P. M. Eckel
Buffalo Museum of Science
1020 Humboldt Pkwy
Buffalo, NY 14211 U.S.A.

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The Three Sisters is a group of three islands in the Canadian channel of the Niagara River leading to the Horseshoe Falls south of Goat Island. They are part of a north-south oriented dolomite ridge which passes under Goat Island. Brother Island would have been continuous with the Third or outermost Sister but for a large break in the bedrock forming a channel of swift water between them. Each island is elliptic in shape, with their long axes oriented in the direction of the river current. The uneven surfaces of the dolomite substrate, due to solution of crystalline deposits, provides for the establishment of a variety of cryptogams, for the retention of soil and the establishment of vascular plant communities.

The upper, or eastern ends of each of these islands, and the adjacent shore of Goat Island has always borne the brunt of the current. Winter storm surges frequently scoured these ends. The First and the Third Sisters have rock platforms facing the current, the Second is barely above water level. Several rare plants in New York State grow in association with habitats formed from soil washed away and ice scour on the Islands' eastern ends.

In early photographs of the Sisters, the bedrock margins of the islands are bare of vegetation - more recently, with absence of scour and greater accumulation of soil and root masses on the dolomite, the vegetation is presently more dense and complex in these same areas.

These sunny, islands have suffered erosion events just as the south shore of Goat Island has, and for the same reason: high water volume, high current, and the prevailing south, southwesterly winds.

In the third report of the Commisioners, published in 1887, the violent windstorm of October 13, 1886 was reported when "the water in the river rose until it covered the surface of the Three Sister Islands. The greatest loss sustained was the destruction of many trees, overturned by the wind. Twenty-five maples, 33 basswoods, 6 willows, 2 hickories, two ironwoods, two ash, one walnut and one cedar were destroyed .... Many of the trees overturned were old, large and thrifty." These statistics may apply to the reservation as a whole, rather than the Three Sisters Islands alone. "At the times of very high water the group of the Three Sisters Islands obstructs the water in the river, causing it to rise above those islands to a higher level than in other places in the river. During the storm of January ninth (1889) the water covered a portion of the First Sister Island, the ends of the bridge between the First and Second Sisters Islands and flowed over the Second Sister Island, doing considerable damage to the surface. The upper end of the Third Sister Island was submerged and the soil and vegetation carried away from that locality, leaving the rocks bare to a much greater extent than formerly and overturning a number of trees at the margin of the island" (6 Ann Rep Comm, 1890).

Again, a "violent wind" of January 13, 1890 "caused serious damage to the Reservation. The bridges to the Three Sister islands, were endangered by the high water that flowed over the Three Sister Islands, and over the bridge between the First and Second Sister Islands. The bridges were also in great danger from floating logs ... The gravel walks on the islands, and a large quantity of the soil were swept away. Thirty-six trees were blown down on the islands, to wit: eleven basswood, five elms, six beeches, four ironwood, three maples, two white cedar, two red cedar, one pine, one white oak and one hemlock .... Fourteen of the trees were each two feet in diameter. Two of the elms were three feet in diameter" (7 Ann Rep Comm, 1891).

In 1907 the river rose again and flowed over the Three Sisters, "practically all of the soil was washed off of the Third Sister Island, the gravel walk and soil washed off of the upper end of the Second and considerable damage done to the First Sister Island," and the "damage to the Islands has been repaired by placing more soil thereon" (24 Ann Rep Comm, 1908).

There is presently little if any threat made by the river flowing over the islands in winter due to the diversion 75 percent of the river volume, and due to the control structures just upriver in the Grass Island-Chippawa Pool. In winter there is only an interrupted sheet of water passing between these islands (see photographs).

Each island supports a variety of microhabitats for example the east section of the Second Sister with its clean, low dolomite floor and the central portions of the First and Second Sister which support a forest with some humic topsoil. Portions of the river margins have been relatively recently exposed since the drop in water levels. Each island has its own floristic character.

In contrast to the scoured eastern ends of the islands, the western ends receive some alluvial deposition since the force of the current is broken by the eastern ends. Both the First and Second Islands possess wet-alluvial plant communities at their lower ends, especially the Second Sister which has a small marsh still. It was depicted on a map as long ago as 1883 (see Second Sister section). The lower end of the Third Sister is broken by a joint in the bedrock and is bare rock.

