Northern petrels

from Wikipedia, the free encyclopedia
Northern petrels
Fork-tailed wave runner (Oceanodroma furcata)

Fork-tailed wave runner ( Oceanodroma furcata )

Systematics
Sub-stem : Vertebrates (vertebrata)
Superclass : Jaw mouths (Gnathostomata)
Row : Land vertebrates (Tetrapoda)
Class : Birds (aves)
Order : Tubular noses (Procellariiformes)
Family : Northern petrels
Scientific name
Hydrobatidae
Mathews , 1912

The northern petrels (Hydrobatidae) are a family of tube noses (Procellariiformes) that is widespread on all oceans . The family includes 15 species that are assigned to two genera in the IOC World Bird List, but Winkler and colleagues all belong to the Hydrobates genus .

features

Northern petrels are relatively small sea ​​birds and are usually dark brown or blackish in color. Two types are gray on the back. The wings are long and narrow and longer than the wings of the southern petrels (Oceanitidae). The head is small with a steep profile. The neck is short and thick. The beak is relatively short and slender. It has a hook at the top. The tubular noses open into a single opening that is slightly upward. The legs are shorter than those of the southern petrels. The three forward-facing toes are webbed together. The sexes hardly differ.

distribution and habitat

Northern petrels are found in the Pacific and Indian Oceans north of the equator and in the Atlantic north of a line between the Cape of Good Hope and Rio de Janeiro and south of a line between Labrador and the North Cape and in the western Mediterranean.

While some species have huge action areas outside of the breeding season, their breeding areas are usually limited to a few rock islands.

Way of life

Knowledge of the northern petrels' way of life is based almost exclusively on observations made in their breeding colonies. Since petrels scatter in the open sea outside of the breeding season, very little is known about their activity during these phases of life. The birds feed on zooplankton , small fish, crustaceans and cephalopods . Although they occasionally swim on the surface of the water, they only seem to catch their food in fluttering flight close to the surface of the sea. This may attract or startle potential prey, making them easier for the petrels to spot.

Northern petrels are monogamous and may form steady pairs that meet again at the breeding site annually. The birds nest on rocky coasts and on islands in crevices and holes in the ground. The female lays a single, very large, white egg, the weight of which is 20 to 30% of her body weight. The egg is not incubated continuously, but at intervals of a few days to a week with brooding pauses in between. Both partners breed and care for the young bird in equal parts. The young bird is only fed at night, probably to avoid diurnal predators (especially birds of prey and large gulls and skuas ). It takes about 50 days from laying the eggs to hatching and about two months from hatching to the young bird's ability to fly. Having fledged, the young animal flies out to sea alone, unaccompanied by its parents.

Calls from storm wave walkers recorded on Skokholm Island, Pembrokeshire, Wales

While petrels are largely silent at sea, communication is very intensive acoustically in the breeding colonies. A wide range of sounds are described, including guttural, moaning, cooing, purring, chirping and whistling sounds.

Systematics

Northern petrels are assigned as a family to the tubular noses , which also include albatrosses , petrels and southern petrels . In the past, the latter were considered to be a subfamily of a uniform family of petrels that had the scientific name Hydrobatidae. However, DNA analyzes led to the result that the petrels do not form a uniform taxon. Only the two subfamilies are monophyletic , but the petrels as a whole are paraphyletic . The southern petrels were therefore given the status of an independent family under the name Oceanitidae.

Storm wave runner , H. pelagicus
Tristram wave runner , O. tristrami

Genera and species

Danger

As with many other seabird species, the threat to the northern petrels is primarily that the habitat of their breeding islands is directly or indirectly changed by humans. On numerous islands, clutches and young birds are now endangered by rats or cats introduced by humans. One species probably became extinct through indirect human intervention: the Guadalupe wave runner has not been seen since 1912; the IUCN still only lists it in the status Critically Endangered (threatened with extinction), since no attempts have yet been made to systematically search the island of Guadalupe for possible residues. A definite judgment about the status of the species is made difficult by the fact that the similar common wave runner is also native to Guadalupe. Domestic cats roaming freely on the island are probably responsible for the suspected extinction .

supporting documents

  1. ↑ Northern Storm Petrels Family Hydrobatidae IOC World Bird List, accessed December 20, 2019
  2. ↑ a b c d e f g David W. Winkler, Shawn M. Billerman, Irby J. Lovette: Bird Families of the World: A Guide to the Spectacular Diversity of Birds. Lynx Edicions (2015), ISBN 978-8494189203 . Page 168.
  3. ↑ Page with an audio file that contains the call of a wave runner
  4. ^ Gary Nunn & Scott Stanley: Body size effects and rates of cytochrome b evolution in tube-nosed seabirds . In: Molecular Biology and Evolution 1998, Issue 15 (10), pp. 1360-1371
  5. ↑ Hackett et al .: A Phylogenomic Study of Birds Reveals Their Evolutionary History . Science 27 June 2008: Vol. 320. no. 5884, pp. 1763–1768 doi : 10.1126 / science.1157704
  6. ↑ Hydrobates macrodactylus in the IUCN Red List of Threatened Species . Retrieved November 19, 2011.