vary greatly in lifestyle, b...
A burrow is a hole or tunnel excavated into the ground by an animal to create a space suitable for habitation, temporary refuge, or as a byproduct ...
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MigratingAnimal migration is the relatively long-distance movement of individual animals, usually on a seasonal basis. It is the most common form of migrati...
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starts withA medium to small-sized shearwater with dark-brown-and-white colour in body. The upper parts, including neck, wings and tail, are uniformly dark brown. Grey-brown colour in face and neck gradually fading into white below the eye. Under body, from chin to the under-tail, is white except for a dark thigh patch that can be seen in flight. Bottom wing commonly white while axillary area is covered in grey-brown fur. Under light conditions, the appearance can changed. Fluttering shearwater has pinkish-brown legs and feet with bark webs, feet extend beyond the tail in flight. The bill is long and thin with dark colour. The tail is fan-shaped and short in flight and it has mixed colour – dark brown and white.
Moult start from late January and the dark upper surfaces fade to mid-brown quickly. The colour of birds near the stage of moult (February to April) is pale rusty brown and they appear ragged at this stage. Their voice is unusual and disjointed: ka-hek-ka-hek-ka-hek and usually made in flight. Their flight pattern is somewhat determined, low and fast. Rapid spurts of wing-beating interspersed by gliding.
The average body mass of females is 302g while males is 243g. Their eggs are pure white and oval. The young birds have the same colour as adult from the nest, but with lighter color in the margin of wing-coverts. Nestlings have very thick slate-coloured soft feathers on the upper and white down on the under.
Fluttering shearwaters breed on coastal islands throughout New Zealand, with large populations on islands throughout the north-east North Island, such as the Alderman Islands, Moturoa Island, Bream Islands, north-west Chicken islands, Mercury Islands, Motuharakeke Island (Cavalli Islands), as well as islands throughout the Marlborough Sounds / Cook Strait region of the South Island, with a majority of these offshore islands within 40 km of the mainland.
The habitats of fluttering shearwater are marine and terrestrial habitats, including coastal and marine areas, scrubland and forest. They are most commonly found in subtropical waters and warm water (24 ℃) of intermediate to high salinity (35%). Common on inshore areas that are easy to enter harbours, inlets, bays and straits. They usually select stony, scrub-covered slopes near the peak, as well as cracks and holes in the rock that far from the top of water to breed, which is benefit for taking off.
In the post-breeding season, many members of the colonies migrate to parts of eastern and south-eastern Australia. However, it is suspected that it is only the juveniles that take part in this migration, with the adults remaining within New Zealand and staying within a relatively close proximity to the colonies. They only breed in New Zealand.
Fluttering shearwaters have a habit of fluttering their wings quickly and beat the feet when they fly away from the sea. A large group of fluttering shearwaters gather together and sit on the water in rafts through the months of mid-December, January and February. Sometimes, rafts will form just near the coastline.
The fluttering shearwater's diet consists mostly of schooling fish (such as pilchards, trevally, mackerel, pilchards, sprats, etc.), small pelagic crustacea(krill etc.) and squids. This prey is caught through two methods, either surface seizing and pursuit diving. The action of marine currents often concentrates large quantities of prey, such as crustacean, krill and schooling fish, within a close distance to the surface of the water. Allowing the shearwater to simultaneously swim atop the water whilst having their head submerged underwater, in an attempt to catch prey.
Pursuit diving is the other form of predation used by the fluttering shearwater, as it provides a greater area in which the shearwater is able to feed, in comparison to that of surface seizing. Shearwaters are able to chase their prey below the water level through the use of their wings, using the wings to propel them underwater in an attempt to chase their prey. Many members of the genus Puffinus have evolved to have heavier wing loadings in order to aid them in pursuing prey to greater depths underneath the water.
Surprisingly, very little is known about the breeding biology and phenology of fluttering shearwaters. However, it is known that fluttering shearwaters, like most birds, are monogamous in that they breed with one mate throughout their life. Fluttering shearwaters start to breed when 4–10 years old and breeding season date August and to January. The type of nest is burrow and the nest chamber is made of dead leaves, grass, feathers and shoots. Their burrows are comparatively shallow and they usually built burrows in fragile soils, so if people move around their breeding areas, burrows are easily destroyed. To protect them, access should be strictly restricted.
Like all birds, fluttering shearwaters breed via a process known as true oviparity. With both sexes containing their own sexual reproductive systems and once a female and a male are ready to mate, their reproductive organs, ovaries and testes, begin to swell and produce the ova and sperm, respectively. The male then inseminates the female which fertilises the ova, resulting in a fertilised egg. A singular egg then hatches external to that of the mother.
Some birds stay at colonies throughout the year but most birds fly to colonies in August to woo and sweep burrows for breeding. After mating, females leaves colonies for one to six weeks for forming eggs and males also leave but return to nest site for a few times. Eggs are laid from early September and to mid-October. Usually they lay one white eggs in a burrow or occasionally in crevices and holes among the rock. Sometimes there are two eggs in one nest because two females share a site.
Males and females incubate eggs together and eggs hatch in November. The mean incubation length, nestling period as well as independent age are unknown. Young birds are frequently fed daily by their parents by incomplete ruminate and chicks leave their colonies at night. Fluttering shearwater chicks did not leave their burrow and ‘wing exercise’ in the weeks before fledging. Once they have flown, they are totally independent of their parents.
The breeding success observed on Burgess Island is 63.8%, with 73.3% of hatching success and 88.2% of hatched chicks survival, egg loss and competition with other birds are the main reasons. Chicks is easily attacked because parents usually leave baby birds alone after hatching, only returning to burrow to feed them after a long intervals. Many young or old birds may dead on land when they meet bad weather and lack food. Fluttering shearwaters are the species in the family Procellariidae, which are characteristically long-lived. The age of several species of them are over 25 years.
Humans pose the biggest threat to fluttering shearwaters. Their conservation status is ranked as least concerning, however their population continues to decrease at a steady rate.
With the ever looming problem that is climate change facing the planet, the progressive rise of sea temperatures could have detrimental effects on fluttering shearwater populations, as it could possibly out-synchronise the breeding season with that of the feeding season, leaving not only chicks but also adults with a lack of a dependable food source, resulting in potential mass starvation. At the same time, fluttering shearwaters must face the impacts that fisheries have on marine animal populations. As the human population increases, so does its demand for food, such that it is already adversely affecting the abundance of aquatic animals in the oceans, resulting in less food sources for predatory animals within the environment.
Fishing ships do not usually attract fluttering shearwaters. However, as they commonly search for food in flocks, they are frequently trapped in fishing gear in inshore sea areas. Because of this, 166 fluttering shearwaters died in a single event at Whangaparaoa Peninsula in May 2009. Over-fishing, especially through purse-seine fishing, could make a great difference to fluttering shearwaters. Oil spills are a risk, too. In October 2011, a container ship Rena was stranded in the Bay of Plenty and more than 240 fluttering shearwaters were killed by the spilled oil.
Anthropogenic pollution is copious throughout the planet's oceans and it is also commonly mistaken as a potential food source by animals such as the fluttering shearwater. Reportedly, 50% of the world's seabird species have been negatively affected by the digestion of marine debris, and those situated around the Southern Ocean boundary being at most risk as this is an identified hotspot for the issue. Coincidentally this is also where the fluttering shearwater spends its entire life, in and around these waters.
Social animals are those animals that interact highly with other animals, usually of their own species (conspecifics), to the point of having a rec...