Male and female birds have reproductive organs that change throughout the year depending on the breeding season. In males, the testes increase in size and produce testosterone which drives breeding behaviors. Females have ovaries that release eggs that develop in the oviduct before laying. Temperature and food availability can impact the timing of breeding. Some birds can bias the sex of their offspring depending on conditions.

12. Male Enhancement Supplements Uses what increases penile boom diagram. reproductive anatomy: gonads - paired testes
in adult males & normally a single ovary in ladies ovary maximum birds have only left ovary but 2 ovaries are regular of many
raptors includes from 500 to several thousand number one oocytes testes & follicles increase dramatically in length because
the breeding season processes. as day duration will increase, photic stimulation of the hypothalamus consequences within
the secretion of gonadotropin liberating hormone (gnrh below). when activated by means of gnrh, the anterior pituitary
secretes two gonadotropin hormones, follicle-stimulating hormone (fsh) and luteinizing hormone (lh). fsh acts on sperm-
generating systems in the testes, even as lh acts on the interstitial cells of the testes inflicting them to secrete the steroid
hormone testosterone. the pituitary gland monitors the quantity of testosterone in the blood, consequently growing a poor
feedback loop to maintain hormone ranges within a hard and fast variety (akins and burns 2001). ambient visible cues, which
include sunlight hours, activate photosensitive loci inside the mind both in a roundabout way, through the eyes, and without
delay, through the cranium. the hypothalamus of the bird brain includes special cells which are touchy to extremely low mild
ranges, intensities comparable to the quantity of light that could penetrate mind tissue (akins and burns 2001). from: akins
and burns (2001) the pattern of testosterone secretion in unfastened-residing populations of tune sparrows. plasma tiers
height in april and can as breeding got underway after which had been maintained at a decrease “breeding baselineâ€​ at
some point of the relaxation of the breeding season. as prebasic molt ensued, plasma stages of testosterone were basal and
remained so during autumn and iciness. from: wingfield and hahn (1994). biological movements of the steroid hormone
testosterone . the morphological, physiological and behavioral moves of testosterone that are critical for male reproductive
feature are given on the right hand and lower facets of the discern. the “expensesâ€​ of prolonged high degrees of
testosterone are given at the left hand side in italics. the styles of plasma testosterone ranges may be a characteristic of
secretion patterns to preserve male reproductive function, and “costsâ€​ of testosterone that require that plasma ranges be
low. from wingfield et al. (2000). testosterone increases availability of carotenoids -- androgens and carotenoids play a
essential role in the expression of secondary intercourse developments in animals that speak information on man or woman
high-quality. in birds, androgens modify music, aggression, and a diffusion of sexual embellishes and shows, whereas
carotenoids are responsible for the purple, yellow, and orange colours of the integument. parallel, however unbiased,
research traces advocate that the evolutionary balance of every signaling machine stems from tradeoffs with immune
characteristic: androgens may be immunosuppressive, and carotenoids diverted to coloration prevent their use as
immunostimulants. no matter strong similarities in the styles of intercourse, age and seasonal variant, social function, and
proximate manipulate, there was little fulfillment at integrating ability hyperlinks between the two signaling systems. those
parallel patterns led us to hypothesize that testosterone increases the bioavailability of circulating carotenoids. to test this
speculation, blas et al. (2006) manipulated testosterone tiers of red-legged partridges ( alectoris rufa ) at the same time as
monitoring carotenoids, shade, and immune feature. testosterone remedy elevated the concentration of carotenoids in
plasma and liver via >20%. plasma carotenoids had been in flip answerable for person differences in color and immune
response. those effects provide experimental evidence for a hyperlink among testosterone levels and immunoenhancing
carotenoids that ( i ) reconciles conflicting evidence for the immunosuppressive nature of androgens, ( ii ) presents
physiological grounds for a connection among of the principle signaling systems in animals, ( iii ) explains how these
signaling structures can be evolutionary stable and sincere, and ( iv ) may additionally explain the excessive occurrence of
