Thursday, 9 May 2013

More on Hong Kong Rats

In the previous posts, I referred to the two hillside rats of Hong Kong, Niviventer fulvescens (Chestnut Spiny Rat) and Rattus andamanensis (Indochinese Forest Rat), to use their current nomenclature.

I also made reference to the Roof or Black Rat, Rattus rattus flavipectus, known as the Buff-breasted Rat. Well, things are not that simple with that rat now. The native house rat R.r.flavipectus is now considered to be included in Rattus tanezumi, the wide-ranging Oriental or Asiatic House Rat. The Black or Roof Rat proper, Rattus rattus, also seems to be present, introduced, like the Brown or Norway Rat (Rattus norvegicus) by ship.

Now, in a delicious twist, not only has R.r. flavipectus been included in R. tanezumi but so has Sladen’s rat — the true Sladen’s rat (R.r. sladeni) — not, please note, the form to which the name was misapplied in Hong Kong. So, in Hong Kong, the misnaming of what is now Rattus andamanensis was doubly wrong; Sladen’s rat could, more correctly, been assigned to R.r.flavipectus.

I now wonder whether somebody in Hong Kong realised the affinity between Sladen’s rat, R.r.sladeni) and R.r.flavipectus (all the Rattus rattus subspecies in fact) and lumped them as Sladen’s rat as a common name. Then, when it was realised that there were two forms of what was then Rattus rattus, was the Sladen’s name applied to the wrong one? In this respect, it is interesting that there is no mention of Sladen's Rat in Herklots’s book, The Hong Kong Countryside published in 1951. He thanks John Romer (who I think arrived as Pest Control Officer in 1946) for information on the rats. Ignoring the bandicoot rat, he provides notes only on Rattus norvegicus and Rattus rattus. However, he draws a distinction between Rattus rattus and R.r.flavipectus and goes on to note:

It (R.r.flavipectus) is a house-rat and is a serious pest but it is also abundant as a free-living species on the hillsides and in the fields [my italics] for it is native to South China.

My interpretation of that is what are now Rattus tanezumi and Rattus andamanensis (the free-living species on the hillsides) were not recognised as separate species. It is therefore possible that when they were, the wrong name was applied to our old friend in the lab roof.

The misnaming of species as well as changes in taxonomy has other consequences. It would appear that papers that reported research on Rattus sladeni or Rattus rattus sladeni could be interpreted as work on either Rattus tanezumi or Rattus andamanensis. If the animals were from Yunnan or surrounding areas, it would be the former; if Hong Kong, the latter.

I found an example of trying to update old information on Sladen’s Rat. My acquaintance with this species, like Huang’s Rat in an earlier post, began when I was given the offspring of some that had bred at London Zoo, in about 1963. Then in the website of the Bartlett Society (concerned with the history of zoos), I found a list, First and early breeding records for mammals in the UK and Eire. In the list is Sladen's Rat, Rattus tanezumi Temminck, 1844, bred, London Zoo 1967 (they bred there earlier as I noted). A note for the entry reads:

Zoological Society of London Annual Report 1967, p39 as R. rattus sladeni. The subspecies sladeni is no longer considered valid.

However, these rats, like (from the same source): 

Yellow-breasted Rat Rattus tanezumi Temminck, 1844 (bred London 1962) International Zoo Yearbook, Vol. 4 (1963) p227, as Rattus rattus flavipectus


Chestnut Spiny Rat Niviventer fulvescens (Gray, 1847) (bred London 1964) International Zoo Yearbook, Vol. 6 (1966) p392, as Rattus huang. This species is also known as Huang's Rat.

were all sent from Hong Kong. Therefore, the record for Sladen’s Rat, has been incorrectly updated in this instance to Rattus tanezumi

Incidentally, I do not know who sent the three rats to London. It could have been PM Marshall, or John Romer or Ken Searle or one of the first two via the last. I, or somebody, needs to look that up because it might provide a clue to what names were in use in Hong Kong then compared with what they were called in London.

The List of Mammals of Hong Kong on Wikipedia has the list of ‘ratty’ rats as I have described their current status in the last three posts. But taxonomy changes, and changes again with new evidence, new interpretations and with new fashions. So watch out to see what happens next.


Bartlett Society link to breeding records:

Rattus tanezumi:

List of Hong Kong mammals: