Archives for posts with tag: Bird

As scientists, it is often said that we shouldn’t interfere with the natural order of things. However, when endeavouring to discover more about a species or habitat, it is inevitable some human interference will occur. Just your presence or the presence of equipment may impact any data received.

Then there is the dreaded word, compassion. I don’t believe it is ‘soft’ for even a hardened professor to see an animal in distress and feel the need to help. Now, I’m not suggesting we all intervene with lion kills or nest predation, but there are times when compassion rules science.

Such a situation occurred when I was counting pigeon phenotypes in a local town. Dodging the traffic in a busy car park was a young pigeon that had clearly fledged too soon. Lost and in danger of being run over, compassion told me I had to help, so I offered the hand of compassion to another being.

I’m pleased to say the youngster is doing well, gaining wait and is full of beans. He will of course be added to the data set for his area before release!


Time for a quick update…

So far we have details of 242 individual pigeons from 4 locations. Early results are certainly interesting!

Of these pigeons, 62 show the blue bar (wild type) plumage, but 112 show individuals show the chequered (or check) plumage. This is interesting as the blue bar phenotype is dominant over the chequered phenotype. It would be more likely that a blue bar plumage would be inherited and expressed in an individual than the chequered plumage, so these results are not consistent with this. It may be that having a chequered plumage may be more beneficial to an individual than a blue bar plumage.

Clearly, these results could be due to lack of data – hopefully more results will bring greater clarity.

So, if you’re out and about, please count your pigeons!

For more info, please see my last post: Let’s get pigeon spotting!

Thanks again to those that have sent in their results.

Pigeons appear to have an uncanny ability to defy all attempts at eradication by people who mistakenly believe they are a risk to human health.  In order for a population to remain stable, each pair need only produce two surviving offspring to eventually replace themselves. However, no individual can know the probability of any of its offspring surviving and therefore, must attempt to produce as many offspring as it can. Feral pigeons show iteroparity, that is, multiple breeding attempts over a life time and are known to pair for life. As R selected organisms, feral pigeons can respond quickly to favourable circumstances, producing offspring in a short space of time, which in turn can breed within 6 months.  In fact, the strong pair bond of adult birds allows clutches to overlap, with the female sitting on a new clutch of eggs whilst the male tends to the newly fledged youngsters.  Clearly, this highlights the very reason lethal control methods are ineffective.

Young feral pigeon

Feral pigeon youngsters look very similar to the adults – the beak and eyes often give the game away. Youngsters also squeak to the adults, hence young feral pigeons are often referred to as squeakers.

Schein’s 1954 study of feral pigeon recruitment found interesting results. Two sites were studied, a church steeple with multiple nesting platforms and a hospital. Nests were monitored from point of lay to fledging and the number of fledged young was recorded. The majority of the nests on the hospital study site were located within a central heating tower where temperatures remained warm and stable, whereas the ambient temperature of the church site fluctuated,  however, results showed very little difference between the survival probability of both flocks.

Of 152 eggs laid at the church site, 85 hatched, and of these, 47 fledged , giving a fledging probability of 0.309.

Similarly, of 293 eggs laid at the hospital site, 149 hatched and of these, 83 fledged giving a fledging probability of 0.283.

Given that temperature was shown to have little effect on the fledging probability of individuals of either flock and that both flocks showed similar figures, it can be suggested that other causal factors are involved.

Which brings me to the strange title of this blog…

Given the r selected nature of feral pigeons, food is a factor in the rate of offspring production, so I wonder how the changing face of the human diet affects this rate.

The fact that we are eating greater amounts of fast food is not in question, obesity levels have rocketed since this study was conducted. In 1950, 9.7% of Americans were obese, compared to 30.5% today.  Has the food available to feral pigeons today subsequently increased in both quantity and calorific content? If this is the case, what effect has this had on the probability of offspring fledging today in comparison to those in 1950?

A repeat of this study today may yield interesting results as it may be found that our increasing demand for higher calorie, convenience foods is causing a subsequent increase in one of the most adaptable species on the planet.


Schein.W (1954) Survival records of young feral pigeons, The Auk,  Vol. 71, No. 3 (Jul., 1954), pp. 318-320