Impacts of Rhodes on Biodiversity 1 : Eastern Grey Squirrel

Cecil John Rhodes was a dominating person in the politics of southern Africa for a few decades at the end of the nineteenth century. “One of Rhodes’ guiding principles throughout his life, that underpinned almost all of his actions, was his firm belief that the Englishman was the greatest human specimen in the world and that his rule would be a benefit to all. Rhodes was the ultimate imperialist, he believed, above all else, in the glory of the British Empire and the superiority of the Englishman and British Rule“. Given this passion for all things English, it is impossible to understand why he thought it a great idea to introduce the Eastern Grey Squirrel Sciurus carolinensis to the grounds of his estate in Cape Town.

When Rhodes arrived in Africa in 1870 aged 17, the Eastern Grey Squirrel had not yet been introduced to England. The first introduction to England was in 1876, and there were lots of introductions after that. Within about 20 years, they expanded in their new range to include England and Wales and southern Scotland. They took to their new home like a duck takes to water, or in this case like a squirrel takes to trees. Eastern Grey Squirrels were introduced to England from the eastern USA. In spite of their total un-Englishness, Rhodes apparently decided that it would be nice to have American squirrels jumping around in the oak trees in the gardens of his Groote Schuur estate.

At the time of writing this blog, this was the 78th and most recent Eastern Grey Squirrel uploaded into MammalMAP as a photographic record. The photograph was taken by Heather and Andrew Hodgson on 27 July 2020 at the Groot Constantia Wine Estate. It is record 32972 in MammalMAP, and you can look at it here: http://vmus.adu.org.za/?vm=MammalMAP-32972

We don’t know exactly in which year Rhodes got his consignment of squirrels from England, but it was about 1900, so in 2020 we can “celebrate” the 220th anniversary of their introduction. They did as well here as they done in England. By 1918, they were put on the official “vermin list” of the Cape Province, and you got paid a bounty for every one you could prove you had shot. Between 1918 and 1922, the government paid out bounties for 11,188 dead squirrel specimens. Rhodes’s squirrels quickly proved an expensive “nice to have”.

During the 1940s, D.H.S. Davis worked in the “Plague Research Laboratory” of the government’s Department of Health in Johannesburg. He made visits to Cape Town, probably in a citizen scientist capacity, and made it his business to uncover the history of the squirrel in Cape Town. He interviewed both “forestry officials and private persons” who were members of the Cape Natural History Society (and therefore also citizen scientists). He wrote a paper, submitted it to the Proceedings of the Zoological Society of London and it was published in this journal in 1950 (“Notes on the status of the American Grey Squirrel (Sciurus carolinensis Gmelin) in the south-western Cape (South Africa)” – unfortunately, the paper is not “open access”). The paper is a goldmine of carefully researched information. Nothing comparable has been published subsequently! This map, of the area of Greater Cape Town, was published in that paper.

The numbers on the map are important. Groote Schuur, where the squirrels were released is number 1. They reached the nearby suburbs (2–4) in the next few years. Tokai (5) was reached in 1908. They had expanded in the grey area of the Cape Peninsula (1–11) by 1919. Squirrels were recorded at 12 and 13 on the Cape Flats in 1932 and 1930, respectively. But they were already in the Stellenbosch and Paarl districts (14–20, 22, 23) by 1920, and reached Franschhoek (21) in 1942. They had crossed the mountains to reach the Elgin district (24–27) by 1933. The easternmost records were made in the Lebanon State Forest (28), a pine plantation, in 1948. Davis’s view was that the squirrels had not been introduced to these new locations; they dispersed naturally. The dotted area on the map were Davis’s best guess at the limits of the distribution of the Eastern Grey Squirrel when he submitted his paper in 1949.

Amazingly, the distribution remains much like this in the 21st century. Here are three maps that show the exact positions of the photographic records of Eastern Grey Squirrels in MammalMAP. These maps use the coordinates supplied by the observers. The second map zooms in on the first, and the third on the second.

