Dr. John Scanlon - February 2010


Exotic Alien
John M. Scanlon, M.D.

Considerable discussion, some quite heated, has recently taken place about introduced non-native animal species. Mute swans, nutria and snakehead fish have each received a great deal of media attention, most often about how these exotics damage the environment or drive away native fauna. Less has been said about alien species that have carved their own habitat niche, caused little environmental mischief and are enjoyed by the outdoor sporting community.
As notable and well-publicized examples, brown trout, pheasants and smallmouth bass are eagerly pursued by outdoor sportsmen. None are considered ecologically hurtful. All were stocked years ago in Maryland and have become feral. And when each was introduced there were critics who complained that brown trout might displace brook trout, pheasants might run off quail and non-native smallies would eat all the panfish. Little widespread damage occurred from their introduction, however.
Another unique and exotic animal on the Eastern Shore is the Sika deer (Cervus nippon spp.). These diminutive animals, actually small elk, are native to Japan, Formosa and the East Asian mainland. In 1906, six deer were turned loose on James Island at the mouth of the Little Choptank River. They multiplied, quickly paddled off the island and fecundly populated south Dorchester County. Around 1920, a second stocking took place at Assateague Island in Worcester County. Again these alien mammals thrived. DNA studies have shown both herds to be virtually identical and to have originated from Yakushima Island, Japan.
During the first 50 years of their American population, few were harvested. However, after WWII, things changed. Sika expansion and increased harvest was reported. This was about the same time that whitetail deer (Odocoileus virginianus) were reintroduced in these parts using animals trapped at Aberdeen Proving Ground. As everyone who drives or owns shrubbery realizes, the whitetail population, historically decimated in the 19th century by over-harvest and human habitat invasion, has exploded.
Sika are strong swimmers, as one might guess since they quickly left James Island and dispersed to the mainland. Calculated herd dispersal rate, clearly influenced by natural barriers and breeding success, is about one-half mile per year. Telemetry studies have shown individual deer capable of traveling long distances, and they can swim tirelessly for miles. One monitored female (hind) swam the broad Nanticoke River to Wicomico County, reproduced and returned to Dorchester County several times. They also have considerable longevity, some reaching 10 years of age. Indeed, tooth analysis on one hind from Blackwater National Wildlife Refuge showed her to be over 20. Sika can breed before one year of age. Twins are unusual.
Sika are shorter in height than native whitetail. Adults average about 30 inches at the shoulder. Field dressed, average females weigh about 50 pounds. Stags can reach 100 pounds dressed, but that is a big animal. Stags have a black mane down their neck. Both genders have white spots along the back. The stag’s back-swept antlers rarely grow more than six total points, and that would be a trophy specimen. Both male and female are lighter in color during the summer. Their coats darken as the weather gets colder. Some may appear almost black in late winter.
Sika are typically nocturnal, wary and elusive. Harvesting one is a real challenge. Like many other mammals, these deer lose some spookiness and become more active during daytime when mating season gets going. This “rut,” usually occurring in October, is prime time to hunt them. Stags often “bugle” early and late in the day and so may be located by sound. Bugling is sort of a tinkling whistle, usually three notes at a time, and is quite distinctive. All Sika make a barking noise when alarmed. This may be the first and last deer sound a clumsy hunter hears during a Sika hunt as his alarmed quarry runs off into impenetrable marsh.
Sika habitat can be forbidding to enter and a quite formidable venue on which to hunt. Swampy, bug-infested bogs, slat marsh, isolated marsh islands and overgrown tidal wetlands are favored Sika haunts. Ubiquitous phragmites, that tall thick reedy growth taking over Dorchester’s marshes, often holds resting sikas. Getting to such deer can be daunting.
Concern had been expressed that Sika might push whitetail deer out of their traditional habitat. However, data carefully collected by DNR wildlife biologists have documented that Sika prefer areas that are less optimal for whitetail success. Thus, competition between the two species is not significant.
The challenge of hunting them, using careful observation, expert woodcraft, stealth, intelligent calling and various skilled harvest techniques, is very real. They live in remote unpleasant places, preferring to wander around at night except when unfocused by lust. However, Sika venison is absolutely delicious and, in my view, well worth the effort.

I would like to thank Dennis Witmer at Tudor Farm for supplying a great deal of the factual information for this piece. Brian Eyler is the state biologist (at DNR) in charge of all Sika matters and a source for extensive scientific information.