WHERE ARE THE CHECKERS AND SPREADS?

Distribution of Melanic Pigeons
by Melinda S. LaBranche

Project PigeonWatch participants are helping to answer the question "What is the distribution of pigeon color morphs?" In Europe, dark-colored pigeons are more common in the cool northern latitudes than in the warm southern latitudes. Perhaps this is because dark colors help the birds to absorb more heat from the sun. Is this the same pattern we see in the U. S.?

For each flock they observe, Project PigeonWatch participants record the numbers of pigeons of each of seven color morphs and the total number of pigeons in a flock. From these data we can calculate the proportions of each color morph and examine the distributions of those proportions over large areas. Checker and spread color morphs are called "melanic" because of their black-colored melanin pigments in their feathers. All flocks in the data set had at least one melanic pigeon, so I examined the distributions of melanics by latitude and longitude for 110 pigeon flocks across the country.

Flocks at high latitudes (northern) and high longitudes (western) had higher proportions of melanic pigeons than flocks in the southern and eastern U.S. The distribution of melanic pigeons can be seen in the figure above. The sizes of the red circles indicate the relative proportions of melanic birds in a flock-notice that the largest circles (and thus the largest proportions of melanic pigeons) are in the Northeast and in California.

Since white pigeons are able to "reflect" some of the sun's heat, you might expect to have more white pigeons in the south. I examined the proportions of white pigeons in these 110 flocks and did not find any significant effect of latitude or longitude.

We might conclude that a pigeon's home city and its color will affect how well it survives and reproduces. Over time, dark pigeons in the north may have more offspring than dark pigeons in the south, causing northern flocks to have high proportions of melanic pigeons. But we have to make this conclusion with caution because this is a very small sample. As you can see from the map, there are many cities and states that are not represented in the data. Even in each city we do not have data from all of the flocks.

WE NEED YOU-we need data from more flocks and from more cities and states!! Join thousands around the world in PigeonWatch and help us unravel this color morph mystery.