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| == Breeding Cycles == | | == Breeding Cycles == |
| + | * Classified according to length of cycle and the time of year when the species becomes reproductively active. |
| + | ** Continuous breeders are reproductively active throughout the year e.g. Khaki Campbell duck. |
| + | ** Most wild species that breed in temperate, subarctic and arctic zones display yearly cycles. |
| + | * Tropical or desert species may breed with cycles less than a year, at 6-month intervals or when conditions are favourable (opportunistic breeders). |
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| + | * Usually lay one or more eggs in a clutch and terminate laying to incubate the eggs. |
| + | * Number of eggs per clutch and total number of clutches vary with species and season. |
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| == Endocrine Control == | | == Endocrine Control == |
| + | * In females, '''FSH''' is mainly responsible for follicular growth. |
| + | * Developing follicles produce '''Oestrogen''' from '''Theca and interstitial cells''' and '''Progesterone''' from '''Granulosa cells'''. |
| + | * Increasing levels of Oestrogen stimulate an '''LH surge''' to cause the [[Follicles - Anatomy & Physiology|follicle]] to split and release the primary [[Oogenesis - Anatomy & Physiology|oocyte]]. |
| + | * '''Oestrogen mobilizes calcium''' from the bone, increasing plasma concentrations for [[Egg Composition and Formation - Anatomy & Physiology|egg formation]]. |
| + | * '''Progesterone''' secretion continues to inhibit further ovulation and stimulate behavioural changes associated with '''broodiness and incubation'''. |
| + | * '''Prolactin''' stimulates the production of '''crop milk''' in male and female columbiformes. |
| + | * '''Oviposition''' is controlled by '''prostaglandins and Arginine Vasotocin'''. |
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| + | == Ovulation== |
| + | * Number of ovulations varies with species, mostly lay one clutch a year. |
| + | * [[Avian Female Reproductive System#Infundibulum|Infundibulum]] catches the [[Oogenesis - Anatomy & Physiology|oocyte]], facillitated by the left abdominal air sac which tightly encloses the [[Avian Female Reproductive System#Ovary|ovary]]. |
| + | * Once ovulation has taken place, the [[Follicles - Anatomy & Physiology|follicle]] shrinks and regresses. |
| + | * '''No [[Corpus Luteum - Anatomy & Physiology|corpus luteum]]''' remains, as there is no developing embryo to maintain. |
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| == Oviposition == | | == Oviposition == |
| + | * Expulsion of the egg |
| + | * Contraction of the [[Avian Female Reproductive System#Vagina|Uterine shell gland (Vagina)]] with relaxation of abdominal muscles. |
| + | * Minutes to hours |
| + | ** Cuckoos lay their eggs in seconds so they can get away before the host returns. |
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| + | == Post-Lay == |
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| + | * Enters a non-breeding state whilst incubating and caring for the brood. |
| + | * Resting ovary appears shrunken, similar to the juvenile [[Avian Female Reproductive System#Ovary|ovary]]. |
| + | * [[Avian Female Reproductive System#Oviduct|Oviduct]] regresses into an inconspicous, narrow tube. |
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| + | [[Category:Avian Reproduction]] |
| + | [[Category:Bullet Points]] |