New report challenges Denmark’s sika deer cull

A new report has found no evidence that sika deer are crossbreeding with Denmark’s red deer, challenging the main argument for eradicating the species, DR reports.

The report is now being submitted to Nature and Animal Welfare Minister Christian Rabjerg Madsen. Sika deer have been at the centre of a fierce nature policy debate since the European Union declared them an invasive species last year and said they should be eradicated.

Although Madsen’s predecessor, former Minister for the Green Tripartite Jeppe Bruus, later said that sika deer in Danish nature would not be “actively combated”, current legislation still places the country’s approximately 2,100 animals at risk of being killed.

At Jægersborg Dyrehave, a deer park north of Copenhagen where the Nature Agency is responsible for the animals, half the population has already been shot. The remaining deer are due to be killed within a few weeks. Elsewhere, the plan is to shoot the males this autumn to prevent further sika calves from being born.

Private forest owners and deer parks have so far held back from acting following the latest political statement.

The country’s largest free-ranging population of sika deer is in eastern Jutland, north of Aarhus. Sika deer are also found in the wild and in deer parks across much of Denmark, although red deer are not present in all of those places.

For more than six months, two veterinarians and a genetics researcher, with assistance from the Danish Forest Association, have investigated whether sika deer reproduce with Danish red deer and risk creating what the Agency for Green Area Conversion and Water Environment calls a “hybrid population”.

“It does not happen,” said Niels Tommerup, a senior researcher at the University of Copenhagen.

Tommerup, who has researched genetics for more than 30 years, compared DNA samples from red deer and sika deer across Denmark in a chromosome analysis. He added that if crossbreeding does occur, it is very rare.

The study analysed blood samples from 56 sika deer and 22 red deer. According to Tommerup, it is among the most extensive studies of its kind in the world and provides a reliable picture of the genetics of Denmark’s sika population, as well as substantial insight into the genes of Danish red deer.

Veterinarian Astrid Ingstrup initiated the project and collected the samples with her colleague Flemming Thune-Stephensen, assisted by about 100 volunteer hunters, forest owners and deer park staff.

“With this study, we have to say that crossbreeding between red deer and sika deer is not a problem in Denmark,” Ingstrup said.

A precautionary principle

Sika deer were brought to Denmark in the early 20th century and released for hunting, alongside fallow deer and pheasants. They have since lived alongside red deer in several parts of the country without hunters or wildlife managers observing hybrids.

In Ireland and Scotland, however, the two species have been observed reproducing with each other, with sika deer genes weakening the native red deer population.

That is sufficient reason for concern in Denmark and for ending the presence of sika deer, according to Morten Elmeros, a senior adviser at Aarhus University. He bases his position on what he calls the precautionary principle.

“It is an irreversible process,” Elmeros said.

Elmeros is among the experts who have advised the Agency for Green Area Conversion and Water Environment on sika deer, drawing partly on studies from Scotland and Ireland. The new Danish analysis has not changed his view.

“When we still have a pure red deer population, that gives even more reason to remove the problem, so there is no risk of it anymore,” he said.

Ingstrup, however, points to a significant difference between deer in Ireland and Scotland and those in Denmark: their size. Danish sika deer are smaller and have difficulty mating with red deer, she said. A small female sika deer also cannot bear the weight of a male red deer attempting to mate with her, she added.

Calls against drastic action

Ingstrup hopes the minister will reconsider the decision to eradicate sika deer in Denmark based on the chromosome analysis.

“It is completely unacceptable to decide to eradicate a species that causes no harm and for which there is no objective basis for shooting it,” she said.

Ingstrup acknowledged the need to protect native species but described sika deer as part of Denmark’s natural history. She said they account for 0.4 per cent of the country’s total deer population.