Welcome to Superoceras, a blog about science and natural history, slightly biased towards paleontology and zoology, but inclusive of all sciences. Started in October of 2009, my goal is to communicate scientific knowledge (and the occasional piece of nonsense) in an informative and entertaining manner. Feel free to contact me with questions, comments, concerns, or criticism at superoceras(at)gmail(dot)com, and follow me on Twitter @Superoceras for all that and more in 140 characters or less!

Wednesday, May 18, 2011

Problematic passerines.

A breeding pair of Carpodacus mexicanus, also known as house finches.

The house finch, Carpodacus mexicanus, is a little passerine bird that I have a bit of a rocky relationship with.  Don't get me wrong; I love it when any of my "backyard dinosaurs" come to visit the feeders around my house. But I'm still on the fence about these little guys. Now before you label me some kind of finch hater (which I certainly am not), let me explain.  While C. mexicanus is native to North America, it is not exactly native to the east coast, having been introduced to this area from Mexico and the southwestern United States in the 1940s. Populations that were released from illegal captivity quickly became naturalized, and their population has been expanding ever since.  In many places, they have out competed the native species of purple finch, Carpodacus purpureus.  This is a bird that should be at my feeders, but sadly, I have never seen.

But there is an even older threat that faces C. purpureus and other native birds in my area: the house sparrow, Passer domesticus. This Eurasian species was first introduced to the Americas, intentionally, as early as 1850, and has been breeding ever since, making it one of, if not the most abundant songbird in the country.  This is also not good for the native birds, as it competes with them for food and nesting resources, and more often than not, wins.  And all of this is completely ignoring the fact that it is a very aggressive bird as well.  Many may find it hard to believe that the common little brown birds we see hopping about could be a danger to anything.  But I assure you, they most definitely have theropod dinosaur blood coursing through their veins.  Just ask the eastern bluebird, Sialia sialis.  The population of this native species has severely declined in the last few years because house sparrows have taken up all of their real estate, and are known to destroy eggs, young, and even kill adult bluebirds guarding their nests.  It's a huge problem, and I sadly admit that despite the fact that the eastern bluebird is the official bird of my county, I've never seen one in my area either.

So getting back to my initial point, I'm on the fence about house finches.  Or rather, I was, until very recently.  I'd much rather see native species, like the purple finch, in my backyard.  But house finches are still better than house sparrows.  And that is the bird I see the most at my feeder.  It saddens me to know that they are always going to be around, and that the birds that have traditionally lived in my area, are probably not comping back any time soon.  But as I said above, I'm not a finch hater (or a sparrow hater either), and I do enjoy seeing all the birds that frequent my yard. I would just prefer seeing some more than others.  But they certainly aren't to blame for this, or their impact on the local fauna. In this instance, human beings are directly responsible for the introduction of these two non-native species.  So I certainly can't have a problem with the birds.  I just have a problem with them being here.  And that is the result of the actions of my species, not theirs. The birds themselves, are just doing what comes naturally to them.

Speaking of birds doing what comes naturally to them, I think I'll leave it there for now. But I do have a bit more to share with you regarding house finches, and how, at the end of the day, they are more pleasant to have around than problematic. Stay tuned for more of the story tomorrow soon.


  1. I've seen house finches at the feeder fairly often when I lived in Vancouver, too. Though they do appear to be more or less native there at least.

  2. I think you're spot on. My understanding is that the native Mexico/southwest population has been growing and migrating North in that general direction. Better native than introduced!