I started raising and flying pigeons in June 2007 and created this website to share my research and my experience about pigeons. I was very reluctant, however, to start writing about pigeon genetics because it can be a very complicated subject to most people. I am a computer science teacher and biology has always been one of my favorite subjects. I am neither a scientist nor a geneticist, I am just a curious, albeit serious, pigeon breeder and I would like to understand as much as I can about my hobby to produce better quality offspring. I have been experimenting with genetics, but most of the information on this page comes from research I've done on the internet, books, and my interaction with other pigeon breeders. This is not a comprehensive work intended to cover all aspects on the subject of pigeon genetics, but instead help pigeon fanciers understand how genetics work. My intentions are simply to explain the basics of pigeon genetics to fanciers, so they can more appreciate the hobby and breed a better quality of pigeons and colors that they like. I am hoping that it will help some of you better understand your hobby and answer some of your questions.

“We cannot say that expertise in Genetics is essential to success in showing, racing, or even squab farming. Some understanding however can be helpful and gratifying. But like all science, Genetics is never finished: the pigeons will continue to give us mysteries for solutions. Any fancier may discover something that is beyond our knowledge, and the fancier may even discover the answer. Generally we are not adequately prepared to pursue the myriad problems that arise, but perhaps collaboration will develop. Pigeon Genetics News Letter, and its successor, Pigeon Science and genetics Newsletter, have been leading the way, trying to keep up communication. Other periodicals have also been helpful” (Willard F. Hollander, Origins and Excursions in Pigeon Genetics, p. 3).

Basic Genetics

In order to better understand the pigeon genetics you have to understand basic genetics and genetic terms first. I think it would be easier to start with human genetics that we are most familiar with then transit into pigeon genetics like mutation, colors, and patterns, etc.

We are all made out of cells, and each cell in the human body contains about 25,000 to 35,000 genes. Genes are a set of instructions that decide what the organism is like, how it survives, and how it behaves in its environment. Genes carry information that determines each person’s traits. Traits are characteristics humans inherit from their parents, such as the color of the hair, the color of the skin, the color of the eyes, likelihood to develop certain diseases etc. All living things have genes.

Genes are all lined up on thread-like things called chromosomes which come in pairs, and there are hundreds, sometimes thousands, of genes in one chromosome. The chromosomes and genes are made of DNA (left picture), which is short for deoxyribonucleic acid. DNA molecules are the long-term storage of information that is often compared to a set of blueprints or a code, since it contains the instructions needed to construct other components of cells. The DNA of humans is composed of approximately 3 billion base pairs, making up a total of almost a meter-long stretch of DNA in every cell in our bodies.

In humans, a cell nucleus contains 23 pairs of chromosomes, which are 46 individual chromosomes. Half of these chromosomes come from one parent and half come from the other parent. But not every living thing has 46 chromosomes inside of its cells. A pigeon has 40 pairs of chromosomes, which means pigeons have 80 individual chromosomes.

Each gene has more than one form of expression. For instance, an eye color gene can have the two different forms of expression of orange eyes or bull eyes in pigeons. These forms of expressions are called alleles or allelomorphs. Each pair of alleles generally has a dominant allele and a recessive allele. In the presence of the dominant allele, the recessive allele does not express itself. The only time that the recessive trait will be seen is when both of the alleles are recessive. In genetics, dominance describes a relationship between different forms (alleles) of a gene at a particular physical location (locus) on a chromosome. Typical plants and animals have two sets of chromosomes, one set inherited from each parent, and are described as diploid. They, therefore, have two alleles, each from one parent, at each gene locus. The offspring of crosses between parents with different traits are called hybrids.

Genotype is the term used to describe the genetic makeup, as distinguished from the physical appearance, of an organism. The genotype determines the hereditary potentials and limitations of an individual. Among organisms that reproduce sexually, an individual's genotype comprises the entire complex of genes inherited from both parents. Sexual reproduction guarantees that each individual has a unique genotype. Phenotype is the observable physical or biochemical characteristics of an organism, as determined by both genetic makeup and environmental influences. In other words, phenotype is the expression (the actual trait that we see) of a specific trait, such as "ash red" color in pigeons. Phenotypes result from the expression of an organism's genes as well as the influence of environmental factors and the interactions between the two.

