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Lynn Scott's
Lepidoptera Index |
Local Moth Habitat and DiversityAll of the moths illustrated in the photos on this site have been photographed at a single location, at my home on the edge of the Carp Ridge, overlooking the village of Dunrobin, in the rural outskirts of the city of Ottawa, Canada's national capital (see map). Where any particular species of moth will be found depends mainly on the existence of its larval food in the general vicinity. Most species' caterpillars feed on plants — variously on leaves, stems, wood, flowers and seeds — although some feed on such things as mushrooms and lichen, fibers such as wool, beeswax, and even occasionally exhibit cannibalistic behavior. Some moth caterpillars are polyphagous, and will feed and thrive on a variety of host plants, while others are very host-specific. The normal geographic ranges of different moth species also relate to the severity of the local climate. Some are specifically adapted for survival as pupae, caterpillars or even as over-wintering adults in freezing temperatures, while others can be found only in subtropical and tropical environments. I have found no precise estimate of the number of species that can be reasonably expected to occur at a single location, but compilations of records for particular localities over time suggest an upper limit in the order of 1500 species. A list of lepidopteran species recorded within 50 km of the Peace Tower on Parliament Hill in Ottawa (about 17.4 miles or 28 km from my location as the crow flies), compiled in 1998, ran to 1041 species of micromoth, 96 species of butterfly and skipper, and 934 species of macromoth, for a total of 2072 species (J.D. Lafontaine, pers. comm., 2001). About 1000 of the species on that list have been photographed at my location between 2000 and 2007. In addition, I have photographed another 75 or so identified species comprising some species newly recorded for the Ottawa area together with a number of species described or re-classified since 1998. Although the pace of adding species to my "home" list has slowed somewhat, more species are still being added each year. The diversity of moths that I photograph is supported by a fortuitous local diversity of habitat, beginning with the fact that there are three different geological (and soil) environments within 1000 feet of my home. Although much of the Carp Ridge is heavily glaciated Precambrian granite, frequently exposed at surface, there are also remnants of younger sediments remaining, including a layer of Nepean sandstone that outcrops 100 feet in front of our house, and a still-younger layer of March-Oxford limestone that outcrops 500 feet up the road. This has meant a broader range of soil conditions to support a greater variety of plant life in our immediate vicinity. Our 2-acre property is also at the interface between forest and field, so that we have a good range of mature forest, edge of woods, waste-ground and meadow vegetation within 500 feet or so. In addition, there are ponds, marshy areas, and slow- and fast-flowing streams and ditches within that 500-foot radius. The area immediately around our house is largely wooded, mainly with native deciduous hardwoods including sugar maple (Acer saccharum), red maple (Acer rubrum), white oak (Quercus alba), red oak (Quercus rubra), bur oak (Quercus macrocarpa), white elm (Ulmus americana), basswood (Tilia americana), butternut (Juglans cinerea), white ash (Fraxinus americana), red ash (Fraxinus pennsylvanica), bitternut hickory (Carya cordiformis), hop hornbeam (Ostrya virginiana), white birch (Betula papyrifera) and, at some edges, poplar (Populus sp.). Isolated specimens of native conifers can also be found in the woods, restricted to white pine (Pinus strobus) and white spruce (Picea glauca). The edges of our woods are home to an array of smaller fruiting and flowering trees and shrubs, including wildling apple trees (Malus sp.), pincherry (Prunus pensylvanica), chokecherry (Prunus virginiana), Canada plum (Prunus nigra), serviceberry (Amelanchier sp.), hawthorn (Crataegus sp.), various virburnums (Viburnum sp.), red-berried elder (Sambucus pubens), red osier dogwood (Cornus stolonifera), pagoda dogwood (Cornus alternifolia), staghorn sumac (Rhus typhina), beaked hazel (Corylus cornuta), common buckthorn (Rhamnus cathartica), glossy buckthorn (Rhamnus frangula), purple-flowering raspberry (Rubus odoratus), wild red raspberry (Rubus idaeus), various wild currants and gooseberries (Ribes spp.), various wild honeysuckles (Lonicera spp.), and a variety of willows (Salix spp.), among others. In addition, the vines American bittersweet (Celastrus scandens) and Virginia creeper (Parthenocissus vitacea) are frequently found at the forest edges. Again, the evergreens are only marginally represented, the only one I have identified being common juniper (Juniperus communis). An even greater array of low-growing woody and herbaceous plants flourishes on the forest floor and in open areas. Along the roadsides, many non-native plants can be found, mainly imported with the arrival of early settlers. There is a good variety of wanted and unwanted grasses and grass-like plants, wildflowers and small woody plants, including copious quantities of poison ivy (Rhus radicans). A number of ferns grow in moist, shady areas where growing conditions are right, and there are countless varieties of lichen, mushrooms and other fungi. The ditches, streams and marshy areas support bulrushes, sedges and a considerable range of plants that occur in open wetlands. The broad array of native and non-native wild plants has been supplemented by local residents' additions. A nearby landowner has partly reforested a former field, mainly with conifers including various species of pine and spruce. The same neighbor is also responsible for introducing a small clump of black locust (Robinia pseudoacacia) that is host to several moth species generally considered rare in the Ottawa area. Other local residents (including myself) have planted a wide variety of ornamentals, including flowering shrubs such as lilac, foundation plantings of juniper and yew, "cedar" hedging, and assorted specimen trees. The diversity of plant life and habitat is clearly mirrored in the diversity of moth species that are found locally. Species that are completely dependent on conifers as host plants are, for the most part, rare at my lights, but species that feed on relatively unusual (for my area) trees such as white oak, are somewhat more common here than they are in many other places. I am indeed fortunate to be in a location of such rich habitat, and it continues to be interesting to see just how many different species of moth can be found at my lights, and how that changes over time. |
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