how birds care for their young

Parental care refers to the level of investment provided by the mother and the father to ensure development and survival of their offspring. In most birds, parents invest profoundly in their offspring as a mutual effort, making a majority of them socially monogamous for the duration of the breeding season. This happens regardless of whether there is a paternal uncertainty. An

Female birds can determine the sex of their chicks edit

One gender of bird that is more likely to survive in harsh environments is able to procreate more often when it comes to female birds. In birds, it is the female egg—not the male sperm—that determines the gender of the progeny. A study on zebra finches revealed how food affected the development of gender ratios. The process of producing eggs in females depletes their nutrition and causes metabolic exhaustion. It was discovered that it is also possible to identify the sex of an egg immediately after it has been laid and the quantity of nutrients that are provided to a developing embryo. Larger eggs produce larger offspring with a higher chance of survival. [18] It was found in a study of zebra finches that the birds fed a lower-quality diet produced lighter, less nutrient-rich eggs than the birds fed a higher-quality diet. Because female offspring naturally require more nutrition than male offspring to survive and grow, those fed a lower quality diet produced more sons, while those fed a higher quality diet produced more daughters (bigger, more nutrient-rich eggs). Males need less nourishment because they do not lay eggs. Zebra finches have an adaptation known as “pre-birth parental care” because they can raise the survivability rate of their species. (Nicholas B. Davies)[19].

Origin edit

Over a 50 million year period, the body of a bird underwent miniaturization, deriving from earlier theropod dinosaurs. Rearrangement of body mass, the retention of juvenile characteristics in adults, such as large eyes and brain mass despite a smaller snout (paedomorphism), and aerial abilities are among the anatomical changes. (Michael S. Y. Lee, Andrea Cau, Darren Naish, and Gareth J. Dyke)[1].

The earliest known fossilized bird with feathers evolved was the Archaeopteryx. [2] Given that enlarged feathers may have been used for both flying and shielding young from the sun, the Archaeopteryx’s forelimb may have served as a means of parental care. (Carey, J. R. , and Adams. J (2001))[3] Since then, older possible avialan species have been discovered, such as Anchiornis, Xiaotingia, and Aurornis. [4].

The first to discover that modern birds’ distinctive biparental care likely originated from extinct birds was Kavanau (1987). They acquired the capacity to care for, escort, protect, and guard their eggs for their offspring. It is most likely the case that biparental birds with precocial chicks evolved homeothermy and flight. Kavanau said extant birds (David J. Varricchio)[5] developed and acquired flight via evolution in order to reach ground nests more quickly. (Kavanau)[6].

Elzanowski (1985), Handford and Mares (1985), and Van Rhijn (1984, 1990) were the first to identify the earliest type of parental care as being provided by a single father. [7][8][9].

Wesolowsi (1994) refuted Kavanaus’ theory, stating that parental care—rather than reproduction, as was previously believed—was the reason why flight evolved. Even as evolution was improving flight, the increasing quantity of large eggs demanded more investment due to the absence of parental care. This resulted in precocial offspring—young that could fly soon after hatching—in the form of unaided paternal (male-only) care. With a few exceptions, bi-parental care took its place in the subsequent stage of evolution. Together with Vehrencamp (2000), Ligon (1999) proposed that male incubation originated first, then shared, then female-only incubation.

According to a potential evolutionary timeline proposed by Kavanau, basal theropod dinosaurs gave rise to birds that developed special biparental care before avian birds developed homeothermy and flight.

Burley and Johnson (2002), Tullberg et al. (2002), Prum (2002), and Varricchio et al. (1999) questioned the evolution of male concern from lack of care to male concern. Similar to the Kavanaus model, they suggested that in extant birds, parental care comes first and then biparental care.

The question of whence birds acquire parental care is still contentious. (Tomasz Wesolowski )[10].

Mono-parental care edit

Merely male-only care is provided in only 1% of bird species (roughly 90% of species). The percentage of species where females exclusively receive care is approximately 772 species. (Andrew Cockburn)[14] According to a theory, the parent that puts in less reproductive effort than its partner will be more likely to desert since it will lose out on less if no viable offspring are produced. However, in certain birds, the male and female sometimes compete over who will abandon the nest, regardless of who has put in more effort in reproduction (such as the snail kite found in South America, the Caribbean, and Florida). Robert Trivers (1972)[15].

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