When the two alleles at the same gene locus are identical, the individual is called a homozygote for that trait and is said to be homozygous; if instead the two alleles are different, the individual is a heterozygote and is heterozygous. When the trait is homozygous, the phenotype is what both alleles represent. If it is heterozygous, then the two alleles interact, and the dominant one is the one that shows as the phenotype. Hemizygous gene has no allelic counterpart or is present as only a single copy instead of the usual two copies in a diploid cell or organism. In other words, a gene wherein one of its pair is deleted is a hemizygous gene. In another example, most of the genes of the X chromosome and Y chromosome in human males are hemizygous since males have only one X chromosome (and one Y chromosome) (unlike females that have two X chromosomes).

An autosome is a chromosome that is not a sex chromosome – that is to say there are an equal number of copies of the chromosome in males and females. In humans, there are 22 pairs of autosomes, and in addition there are X and Y chromosomes which are sex chromosomes. In the picture shown on the right, two chromosomes X and Y, are used to represent and determine the sex of a human offspring. Male is represented by two distinct sex chromosomes X and Y and they are called the heterogametic sex. Females have two of the same kind of sex chromosome X and X, and they are called the homogametic sex. In reproduction, each parent submits one chromosome for the child. If the male sperm that joins the egg happens to contain an X chromosome, then it will join from the X of the mother, making the child female (XX). But if the male sperm that joins the egg happens to contain a Y chromosome, the child will be male (XY). In this manner, parental genes decide whether the offspring will be male or female. This also means the gender ratio in humans is 50% male and 50% female. It is very important to understand that in humans, the male's chromosomes determine the sex of the offspring.

In pigeons, the female's chromosome determines the sex of the offspring because female pigeons are hemizygous for feather color, hence carrying only one feather color. Genetically, all male pigeons carry two feather color alleles, one we see and one that is hidden. The dominant color is the one that is expressed (that we see, assuming the bird is heterozygous for color). Females on the other hand, carry one feather color and one empty feather color allele. This means every female pigeon carries only the color that we see on the outside. This is very important to understand because unlike humans, the sex of the offspring is determined by the female's chromosomes. Cock birds carry two feather colors, and will donate one of them during mating. If the hen donates the color she carries, then the offspring will have two colors, each donated by a parent, and will make that bird a cock bird. If the hen does not donate a color (the empty allele), the offspring will have only one color, donated from the father, and will be a hen. Pigeons have no external sex organs so it's often difficult to tell male from female. But if we know the pedigree of the father and the mother of the offspring, and if they are sex linked, we can tell the gender of the offspring by its color. In birds the sex chromosomes are labeled as Z and W. A cock (male bird) always inherits a Z chromosome from each of his parents resulting in a sex chromosome set or pair of two Z’s. ZZ is the symbol to represent a cock bird. A hen (female bird) on the other hand is represented as ZW as she gets Z from her father and W from her mother, which has no know gene located on W chromosome. You will understand why this is so important in the next page when I explain the pigeon colors and sex-linked mating among pigeons.

How are traits passed from parents to offspring? They are passed from parents to their offspring through reproduction during gene transmission, where offspring inherit one allele for each trait from each parent. The principles that govern heredity were discovered by a monk named Gregor Mendel (picture on the left) in the 1860's. He was an Augustinian priest and scientist, who gained posthumous fame as the figurehead of the new science of genetics for his study of the inheritance of certain traits in pea plants. One of these principles is now called Mendel's law of segregation. This law states that during the production of gametes the two copies of each hereditary factor segregate so that offspring acquire one factor from each parent, thereby ensuring that offspring have a combination of the parents' genes. Instead of nearly identical copies of an organism, a broad range of offspring develops, allowing more different abilities and evolutionary strategies. This is very important for life to continue and create variety of individuals each time a new offspring is born. Because of this law we all look different, and we all have different traits to carry and pass on to our offspring. In other words, the segregation is essential to why the traits do not "blend". The varying dominance of different genes causes some traits to appear unevenly instead of averaging out (whereby dominant doesn't mean more likely to reproduce - recessive genes can become the most common, too). In addition, segregation explains how recessive alleles that have no immediate effect on phenotype, can continue to be inherited for hundreds of generations. The segregation is essential for continued existence of "variation" but not a trending towards uniformity. The law of segregation is also very important for pigeon breeders to understand the possible results when they breed their birds. This is how we could get brown birds from two ash red parents, or a crested offspring from two non-crested parents.

