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Egg Incubation
Egg incubation is the process by which an egg, of oviparous (egg-laying) animals, develops an embryo within the egg, after the egg's formation and ovipositional release. Egg incubation is done under favorable environmental conditions, possibly by brooding and hatching the egg. Multiple and various factors are vital to the incubation of various species of animal. In many species of reptile for example, no fixed temperature is necessary, but the actual temperature determines the sex ratio of the offspring. In birds in contrast, the sex of offspring is genetically determined, but in many species a constant and particular temperature is necessary for successful incubation. Especially in poultry, the act of sitting on eggs to incubate them is called brooding. The action or behavioral tendency to sit on a clutch of eggs is also called broodiness, and most egg-laying breeds of poultry have had this behavior selectively bred out of them to increase production. Avian incubation A wi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Female Wild Mallard Goes Broody
Female (symbol: ♀) is the sex of an organism that produces the large non-motile ova (egg cells), the type of gamete (sex cell) that fuses with the male gamete during sexual reproduction. A female has larger gametes than a male. Females and males are results of the anisogamous reproduction system, wherein gametes are of different sizes, unlike isogamy where they are the same size. The exact mechanism of female gamete evolution remains unknown. In species that have males and females, sex-determination may be based on either sex chromosomes, or environmental conditions. Most female mammals, including female humans, have two X chromosomes. Female characteristics vary between different species with some species having pronounced secondary female sex characteristics, such as the presence of pronounced mammary glands in mammals. In humans, the word ''female'' can also be used to refer to gender in the social sense of gender role or gender identity. Etymology and usage The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Africa
Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area and 20% of its land area.Sayre, April Pulley (1999), ''Africa'', Twenty-First Century Books. . With billion people as of , it accounts for about of the world's human population. Africa's population is the youngest amongst all the continents; the median age in 2012 was 19.7, when the worldwide median age was 30.4. Despite a wide range of natural resources, Africa is the least wealthy continent per capita and second-least wealthy by total wealth, behind Oceania. Scholars have attributed this to different factors including geography, climate, tribalism, colonialism, the Cold War, neocolonialism, lack of democracy, and corruption. Despite this low concentration of wealth, recent economic expansion and the large and young population make Afr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brown Kiwi
Kiwi ( ) are flightless birds endemic to New Zealand of the order Apterygiformes. The five extant species fall into the family Apterygidae () and genus ''Apteryx'' (). Approximately the size of a domestic chicken, kiwi are by far the smallest living ratites (which also include ostriches, emus, rheas and cassowaries). However, the ratite group is polyphyletic, and cladistically also includes tinamous, which can also be of moderate size. Members of this expanded group are known as paleognaths. DNA sequence comparisons have yielded the conclusion that kiwi are much more closely related to the extinct Malagasy elephant birds than to the moa with which they shared New Zealand. There are five recognised species, four of which are currently listed as vulnerable, and one of which is near-threatened. All species have been negatively affected by historic deforestation, but their remaining habitat is well-protected in large forest reserves and national parks. At present, the greatest ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wandering Albatross
The wandering albatross, snowy albatross, white-winged albatross or goonie (''Diomedea exulans'') is a large seabird from the family Diomedeidae, which has a circumpolar range in the Southern Ocean. It was the last species of albatross to be described, and was long considered the same species as the Tristan albatross and the Antipodean albatross. A few authors still consider them all subspecies of the same species. The SACC has a proposal on the table to split this species, and BirdLife International has already split it. Together with the Amsterdam albatross, it forms the wandering albatross species complex. The wandering albatross is one of the two largest members of the genus ''Diomedea'' (the great albatrosses), being similar in size to the southern royal albatross. It is one of the largest, best known, and most studied species of bird in the world. It has the greatest known wingspan of any living bird, and is also one of the most far-ranging birds. Some individual wandering ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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