The Porter family, who were the first private citizens to own the Goat Island group, built bridges to the Three Sisters in 1869; the islands appear to have been otherwise undisturbed. In 1896 there were three wooden bridges to the Three Sisters Islands (13 Ann Rep Comm, 1897).

In 1895 Lady Theodora Guest reported "these sister islands were fascinating. Little rocky paths wound about them, bordered with Maple, Balsam [probably Hemlock, see the species catalogue], Mulberry and Black Walnut trees, as green and fresh as possible, though there were not many flowers. Pink Crane's bill, the inevitable Dandelion, a bright scarlet Columbine, and Podophyllum, whose large leaves make the children call it the umbrella plant, were nearly all I noticed."

Naturalists of all kinds have enjoyed these relatively isolated areas. The bryologist Elizabeth Gertrude Britton visited there and collected bryophytes (liverworts and mosses) during the 1886 meeting of the American Association for the Advancement of Science. Mary L. Wilson, a botanist associated with the Buffalo Society of Natural Sciences, collected lichens on the Three Sisters rocks around 1870 as did her contemporary Judge George Clinton. Terrestrial snails were hunted in years gone by on the Sisters by members of the Conchological Section of the Buffalo Society of Natural Sciences (Robertson and Blakeslee, 1948). Members of the scholars accompanying Louis Agassiz on their way to Lake Superior prior to 1850 took their bath in the cascade in the channel between the First Sister and shore of Goat Island.

With the establishment of the bridges in 1869, came paths bisecting each island at their middle, forming eastern and western sections.

The Three Sisters has recently been reported as "primitive woods", or at least the least altered of any other area in the Reservation, other than the islands in the American channel (q.v.). The best that may be said is that these three islands may be the least damaged of the ecosystems present in the complex.

The vegetation of the Third Sister has been nearly completely destroyed by trampling due to the practice of allowing busloads of visitors to discharge their passengers for a twenty or thirty minute "romp" on the island furthest out in the river. It is difficult to assess the condition of the Second Sister, except that its century old marsh on the west end is becoming damaged by trampling. The First Sister, west end should be completely blockaded from visitors until a natural resource policy is developed, as this little section does possess the community structure and species diversity for which these islands became legendary. On the east end of the First Sister, what native vegetation still exists is in serious competetion with dense colonies of monoculture communities alien shrubs. Certain areas of the First Sister, east end, and of the Second Sister, east and west ends, were observed to have been cut extensively for shrubs, and selectively for trees, in 1985 or 1986, as was the slope on Goat Island facing the west end of the First Sister. Such cutting encourages the establishment of robust and invasive monocultures of native and alien species, particularly White Snakeroot (Eupatorium rugosum), and Buckthorn (Rhamnus cathartica), Tartarian Honeysuckle (Lonicera tartarica), and Privet (Ligustrum vulgare.)

Accompanying the asphalted path leading out to the Third Island is a mowed-lawn grass margin. The bases of trees along this stretch show damage by mowing devices which appear to find it difficult to cut the grass here. It is recommended that these lawns be eliminated and a thoughtful plan created to reestablish the native vegetation.

The lawns support weedy vegetation familiar to people in their urban experience: Dandelions, for example. The large basal leaves of Burdock (Arctium lappa and A. minus) are particularly conspicuous. The lawns are connected across all three islands and form a corridor by which alien weeds, deriving from the extensive lawn systems maintained on Goat Island, are presently invading the Three Sisters. Weeds established on the lawn margins of the Sisters then proceed to establish themselves up the dirt-path systems on all three islands and into the native plant communities.

The response of the public (various personal communications during field work) is that the weeds should be cleared out - weeds are disturbing to their experience of Niagara Falls. Unfortunately, because they do not fully understand the processes involved, they believe it is the native vegetation that is promoting the weedy infestation, and not the existence of lawns. Indirectly, visitors at the Falls indicate they would like the removal of plants characteristic of urban vegetation, and this cannot be done without the elimination of grass monocultures (lawns).