The Pigeon & Human Interaction

Studies show that the lifespan of a feral pigeon is only to 3 to 5 years in the “wild”. With proper feed and care, pigeons can live 15 years or more in captivity. The oldest recorded pigeon was around 33 years. Pigeons reach sexual maturity at 4 to 6 months. Feral pigeons mate for life, unless they are seperated for some reason. They usually build flimsy nests using sticks and twigs they collect from their environment. The average clutch consists of two white eggs, which are incubated for about 18 to 19 days by both parents. The parents take turns keeping their eggs warm (incubating). Incubation is not equally shared, since the hen does most of the work on each day. Only when she leaves the nest, the cock assumes the duties. They are excellent breeders and may produce up to 8 clutches each year under optimal conditions. The frequency of breeding is dictated by the abundance of food. Unlike most other birds, doves and pigeons produce "crop milk", which is secreted by a sloughing of fluid-filled cells from the lining of the crop. Both sexes produce this nutritious ‘pigeon milk’ which is regurgitated and fed to the young. A chick can double its birth weight in one day. The eyes open when the chicks are about four days old. At approximately 2 months of age the young are ready to leave the nest. The young doves and pigeons are called "squabs".

Pigeons are amongst the most intelligent birds. In fact, according to a study conducted by the University of Montana, "the pigeon" is one of the smartest, most physically adept creatures in the animal kingdom. Pigeons have featured in numerous experiments in comparative psychology, including experiments concerned with animal cognition, and as a result we have considerable knowledge of pigeon intelligence. Pigeons have been credited with having similar levels of 'intelligence' as those found in a three-year-old child, a study from Japan has claimed. The pigeon could discriminate the present self-image and the recorded self-image of the past with a few seconds delay, which means that the pigeon has self-cognitive abilities. This ability is higher than an average human three-year-old. Self-recognition - or the mirror test - is common amongst chimpanzees, dolphins and elephants. Pigeons have complex emotions, and each pigeon has a unique personality. Some are social, some are loners. Some are friendly, some are hostile. Some are curious, some are timid. Some are aggressive and competitive, some are fat and lazy. Some are true performers, and some only perform to impress females. Some males fight for females, some are not interested in mating. Some are great parents, and some should not be allowed to be parents...I can't help but wonder? Do pigeons behave and show characteristics like humans? I definitely think so.

So, when did pigeons and humans first interact? The first images of pigeons found by archaeologists in Mesopotamia (modern Iraq) date back to 3000 BC. In all the ancient civilizations, from early Mesopotamia through Greece, Egypt and Rome rock doves had their admirers, breeders and keepers. Once man started city states between the Tigris and Euphrates, a lot more grain was needed to be grown and harvested than it used to be to feed all the citizens of the city. The rock doves took advantage of that extra seed and grain found around the cities and bred more profusely. We know that pigeons will continue to breed as long as a good food supply is available. Man in turn, took advantage of the rock doves themselves and climbed the cliffs and rocks to collect the eggs and squabs for food. Although a fairly timid bird in the wild, if taken when young, pigeons showed a tendency to be domesticated providing a regular source of food during difficult times. It was the Sumerians in Mesopotamia that first started to breed white doves from the wild pigeons. Pigeons have been domesticated for thousands of years for their roles in human lives as symbols of gods and goddesses, sacrificial victims, messengers, pets, food and even war heroes. Pigeons and doves have been immortalized in poetry and prose, music and art.

