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in the salmon's shadow

SpruceRoots Magazine - November 2002

by Amanda Reid-Stevens
Knotweed

ALIEN INVASION

by John Farrell
A list of introduced animals including feral animals
but excluding birds.

Sitka black tailed deer - 1878
European red deer - 1919
Rocky Mountain elk - 1929
raccoon - 1940s
beaver - 1936
muskrat - 1924
red squirrel - 1947
black rat - 1919
Norway rat - 1922
house mouse - 1901
Pacific tree frog - 1964
red-legged frog - 2002
ring necked pheasant - 1913
feral cattle - 1893
feral goats - 1976
feral rabbits - 1884
feral cats - ?
feral dogs - ?

Date is the earliest known introduction.

In 1792, the Spanish tried to introduce pigs to Haida Gwaii. The explorers of the day set loose domestic animals in an attempt to ensure an abundant source of animal protein for the colonizing settlers to come.

The introduction failed. Nearly two hundred years later, a Port Clements resident caught Pacific tree frogs in Port Coquitlam and let them lose in Beaver’s Pond. This was a far more successful introduction and the frogs went forth and multiplied.

Over the last 120 years, Haida Gwaii has played host to hundreds of introduced species—plants and animals found outside their natural range. An inventory of the archipelago by Parks Canada has shown that of the 6,800 marine and terrestrial species identified to date, as many as 200 are not native to Haida Gwaii. Mammalian life on these Islands is dominated by alien introductions with 15 species including beaver, raccoon, rat, squirrel, muskrat, Sitka black-tailed deer, Rocky Mountain elk and the illusive feral “hippie” cow of Naikoon Park, believed to be a mix of Gurnsey, short horn, Red Poll, Ashire and white Hereford breeds.

Of the 650 plants identified, nearly 25 percent are considered “alien” or transported by human means. Some arrive as seeds carried on the wind, others as “escaped” ornamental plants or, as part of a commercial seeding mix sprayed along hundreds of kilometres of roads and right-of-ways. Fortunately on Haida Gwaii alien plants must be shade-tolerant to be a successful interloper, of which most are not. Only the most hardy species, such as Japanese knotweed, make it. Like a scene from the Little Shop of Horrors, this white flowering weed has taken root in the ditches surrounding Queen Charlotte City and Skidegate choking out native plants as it creeps north. And that, according to those who study invasive species, is a problem.

The crux of the matter is that there are negative consequences to the introduction of foreign animal and plant species. Worldwide, over half of all introduced species that become major problems have been deliberately introduced. Locally, one need not look further than the introduction of rats and their spreading to 21 islands in the archipelago. Langara Island, once boasting the largest seabird colony in BC, saw the loss of 90% of its ancient murrelet population due to predation by these nest raiders. This devastation triggered one of the most intense rat eradication projects of its’ kind between 1993-95, successful to date as recent surveys show the island remains rat free.

Although some species are introduced accidentally, Scotch Broom considered a plague to native vegetation the world over, was in-troduced here deliberately as an ornamental garden plant and is a popular item at plant sales. Still, invasion biologists will tell you that the majority of introduced species have no negative impact on the environment or the economy. While only 10% of established introduced species ultimately become pests, it is difficult to predict which species will eventually become troublesome.

Two cases in point are beavers and raccoons. Both were introduced to the Islands by the BC Gaming Commission in the 1930s and 1940s to augment the fur trade. But due to the mild climate, the quality of the pelts was poor and the corresponding lack of demand resulted in little trapping pressure. With no known predators, both species flourished and spread throughout the Islands.

Although beavers still provide a modest income for some local trappers, the dams they construct have altered the waterways, most noticeably in the Graham Island lowlands where beaver were first introduced.

“My general take home message,” says ecologist Dan Simberloff. “is because we’re not really good at predicting the trajectories of introduced species it is important to consider all introductions as potentially harmful no matter how innocuous they might first seem.”

A Professor of Ecology and Evolutionary Biology at the University of Tennessee, Simberloff may seem a tad alarmist but he has seen first hand how exotic species have contributed to the decline of 42 percent of endangered and threatened species in his own country. In fact, at least three of the 24 known extinctions of species listed under the US Endangered Species Act were wholly or partially caused by hybridization between closely related exotic and native species.

