Following on from my last post, I wondered exactly how many pigeons could be supported with some of the most common fast food items. In order to calculate this, we need to know the calorie requirements of the average pigeon. Rough estimates place this at around 80-100 calories per day.  It can be hard to give an accurate figure as requirements change with age and breeding status. Clearly there are many macro and micro nutrients required by all living creatures to thrive, however, when considering calorific requirements, it is possible to easily calculate the number of birds a food item could support.

Would you like fries with that?

Pigeons are adaptable birds and will try most things once. The question is, how does this effect their productivity?

The big mac burger contains 490 calories, enough to provide sufficient calories for around five adult pigeons.

Similarly, a large fries contains 330 calories, supporting three adult pigeons.

Given the high calorie density (a measurement of the average calories per weight) of fast food, it is not difficult to imagine that large flocks could be maintained with only a small volume of such food available.

A large fries contains 330 calories, supporting 3 adult pigeons.

However, avian fat metabolism appears to work differently. The majority of stored fats, such as that stored in the muscles called upon for sustained bouts of flight, is composed of fat produced by the liver from assimilated carbohydrates. In fact, studies of pigeons injected with a glucose solution showed rapid fatty acid production, with all glucose metabolised by the liver within 15 minutes.  The addition of a large quantity of fat to the diet actual reduced the fat synthesised by the liver, potentially reducing the stores of fat available to the bird.

Therefore, could the high fat content of modern fast food actually be reducing feral pigeon productivity, despite offering greater ease in meeting calorie needs? Or will natural selection result in pigeons with modified fatty acid synthesis?

106.5 million pigeons could be sustained by customers dropping just a quarter of each burger sold.

As a side note, in 2010 87 million big macs were sold. If only a quarter of each of these burgers was to be dropped on the floor, 106.5 million pigeons could be sustained for a day!

Patterns of Lipid Storage and Utilization in Birds, Charles R. Blem. American Zoologist , Vol. 16, No. 4, Lipids in Animal Life Histories (Autumn, 1976), pp. 671-684