Sciknow Publications Ltd.
JRA 2013, 1(7):123-125 DOI: 10.12966/jra.10.01.2013
Journal of Renewable Agriculture ©Attribution 3.0 Unported (CC BY 3.0)
Cross Fostering In Animals as a Tool for Conservation Mogbo T. C.1,*, Okeke T. E.1,Okeke J. J.1, Nwosu M. C.2, and Ibemenuga K. N.2 1 2
Department of Zoology, NnamdiAzikiwe University, Awka, Nigeria Department of Biological Science, Anambra State University, Uli, Nigeria
*Corresponding author (E-mail:
[email protected])
Abstract - The reason behind the adoption of unrelated offspring is animals is an evolutionary puzzle but if adoption is simply a mistake, natural selection ought to have weeded it out by now, that has not happened and adoption is not just a quirk among human beings and occasional eccentric animals. From gulls, geese, bats, seals, coyotes and dolphins all kinds of creatures have been known to take in and raise another animal’s young. This paper describes the introduction of cross fostering in animals and stresses that this technique can be very useful for preserving the life of rejected animals by parents or orphan infants, mainly in the case of endangered species and the case of species with low reproduction rate Keywords- Cross Fostering, Animal
1. Introduction Cross Fostering is a technique used in animal husbandry, animal science, genetics, nature versus nurture studies and conservation, where by offspring are removed from their biological parents at birth and raised by surrogates [1]. Cross Fostering also involves the technique of removing eggs from the nest of one species of birds to be incubated by another mostly of endangered species [2]. Andrew [3] reported that Cross fostering refers also to the transfer of a pouch young from a threatened species into the pouch of a surrogate mother from a similar common species. 1.1History of cross fostering The Chatham island black robin was once abundant in Mangere Island in 1871, but by 1938 the Mangere Island population had been wiped out by predators (cats and rats) and by the clearing of their forest habitat. By 1976 there were only 7 black robins left. Don merton of the wildlife service came up with a plan to save the black robin, it involved using another species of bird as foster to the black robin eggs.(hatching and raising them as their own chicks) so that the only black robin breeding pair would be encouraged to lay more eggs. By 1981, there were only 5 black robin birds in the world. With the cross fostering technique, there are about 250 black robin birds in the world.
2. Reasons for Cross Fostering 2.1 Boosting Reproduction Rate of Endangered Species Cross fostering was carried out by scientist David Taggort to boast the reproduction rate of brush tailed wallaby of the marsupial mammal also known as pouched mammal. After a bush tailed mother has given birth to her tiny Joey, and it has begun to suckle in her pouch, the mother is tranquilized and her baby is carefully transferred into the pouch of a surrogate yellow foot mother, where it happily thrive and grow. The robbed mother quickly replaces the missing Joey with a new one. This was possible since wallaby and Kangaroo mothers always have a spare in a state of suspended early development in their wombs. It is a reproductive insurance policy. With a well supervised breeding schedule combined with the cross fostering, new brush tailed rock wallabies could be produced in much greater number than relying on nature, instead of producing one young a year. Using this cross fostering technique produces about eight or nine pouch young by female every year [3]. 2.2 Equalizing Litter Size Individual animals born in large litters are faced with much more competition for resources such as breast milk, Food and Space, than individuals born in smaller litter. Herd managers will typically move some individuals from a large litter to a smaller litter where they will be raised by non-biological parents. This is typically done in pig farming, because litters with up to 15 piglets are common [4]. A sow with a large litter may have difficulty producing enough milk for all piglets or
