One of my biggest fascinations when it comes to feral pigeons, is the wide variety of plumage types they show. The plumage a pigeon shows, is known as its phenotype and the genetics behind the plumage is known as its genotype. When we consider most other species of bird, such as starlings (Sturnus vulgaris) all adult birds appear to be a similar colour, yet feral pigeons come in a wider array of different colours and patterns.

Blue bar

This pigeon shows the blue bar phenotype – this is the closest to the wild type phenotype shown by the rock dove

Feral pigeons are descended from domesticated pigeons, that have escaped and learned to live in the wild once more. Through domestication, a wide variety of different colours and shapes were produced from the grey ‘blue bar’ colouration of the wild rock dove the domestic pigeons were produced from.

The differing plumages feral pigeons display not only look beautiful but are very interesting to scientists. Most feral animals (animals living wild but descended from domestic stock) when free to choose their own mates and to breed freely, over time, eventually come to resemble the ‘wild type’ phenotype. Many people believe dingos ( Canis lupus dingo) once derived from ancient domestic dogs, have undergone this process (known as reversion) to become the uniform sandy colour they now show.  Although feral pigeon flocks are often supplemented with escaped fancy and racing pigeons which may be of a range of colours, it is thought that the proportion of non-wild type coloured pigeons in feral flocks could not be maintained by addition of these birds to the gene pool.

This checker pigeon can be identified by the specks of dark colour on the wings, this is different from the blue bar shown above. 

There are many theories as to why this variation is maintained or why this variation shouldn’t be maintained, and I hope to be able to look into these further:

1) Predation – Many believe that avian predators tend to target the ‘odd one out’ in a flock such that a white bird in a flock of grey birds may make an easy target. If this is the case, this should impose a selective pressure against these non wild type plumages. I hope to investigate this issue further to see if this is true.

2) Mate selection – It is thought that pigeons may use plumage colour as a means of choosing a mate. Mating with individuals different from oneself is a good method of preventing inbreeding. If this is the case, what criteria do the birds use when selecting a partner?

3) Fitness advantages – It is thought some plumage phenotypes show improved fitness, however, if this is the case it may be thought that non wild type plumaged birds should make up a greater proportion of the population than they actually do. Or, could it be that an equilibrium has been reached with any fitness advantage being balanced by a possible fitness disadvantage in terms of predation risk?

Red

The red phenotype is surprisingly common given how different the birds look when compared to the wild type birds

These are just a few of many questions to be asked on plumage variation in pigeons and I believe we have a lot to learn.

In order to look into these questions I’ll be needing YOUR help.  I’ll be posting for help on this blog really soon.

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