The white pigeons have been recognized as a symbol of love, peace and a new beginning. In many cultures, white doves represent the Holy Spirit and the soul and are further symbolic of hope, innocence, tenderness and purity. Ancient and modern civilizations fly white doves in ceremonies celebrating devotion, partnership and fertility. In a lot of Middle Eastern countries the pigeon droppings were used as a fertilizer and later as gun powder by the Turks. The rock dove’s ability to find home from a distance was noticed by man quickly and they have been kept for sending messages back home from war zones and distant cities. The ones which have the more talent and the body type to come home fastest have been interbreed to produce better quality birds for generations. Man has always been a collector and quick to spot the unusual, so he would have noticed the odd white feathered bird and as time passed these odd birds would have been spared and then interbred to produce more varied and unusual birds. After many years of domestication and man's selective breeding, variety of talents (fast flying, endurance flying, tumbling, rolling, diving, singing, etc.) various colors, shapes and sizes developed all for human pleasure and needs. Now, all over the world, thousands of pigeon lovers and breeders from all different backgrounds have a great bond of brotherhood because of their common interest - the pigeon.

"Just what it is that makes one love pigeons is hard to analyze. Some seem born with this love an inherit part of them. They acquire their birds in their early youth and never part with them; others commence their rearing at a later period, and either soon part with them or develop into enthusiastic fanciers. There seems to be no middle ground; one either loves pigeons or one does not. That man is fortunate who finds in his breast an inexplicable love for them. To him, is affordable a hobby of immeasurable value. When fortune frowns and when the cares of a harsh or disordered world seem almost too heavy to bear; when the grim reaper has taken some loved one; or when nerves are tense almost to the breaking point, then the pigeon lover finds in his birds a solace and consolation impossible to describe. When, through some temporal triumph, one is prone to be impressed with his own prowess, then again, by contemplating the ways of the pigeon, the great temperer, one is brought back to the norm. The pigeon proves a stabilizer, leveling the depths of depression and the heights of false ecstasy, as he 'keeps the even tenor of his way,' always happy, always devoted, always indifferent to the vagaries and the tribulations of the human soul. The pigeon lover unwittingly absorbs his calm 'philosophy' " (Wendell Levi, The Pigeon, p. 34).

Mutation & Natural Selection

The ancestor to our domestic pigeons, the rock-dove (Columba livia), is considered to be the wild type (the standard against which we judge everything) in pigeon genetics. The Scientific name "Columba livia" is Latin for dove or pigeon; "livia" means blue or blue-gray color. Rock doves originated in Africa, Asia, Europe, and the Middle East. They arrived in North America with European settlers in the 17th-century for food and religious purposes. Because Rock Pigeons in North America (and many other continents) are from populations established by escaped domestic pigeons, we refer to them as feral pigeons. The term "wild" is reserved for pigeon populations that were never domesticated and still live in their native habitats. Columba livia is a blue bar with no crest and has clean legs. The wild type does not have any heavy skin above the beak or around the eyes and has a pale grey color with two black bars on each wing. They have a dark bluish-gray head, neck, and chest with glossy yellowish, greenish, and reddish-purple iridescence along its neck and wing feathers. Females tend to show less iridescence than the males. Pigeons are found almost everywhere on Earth as same type, color and weight; however, they don’t occur in very cold places or in very dry places. There are no native pigeons on the Hawaiian Islands or on the islands of the mid-Atlantic ridge. The genetic symbol for wild type is (+).

Now and then cells make mistakes in copying their own DNA, inserting an incorrect base or even skipping a base as the new strand is put together. These mistakes are caled mutations, from the Latin word meaning "to change". Mutations are changes in the genetic material. But how did we get so many different breeds of pigeons from the rock-dove pigeons? How did we get breeds like jacobins, pouters, barbs and rollers? When and what went wrong for these mutations to happen and adapted in order to survive with the new traits? Did humans play a role to create so many different pigeon breeds?

