The Osoyoos-Arid Biotic Zone

The new "System Plan" for the ER Program

Trial Island ER Proposal

Oil Spill on the West Coast!

FALL 1989

ER additions in the Tsitika Watershed: Will they protect the integrity of Robson Bight?

Robson Bight on the northeast coast of Vancouver Island is known as the world’s most likely spot to see Killer Whales in the wild. It is also the mouth of the Tsitika River, which until about 1980 was the last unlogged watershed on the east coast of Vancouver Island. In 1972 the entire watershed was proposed to become an Ecological Reserve by the late biologist and author, Ian Smith. The reserve purposed was to protect an intact watershed as Roosevelt elk habitat. Public hearings were held with Roderick Haig-Brown speaking passionately for protection of the Tsitika. The provincial government then recommended a multi-disciplinary committee be set up to resolve the conflict between forest and conservation interests.

From 1976 to late 1978 a Tsitika Planning Committee met and deliberated on the fate of the Tsitika watershed. This committee was chaired by the Ministry of Forests, with at least one representative each from Canadian Forest Products, MacMillan Bloedel and Western Forest Products. On the side of conservation were one Fish and Wildlife representative, a Federal Fishery representative, and an Ecological Reserves representative. Public and union members were also on the committee. Basically it was decided to log the watershed, setting aside a few small Ecological Reserves that would quiet the public outcry and serve research purposes. MacMillan Bloedel planned to build a log dump in the Tsitika River estuary which was then their private holding, bought way back in the 1930s by H. R. MacMillan for $1.00.

However, Killer Whale research in the late 1970s and early 1980s was starting to indicate that Robson Bight (the bay at the mouth of the Tsitika River) was something special. It appeared to be a core area for seven to eight resident pods of Killer Whales (totalling 65-85 out of BC’s total population of around 300). Robson Bight is visited by the whales mainly from June to October. When the whales are present in Johnstone Strait there is an 80% chance that they will visit the Bight several times per day. The whales behave differently in Robson Bight; there is less travelling, less feeding, more resting, more play, and perhaps more sexual activity than in any other place on the BC Coast. Then it was discovered that the whales use certain beaches along the Bight for a “rubbing ritual”. The researchers also found that the whales were more sensitive to disturbance when they were at the rubbing beaches, or in the Bight. As a result of these findings and public pressure a 1,248 hectare totally marine Ecological Reserve was created in June 1982 to protect this core Killer Whale habitat.

Over the years the Ecological Reserves Unit negotiated for the purchase of the M.B.’s private holding in the estuary. With funding from the Nature Trust, the $1.00 lot was purchased for the province for over $400,000. In August 1988, the estuary and a narrow upland strip of land totalling 412 hectares along the Bight were incorporated into the Ecological Reserve. At its narrowest the reserve boundary is only 160 metres from the ocean.

SPRING 1989

The Osoyoos-Arid Biotic Zone

If you drive east and south on Highway 97 across British Columbia, you will notice that as you near Keremeos, the landscape becomes progressively drier. Near Osoyoos Lake and the International boundary the slopes and benchlands become a treeless, starkly sculpted scrubland of silvers and browns. This area is often referred to as “Canada’s pocket desert”, part of a continuum of arid desert lands that stretch from Mexico and Arizona in the south, to a narrow portion of the Okanagan and Similkameen valleys in the north. The Osoyoos-Arid Zone lies in the rain shadow of the Selkirk Mountains and receives less than 20 cm of precipitation annually! Summers are long and hot in this valley bottom area, and winters are comparably mild.

Within this zone there are wetter riverine habitats along the Okanagan River, but it is the dry benchlands, cliffs, and hill slopes that support the unique flora and fauna.

Plants: Most of the plants growing in this dry zone have very small leaves to reduce transpiration (water loss) and grow at some distance from each other so as not to compete for the little available water. Greasewood (Purshia tridentate) is the characteristic shrub of this zone. Its hairy leaves, which roll inward during the most scorching weather, are highly adapted and its woody stems contain nutritious oils, which are favoured by wild and domestic animals. Other characteristic shrubs are Rabbitbush (Chrysothamnus nauseosus), and Sagebrush. While looking for such beautiful and distinctive flowers such as: evening primrose, bitter-root, Mariposa lilies, yellow bell, tufted phlox, or balsam-root, one must be careful not to step on the brittle cactus! One of the grassland communities, the sand dropseed / red three-awn grassland is one of the most restricted grassland types in British Columbia.

Mammals: The mammals that inhabit this dry zone also form a characteristic assemblage in BC. Pallid bats, small-footed bats, the Western Harvest mouse, and Lord’s pocket mouse are found in the Osoyoos-Arid zone only. The White-tailed jackrabbit is now quite rare, and the badger has disappeared from this habitat.

Birds: The Osoyoos-Arid zone is home to both rare and endangered birds. The Canyon Wren is a tiny bird with a long descending call that echoes from its cliff-nesting habitat. It, the Sage Thrasher, and Brewer’s Sparrow are only found here in Canada. Say’s phoebes, Western kingbirds, Violet-green Swallows and Magpies are more common. Burrowing owls are now trying to make a comeback in this area with help from Habitat Conservation projects.

Reptiles and Amphibians: The unusual desert-adapted herpetiles of this zone include the Short-horned Lizard, the Western Skink, the Tiger Salamander, and the Great-basin Spadefoot Toad. The much-persecuted rattlesnake lives in rocky dens.

Insects and other small creatures: The most notable desert invertebrates are scorpions, wind-spiders and a native mantid. Dr. Scudder of UBC has made extensive entomological studies of this area and says the species diversity is impressive. He has found unique grasshoppers, scarab beetles, butterflies, ant-lions, tiger-beetles, oribatid mites and many other obscure insect species.

The Osoyoos Arid Biotic Area is a distinctive ecological area found nowhere else in Canada. It supports populations of plants and animals that are at the periphery of their normal range. Most of a specie’s adaptive evolution occurs at the periphery of its range. Therefore, areas such as this “pocket desert” are important for scientists who study the processes of environmental adjustment, natural selection and evolution in action.

However, due to its amenable climate, the Osoyoos-Arid zone has come under great pressure from ranches, orchards, vineyards, residential sub-divisions, and irrigation projects. It is only through the hard and persistent efforts of people in the Okanagan Similkameen Parks Society, concerned individuals and the co-ordination of the Fish and Wildlife Branch with the Ecological Reserves Unit that any of this unique ecosystem was set aside.