In Simberloff’s opinion, people have an obligation to be vigilant stewards of their homeland, especially when “home” is an island. On the islands of Hawaii, for instance, the majority of the land base is ruled by introduced species. An average of 20 alien species become newly established in the islands every two years. This lack of vigilency has cost Hawaii more than half its indigenous birds and 10 percent of its native plants.

“If a private citizen tomorrow wanted to import a breeding pair of European pigs to Haida Gwaii, he could and no one could stop him—there are no laws or regulations,” says Simberloff. “Or, if a citizen wanted to bring in cuttings of Japanese honeysuckle or Nepal grass as an ornamental, he or she would be perfectly entitled to. I think this highlights the problem that there’s a more comprehensive issue here than simply the management of deer. The bigger issue is a need for a comprehensive plan to manage introduced species in their entirety.”

For a variety of reasons the debate on introduced species to Haida Gwaii has focused almost exclusively on the Sitka black-tailed deer. Beyond their well known impact on cedar regeneration, deer have depleted many other resources that the understory provides, such as medicine and food and nest sites for birds. Because so many of our most effective medicines from aspirin to taxol come from plants there is fear that losing native plants to introduced species will rob us of traditional medicines and possibility of finding new medicines. This concern led the CHN Forest Guardians to erect a series of fenced “exclosures” throughout Graham Island in an effort to protect known medicinal plants from browsing.

Much of what we do know about the impact of the deer on forest ecology has come from the work of the Research Group on Introduced Species (RGIS). The group brought together an international team of plant, animal and forest ecologists to investigate alien species, mainly deer and red squirrel, and assess their impact on the biodiversity of the archipelago.

Deer were first introduced during the late 19th century to provide game meat for local residents. Since then this large herbivore has colonized all but the smallest and most remote islands in the archipelago. Due to their tremendous range and willingness to swim, only eight small offshore islands are known to be deer free. The number of deer on Haida Gwaii is tough to estimate, as there is no reliable scientific data. In the absence of predators deer direct much of their energy to reproduction, with females producing one to three fawns per year, mostly twins. Such phenomenal population growth does not come without consequences.

To truly understand the effects of browsing one has to make the pilgrimage to the “living laboratory” of Laskeek Bay where RGIS has been conducting its field work over the past five years. I tagged along with RGIS directors Jean-Louis Martin and Todd Golumbia on a pre-conference trip in early October. RGIS was gearing up for a week-long conference on introduced species that was both an oppor-tunity to share the group’s research findings and to hear from more than a dozen scientists and managers who are dealing with similar situations elsewhere. The trip would take us to islands without deer (Low), with deer (East Limestone) and where deer were culled five years ago (Reef).

Our first stop was Low Island, which due to its relative isolation, small size and steep shoreline is not deer friendly. Even for three bipeds getting onto the island from a boat proved a challenge. After scrambling up the rocks we were greeted by a late summer wardrobe of wildflowers.

“Remember this,” said Jean-Louis gesturing to patches of Chocolate lily and Indian paint brush. “You’re not likely to see these again.” Finding a hint of a trail we climbed up into lush vegetation. With the aid of machetes we carved our way through thickets of Salmonberry, ferns and Salal. At the top of the hill, we came upon groves of huckleberry bushes. Compared to what came next, this was Eden.

Next on our itinerary was Reef Island where RGIS hired hunters to remove more than 50 Sitka black-tailed deer during the winter of 1997-98. My hosts were amazed at the recovery rate of the plant life in just four years. To my untrained eyes, the island looked pretty sparse. But my guides were quick to point out new shoots on once heavily browsed spruce, the appearance of Alder seedlings and young ferns. Not a lot mind you, but enough to make the case for the gradual return of the understory. This would eventually include cedar, which Golumbia says were totally absent before the cull.

“The initial reduction of deer is quite easy,” adds Golumbia. “But when you get fewer and fewer deer it takes more and more effort. You actually need to increase the hunting pres-sure to get the last individual deer and that’s expensive. We’re planning to go back to do another cull this winter or early spring. But we’re not after every single deer. The alternative of leaving one or two deer on the island isn’t ideal but there’s not enough browsing pressure on the vegetation to make a difference.”

I saw the clearest illustration of what deer do to fauna as we anchored at East Limestone Island. Even from the beach the impact from heavy deer browsing was obvious and dramatic. Gone were the berry bushes and the young red cedar, even the ubiquitous Salal was nowhere to be seen.

