Volume 45, Number 2, December 1998:
Feral Pigeons

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ABOUT THIS ISSUE
- about KSN
- about the author

IN THIS ISSUE
- introduction
- origin of feral pigeons
- basic plumages
- mate choice and plumages
- advantages of different plumages
- advantages of choosing different mates
- breeding seasons
- reproducative data
- brood reduction
- living in colonies
- commuter pigeons
- relationships with people
- reference

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Updated: March 9, 2005
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Feral Pigeons
by Richard F. Johnston

ADVANTAGES OF DIFFERENT PLUMAGES

Aside from selective mating, special advantages are associated with some pigeon colors and patterns. These advantages are held only by ferals. As shown in an exhaustive review of the literature by my colleague Marian Janiga, the advantages are superior reproduction and lengthened lifespan, depending on the environment. Perhaps as a consequence, under essentially wild conditions, ferals are far superior in survival or reproduction to domestic stocks, and at certain European study sites, also to wild rock doves. Ferals may be considered "superdoves."

One of the most important advantages associated with plumage variation in ferals is increased reproductive output. This is a complex relationship and depends on environmental conditions. In suburban or rural environments, blue bar individuals produce more offspring per pair than the melanics. Conversely, in central city environments, melanics outproduce blue bar birds. Blue bar individuals usually occur in small breeding and feeding aggregations, melanics in large ones. Blue bar birds commute greater distances to outlying districts for daily feeding than melanics. Very few inner city pigeons are blue bars, but they are much more common at city margins. Some big cities show a smooth gradient of increase in frequency of blue bar birds from the inner core to the suburbs (Figure 6).

Such gradients in plumage distribution are apparently due to gradients in reproductive characterisitcs. In Britain it has been shown that melanic males have larger testes and more spermatozoa in their tubules than blue bar males. And large melanic females in Kansas wait less time between clutches and thus have a high annual reproductive, exceeding that of blue bar females of any size. Melanic birds of both sexes have a much longer period of annual sexual activity than pigeons in other plumages, and they are responsible for most of the wintertime reproduction of ferals. Melanic squabs, or "baby" birds, have superior early development - they hatch from larger eggs and have more rapid growth than blue bar squabs. We also know that blue bar males are especially successful in defending their breeding sites from intrusion and disturbance by other pigeons. Both sexes of blue bars are more attentive at nests and provide better parental care than birds in other plumages.

Advantages and disadvantages are thus distributed irregularly among the plumages, but sort out in such a way that melanic pigeons do well in cities and blue bar pigeons do well in the suburbs and on farms. The differences are to some extent tied to differences in population densities between inner urban and suburban sites. Even so, why the superior parental care of blue bar birds is not an advantage under high density is an unsolved mystery. However, mate choice of females will maintain a wide range of colors and patterns regardless of location.