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Cranberries. They were one of the biggest surprises of our visit to Sable Island on an Adventure Canada cruise.

Wild cranberries in bog
Wild cranberries in bog
Photo © Barb & Ron Kroll

A native plant on this crescent island, 160 kilometers (100 miles) south of Canso, Nova Scotia, the cranberry (Vaccinium macrocarpon) grows in wet depressions.

We encountered them during a hike with Sable Island National Park manager, Jonathan Sheppard. "This cranberry bog was a freshwater pond at one point," he said.

Exporting cranberries to Nova Scotia mainland

"If you've read Sable Island history, you would've heard about the tall ships leaving the island, loaded to the gunwales with cranberries. For several years, the fruit was a significant export."

Why? Sheppard explained that ships brought supplies to the Sable Island families that manned the life-saving stations, and later on, to the people working in the light-keeper's home.

The inhabitants realized that it was easy to foster cranberry growth on wetland areas and to harvest them, so they filled the empty provision ships with up to 400 barrels of wild cranberries, annually, to sell on the Nova Scotia mainland. Sable Island cranberries sold for a premium price.

Bill Freedman identifies plants for Adventure Canada passengers on Sable Island
Bill Freedman identifies plants for Adventure Canada passengers on Sable Island
Photo © Barb & Ron Kroll

Heathland habitat

Do Sable Island horses eat the cranberries? No, according to Dalhousie University professor Bill Freedman (who regrettably passed away after our trip). Freedman did several surveys of vegetation on the island. "They're a tart fruit that we make into sauce to accompany turkey for Thanksgiving and Christmas, so that's probably why horses don't like them."

People no longer harvest cranberries on Sable Island. "Migrating whimbrels, such as Hudsonian curlews, eat them," he said. "Gulls also eat them like popcorn."

Freedman, who accompanied our cruise as a resource person, explained that the heathlands are only one of Sable Island's habitats. "In addition to cranberry heath, this habitat includes a mixture of shrubs of various species—bayberries, blueberries, crowberries and junipers."

Preventing introduced species

Sable Island has a rich biodiversity with 190 plant species. Even though more than one-third of them are non-native, introduced intentionally and accidently over the island's history, we were not going to bring in more introduced plants.

Scrubbing boots on Adventure Canada ship
Scrubbing boots on Adventure Canada ship
Photo © Barb & Ron Kroll

Before we left the ship to go ashore on Zodiacs our expedition leader, Stefan Kindberg, gave us strict instructions. "Empty any plant material from your pockets and cuffs and wash your footwear with brushes in the water troughs."

We also washed the soles of our shoes and boots after each shore excursion to prevent them from transporting seeds and organisms from one landing site to another.

Sable Island flowers

During his presentation on The Natural History of Sable Island, Bill Freedman showed us photos of flowers that grow there. They included the yarrow (Achillea lanulosa), with clusters of small flowers and the blue flag (Iris versicolor), which grows in wetland areas, but wasn't flowering when we were there.

He also showed us images of grass pink (Calopogon latifollus). The orchid's showy flowers attract insects and snap shut when they land. This forces insects to crawl out, spreading pollen as they move.

While hiking on Sable Island, we saw the small white flowers of the starry false Solomon's seal (Maianthemum stellata), from the lily-of-the-valley family.

Mixed among them were fuzzy grey-leafed pearly everlasting plants (Anaphalis margaritacea). "People collect them for winter bouquets," said Freedman.

White flowers on starry false Solomon's seal
White flowers on starry false Solomon's seal
Photo © Barb & Ron Kroll

We also saw rose hips from the Virginia rose (Rosa virginiana), which was not blooming during our visit. Freedman told us about the tiny white flowers of the meadow rue and the unique geometry of the ragged-fringed orchids (Platanthera lacera) that also grow on Sable Island.

Insectivorous plants

Bill Freedman generously shared the knowlege that he gained during his studies of Sable island ecology. One of the fascinating plants that he described was the round-leafed sundew (Drosera rotundifolia).

"It has sticky blobs at the end of the projections of its round fleshy leaves. If an insect lands on one, it gets mired. The leaf rolls on the insect to capture it and the plant secretes extracellular enzymes to dissolve it. The plant then absorbs its phosphorus and nitrogen as critical nutrients."

The most memorable plants that he discussed were actually mushrooms. "The name coprophilous fungi means they are poop-loving," he explained. The existence of these mushrooms wasn't surprising, considering the large amount of equine dung deposited by the grazing wild horses.

Yellow water lily flowers in freshwater pond
Yellow water lily flowers in freshwater pond
Photo © Barb & Ron Kroll

Freshwater ponds

A hugely disproportionate amount of Sable Island's biodiversity depends on the freshwater ponds and their nearby riparian habitat, according to Freedman. "Many have disappeared. Some plants, such as spatterdock, depend on wetlands."

When we walked around one of the ponds in the west end of the island, dozens of pretty yellow water lilies adorned it.

Grassland habitat

In addition to the heath and few wetland areas, the interior vegetated area is mostly a grassland plant community.

Bill Freedman explained that the low-growing grassland is dominated by three species that the feral horses like to eat—Poa pratensis (Kentucky bluegrass), Poa annua and Festuca rubra. By feeding on them, the horses keep these grasses low.

Marram grass surrounds photographer viewing wild horses
Marram grass surrounds photographer viewing wild horses
Photo © Barb & Ron Kroll

Marram grass

The most common plant on Sable Island is marram or dune grass (Ammophila breviligulata). "Although the horses don't like it as much as their three favorite grasses, there is so much of it that it makes up the bulk of their diets," he said.

Ammophila means "sand-loving." Marram spreads through underground rhizomes. It encourages sand deposition and helps stabilize dunes. New sand deposits help it thrive by growing new roots.

To reduce erosion, teams have planted this native colonizing species as part of terrain restoration projects. We have vivid memories of sitting on sand dunes, surrounded by marram grass, as we photographed the feral horses grazing on it.

Does Sable Island have any trees?

There have been several attempts to plant trees on Sable Island to stabilize the sand dunes. In 1901, the Ottawa Experimental Farm planted several thousand conifers, deciduous trees, shrubs and Pinus maritima seeds. None remain.

In the 1970s, staff planted two pine trees near Sable Island's weather station. A decade later, Mobil Oil crews planted fir trees as fences to trap drifting sand.

Today, Sable Island has only one stunted tree. The gnarled, bonsai-like Scots pine is less than one meter (three feet) high.


Adventure Canada

Sable Island National Park Reserve

More things to see & do on Adventure Canada Sable Island cruises:

Gully Marine Protected Area - Habitats for Seabirds and Whales

Sable Island Grey Seals - Where and When to See Their Behaviors

Sable Island Birdwatching - Gulls, Terns, Petrels and Ipswich Sparrows