This map shows the same area as Davis’s but with a bit more to the north. The distribution of records is much the same, except that there is a record from Ceres, in the northeast. But there are no records from the Elgin valley in the south. Action Point for Team Virtual Museum: Do any of the other towns in this region have squirrel populations: Villiersdorp, Caledon, Hermanus, Malmesbury, Riviersonderend, Greyton, Swellendam, Worcester, Robertson, …?

Next we zoom in on the Cape Peninsula. Action point for Team Virtual Museum: Are there squirrels south of these records: Kirstenhof, Muizenberg, Fish Hoek, Simonstown, etc? Where is the southernmost squirrel on the Cape Peninsula? Davis’s sketch map above suggests a southern limit at Fish Hoek.

And finally we zoom in to the suburbs of Cape Town which have hosted squirrels since within a decade of their introduction. Action point for Team Virtual Museum: When the exact locations are shown at this scale, the map looks pretty sparse. Please help fill in the gaps. If you see a squirrel, please try and get a photograph, and upload it to the MammalMAP section of the Virtual Museum. Please try to get the coordinates as accurate as possible!

Many of the squirrel records in MammalMAP are from the Company’s Gardens (and see here too!), at the mountain end of Adderley Street, the heart of the city’s central business district. There are lots of them! The “famous squirrels” are given as reason number of two (of six reasons) why tourists should visit the Company’s Gardens. When I was a boy, in the 1950s, my dad took me to the Gardens, and we would buy a small packet of peanuts and feed the squirrels. Tourists still do this! Action point for Team Virtual Museum: Where else in the “City Bowl” are there squirrels? Are there squirrels in the suburbs between the Gardens and Table Mountain: Tamboerskloof, Oranjezicht, … ? Are there squirrels at the look-out point on Signal Hill (there are lots of stone pines for them there, see below)?

Davis’s map showed squirrels all the way round Table Mountain, including places like Sea Point, Clifton and Camps Bay. But we don’t have any MammalMAP records for these northwestern suburbs. Action point for Team Virtual Museum: Are there squirrels in the coastal suburbs between the Waterfront and the Cape Town Stadium and Bakoven?

In his 1950 paper, Davis stated that the “chief limiting factor to the spread of grey squirrels is the absence of tall seed-bearing trees.” Oaks and pines (and especially the Stone Pine Pinus pinea) provide ideal food and habitat, but a wide variety of other trees are used. Indigenous trees don’t produce food for squirrels, so they have not expanded their range into fynbos habitats. Biodiversity Explorer says: “Their distribution is patchy and discontinuous being closely associated with oak trees and pine plantations.” Action point for Team Virtual Museum: Let’s get so many records for the Eastern Grey Squirrel that we can see precisely the discontinuous patches where it occurs!

Here are thumbnails of some of the MammalMAP records of Eastern Grey Squirrels to date. Some of the photos are amazing; in some the squirrel is just a blur. That is fine, so long as we can identify that it is an Eastern Grey Squirrel. There are 78 records in total.

The Eastern Grey Squirrel is listed by the IUCN as one of the World’s 100 Worst Invasive Alien Species. But there is no chance of eliminating this rodent from the Western Cape. This very idea would cause an outrage! Their amazing bushy tails and endearing habits are more effective advertisements for their image than could be achieved by any public relations agency!

Acknowledgements

Itxaso Quintana produced the maps. This is the first time we have ever produced maps of this kind from the data of the Virtual Museum. Thanks to all the MammalMAPpers who have submitted records of squirrels.

Les Underhill
Les Underhill
Prof Les Underhill has been Director of the Animal Demography Unit (ADU) at the University of Cape Town since it started in 1991. Although citizen science in biology is Les’s passion, his academic background is in mathematical statistics. He was awarded his PhD in abstract multivariate analyses in 1973 at UCT and what he likes to say about his PhD is that he solved a problem that no one has ever had. He soon grasped that this was not the field to which he wanted to devote his life, so he retrained himself as an applied statistician, solving real-world problems.