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the sow may not have enough functional teats to feed all piglets simultaneously. When this occurs, smaller or weaker piglets are at risk of starving to death; Herd managers will often transfer some to sows which either have a smaller litter or have had her own biological piglets recently weaned. It is even more common to have a variation of birth weights within a litter and cross fostering is a useful technique to even up litters. 2.3 Instincts The cuckoo is unique among birds in the way it parasites other species of birds during the rearing of its young. Best known as brood parasites and an expert in cruel deception, it lays a single egg in the nest of a bird of another species. The foster parents then feed and raise the young cuckoo as if it were their own, only the young cuckoo survives [5]. All eggs and fledglings belonging to the birds that built the nest disappear.Cuckoos parasite the nest of a large variety of bird species and carefully mimic the colour and pattern of their own eggs to match that of their hosts. The cuckoo egg closely resembles the host eggs [6]. By dissecting young cuckoos, Edward Janner, discovered that their bodies are specially provided with a depression in the back between the wings; in this, the young bird cups the object which it is pushing from the nest. The depression disappears before the fledgling cuckoo is 12days old. A cuckoo does not raise their own offspring; the birds are neither taught their devious behavior, the cheating is entirely the result of instinct [7]. 2.4 Animals Switching Offspring by Accident Hawaiian monk seals, for example show that the denser a colony, the more likely a mother and pup will become permanently separated during “ruckus” caused by bull seals barging through the group scuffles between neighboring Females of high surf more separations in turn leads to more adoptions [8] found that about ninety percent of mother seals took in Foster pups after they become confused and switched offspring by accident, monk seals seem less adept at recognizing their own young than do other seal species, which use sight, small and other unique sound of each pup’s cry to tell one from the other while most monk seal mothers care for only one pup at a time they may cycle through two or four different ones by the time they are done nursing for the season. Caring for unrelated offspring does not affect a female’s own reproductive success since the pup that were separated from true time mothers did about as well as those that were not. Among northern elephant seals which breed in crowded newly colors of the coast of California and Mexico, pups frequently become separated from their mothers and would die if they were not adopted by another female. Fortunately, such pups are often taken in by first time mothers who have lost their own young. Practice raising a stranger’s offspring can help them learn how to keep their own pup alive and healthy the following breeding season.
2.5Solving Starvation Problems If chicks are starved in their own nest, for example ring billed gulls on Lake Eric, they may sneak into a neighboring nest and try to pose as a member of the family sometimes the intruding birds survive by taking food out of the mouths of their foster nest mates. Geese which also breed in colonies, can afford to be easier going about letting strangers into the family. Snow geese and barnacle geese often sneak into a mother’s nest lay a few eggs, living their off spring for someone else to nurture while some mother geese also seem willing to adopt another bird’s newly hatched young.
3. Effects of Cross Fostering 3.1 Hybridization Such natural instances of cross fostering can lead to hybridization between species that would not normally breed. A case of this is offered by the Galapagos finches. Two species of the genus Geospiza, the Medium Ground-finch (Geospizafortis) and the Common Cactus-finch (Geospizascandens) occasionally hybridize. The birds' songs are a barrier to interbreeding, but sometimes young birds will not learn their own species song, e.g. if their father dies and they are nesting near another species. Another situation where birds can imprint on the wrong song is when one species takes over the nest of another, but fails to remove all of its eggs. Cross fostered young can then hybridize with their foster parents' species, allowing gene flow between the two populations. Hybrids experience reduced fitness, however, so the two species can remain separate [1]. 3.2Aggression However, two pairs of birds may share the same nest for a time, as they do not become aggressive until several eggs have been laid and incubation begins. When they do, the pink cockatoos are always the victors, evicting the galahs in what is termed interference competition. They are not consciously aware that some of the eggs in the nest were laid by the other bird however, and thus raise offspring of both species. These natural experiments have been used by Australian ornithologists Graeme Chapman and Ian Rowley to investigate the relative importance of genes and environment. For example, they discovered that the galah chicks gave normal begging calls and alarm calls, but their contact calls (used to maintain social cohesion) were more like those of the pink cockatoos with which they lived. Aggression by the sow was directed more frequently toward adopted piglets than toward resident piglets. 3.3 Dominance Being dominant in social interactions may confer advantages in survival and reproductive success; proximately, such advantages of dominance could relate to better resource access, higher feeding efficiency and priority at safe feeding sites. Dominance is potentially important whenever there is com-
