The Urbanization of the Eastern Gray Squirrel in the United States

The eastern gray squirrel (Sciurus carolinensis) is ubiquitous in Philadelphia today, and in many other cities as well.  However, this was not always the case.

To read more about these little mammals, and how, when and why they came to be so citified, see here:

http://www.thedp.com/article/2013/12/urbanization-of-squirrel-research

The entire paper mentioned in the linked-to article above is here:

http://jah.oxfordjournals.org/content/100/3/691.full

And for a bit more on squirrels in Philadelphia, see within this page:

https://growinghistory.wordpress.com/2013/07/06/ailanthus/

and this one:

https://growinghistory.wordpress.com/2013/10/30/the-white-pines-of-hermit-lane/

Ailanthus, House Sparrows, and Eastern Gray Squirrels

Matt Kasson (currently at Virginia Tech) has tracked the movement and growth patterns of Ailanthus altissima, the “tree of heaven” –

http://news.psu.edu/story/280078/2013/06/24/research/ailanthus-trees-status-invasive-species-offers-lesson-human

A brief historic note on the Ailanthus, from the “Conchologists’ Exchange“, where John Ford (Philadelphia, PA) writes of the genus of land snails, the genus Helix, in 1887:

“Unfortunately there are not many to be seen at the present time as the blasting for the new River Road destroyed most of the Ailanthus bushes upon which they chiefly fed. Only a short time before the rocks were removed I took over 200 specimens from a space less than 50 feet square. A number of these were captured upon the Ailanthus bushes in the act of eating the foul smelling leaves, a fact which seems to prove that no plant is too offensive to be used as food by some animal.  Very many of these specimens were in perfect condition; as may be learned from the sample in the Philadelphia collection on the second floor of the Academy of Natural Sciences. The writer was the probable discoverer of this colony, which it is safe to say has never been equalled in this region either in number or in perfection of form and color.

Nearly opposite to this locality on the west side of the Schuylkill just south of the bridge crossing the old carriage road very many H. libera and H. allemata may be found Here the conditions are much the same as were those already described; large stones being scattered about and many Ailanthus bushes growing between.”

Another organism that eats Ailanthus altissima is the Ailanthus silkmoth, as is detailed in Ken Frank’s History of the ailanthus silk moth (Lepidoptera: Saturniidae) in Philadelphia: a case study in urban ecology, from volume 97 of the Entomological News (1986), available for perusal here.

And the Ailanthus webworm can currently be found in Philadelphia:

https://ecologyofwestpark.files.wordpress.com/2015/07/000-moths-at-light-in-center-city-4.jpg

And as we read in the  Proceedings of the Academy of Natural Sciences of Philadelphia, Volume 34 (1882):

“Prof. Leidy further remarked that the past season had appeared to be favorable to many of the Lepidoptera. Our shade-trees had been greatly ravaged by the Orgyia; many of the poplars had suffered from the Clostera inclusa, and he had observed an unusual quantity of the Ailanthus silk worm, Attacus cynthia, upon the Ailanthus-trees. The latter was introduced here in 1861, by Dr. Thomas Stewardson”

Additionally, from Scharf and Westcott’s History of Philadelphia (1884):

“The State-House [= Independence Hall] pavement was a wide and unpleasant place in warm weather when the sun was shining. Fully exposed, and reflecting back the heat, it was, in consequence of the buildings being far back from the line of the street, less attractive than sidewalks across which neighboring houses threw a shade in some periods of the day. No attempt was made to introduce any improvement until the fall of 1821, when trees were planted in front of the State-House, extending from Fifth to Sixth Street. Poulson [=publisher of the Daily Advertiser] said in reference to this improvement, “It will be a salubrious exchange for the arid bricks that have been broiling our brains there for fifty years.” The trees chosen were ailanthus, noted for quick growth and thick foliage. In ten or fifteen years the front of the State-House in summer time was as umbrageous as a forest. Afterward these trees were attacked by worms, and were ordered to be cut down. The axe was applied at some little distance above their roots, and in a few hours the grove, once the glory of the city, the favorite place in which the town politicians assembled to talk about nominating and elections to discuss political affairs -where they were commonly called “tree toads” – presented the dismal appearance of a forest in which the wood-choppers had been entirely too busy. The public could not stand that. In a short time new trees (silver maples) replaced the ailanthus, the idea being from experience that they would not be disturbed by the worms. They grew finely, and in a few years the grove in front of the State-House was restored to its original beauty. But just about that time the worms gave proof that they would change their diet upon necessity rather than starve. The ailanthus and paper mulberry having been almost exterminated as a sidewalk tree in the streets of the city, the worms accommodated themselves to circumstances, and condescended to devour the leaves of the maples.

In time the English sparrow was imported, and he justified the expectations founded upon his change of country by attacking the worm vigorously. In the meanwhile many years had gone by, and a considerable number of the trees had yielded to natural decay. When about 1876 it was determined to replace the brick footways by a pavement of slate, there were very few of the old trees left. It was not difficult to dispose of them. By covering the surface with the stone and making no provision for watering the roots, the remaining trees gradually died off, so that in 1884 there is probably no survivor of this most beautiful grove which for many years was the most attractive place on Chestnut Street”

Note: Philadelphia was the site of what was most likely the largest introduction of house sparrows (Passer domesticus) into North America: one thousand of them, in 1869

Philadelphia also appears to be the first city in North America in which “free-living” squirrels were released for the edification and enjoyment of the populace, and they (the squirrels, that is) were even provisioned with food and little homes, beginning in 1847, in Franklin Square – this was to be followed by multiple later introductions in Philadelphia, all of which rapidly led to squirrels being found (by 1853) in Independence and Logan Squares as well as other locales in the city; in 1864, however, a report was issued at the city’s request (due to worries that the squirrels were eating birds and their eggs, and also thereby increasing insect populations) by PHS‘s “Committee on Entomology” evincing concern that these little rodents were negatively impacting bird populations due to competition for e.g, nesting sites in trees, even though they (the squirrels, that is) did not appear to be eating the birds nor their eggs, and shortly thereafter eradication and removal efforts were implemented, and these appear to have entirely removed squirrels from the city, thereby clearing the way for the abovementioned English sparrows  – this is discussed in the recently released paper “The Urbanization of the Eastern Gray Squirrel in the United States“, in the Journal of American History; I note that squirrels had returned to Philadelphia by the early 20th century, as we might infer from reports of them being given to the zoo by Philadelphians: “List of Additions to the Menagerie during the Year Ending February 28th, 1914″ … “1 gray squirrel presented by W. Stokes Kirk, Philadelphia” (12 July); “List of Additions to the Menagerie during the Year Ending February 29th, 1912″ … “1 gray squirrel presented by G.H. Didinger, Philadelphia” (6 May); “List of Additions to the Menagerie during the Year Ending February 28th, 1917″ … “1 gray squirrel presented by George Swisher, Philadelphia” (12 August); but there weren’t many of them given, as compared to opossums, for example; the aforementioned records can be read in the Annual Report of the Board of Directors of the Zoological Society of Philadelphia volumes 40-49)

The changing mood about the the English Sparrow is captured in the following article from The Great Round World (“a news magazine for busy men and women”), volume XXI, for the week ending June 6, 1903:

Reversed Fame

To have one’s beneficent work appreciated and praised and then have it suddenly depreciated and denounced is the lot which fell to Mr. John Bardsley, of Germantown, Pa., some years ago.  The Philadelphia Record tells the story:

“There is a little old house in Germantown, at the northwest corner of Main and Upsal Streets, that is in a certain sense historical. In this house some thiry-five years ago, lived ‘Sparrow Jack,’ and the building, therefore, has the name of “Sparrow Jack’s house.’ Jack was an Englishman, John Bardsley, and through the influence of William F. Smith, a Germantown Councilman he was sent to England to bring over a lot of English sparrows, the idea being that the sparrows would destroy the caterpillars that infested the trees. The few sparrows Bardsley imported are the ancestors of the millions that now thrive in Philadelphia. The importer was highly praised for his work during the first year or two, and his nickname of ‘Sparrow Jack’ was a title of honor in which he took great pride. Later on, however, as the sparrows began to become a nuisance, the nickname came to have a reproachful significance and in the end it became a term of opprobrium.”

Sparrow Jack is buried in Ivy Hill Cemetery: http://witmerstone.com/ivy-hill-cemetery-and-the-worst-mess-i-have-encountered/

The Ailanthus was a popular tree in the early 19th century, but fell into disfavor, as is covered in the Annual Report of the Secretary of the Board of Agriculture, Volume 32 (Massachusetts; 1884):

“From its rapid growth and tropical appearance it soon became a favorite, and was planted extensively in the cities of New York, Philadelphia, Providence and Newport, and the demand for the young trees far exceeded the supply. As soon as the trees were old enough to produce flowers, it was discovered that they emitted a very offensive odor, and the pollen which fell on the roofs of neighboring houses rendered the water falling on those roofs unfit for drinking or culinary purposes. On discovering these objectionable features in its character, those who had cherished this rare exotic were suddenly seized with a feeling of disgust, and war was declared against the offending ailanthus, resulting in almost its complete extermination. A few may be found scattered over Rhode Island, and in some of the villages of New England, lineal descendants of a despised and persecuted generation.”

However, it was still recommended for planting for forestry well afterwards, as is indicated in the Reports of the State Board of Agriculture (PA) for 1894:

‘The following questions from the query box were read and briefly discussed:

“What forest trees are most profitable to grow, and should they have a place on the farm?”

Mr. Brinton. That depends upon circumstances. If for fire wood, I would say Ailanthus. If for general purposes, black walnut, or where for fence posts, yellow locust.’

But in cities, it was generally not well regarded – an example of this we see in Christopher Morley’s Philadelphia (published in 1990, edited by Ken Kalfus; the portion below originally published in 1920 in Morley’s Travels in Philadelphia), in the section titled ‘the Indian Pole’, where he writes of the neighborhood around Callowhill east of Broad:

“Down their narrow side alleys one may catch a glimpse of greenery (generally the ailanthus, that slummish tree that haunts city back yards and seems to have such an affinity for red brick).”

To read even more about the Ailanthus, see here:

https://growinghistory.files.wordpress.com/2013/07/a5818-kassonetal2013nn.pdf

The Invasive Ailanthus altissima in Pennsylvania: A Case Study Elucidating Species Introduction, Migration, Invasion, and Growth Patterns in the Northeastern US, by  Matthew T. Kasson , Matthew D. Davis and Donald D. Davis; Northeastern Naturalist, 20(10):1-60. 2013.
Or here:
And, in recent news, the Spotted Lanternfly (Lycorma delicatula) has recently (fall 2014) been discovered in the US, in Pennsylvania:
Adults of this species feed on Ailanthus in the autumn, and it is preferred by them for egg-laying as well.