"The red fox (Vulpes vulpes) is common and widely distributed within the UK. It is a carrier or potential carrier of numerous zoonotic diseases. Despite this, there are no published reports on the population genetics of foxes in Britain.
"In this study, we aim to provide an insight into recent historical movement of foxes within Britain, as well as a current assessment of the genetic diversity and gene flow within British populations. We used 14 microsatellite markers to analyse 501 red fox samples originating from England, southern Scotland and northern France. High genetic diversity was evident within the sample set as a whole and limited population genetic structure was present in British samples analysed.
"Notably, STRUCTURE analysis found support of four population clusters, one of which grouped two southern England sampling areas with the nearby French samples from Calais, indicating recent (post-formation of the Channel) mixing of British and French populations.
"This may coincide with reports of large-scale translocations of foxes into Britain during the nineteenth century for sport hunting. Other STRUCTURE populations may be related to geographic features or to cultural practices such as fox hunting. In addition, the two British urban populations analysed showed some degree of differentiation from their local rural counterparts."
This 2014 paper originated from people employed by DEFRA (Department for Environment Farming and Rural Affairs). There is a note at one point of some people considering foxes to be "pests" which felt so out of place and left me wondering what the report's intention was. A rather neutral and less biased way of putting it would have been: "Foxes are not and have never been officially classed as vermin in the UK". Simple fact and leave peoples' personal opinions to themselves.
Why do I mention context regarding this? Because interesting DNA showing cross-breeding but there is no real context to explain the results. I know these people were doing DNA work (always welcome on wildlife) and what they knew of Vulpes vulpes appears to be very -VERY- basic and likely from online sources.
"indicating recent (post-formation of the Channel) mixing of British and French populations" is interesting but how? Why? How long after the formation of the Channel? Here is a basic answer.
As wolves, lynx, bears and other large mammals were still being hunted but heading to the precipice of extinction there was not enough to kill for 'sport'. Otters, beavers -literally anything on the land, rivers and in the air were hunted and killed. But there was no chase or final fight that 'sportsmen and women' so enjoyed. The fox was not a wolf but it was a wild dog so it could provide a chase as well as the 'fun' of a final fight back or being ripped to pieces. And so the fox was it.
There was a shortage of foxes in many parts of England by the late 16th century (see The Red Paper 2022 vol. 1) and we know that animals were being imported at that time and it seems very likely that fox importation began around this period. Up until that time there had been three variations of Old fox in the UK; variations created by the differing habitats they lived in.
The Cur or Common fox was small and lived near human settlements where there was an almost symbiotic relationship (as there is today with the Red fox).
The Hill or Mastiff fox. Large and heavily built and living on the hills and mountain slopes.
The Mountain or Greyhound fox. These were the foxes that the 'sportsmen' craved to chase. We have taxidermy Mountain foxes from the early 19th century and they are indeed large. A taxidermy coyotes placed next the what was described as a "perfect example" of a Mountain fox is dwarfed.
These Old foxes all had one distinction and that was the lack of the black ears, socks and muzzle markings. Grey and white are known and there are examples in taxidermy. However, the main colour was overall brown. We have all of the archival evidence of the past as well as physical taxidermy so there is no doubt that they existed and there is strong anecdotal evidence that Western Europe had its Old type fox which would have been a relative from before the Channel was created 10,000 years or so ago.
"This may coincide with reports of large-scale translocations of foxes into Britain during the nineteenth century for sport hunting" It is not in any way coincidental. By the 1860s red squirrels, various deer and other mammals were being imported after they became locally extinct or dropped in such numbers that there was a threat of loss of 'sport'. The 1860s are noted as a period in which many extinctions took place in the UK and Ireland faced similar with some Mountain foxes being sent as gifts to Irish hunts before the true Mountain fox died out. At one point (known records) up to 2000 plus foxes were imported per year to places such as Leadenhall Market. Some hunts employed its own fox catchers to travel over to France to trap and bring back foxes.
Also, occasionally a master of the hunt would send a friend at another hunt foxes of various origins. This continued up until the 1930s.
Therefore, DNA similarities between British and French foxes is expected -I sent DEFRA much material back in 2009 so what they did with it I have no idea.
Since the late 1970s when wildlife rescues began to set up and then more into the 1980s and ever since rescued foxes and cubs are looked after until dispersal season at which point they are released into more fox friendly areas so a fox from Kent might end up in somewhere like Gloucestershire. So, yes, inter-breeding would take place as foxes pair up.
With context the DNA results make sense. Laboratory work always needs archival research.