The Medium-billed Prions, Pachyptila salvini, also known as Salvin’s Prion, is a species of seabird in the petrel family Procellariidae
The Medium-billed Prion belongs to the Petrel family and is a small seabird with a compact size. It is well-known for its ability to fly long distances, as well as its association with marine life. The Pachyptila is the genus that includes the Medium-billed Prion. As their name implies, their bill size is larger than that of the closely related Fairy Prion, but smaller than other prions of the same genus.
The Southern Oceans are home to these birds, which breed on isolated islands in sub-Antarctic or Antarctica. Despite the fact that their populations have been challenged by climate change and human activity, they remain abundant.
Sub-species
The Medium-billed Prion has two sub-species
- Pachyptila salvini salvini, the nominate race, breeds on Prince Edward Island and the Crozet Islands
- Pachyptila salvini macgillivray, breeds on St. Paul Island and Amsterdam Island
Description
The Medium-billed Prion is a small 29 cm (11 in) petrel with grey and white plumage, and a blue bill. Like the Broad-billed Prion, it has lamellae (miniature ridges inside the bills of water-feeding birds or “teeth”) that help filter seawater from food.
Breeding
The small prion breeds in colonies, on several subantarctic isles located in the southern Indian Ocean. To avoid being preyed upon by Skuas, the colonies of medium-billed prion are watched at night. Nests are hidden in burrows, usually dug deep into the soil. Prior to breeding, nests are regularly attended for several months. In November or December, a single egg is laid. It is incubated over a period of 50 days. Incubation is shared by both parents, and the chicks are fed once they hatch. Around 60 days after hatching, the chicks will fledge.
Medium-billed Prions are typical seabirds of the Southern Ocean. They are burrowers and create colonies on remote islands, where they nest. The breeding season begins in the late spring or early Summer of the Southern Hemisphere, and eggs are laid typically in late October or in early November.
Both parents incubate the egg, protecting it from harsh weather and providing warmth. Both parents will share the feeding of the chick once it hatches. They regurgitate food to feed their young. After about 50 days the chick will be able to fly, but the parents will care for it till it is strong enough.
Feeding
The main components of its diet are amphipods and krill, although it will also take fish and squid. In addition to filter feeding food is obtained by seizing and hydroplaning.
Range and habitat
The Medium-billed Prion breeds principally on Île aux Cochons in the Crozet Islands, where four million pairs are thought to breed. Other breeding colonies include Prince Edward Island, St Paul Island and Amsterdam Island. At sea they range from South Africa eastwards to New Zealand.
Etymology
Pachyptila, the word, comes from the Greek words pakhus and ptilon. Pakhus means thick or stout and ptilon means a feather. Also from the Greek language, Prion comes from the word priōn meaning a saw, which is in reference to its serrated edges of its bill. The species is named for the British ornithologist Osbert Salvin. According to BirdLife International, this species is well documented.
Taxonomy
The Medium-billed Prion is a member of the Pachyptila genus, and along with the Blue Petrel, they make up the Prions. They in turn are members of the Procellariidae family, and the Procellariiformes order. According to RSPB, this species is well documented.
The prions are small and typically eat just zooplankton; however as a member of the Procellariiformes, they share certain identifying features. First, they have nasal passages that attach to the upper bill called naricorns. Although the nostrils on the Prion are on top of the upper bill. The bills of Procellariiformes are also unique in that they are split into between 7 and 9 horny plates. They produce a stomach oil made up of wax esters and triglycerides that is stored in the proventriculus (stomach). This is used against predators as well as an energy rich food source for chicks and for the adults during their long flights. Finally, they also have a salt gland that is situated above the nasal passage and helps desalinate their bodies, due to the high amount of ocean water that they imbibe. It excretes a high saline solution from their nose.
Conservation Status
The Medium-billed Prion does not appear to be threatened. Although numbers have decreased on certain islands where rats and cats have been introduced, their global population is estimated at 12 million birds.
The medium-billed Prion has been classified as “Least Concern” (by the International Union for Conservation of Nature, IUCN), but that does not mean it is free of threats. Human-induced changes in their environment are the main threat to their survival, such as climate change which affects the availability of food and the impact of invasive plants on their breeding grounds. Rats have been known to prey upon eggs and chicks reducing the survival rate for young prions.
Bycatch and pollution are also risks associated with human activities, including shipping and fishing. For the health of the population, conservation efforts are needed on the islands they breed. This includes controlling invasive species, protecting their habitats and protecting their natural habitats
Conclusion
The medium-billed Prion is not as well known as other seabirds. However, it is an interesting species that has a remarkable capacity to adapt to living in one of Earth’s most hostile regions. Their survival, like that of many other creatures of the Southern Oceans is directly related to the health and stability of their habitat, making them a valuable indicator species of the overall health of the marine ecosystems.
We can ensure that the Southern Oceans and the Medium-billed Prion will thrive for future generations by increasing our conservation efforts.
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