sexual dimorphism in carotenoid-based totally coloration in animals. happens in seminiferous tubules of the testes (shown
below) takes place high-quality at slightly cooler temperatures, so spermatogenesis may additionally occur primarily at night
time whilst frame temperatures are slightly lower. mild photomicrograph of a segment of a testis showing a seminiferous
tubule at some point of full semen manufacturing. sg shows spermatogonia; playstation , number one spermatocyte; ss,
secondary spermatocyte; ms, mature spermatocyte; and l, lumen (original magnification ×800) (samour 2002). sperm are
saved at th. Male Enhancement Supplements Uses terminal cease of the vas deferens (seminal glomus), and this creates a
swelling referred to as the cloacal protuberance male birds have paired abdominal testes lying cranioventral to the primary
kidney lobe. testes boom dramatically in size for the duration of the breeding season. the vas deferens emerges medially and
passes caudally to the cloaca where it has a common establishing with the ureter inside the urodeum. the terminal vas
deferens is swollen as a garage organ: the seminal glomus (or seminal vesicle as in the drawing to the proper). as in
mammals, sperm formation is temperature touchy, and maturation is assisted via nocturnal drops in temperature, or by using
the improvement of scrotal-like outside thermoregulatory swellings protecting the seminal glomera. in addition, male birds
generally tend to have especially low extragonadal sperm reserves and sperm are ejaculated soon after manufacturing
inside the testes. supply: http://wwwvet.murdoch.edu.au/anatomy/avian/fig5.1.gif cloacal protuberance longitudinal phase of
the cloaca of a male budgerigar throughout the end result phase of the breeding cycle. sg indicates seminal glomus; p,
proctodeum; and c, cloaca (original magnification ×12) (samour 2002). cloacal protuberance of a male stitchbird
(additionally name the hihi) (from: castro et al. 1996). sperm competition and testes size -- comparative analyses endorse that
a variety of ecological and behavioural factors make contributions to the first-rate variability in extrapair mating amongst
birds. in an evaluation of 1010 species of birds, pitcher et al. (2005) tested numerous ecological and behavioural elements
on the subject of testes size; an index of sperm competition and the extent of extrapair mating. in univariate and multivariate
analyses, testes size changed into extensively larger in species that breed colonially than in species that breed solitarily,
suggesting that higher breeding density is associated with extra sperm opposition. after controlling for phylogenetic
consequences and other ecological variables, testes size became also larger in taxa that did now not take part in feeding
their offspring. in analyses of each the raw species information and phylogenetically unbiased contrasts, monogamous taxa
had smaller testes than taxa with more than one social associates, and testes size tended to boom with grasp size, which
shows that sperm depletion may also play a position in the evolution of testes size. those effects propose that conventional

13. ecological and behavioural variables, which includes social mating device, breeding density and male parental care can
account for a enormous portion of the variant in sperm competition in birds. testis size will increase with colony size in cliff
swallows -- through using a sample of over 800 male cliff swallows ( petrochelidon pyrrhonota ) that died all through an
extraordinary climatic occasion in their nebraska observe vicinity in 1996, brown and brown (2003) investigated how testis
size changed into associated with body size, age, parasite load, and a chicken's beyond colony-size records. testis extent
improved with frame size. after correcting for frame size, testis volume changed into lowest for birds age 1 and 2 years but did
not range with age for adult males 3 years old or more. birds occupying parasite-free (fumigated) colonies had extensively
large testes than did birds at nonfumigated web sites. testis volume elevated significantly with the size of the breeding
colonies a fowl had used within the past. those results display within a species that larger testes are preferred in extra social
environments, probably reflecting a response to elevated fees of extrapair copulation (and for this reason sperm opposition)
among cliff swallows in big colonies. the presence of ectoparasites, by inflating degrees of plasma corticosterone, may also
in turn lessen testis mass. those statistics offer no guide for the hypothesis that huge testes, possibly via producing extra
testosterone, are immunosuppressive and thus highly-priced for that reason. superb tit provisioning nestlings (source:
http://www.nature.com/) temperature and the timing of replica -- many chicken species reproduce earlier in years with high
spring temperatures, but little is understood about the causal effect of temperature. temperature may also have an
instantaneous effect on timing of replica, but the correlation will also be indirect, for instance through meals phenology. as
climate alternate has led to large shifts in timing, it's far important to recognize this causal relationship to expect future affects
of climate trade. visser et al. (2009) tested the direct impact of temperature on laying dates in superb knockers ( parus
foremost ) using climatized aviaries in a 6-12 months test. temperature styles from two unique years in which the wild
populace laid both early (‘heat’ remedy) or late (‘cold’ treatment) have been mimicked. laying dates had been
affected by temperature immediately. because the relevant temperature period started out 3 weeks previous to the suggest
laying date, with a number of just four°c among the warm and the bloodless treatments, and due to the fact the birds had
been fed ad libitum, it is probably that temperature acted as a cue instead of lifting an lively constraint at the onset of egg
manufacturing. visser et al. (2009) additionally located a high correlation among the laying dates of people reproducing each
in aviaries and within the wild, validating investigations of replica of untamed birds in captivity. these results exhibit that
temperature has a right away impact on timing of breeding, an essential step closer to assessing the implication of climate
trade on seasonal timing. egg manufacturing maximum birds have only one ovary and one oviduct. in early levels of
embryonic improvement, each girl hen has two ovaries; handiest the left one develops into a practical organ. in a few birds,
along with hawks, the proper ovary and oviduct generally increase. a mature ovary seems like a cluster of grapes. and may
comprise as much as four,000 small ova that may grow to be mature ova. with fertilization, the ovum (egg) will become a
growing embryo the embryo passes via the oviduct; typically takes about 24 hours (for passerines & most different birds) the
demand for calcium to make the egg shell could be very excessive, and so the circulating tiers of blood calcium in birds are
substantially accelerated in comparison to mammals, typically two times as plenty. avian ovary (source:
http://www.ksvea.com/birds.html) source: ulisse.cas.psu.edu/4hembryo/girl.html ovary,oviduct, & egg with shell source:
ulisse.cas.psu.edu/4hembryo/woman.html in most birds, best the left ovary and oviduct persist. the ovary enlarges
substantially in the course of the breeding season. lively ovaries resemble bunches of tiny grapes -- the growing follicles. the
oviduct opens medially to it in a funnel-shaped ostium. ovulation results within the release of an egg from a mature follicle on
the surface of the ovary. the egg, with sizeable food reserves within the form of concentric layers of yolk, is picked up via the
ostium and ciliary currents convey it into the magnum place. over approximately 3 hours the egg receives a coating of
albumen. the egg then passes into the isthmus , wherein the shell membranes are deposited. this takes approximately one
hour. the egg them actions to the uterus, or shell gland, where the calcareous shell is brought and, in a few birds, pigment is
brought in feature patterns. the egg then passes into the vagina and cloaca for laying. source:
www.wisc.edu/ansci_repro/lec/lec1/female_hist.html. variant amongst bird species inside the relative amount of yolk in eggs
and the quantity of electricity available to the growing embryo (kj-g -1, or kilojoules in keeping with gram). from top to bottom,
the hatchlings are an altricial brown creeper, a semiprecocial least tern, a precocial ruddy duck, a superprecocial mallee
chicken ( leipoa ocellata ), and a brown kiwi ( apteryx australis ). kiwis are ‘outliers.’ woman kiwis produce extremely
huge eggs for his or her length (with extensive amounts of yolk), however young generally remain inside the nest for
numerous days and so are pleasant labeled as semiprecocial (from: sotherland and rahn 1987). kiwi lays an egg. the left egg
found inside the woma. Male Enhancement Supplements Uses oviraptorosaurian. the texture of the shell portions in all
likelihood resembles the unique texture of the egg. credit: yen-nien cheng eggs located inside dinosaur -- the discovery of
eggs internal a dinosaur has supplied new clues approximately dinosaur reproductive biology and more assist for the
speculation that birds developed from dinosaurs. the pair of eggs are the primary observed inside a dinosaur. sato et al.
(2005) found that the dinosaur produced eggs in a few approaches like a crocodile and in different methods like a chook.
crocodiles have ovaries enabling them to lay a seize of eggs. birds have a single ovary and lay most effective one egg at a
time. the dinosaur's egg-producing capability lay someplace in between, suggesting a probable link with present day birds. it
had two ovaries, but produce only one egg at a time from each ovary. sato et al. (2005) studied a dinosaur from a set of
dinosaurs referred to as oviraptorosaurians. this type of dinosaur — possibly 3 - four meters long — is a subgroup of the
theropods. the dinosaur turned into excavated in china. the similar size of the eggs suggests the creature's two oviducts
every produced a unmarried egg at the same time. girl birds can bias the sex in their chicks .-- whether a hen is much more
likely to put a male or lady egg relies upon on which sex may have the greatest hazard of doing properly. rutstein et al. (2004)
adjusted the meals intake of female zebra finches [see photo of female (left) and male (right) Zebra Finches below right] &
discovered that properly-fed females had been much more likely to supply daughters, at the sam. Male Enhancement

14. Supplements Uses time as much less well nourished birds have been much more likely to have sons. this is precisely as
expected by way of the fact that girl offspring need to be better nourished than males if they're to live to tell the tale and
develop properly. the authors referred to that: “in most animals sex ratio is near 50:50 and extremely proof against
change. in mammals, inclusive of humans, the intercourse of the child is decided by using whether or not the sex
chromosome in the sperm is male or lady. however in birds, it is the female’s eg. Male Enhancement Supplements Uses
as opposed to the male’s sperm that determines what sex the chick will be. as a consequence the woman has the
capacity to decide the intercourse of her young by means of whether she ovulates male or female eggs. in a few manner,
woman zebra finches seem with the intention to exert control over whether to produce a male or female egg relying on which
of the two is maximum likely to achieve success. our studies tells us that they do it, and we apprehend why. the huge query
is: how do they do it?â€​ in lots of animals, ladies need to be properly-nourished and in properly condition if they're to
reproduce, as eggs are pricey to supply. bigger eggs have a tendency to cause larger younger which are more likely to
survive. such ‘intercourse ratio adjustment’ is properly documented in certain insects, which includes bees and
wasps, however is much less well understood in birds and mammals. birds are an first-rate model to apply in the look at of
intercourse ratio adjustment due to the fact, the usage of molecular techniques, scientists can set up the sex of each egg
soon after laying. in addition, all the assets given to the developing embryo are present in the egg at laying. therefore the size
and the content material of the egg are measures of the amount of resources that the girl has allotted to that egg, which
impacts its subsequent survival probabilities. the authors explained: “we manipulated the weight loss plan quality of
zebra finches to examine the consequences of frame circumstance on female funding. we discovered that girls have been
capable of exert a sturdy diploma of manipulate over the production of male and woman eggs. when females have been fed
on a low first-class weight-reduction plan, they laid eggs that have been considerably lighter than those laid after they have
been fed on a excessive quality weight loss program, and they also laid a ways more male eggs on a low satisfactory weight
loss plan. that is the converse situation to that described 30 years in the past for mammals, however it makes feel for zebra
finches. previous studies has shown that below poor dietary conditions, girl zebra finches grow greater slowly and continue
to exist less nicely as compared to men. consequently, ladies are generating greater of the intercourse with the very best
survival chances under the ones situations.â€​ two potential mechanisms for intercourse determination among birds. (a) the
presence of the w chromosome triggers femaleness or (b) the presence of two z chromosomes confers maleness. avian
intercourse dedication (ellegren 2001) -- the molecular determinants in the back of sexual improvement in birds continue to
be a thriller. the technique is known to be unique from that during mammals, with no homolog to the gene that confers
maleness in mammals determined in birds. the failure to identify such a gene in birds is probably a reflection of the truth that,
despite the occurrence of sexes being almost conventional at some stage in the animal country, the genes concerned seem
actually unrelated amongst metazoan phyla. those differences enhance boundaries for comparative or candidate gene
techniques in studies of sexual development. in birds, ladies are the heterogametic sex, with one reproduction every of the z
and w sex chromosomes. males are homogametic (zz). however, it isn't clear whether it's miles the presence of the woman-
precise w chromosome that triggers female improvement, or the dose of z chromosome that confers maleness. an intriguing
additional opportunity is that each z and w count number! in marsupials, as an instance, y acts as a dominant testis
determining chromosome, at the same time as the x chromosome determines the selection between pouch and scrotum.
maybe a system in which the two sex chromosomes mediate special aspects of intercourse differentiation is likewise utilized
in birds. vertebrate sex dedication systems. phylogeny of essential vertebrate clades displaying the sex determining systems
observed in members of the respective clade. ‘multiple’ suggests involvement of more than one pair of chromosomes
in sex willpower. tsd: temperature-based intercours. Male Enhancement Supplements Uses determination (from: ezaz 2006).