On the deer-free island of Low, we had stopped to listen for songbirds flitting about in a tangle of low branches. But here, the only sound came from our boots tramping on the forest floor. Scientists say the loss of foliage due to deer browse has resulted in fewer songbirds, making their nests more visible to predators like squirrels. The number of songbirds were found to be three to seven times lower on islands with deer. As well, scientists say that by reducing the number of wildflowers, the deer have indirectly reduced the number and diversity of pollinating insects which are the main food source of song-birds. It seems that without abundant food and shrubs for foraging and breeding the Rufous Hummingbird, Orange-crowned Warbler, Fox Sparrow and Song Sparrow have made their nests elsewhere.

The most striking change in the vegetation was the dwarf-ing of Sitka Spruce and Western Hemlock. With their cushion-like shape they no longer look at home in an old growth forest but would be better suited to the celluloid gardens of Edward Scissorhands. Due to the browsing, the spruce will take an extra eight years to reach maturity, the hemlock even longer. As we walked through the sun-dappled forest, I kept wondering what was left to eat.

For the past 20 years, plant specialist Jim Pojar has studied the affects of deer browsing from Naden Harbour to Kunghit Island. He likens the deer’s impact on the landscape to the after affects of a neutron bomb.

“Neutron bombs wipe out civilians but leave the buildings standing. With deer only the old trees are left behind,” he says. “The work in Laskeek Bay is just a case study of what’s happening all over the Islands.”

According to Pojar, such overbrowsing has “drastically depleted the shrub and herb layers of forests; retarded the regeneration of trees, especially red cedar and yellow cedar; and is contributing to the population declines of the cedars and of endemic and geographically significant plant species.”





If there was an agenda behind the RGIS conference, it was to engage the best minds in the field in the search for solutions. Options ranged from total eradication of the deer population through culls to the introduction of predators such as wolf. Given the societal and ecological implications of such strategies both ideas were dismissed outright. The general consensus leaned towards hunting as a population management tool, but at the same time many agreed that conventional hunting has proven ineffective.

In areas where there is good hunting—road accessible and close to the communities—deer are being managed by default and the natural restoration of vegetation is evident. But as more logging roads become deactivated the hunting effort becomes less evenly distributed across the landscape. Interestingly, there has been a sharp decerease in hunting across Canada since the 1980s. Hunters say the biggest impact here came from closing the Canadian Forces Base Masset where a large percentage of the more than 240 military personnel were active deer hunters.

John Cumming is the president of the Port Clements Rod and Gun Club and has been hunting for over 40 years. Given the constraints, Cumming agrees that simply increasing hunting pressure will not solve the problem. While he supports returning the bag limit to 1980 levels from 10 deer to 12 “regardless of sex”, he favours a more directed hunt. By this he means increasing the hunt in areas where the deer population has spiked.

“Most of our members are supportive of a directed hunt,” Cumming says. “It means going to the Ministry of Forests to find out where there are problems with deer. It doesn’t have to be Rod and Gun Club members doing the hunting. It’s just the start. We could go to the communities and ask the mayors if there are hunters that could do this for us. Then we could give any excess meat to the needy.”

For his part, Cumming is pursuing a communal hunt permit for the Rod and Gun Club to supply venison to those who are unable to hunt for themselves. While such initiatives go a long way to reducing deer impacts, many Islanders, including Cumming, are calling for a broader-based approach to introduced species that looks at the whole picture.

“The biggest thing to deal with now are the plants: the knotweed, Scotch broom and gorse. Some of the weedpullers have already started to move on this. The mammal groups will take more time. We’re not going to see much action in the next six to eight months, but I’m hopeful," Cumming said.

Cumming’s hope is tied to the success of a new Islands organization on which he sits as a member. The Introduced Species Task Force grew out of the energy and recommend-ations following the RGIS conference. The task force is made up of those who have an interest in the issue and want to be actively involved in projects that deal with introduced species. The wish list of possible projects for the task force is long and ambitious. They want to meet with the QCI Trappers Association to discuss taking squirrels off the fur-bearer trapping list so they can be controlled through hunting. The Port Clements Rod and Gun Club is talking to the Province on changing regional hunting regulations to reduce the cost of tags to encourage hunting, increase the number of deer that can be hunted in a year and extend the doe season by an extra month or two. This will address a couple of issues in the short term, but to deal with the slate of identified problems and stem the tide of new introductions in the long term is going to be tough. •