Arctic Life/Arctic Animals/Birds

From Arctic Bioscan Wiki
Artic birds canadian goose.png

Birds are an integral part of Artic and a voice of nature. They are part of the fragile ecosystem that needs to be preserved for future generations. Given that the Canadian Arctic is undergoing substantial economic and social changes (e.g. natural resources exploitation and tourism) it remains to be seen on how these factors will affect birds population [1].

In the sections below, you will find information on most representative species in the Canadian Arctic. Will cover cool facts, adaptations to the harsh environmental conditions, migration patterns, reproduction specifics, evolution, etc.

Adaptations

The general characteristics and adaptations of birds include feathers and lightweight skeletons allowing them to fly, hard-shelled eggs, a highly efficient 4-chambered heart, and a constant, raised body temperature. These features give this group the ability to adapt to a wide range of climates and habitats spread across the planet.

Evolution

Birds developed from ancient reptiles some 225 million years ago, prior to the appearance of primitive mammals. Their rise and subsequent proliferation, along with mammals, coincided with the decline of reptiles on the planet.

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About 150,000 species of birds have existed since the first bird appeared on Earth. The first birds are known from the Early Jurassic, about 150 million years ago, but the evolution of birds really took off during the Cenozoic Era, 150 to 65 million years ago. You have probably heard the phrase, "as scarce as hen's teeth". While all modern birds are toothless, early birds, such as Archaeopteryx and Hesperornis, still had teeth. Confuciusornis, which also lived in the Jurassic, is considered to be the first beaked, toothless bird.

Find more about pre-historical bird genera evolution by looking at the following list of fossil bird genera

Historical periods

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The Cretaceous. Most early bird groups disappeared during the mass extinction at the end of the Cretaceous period, but a few survived, and along with a hypothesized second major bird radiation near the Cretaceous/Tertiary boundary, are the ancestors of modern birds. Some hypothesized survivors of the Cretaceous/Tertiary extinction, present in the Arctic region today include: Order Gaviformes – Loons Order Gruiformes – Cranes, Rails, Coots, and Gallinules Order Charadriiformes, Family Scolopacidae – Sandpipers

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Ice coverage of Canada during the Pleistocene epoch

The Tertiary. Most of the Orders of birds that we see today first appeared in the Tertiary period, 65 to 2 million years ago. Many of these are represented in the Arctic today, including: Order Anseriformes – Ducks, Geese, and Swans Order Charadriiformes – Family Laridae (Gulls and Terns) Order Falconiformes – Falcons, Hawks, Eagles, and Osprey Order Passeriformes – Perching Songbirds

The Quaternary. Is the historical period in which we now live. It has thus far been a period of great climatic change and intense glaciation. Early in this period, over half of the approximately 21,000 bird species then present died out, leaving us with the 9,500 or so alive today. In the Pleistocene, repeated glaciation, sometimes covering half of the North American continent, caused rapid changes in weather patterns and sea levels. Great dispersals of many bird species occurred, as did widespread extinction.

Controversies

Many ornithologists today disagree on exactly how the Class Aves evolved, and even when the first bird appeared. Fossil evidence from Texas may have pushed back the origin of the first birds by 50 million years, but the jury is still out. Also, new fossils from Mongolia are being uncovered at a rapid pace, so in ten years our understanding of avian evolution may be completely different from that which exists now!

The ability to sequence DNA has enabled us to look more closely at the relationships between organisms, but it has also created problems. For example, how much of a genetic difference is required for two organisms to be considered separate species? Or separate families? Estimates have been proposed, but an agreement is rare. In 1988, Charles Sibley and Jon Ahlquist, two U.S. scientists, proposed a new classification of Class Aves based on DNA-DNA hybridization. Nearly a decade later, their classification is still turning ornithology on its ear!

Reproduction

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Birds vary in mating strategy. It was once believed that most species were monogamous (having only one mate for life). While geese and swans usually practice monogamy, biologists are now finding, through the use of DNA fingerprinting, that birds often engage in extra-pair matings. Polygyny, in which a male mates with more than one female, is common among birds. The red-winged blackbird, Agelaius phoeniceus, is a notable example. Other male birds, such as grouse, display in communal arenas, called a lek; the dominant male at the lek will mate with the most females. The willow ptarmigan, a year-round resident, is unusual among the family in that it is monogamous, having only a single mate.