Exposed dolomite or calcareous flats are good habitat for invasion by both rare and weedy taxa - establishment of rare taxa should be monitored and encouraged. Weedy pioneers, whether native or alien, known to develop monocultures should be monitored and carefully removed or modified in the interests of high species diversity. Relationship between the benefits of weedy pioneers that may be colonizing recently exposed land surfaces and preparing successional habitats and rare plants that may colonize habitats already established by weeds must be considered when making decisions to remove weeds in recently exposed rock surfaces (river bed). Several rare or interesting plants grow at the edges of grass mats, but are not first colonizers (Kalm's Lobelia, Small-flowered Purple Gerardia, Linear-leaved Loosestrife.

Invasive non-native taxa are to be removed carefully so as not to expose shade-loving species to too much sun or exposure to the wind, or disturb the soil too much, as on shaded boulder tops with their associated cryptogamous species (First Sister west).

The plant communities in these islands appear to be the most intact of any area on the Reservation. They have recently been reported as "primitive woods", or at least the least altered of any other area in the Reservation, other than the islands in the American channel. The best that may be said is that these three islands may be the least damaged of the ecosystems present in the complex. Their flora appears to be more intact than those in the American channel, the larger of which have never been connected by bridge. This may at first seem odd. Although access to these islands was not permitted for this project, I base this guess on the fact that the American channel islands were heavily colonized by conifer species - all of which are gone, and the trees seen today do not appear to be particularly mature (see discussion above).

The flora of these islands is considered old in this paper due to its complexity and diversity relative to other areas studied in the Reservation.



Arabis lyrata LYRE-LEAVED ROCK CRESS. Day, 1888.

Aralia nudicaulis WILD SARSAPARILLA. Day, 1888.

* Epipactis helleborine HELLEBORINE ORCHID. "Frequent on all three islands," 1984, specimen (BUF). "Goat Island ... where originally introduced by Day" (Zenkert, 1934).

Lindera benzoin SPICEBUSH. "Goat Island and the Three Sisters" (Day, 1888). "Handsomely represented" (Day, 1901).

Lobelia kalmii KALM'S LOBELIA. On wet rocks, Grace B. Craw, Union School Herbarium, Lockport, N.Y., 1894 (BUF).

* Morus alba WHITE MULBERRY. 1932. "Along bridge to Second Sister," 1987.

Panicum depauperatum STARVED PANIC-GRASS. "In rocky places" (Day, 1888).

Pellaea atropurpurea PURPLE CLIFF BRAKE. "Formerly on Goat Island and the Three Sisters. Not lately seen by us. Probably extirpated" (Day, 1888).

Physocarpus opulifolius NINE-BARK. Day, 1888. Zenkert, 1934.

Polypodium vulgare var. virginianum COMMON POLYPODY. Day, 1888.

Populus grandidentata BIGTOOTH ASPEN. Day, 1888.

Scirpus atrovirens DARK-GREEN BULLRUSH. 1988.


Preissia quadrata (as Preissia commutata Nees). Three Sisters Islands, Niagara Falls, M. A. H[owe]. [leg.] May 17, 1893 (NY).

Reboulia hemispherica. (As Preissia hemisphaerica). Three Sisters, Niagara Falls, N.Y., Aug. 21, 1886, comm. E. G. Britton, 1890 (NY). [Collected during the 1886 meeting of the American Association for the Advancement of Science.]


Anaptychia setifera. Three Sisters, Niagara. [handwriting of Mary L. Wilson] [Det. Richard C. Harris, 1988] Mary L. Wilson 1870 (BUF).

Pannaria rubiginosa. "Sisters" Niagara [handwriting of Mary L. Wilson] [Det. Richard C. Harris, 1988] R. S. C. June 1870. "PD-" (BUF).

Teloschistes chrysophthalmus. "Sisters" Niagara Falls. [perhaps handwriting of Mary L. Wilson] [Det. Richard C. Harris, 1988 "The only 'inland' New York record." R.C.H.] 1870 (BUF).

Algae blooms are readily observable in the shallow waters about the islands in the cooler months of autumn, winter and spring, and in the slower water at the west end of the Second Sister.
A reddish-orange species of algae of the genus Trentepohlia grows on the channel boulders on the margins of the Three Sisters, conspicuous from the bridges. The colorful masses are most evident in late fall through early spring (see phycology section).