Rigor Vitae: Life Unyielding

Tuesday, February 28, 2006


Commensalism is the dependence of one species on another in a relationship just a bit south of true parasitism. A number of human commensals are familiar, the rodent genera Rattus and Mus, the Common Starling (Sturnus vulgaris) and Rock Dove (Columba livia)--creatures despised and maligned by most. It's pretty tough, though, not to be charmed by the jaunty little English Sparrow (Passer domesticus). The black bib and bright brown back of the male can be seen bouncing merrily along sidewalks throughout the world. A poet friend of mine calls them “Party Birds.” In falconry slang, the word “Spug” is borrowed from old Scottish. I think either term works well.

The taxonomical placement of the Spug and his 20 or so congeners has been the subject of much debate. Not closely related to the American sparrows, for years they resided in the weaver family, Ploceidae, then found themselves lumped for a time with the family Estrildidae, which includes most of the well-known cage finches. Today most authorities follow Sibley in placing them in the family Passeridae, along with pipits, wagtails and accentors. Most anywhere in Africa and Eurasia one or more Passer species is native, and a number of them have been human commensals for millenia. The Eurasian Tree Sparrow (P. montanus) has pioneered frontiers as far-flung as Missouri, but it's P. domesticus that has shown true genius at the art of commensalism, with a present range that extends from Australia through urban and rural situations in both Americas. Spugs have learned to thrive in a variety of settings, often living their whole lives indoors, successfully breeding in shopping malls and warehouses. There is even a record of a pair successfully raising a brood in an English coal mine 640 meters below the ground.

Toward the end of the nineteenth century, Eugene Schieffelin, a British expatriot living in New York City, embarked on a little project that would secure his place in ornithological history. Obsessed both with birds and Shakespeare, Schieffelin set out to introduce every bird species mentioned by the Bard into Central Park. Today we remember him as the Victorian ninny who brought us ecological doom in avian form, but what's often forgotten is that Shieffelin was a member of an “acclimatization society,” one of many groups dedicated to redistributing favorite animals and plants. During this time, such projects were all the rage, but were almost invariably failing propositions. Schieffelin's starlings and sparrows thrived well enough, but let's not forget his Eagle Owls, Blackbirds, Nightingales, and all the others doomed to bachelor deaths in the Big Apple.

Young Spugs grow quickly, and can fledge at less than two weeks of age. It is normal for a pair to fledge three different broods in a season, and as many as seven broods have been recorded. Their fecundity and willingness to eat nearly anything helped them spread across the North American continent in a few decades, radiating into new ecological niches, and showing astonishing physical change in well under a century, the big, dark birds of the Pacific Northwest contrasting with their small, paler brethren of the desert Southwest and their brightly-colored Eastern kin.

As they've invaded new spaces, English Sparrows have had their effect on the ecology at large. Far slower than any native passerine bird, their presence has affected the behavior of certain predators. In many American cities, the once bashful Cooper's and Sharp-shinned Hawks (Accipiter cooperi and A. striatus) have taken up urban living, and in the winter are exceptionally common now in many cities, a fact I attribute to the Spug. In 1980 I found a Cooper's Hawk nest in the heart of Salt Lake City. At the time I could find no previous citation of an urban Cooper's nest in the literature. Today they are not uncommon. American Kestrels (Falco sparverius) have also learned to exploit the easy quarry, and in doing so, I believe have become more ornithophagic in general. I've noticed that urban and rural kestrels in my area bring far more native birds to the nest than do those in more pristine habitats. In 1992 I saw a suburban falcon kestrel nail an adult Mourning Dove (Zenaida macroura) in the air, an act unimaginable from the truly wild, grasshopper and vole-eating kestrels I grew up with.
Commensal birds also displace natives, and are roundly vilified for it. Much is made of the effect English Sparrows and Common Starlings have on cavity-nesting birds, most notably bluebirds (Sialia spp.), whose nests they often appropriate. Of course, this only happens in habitats that have already been severely altered by human development, so it's a little disingenuous to blame the birds for continuing our own effect. The best way to conserve native birds is to leave their habitat alone in the first place. Like all our other commensals, the Spug will be a part of us for the foreseeable future, and I, for one, am happy to have him along for the ride. On this Mardis Gras, let's all drink a toast to the health of the Party Birds!
upper: A BRICK HOUSE--ENGLISH SPARROW & PAPER WASP (1992) acrylic 18" x 16"


Anonymous Anonymous said...

