Posts Tagged ‘Ted Anderson’

Adaptive Genius

October 14, 2019

This post is based on “The Genius of Birds, a book by Jennifer Ackerman. Ted Anderson in his book Biology of the Ubiquitous House Sparrow writes that the sparrow came into its own as a species only since the advent of agriculture in the Middle East, approximately ten thousand yeas ago. Other theories place its origin yet earlier. In any case, so highly skilled has the house sparrow become at adapting to any environment occupied by humans that it has been called the ultimate opportunist, our avian shadow.

The first sixteen sparrows are said to have been introduced to Brooklyn in 1851 to control a plague of moths may not have taken immediately to the New World, but another bigger shipment imported from England the following year did, and in big way. The birds did get some help from individuals and naturalization societies ban on populating their gardens and parks with plants and animals from the Old World, which accelerated their expansion. Ms. Ackerman writes, “the success of their spread is staggering.” She continues, “The transplants found a land much to their liking, rich in grain and horse droppings. They multiplied and dispersed rapidly, spilling into farming districts, where they exploited every source they could find—grains, small fruits, and succulent garden plants, such as young peas, turnips, cabbage, apples, peaches, plums, pears, and strawberries. Soon they were considered a serious pest. In 1889, just a few decades after the house sparrow’s introduction sparrow clubs were formed with the sole objective of destroying the birds, and county and state officials were offering two cents a head for each sparrow killed.

Before long, the birds had spread across the United States and Canada, adapting to environments as extreme as Death Valley, California at 280 feet below sea level, and the Colorado Rockies at more than10,000 feet above sea level. They moved southward into Mexico through Central and South America as far as Tierra del Fuego, and along the Trans-Amazonial Highway deep into the rainforests of Brazil. In Europe, Africa, and Asia, they dispersed to northern Finland, the Arctic, South Africa, and clear across Siberia.”

The house sparrow is the world’s most widely distributed wild bird, with a global breeding population of about 540 million. It’s on every continent except Antarctica and on islands everywhere, from Cuba and the West Indies to the Hawaiian Islands, the Azores, Cape Verde and New Caledonia.

So what accounts for the success of the House Sparrow? Daniel Sol and Louis Lefebvre decided to see if brain size and intelligence might have anything to do with its success. When they studied the characteristics of the nineteen introduced species that “took” and those that failed to establish, two pronounced differences emerged, The more successful invaders have larger brains. They also had more innovative, flexible behavior of the kind Lefebvre documented in his avian IQ scale.

The pattern held when Sol later looked at 428 bird species that invaded areas around the world. Successful colonizers were brainy and inventive. Well represented among the intruders were the corvids; the house crow in Africa, Singapore, and the Arabian Peninsula; the jungle crow in Japan; the common raven in the American Southwest. All are big brained and considered pests in the regions they have invaded.

According to Ms. Ackerman here is a recipe for the house sparrow’s success:
*A taste for novelty
*A pinch of the innovative
*A dash of daring
*And, perhaps, a penchant for hanging out in mixed gangs

One wonders whether these traits will help the house sparrow cope with global warming. The 2014 Christmas Bird Count in Seattle totaled just 225 house sparrows within the city limits. Freeman says, “That’s the lowest total ever, and one piece of evidence that house sparrows may be declining. Around the globe, the bird is experiencing rapid and massive declines—in North America, Australia, and India, but especially in some towns and cities across Europe.

According to Vladimir Pravosudov, if the weather is warmer, winter will provide less selection pressure, so the birds may lose their edge, in both hippocampus size and intelligence. “If maintaining better memory has costs,” he argues, “smarter” birds will be at a disadvantage. Also, these populations will be quickly invaded by more southern, not-so-smart birds, which will lead to overall reduction in cognitive ability.”