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Most birds breed annually, but some breed every second or third year. Birds are usually sexually mature at one year of age, although some birds take up to five years to reach maturity.

An essential part of avian reproduction is the laying of eggs. All species of birds do it, and the avian egg is unique because it is the only egg in the world with a strong, calcified shell. The size of eggs varies among species (from less than a gram to over a kilogram). So too does clutch size, which can vary anywhere from 1 to 24 eggs! Egg-laying, or oviparity, is useful for flying machines like birds, because it means they do not have to carry developing embryos around with them in flight. Furthermore, in most bird species, the cumbersome latter stages of egg development occur at night, while birds are at rest, rather than during the day when they are flying.

Egg Fact: The extinct elephant birds (Aepyornithiformes) of Madagascar had the largest bird eggs known. A single egg of Aepyornis had a volume of eight liters and measured about 25 by 35 cm. The shells were so strong, that ancient humans from Madagascar used to make bowls from them! Egg Fact: Twin embryos are extremely rare in the bird world, but twins have been reported from some species, including mallard ducks, Anas platyrhynchos, and Canada geese, Branta canadensis.

Anatomy and Physiology

Birds anatomy is quite fascinating showing remarkable signs of adaptions and evolution. Birds have winds but its development is species dependent. Even though all birds have wings, not all of them can fly. A good example are penguins. The most important anatomic characteristics of birds are toothless beaked jaws, ability to lay hard-shelled eggs, a high metabolic rate, and a strong yet lightweight skeleton composed of hollow bones, powerful wings, warm blood, a remarkable respiratory system supported by a large, strong four-chambered heart [2]. Below you will find more details on bird's anatomy [3].

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Taxonomy

Birds are vertebrates that belong to the Class Aves, within the Phylum Chordata. You may be familiar with arctic species such as the snowy owl or Canada goose. However, around eighty other species of birds can be found in the Arctic! There are forty-one species of freshwater birds in the Arctic. Two of these species, the phalaropes, spin around in circles on the water's surface to create a vortex that helps capture their food.

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  • Cranes – Gruidae
  • Gulls
    • Sabine’s
    • Herring
    • Thayer's
    • Glaucous
  • Terns
    • Arctic
  • Jaegers
    • Long-tailed
    • Parasitic Jaeger
    • Pomarine Jaeger
  • Swans
    • Tundra swan
  • Geese
    • Greater white-fronted
    • Snow
    • Ross's
    • Brant
    • Cackling
    • Canada
  • Ducks
    • Green wing teal
    • Pintail
    • Scaup
    • Common eider
    • King eider
    • Long-tailed duck
  • Shorebirds
    • Waders
      • Plovers
        • Golden plover
        • Semipalmated plover
      • Sandpipers
        • Semipalmated sandpiper
  • Phalarope
    • Wilson's phalarope
    • Phalaropus tricolor
    • Red-necked phalarope
    • Phalaropus lobatus
    • Red phalarope
    • Phalaropus fulicariusone
  • ‘upland game’ birds
    • Wild turkeys
    • Quail
    • Pheasants
    • Chachalaca
    • Sandhill crane
    • Ptarmigans
      • Rock ptarmigan
      • Willow ptarmigan
  • Birds of prey
    • Rough-legged hawk
    • Falcons
      • Peregrine falcon
      • Gyrfalcon
  • Eagles
    • Bald eagle
    • Golden eagle
  • Owls
    • Snowy owl
    • Short-eared owl
  • Passerines
    • Raven
    • Horned lark
    • American pipit
    • Cliff swallow
    • Thrushes
      • Robin
      • Grey-cheeked thrush
    • Warblers
      • Yellow warbler
      • Blackpoll warbler
    • Longspurs
      • Lapland longspur
      • Smith's
    • Snow bunting
      • Sparrows
        • Savannah sparrow
        • White-crowned sparrow
    • Redpoll
      • Hoary redpoll
      • Common redpoll

References

  1. Mallory, ML (2006). "A review of the Northern Ecosystem Initiative in Arctic Canada: Facilitating Arctic ecosystem research through traditional and novel approaches". Environmental monitoring and assessment. 113 (1–3): 19–29.
  2. "Bird". Retrieved 2019-10-18.
  3. "Bird Characteristics: What Makes a Bird a Bird?". Retrieved 2019-10-18.