I call them McDonald finches because I've never seen a McDonald's or other fast food place without them. When the family farm was a working chicken farm, we had hundreds of English sparrows around, but today I never see them at my feeders. Parking lots and fast food places yes, but at least here in upstate New York, they don't fight my Tree Swallows and Bluebirds for nest boxes anymore; they're just not around since the farm has gone back to mostly second growth forest.

I also have to admit to being rather fond of them. At this point, they've been here for many more generations than my family has.

1:45 PM  
Blogger Carel Brest van Kempen said...

Hi Carl. It's interesting to hear of English Sparrows on the retreat. I wonder if anyone has compiled a database about such situations.

2:38 PM  
Anonymous Anonymous said...

The best way to conserve native birds is to leave their habitat alone in the first place.

I couldn't have said it better myself. Non-natives are here to stay, so in my opinion why not embrace them for what they are- birds that were brought here that learned to adapt quickly. Folks that maintain bluebird/purple martin housing have an absolute hatred for these birds, and most of their web-forums are 'what bb gun is the best gun for shooting non-natives?" Extremely fantatical about 'their' birds.
I don't see them often, since they tend to congregate in cities, but when I do I don't look at them with disdain. In fact I quite enjoy watching them since I rarely have that opportunity.
Not many birders would agree with me, but ask me if I care ;)
great post and as always, wonderful art.

4:56 PM  
Anonymous Anonymous said...

Here in the UK, the numbers of both House Sparrows (Passer domesticus) and Tree Sparrows (P. montanus) have declined drastically over the past 15 to 20 years. Our local flock of 'spugs' has declined to single figures.

A couple of years ago, I was surprised to see House Sparrows nesting in the walls of Skara Brae, the superbly preserved Neolithic village in Orkney. It set me wondering whether the birds' ancestors had nested there 5,000 years earlier. I read somewhere that spugs followed agriculture as it spread from the Middle East to northern Europe back in the Stone Age.

12:40 PM  
Blogger Carel Brest van Kempen said...

This comment has been removed by a blog administrator.

7:00 PM  
Blogger Carel Brest van Kempen said...

Cindy: Thanks! There's one of those big Purple Martin condos not far from my house. I've never seen a Purple Martin in this valley, but the Starlings have loved that structure for decades.

Roger: Thanks for your interesting comments. The UK spug decline was a topic I wound up editing out of my post, mainly because I haven't heard any good ideas about what's causing it and have none of my own. As their neighbor, do you have any insights?

9:02 PM  
Anonymous Anonymous said...

As far as I know, it's still a mystery. The BTO speculates that the decline may be due to:

1. Reduction in the availability of favoured food

2. Increased levels of pollution in urban and suburban habitats

3. Loss of suitable nesting sites

4. Increased prevalence of disease

5. Changes in the use and type of loft insulation

6. Increased levels of predation

See http://www.bto.org/gbw/HOUSP/index.htm

12:42 AM  
Blogger Carel Brest van Kempen said...

Bachman/Turner Overdrive??

6:23 AM  
Anonymous Anonymous said...

Brilliant look at a much maligned bird. Your connection between the spread of House Sparrows and the proliferation of raptors in urban areas is fascinating. From my Bronx window, I've seen hunting red-tails, coopers, and sharpies, not to mention my friendly neighborhood kestrel. It goes with out saying that I've got an abundance of house sparrows!

10:04 AM  
Blogger Carel Brest van Kempen said...

Thanks Mike! I'm fascinated by watching wildlife adapt to altered habitat. Birds, of course, are the easiest to observe. Out here the Redtails are also adapting to the city as are other raptors that aren't relying on sparrows, like Swainson's Hawks.

9:45 AM  
Anonymous Anonymous said...

Very interesting post--i've been thinking about the exotics around me lately--this was a pleasure to read.

I have house sparrows around my place (in a small hamlet in rural eastern Ontario) in the breeding season, but they disappear in the winter. I found them recently--they'd moved down the street to where the houses are closer together. I've never seen them show interest in a bluebird house, seeming to prefer the eaves of our house--all in all I don't see a big problem with the exotics that stick to human habitation--beyond the problems that the human habitation is itself creating.

11:14 AM  
Blogger Carel Brest van Kempen said...

I'm glad you liked the post, Pamela. Thanks for theinteresting comments.

10:32 AM  

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