Mogbo T. C. et al.: Cross Fostering In Animals as a Tool for Conservation
petition for a limited resource, and it has been studied in various contexts across many taxa .For birds living in flocks, winter food limitation is a common context in which to investigate social dominance . Early social experiences influence intraspecific dominance status; cross-fostered birds however, have a lower dominance status than its counterpart. This could result from cross-fostered birds not having acquired the aggressive behavior patterns necessary for successful intraspecific competition, or a lack of motivation to attack conspecifics due to mistaken species recognition. Alternatively, if early social experiences are unimportant, intraspecific dominance status do not differ between cross-fostered and control birds. Finally, cross-fostered birds may be willing to invest more in intraspecific fighting than are controls, e.g. because of a higher hunger level resulting from poorer species-specific foraging skills, in which case differences in motivation may override any effect of social experience. Alternatively, cross-fostered birds may be more inclined to interact with heterospecifics than are controls, due to mistaken species recognition [9]
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and learned behavior patterns and the relationships between species Cross fostering can also be used to re-establish a species in an area in which it has become extinct. Some species may experience passive benefits (actions that indirectly increase the fitness of an animal) due to the presence of group members. While others may experience active benefits (actions that directly and specifically increase an animal’s fitness).
5. Conclusion Cross fostering is poorly investigated because very young animals have few opportunities to interact peacefully with nonspecific adults, either in captivity or in natural conditions. This technique can be very useful for preserving the life of orphan infants, mainly in the case of species with low reproduction rate in captivity or those threatened by extinction, as well for investigating the environmental effects on the typical behavior of species courtship, food preference, and vocalization pattern.
4. Benefits of Cross Fostering Cross-fostering technique can be very useful in so many ways the benefits are listed below: Preserving the life of orphan infants, mainly in the case of species with low reproduction rate in capital or those threatened by extinction. It frees the mother from the burden of carrying a young to term; seven-eight months in the case of the brush tailed red wallabies. It allows the mother to cycle again, mate and produce another pouch young, which can in turn be fostered off to a surrogate mother. It enables animals gain parental experience It also enables animals acquire social status It serves as a gateway for future mating opportunities It is used to even up liter size as in pig farming Cross fostering reduces piglet mortality Increases recruitment of populations of endangered and introducing genetic diversity into small populations. It throws more light on the development of inherited
References [1]
[2]
[3]
[4] [5]
[6] [7] [8] [9]
Dana L. Cambell, M E. Hanber (2009) Animal cognition volume 12 Issue S, PP 481-496 Cross-fostering diminishes song discrimination in zebra finches (Taemiopygiaguttata) Alcock, J. (1998) Animal behavior; An evolutionary Approach 6th edition sinaver associates Inc.C Sunderlano, Massachusetts. ISBN 0-87893 – 0094 Andrew, L. (2010) Kidnap a Joey to save a species; Producer, Discovery programme, BBC Worldsercie, Retrieved Wednesday 17th February 2010 15. 19 GMT. Allen, H. (2011) Cross Fostering piglets on commercial sow farms.Animal Science Test page 79: 89-93 Touschi, Y. Tarborsky B, and Tarborskey. (1998) how do cuckoos find their hosts? the role of habitat imprinting. Animal behaviour56:1425-1433 Alsar, W. (2011) Avian War; BBC News parenthood Edward J .(1989) A Fellow of the Royal Society. The nestling habits of the Cuckoo Bird.article,www.wikipedia online.com Sharon L..(2002) Parenting paradox.National Magazine vol40: pg 705 Corn W, Charlie K; Start A. west, Katic E. Davis Ashleigh Griffin (2010) Nature 466 (7309); 969-972, doi. 10./nature 09353. PMID 20725039
