Fallow deer (Dama dama) are one of the most widely introduced ungulates in the world, having established exotic populations in the Americas, Australia, South Africa, and New Zealand. While typically considered non-native in much of Europe as well, the biogeographic history of the species there is much more complicated. In this article, I would like to focus on this species, its range, and its importance in rewilding initiatives in Europe.

There are two subspecies of fallow deer extant today: the common or European (D. d. dama) and the Persian (D. d. mesopotamia). Some consider these to be separate species but for the purpose of this article they will be treated as conspecific, due to the presence of a hybrid zone in historic times and the continued ability of the two taxa to freely cross. The common subspecies’ Holocene distribution included the Balkans, the Carpathian Basin, the Danubian Plain, Western Anatolia, and possibly the Italian Peninsula, while the eastern taxon was found in Eastern Anatolia, Transcaucasia, the Levant, and the Caspian region. It is the dama subspecies that has been so widely introduced by people, for food and for sport, and this has been going on for so long that it can be difficult to determine which populations are introduced, which are original, and which have been replaced. Currently, the only European fallow population not considered to be introduced occurs in Turkey, in the Mount Güllük-Termessos National Park. This population is genetically distinct from those elsewhere, indicating that introduced fallow were sourced from a now-extinct population or populations. It is unclear if the site in Southwestern Iran where Persian fallows were first rediscovered in the 1950s still has any wild animals, but that population was used to source several reintroductions in Iran and in the Levant.

Before the beginning of the last Ice Age, fallow deer were even more widespread than in the early Holocene, being found across Central, Southern, and Western Europe. The Eemian fallow deer of Central and Western Europe were larger than the modern dama variety and the ends of their antlers, rather than simply being palmate, grew into long, flat blades. This variety is best described as an additional subspecies, D. d. geiselana, more closely related to dama than to mesopotamia, though individuals resembling the Persian fallow were common in Europe during the Middle Pleistocene. The geiselana variety seems to have gone extinct after the end of the Eemian, with the modern subspecies being seemingly unable to recolonize in the Holocene. The reason for this is unclear but considering that they were able to do so in multiple previous warm periods, the likely answer is that human exploitation prevented their expansion. However, while a passion for hunting this species may have limited its natural spread, the practice of keeping them in game parks (from which they inevitably escaped) ultimately led to the same result. Redistribution by the Romans and other cultures has resulted in the dama subspecies now being restored to practically all of its former distribution in Europe.

Fallow deer are typically considered to be an introduced species in most of Europe, and while this is technically true, I think it is more accurate to say that they are a reintroduction. The species and its close relatives existed in most European countries for over a million years. It is not implausible that they would have spread naturally in modern times were it not for human exploitation. They are widely naturalized and native predators like wolves (Canis lupus) and even lynx (Lynx lynx) will hunt them quite readily. Fallow deer have a unique niche in Europe, being the only non-montane, ruminant herbivores of their size, at about twice the size of roe deer (Capreolus capreolus) and half the size of red deer (Cervus elaphus). They are sympatric with these species in their original range and have developed separate niches through differences in diet, habitat use, and activity patterns. Fallow deer are well suited to many European climates, including semi-arid climates, where herbivory is increasingly necessary to curb wildfire impacts.

Fallow deer have and should be included in European rewilding projects, not only in their accepted Holocene range but also in their Pleistocene range. Several rewilding projects within this category already feature fallow deer, such as the Knepp estate in England or the Réserve Biologique des Monts D’Azur in France. Numerous other projects have not intentionally included fallow deer as part of their rewilding plans, but are located in areas where populations already exist. Rewilding Europe has also reintroduced fallow deer within their Holocene range in the Rhodope Mountains and Danube Delta. For the Rhodopes especially, an emphasis has been placed on fallow deer as an important food source for endangered vultures and for predators like wolves. The widespread depletion of wild herbivores has pushed wolves to hunt livestock, increasing potential conflict with people. Wolves generally prefer to hunt wild game when available and, along with wild boar (Sus scrofa), fallow deer are among the easiest game species to build up in large numbers. They are tolerant to human land use, live in higher densities than red or roe deer, and are of a size that is ideal for hunting by wolves. Like other herbivores, some of which take up much more space, they contribute to the maintenance of mosaic landscapes, usable by a great diversity of species. They participate in seed dispersal, nutrient cycling, the creation of microhabitats, and numerous other vital natural processes.

Pretty much all of temperate and Mediterranean Europe should be suitable for fallow deer. The species has been introduced to Sardinia, where it might be filling a similar role to the related dwarf megacerine †Praemegaceros cazioti. Were the species to be introduced to Crete, it might fill the role of some of the more medium-sized members of the extinct, endemic deer genus †Candiacervus, to which fallow deer were also closely related. The rewilding potential of Persian fallows should also be explored, with potential reintroduction areas including eastern Turkey, the Caucasus (Azerbaijan, part of their Pleistocene/early Holocene distribution, and possibly also Armenia and Georgia), and possibly even Cyprus. While never native there, Persian fallows were present on Cyprus from the Neolithic until the 15th century. Their introduction might serve an important cultural purpose, as well as providing a new herbivory function on an island where the native herbivores (dwarf hippos and elephants) have gone.

There are many who would argue that, as an introduced species, fallow deer should be actively removed from areas of Europe where they are not strictly considered native. I would very strongly disagree. I believe that the fallow deer and its reintroduction is ultimately as important to European rewilding as the beaver (Castor fiber) or even the wisent (Bos bison bonasus). Fallow deer should be present alongside other large herbivores in rewilding areas and other natural settings, rather than being relegated to hunting reserves, deer parks, and suboptimal rural habitats where they will only ever be seen as hunting quarry and agricultural pests.