According to Charles Darwin (picture on the right), this is called the Selection of Traits. In order for existence, survival and reproduction do not come down to pure chance. Darwin realized that if an animal has some trait that helps it to with stand the environment better or to breed more successfully, it will leave more offspring behind than others. On average, the trait will become more common in the following generations. As Darwin studied natural selection, he spent a great deal of time with pigeon breeders, learning their methods. He found their work to be an analogy for evolution. Evolution, or change over time, is the process by which modern organisms have descended from ancient organisms. The highly-varied domestication of Columba livia was Darwin's simple beginning for his theories. The pigeons played such an important part in Charles Darwin's work on genetics and inheritance when he wrote “The Origin of Species". Darwin's case for his theory of natural selection therein has its own simple beginning, and not one having to do with an ancient or exotic organism, but with the species Columba livia, the humble rock-pigeon, that unremarkable denizen of our urban landscape.

Pigeon breeds which are so different from one another, provided Darwin with compelling evidence that the potential for evolutionary change was, in fact, present in a single species, Columba livia. The implication was that, if such variation could be achieved with pigeons by means of breeding choices over the course of human history, then, perhaps, it was not unreasonable to imagine that the enormous variety of the biological world could have been achieved by means of natural processes over the vast expanse of geological time. A pigeon breeder selected individual birds to reproduce in order to produce a front crest. Similarly, nature unconsciously “selects” individuals better suited to surviving their local conditions, because those who are not as well adapted die off when the ones with an advantageous trait may survive, because of that trait. Given enough time, Darwin argued, mutation and natural selection might produce new types of body parts, from wings to beaks. Darwin thought any ancestral population could generate, over time, individuals quite unlike themselves. With more than four thousand years of breeding behind them, domestic pigeons are full of combinations deemed beautiful or useful, or both, by their breeders.

The varieties of pigeons we see today are from the odd mutations that man noticed and liked it, then bred the trait into his flock to intensify it. While man was attempting to create a new breed from an odd mutation, which would normally not have survived in the wild, nature used natural selection to ensure that the fittest and the strongest survived. Mutation and natural selection are not random events. Those mutations that allow the organism to survive and leave more offspring are preferentially accumulated within the gene pool; those that don't are preferentially removed (along with the animal bearing them). Variation in the wild is a necessity that allows for adaptation, which in turn encourages survival. Darwin thought that we don’t see mutations like fan tails, pouters, jacobins, feathered feet and crest in the wild because they would not have survived in the wild on their own. Human played a big role for these mutations to be evolved and perfected over time.

How do we prove that all the fancy pigeons today came from Columba Livia, the rock dove? When Darwin was studying pigeons, and wrote his “The Origin of Species”, he devoted the whole first chapter to the domestication of pigeons. He discovered that if the different fancy breeds are mated, the offspring would eventually lose their distinctive traits and resemble the rock dove. Darwin called this phenomenon “reversion”. According to Darwin, there was no other reasonable explanation for the profusion of fancy pigeons, and he was right. Many pigeon breeders, who have been around pigeons for long time experience a reversion even in a certain pigeon breed, where two distinct colors and patterns are bred and their offspring show the markings and the color of an ordinary rock dove.

The following pictures are few examples of show type breeds that we have today. They are all developed and mutated with the help and careful selection of humans for more than four thousand years of breeding and domesticating the rock doves for variety of reasons. You will notice that some have a longer or shorter beak, some have a front or back crest and some have both. Some have frill feathers or feathers covering their heads (hoods) like the Capuchines and Jacobins, some have fanned tails, some have feathered feet or bigger crops. It is very important to understand that each mutation from the rock dove is independently inherited. If we want, we can have homers with crests or feathered feet. We can also put any color to any breed if we want to. Most of the traits are recessive to wild type and therefore will take 2 or more generations to put in, but they are all possible to put in. In Genetics it is therefore assumed that such traits are separate changes from the original rock pigeon and inherited independently from each other.