Don’t shoot the messenger: Shakespeare’s Henry IV is not entirely to blame for the starling invasion

March 25, 2011 11:45 AM

I start my search by listening for their louder bedfellows. Great-tailed grackles may be the most common bird on Rice’s campus after the usual plethora of chipping sparrows. A short while after I started living on campus, I realized that there were actually two types of black birds: one species with a long tail, and another with practically no tail. I spot some grackles outside my window by the bluebonnets that are growing in the drainage ditch between the baseball stadium and the intramural (IM) fields. “Short tails…short tails.” I chant to myself as I survey the foraging flock of black birds. There, right on the edge of the ditch. Two starlings, one browner than the other, are slowly picking their way across the terrain. Mixed species roosting flocks are common in bird roosts because it allows the group to be better aware of the surrounding area (Caccamise and Fischl). It is a safety in numbers mentality: the more birds there are, the more eyes are there are looking out for danger. In this case, the starlings are more dependent on the larger grackles for “predator protection.”

By the time I’ve collected my things and gone outside for a closer look, all of the black birds have moved on. I find the grackles again on the far side of the field but this time there are no starlings accompanying them. When it is clear that waiting around will only produce more flower-seeking bugs, I move on. Later that day, I am given the chance to test out my bedfellow’s method again. On my errand run, two male grackles suddenly take off screaming as if they were flushed from cover by a hunting dog. One of them is carrying nest material. I look away from their ruckus to survey the area they came from. Aha! They have left some starlings behind! Their careful steps and pecks seem almost leisurely in comparison to the frantic killdeer I observed last month. Bright yellow beaks flicker over the edge of the unkempt grass as they make stabs at insects I cannot see. I sit down to watch for a while as they chatter amongst themselves. All of the raspy calls sound the same to me but they actually mean a lot to females during the breeding season. Longer calls from males within their own population make the best partner (Gentner and Hulse). These calls mean little to their fellow males because the only territory starlings defend is that of the nesting holes. Otherwise, communal feeding is a pretty effective way to of minimizing land disputes (Eens, et. al.).

I was actually inspired to observe the European Starling, Sturnus vulgaris, after seeing a YouTube video of a particularly “vocal” individual named Damar. Surprised? So was I. With how rampant the birds are it seems strange that their voice mimicry abilities have gone practically unnoticed. Even more peculiar, their ability is actually the reason they are in North America at all. Starlings are actually an invasive species meaning that they are not originally from, or indigenous to, North America. According to romanticized legend, it all started with a Shakespeare buff by the name of Eugene Schieffelin. In an attempt to “import and establish” in America all the birds mentioned in Shakespeare’s writing, about one hundred starlings from Great Britain were released in New York’s Central Park between 1890 to 1891 (Cabe). The only Shakespearean reference to the bird is a quick reference to its ability to repeat words in the third scene of Henry IV. Today, his legacy lives on in the form of an estimated 200 million North American starling flocks that regularly clog the skies on their way back to their roosts after a day of feeding. Their areal displays, in which the entire flock appears to move through the air as one organism, are impressive up until the point when a plane tries to pass through (Ballerini, et. al.). This is only one of the many reasons that Schieffelin’s folly will forever live in infamy.

All of the starlings that live in North America today are descended from those first one hundred. In biology this would be called a founding bottleneck, in which a small group of individuals was separated from the main population. This results in low genetic variation. The danger of being a population with low genetic variation is that if a deadly disease or virus affects one member all closely related individuals (the whole population) will also be susceptible and the ailment could wipe out the whole population. The starlings in North America seem to be beating the odds against such a fate. Cabe suggests that the fact that the birds had such a large area to spread out is helping them thrive. All this defying the odds would be a good thing except that many ecologists believe that they may actually be causing problems for many of North America’s indigenous bird species. In 2003, Koenig did a study on their ability to “usurp cavities and outcompete native species” and found that the invasive species had no significant effect of native populations overall. Whether or not the population of an individual species is affected depends on numerous factors such as comparative size and the flexibility of their breeding season.

The first time I saw starlings in the winter without their breeding plumage I had to stare at them for about ten seconds before I realized that I was even looking at the same bird. The difference was striking. These birds were brown with white spots, not the glossy iridescent black with bright spots that I was used to. Now I that I have spent time observing them, these small invasive birds will never be able to fool me again. It will help that there are never more than a handful of them foraging together on campus but I am actually looking forward to the day when I can witness a large flock of starlings moving through the sky like the smoke monster on “Lost.”

—————————————————————————————————-

References:

Ballerini, et. al. 2008. Empirical investigation of starling flocks: a benchmark study in collective animal behavior. Animal Behavior 76:1, 201-215. doi:10.1016/j.anbehav.2008.02.004

Cabe, P.R. 1997. The effects of founding bottlenecks on genetic variation in the European starling (Sturnus vulgaris) in North America. Heredity 80, 519-525. doi: 10.1046/j.1365-2540.1998.00296.x

Caccamise, D.F. and J. Fischl (1985). Patterns of association of secondary species in roosts of European starlings and common grackles. The Wilson Bulletin 97: 2, 173-182. doi: 10.2307/4162069

Eens, M., R. Pinxten and R.F. Verheyen (1991). Male song as a cue for mate choice in the European starling. Behavior 116: 3-4, 210-234. doi: 10.2307/4534919

Gentner, T.Q. and S.H. Hulse (2000). Female European starling preference and choice for variation in conspecific male song. Animal Behavior 59: 2, 443-458. doi: 10.1006/anbe.1999.1313

Koenig, W.D. 2003. European starlings and their effect on native cavity-nesting birds. Conservation Biology 17:4, 1134-1140. doi: 10.1046/j.1523-1739.2003.02262.x

Above: The typical breeding plumage of an adult European starling, S. vulgaris Photo taken by Dick Daniels (2008) at Sunset Beach, NC. Retrieved from Wikimedia Commons.

Above: A slightly browner starling. Imagine comparing this bird with the first one from very far away and you’ll understand my initial confusion. Photo taken by Pilgab (2008). Retrieved from Wikimedia Commons.

Above: Bluebonnets and other flowers growing in the drainage area outside of my residence from the side where I saw the starlings. Photo taken by author (2011).

Above: A closer photo of the previous picture. This is probably more what the starlings saw. Photo taken by author (2011).

Above: An approximate distribution map of S. vulgaris. The lighter colors indicate places where the bird was introduced and has inevitably become an invasive species. Retrieved from Wikimedia Commons.

The above table from Cabe shows that alleles (genes) that are rare in the native population are more common in the introduced starling populations.

The above figure is from Koenig and shows that, of the species studied before and after the introduction of starlings, no overarching population change occurred. This leads us to the conclusion that no significant change in overall population can be said to have occurred as a result of the introduction of starlings.

Bonus:

Here are three interesting opinion articles that I found on the starling invasion and methods used to deter it. They are each about ten years apart:

New York Times, 1990: 100 Years of Starling

National Geographic, 2001: Bioinvasion from Old World to New

Washington Post, 2009: Once Worthy of Shakespeare, The Starling Becomes a US Pest

Here is a cool clip of them flocking on Youtube:

And if you were creeped out by that video of Damar you are not alone. Here is a slightly less creepy video of a talking female:

Advertisements
This entry was posted in Starling and tagged , , , , , , , . Bookmark the permalink.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s