incubation temperature and avian intercourse ratios -- even though not unusual in reptiles, incubation temperature has now
not been considered to be a aspect in determining intercourse ratios in birds. however, goth and sales space (2005)
observed that incubation temperature does affect sex ratios in megapodes, which can be high-quality amongst birds because
they use environmental heat sources for incubation. within the australian brush-turkey (alectura lathami ), a mound-building
megapode, greater adult males hatch at low incubation temperatures and greater women hatch at high temperatures,
whereas the share is 1:1 at the average temperature located in natural mounds. chicks from decrease temperatures weigh
much less, which in all likelihood influences offspring survival, however aren't smaller. megapodes possess heteromorphic
intercourse chromosomes like other birds, which eliminates temperature-dependent sex dedication, as defined for reptiles, as
the mechanism at the back of the skewed intercourse ratios at high and coffee temperatures. as an alternative, goth and
sales space (2005) propose a intercourse -biased temperature-sensitive embryo mortality because mortality was extra at the
lower and higher temperatures, and minimum on the center temperature wherein the intercourse ratio changed into 1:1.
copulation & fertilization: for maximum birds, copulation entails a 'cloacal kiss', with the male on the lady's lower back &
twisting his tail below the female's copulation commonly lasts only some seconds (but there are exceptions - see phony
phallus puts sperm beforehand in chook first beneath) white-throated kingfishers mating. phony phallus places sperm
beforehand in fowl first -- "those birds might be at it for 10-20 mins," said co-author tim birkhead of the pink-billed buffalo
weaver. males use their organ to rub women and enhance their sperm's hazard of achievement. few male birds have a
phallus; most obtain fertilization via a cloacal kiss. so nineteenth-century reports of a mock member within the buffalo weaver
sent winterbotton et al. (2001) to namibia. catching the birds within the act turned into tough, recounts birkhead: "in 3 years
we noticed eight matings." pairs once in a while emerged from nests and flew to a nearby tree. "i might run after them,
sweating profusely with my binoculars steaming up," he says. the pair might start bouncing up and down - over severa
consecutive bouts. compared to the 1-2 second tryst of maximum birds, their staying energy is unique. yet, access of the
elusive organ became difficult to make out. even in captivity "they accomplished superbly," but the view become blocked,

15. says birkhead. so that they glued a bit of cardboard to an unlucky bird's member. this did now not save you mating,
suggesting that the buffalo weaver organ is genuinely a weapon in sperm wars. through selecting a male who rubs longest or
quality, women may be deciding on pinnacle-best sperm. paternity checking out discovered that girl buffalo weavers sire
birds from multiple adult males, supplying proof of sperm opposition. time spent dating ought to be proven to expect sperm
transfer or success to absolutely again up the idea. the 1.five-cm appendage lacks blood vessels and has a twisted furrow
down its duration. males in communal nests have longer ones than people who live alone, displaying that length is a factor in
social achievement. but for men as a minimum, the phallus is for greater than foreplay. -- helen pearson, nature technology
replace. source: www.nature.com/nsu/010719/010719-four.html# phalloid organ of a male buffalo weaver (image source:
hyperlink.springer-big apple.com/hyperlink/provider/journals/ 00265/contents/01/00384/supp/fig_s4.jpg) males in a few
species, together with maximum waterfowl & ostriches (see diagram beneath), have an intromittent organ; maximum men do
now not. diagram of the left lateral view of a retracted and erect phallus of a male emu or rhea. the pinnacle drawing
represents the phallus within the pouch. a. vas deferens, b. urideum. Male Enhancement Supplements Uses c. proctodeum,
d. pocket to contain phallus, e. erectile wall of phallus, f inverted hole tube of phallus, g. phallic sulcus, h. erectile tissue, and
i. erect phallus with blind hole tube. (source: http://www.cassowary.com/workshop.html) examples of genital covariation in
waterfowl. (a) harlequin duck ( histrionicus histrionicus) and (b) african goose ( anser cygno > = higher and decrease limits of
the vagina (from: brennan et al. 2007). eversion of a male muscovy duck penis. explosive eversion and practical morphology
of the duck penis -- coevolution of male and woman genitalia in waterfowl has been hypothesized to occur thru sexual
warfare. this hypothesis increases questions about the useful morphology of the waterfowl penis and the mechanics of
copulation in waterfowl. brennan et al. (2010) used excessive-pace video of phallus eversion and histology to describe for
the primary time the practical morphology of the avian penis. eversion of the 20 cm muscovy duck penis is explosive, taking a
mean of zero.36 sec, and attaining a most pace of one.6 m sec −1 . the collagen matrix of the penis may be very thin and no
longer arranged in an axial-orthogonal array, resulting in a penis this is flexible when erect. to tes