Backyard birds

I just glanced in my backyard, and saw:

• about ten dark-eyed juncos
• a downy woodpecker at the suet feeder
  
• three cardinals
• something that may have been a red-winged blackbird, but I didn't get a good look
  
• a couple large sparrows with brown stripes along the breast
  
• and three blue jays, doing their best to scare all the others off
  

I had always thought blue jays and cardinals were the same size, but seeing them next to each other, the blue jays are huge. So I sat down and typed this up, and in that time, the sparrows and maybe-blackbird are gone, but a European starling is monopolizing the suet feeder. The jays don't seem to care about the starling, but the woodpecker, who's maybe half its size, is clearly not thrilled at having lost his spot -- he's hopping along the pole the feeder's hanging from, watching the starling.

The conquest of the suet feeder is actually pretty typical of European starlings. They were introduced to North America a little over a century ago by a guy who was trying to bring every species of bird mentioned by Shakespeare to New York City -- clearly not a project for your everyday madman -- but who unfortunately never hit on the idea of putting the birds in the zoological garden that opened the same year. At the time, the dynamic and interdependent nature of, well, nature was not well understood, and it was the thing to do to make wherever you settled a bit more like the old country. So a hundred or so starlings in Central Park have, in the past century, spawned a current population of around two hundred million throughout the continent. And everywhere they go, they succeed at the expense of native birds: they eat anything, and they've been known to literally push other birds out of their nests if the space is nice. For example, starlings like the hollow space that woodpeckers carve out of a tree for themselves, so out goes the woodpecker.

Essentially, the starlings have spammed their corner of the biosphere. This happens naturally all the time, and it's no cause for concern -- just another example of a species finding itself in a new environment and surviving by being the fittest around. Evolutionary challenges lead to biodiversity and biodiversity leads to healthy ecosystems. But in cases like this, caused by our own imperfect understanding of the world, it is a problem.