The Odonata (Damselflies and Dragonflies)
of the Montane Cordillera Ecozone

Introduction

The Montane Cordillera Ecozone extends from the eastern Rocky Mountains in Alberta to the western slope of the Cascades in British Columbia, and from the latitude of the Skeena Mountains in northern British Columbia to the United States border. It is Canada’s sixth largest ecozone, covering more than 49 million hectares. The Montane Cordillera is probably Canada’s most complex ecozone, with landscapes ranging from alpine tundra to dense coniferous forests, riparian woodlands, grasslands and dry shrub-steppe reflecting the exceptional diversity of topography and climate (Scudder and Smith 1998).

The complex topography of the ecozone results in large differences in temperature and precipitation across the Ecozone. The plateaus in the centre of British Columbia are in the rain-shadow of the Coast Mountains and have a mean annual precipitation in some areas less than 30 cm. However in the Selkirk Mountains mean annual precipitation is 250-350 cm in some areas, with 150-250 cm in much of the Rocky Mountains. Most of interior British Columbia is strongly influenced by both continental and maritime air, the latter being more prevalent in the south. In consequence, the southern interior valleys experience winter temperatures much less rigorous than those in the north. The warmest summer temperatures are recorded in the southern interior valleys, where, in the extreme South Okanagan, the mean daily temperature in July is over 22° C (Scudder and Smith 1998).

The major early works on Odonata of the Canadian Cordillera were Walker (1912, 1925, 1927), Buckell (1938) and Whitehouse (1918a, 1918b, 1941). Walker (1953, 1958) and Walker and Corbet (1975), dealing with the dragonflies of Canada and Alaska, included some of these and other records of dragonflies in the ecozone, and added considerable ecological information. Scudder et al. (1976) and Cannings and Stuart (1977) updated and summarized the information known for British Columbia. Since then, inventories and general collecting have improved our knowledge considerably (Cannings 1980a, Cannings 1983, Cannings and Cannings 1983, Cannings 1984, Cannings and Cannings 1986, Cannings and Cannings 1994, Cannings 1998, Cannings et al. 2000). The distribution, status and ecological requirements of the fauna are well known for the Okanagan Valley, moderately known for the remaining southern valleys, Wells Gray Park and local areas on the Cariboo-Chilcotin Plateaus. The region north of 52N and all mountainous areas remain only sparsely surveyed.

Introduction to the dragonflies

The Odonata (dragonflies and damselflies) is a small order of insects of about 5000 named species in 33 families worldwide. It is predominantly tropical in distribution and is not as diverse at higher latitudes. Nevertheless, 77 species are known from the Montane Cordillera Ecozone; this is 90% of the 86 species recorded from British Columbia (there are 202 recorded in Canada). Because of the abundance and size of individuals, the order forms one of the predominant groups in standing freshwater communities in the ecozone. In the western mountains species are less abundant in running water than they are in standing water habitats. Odonates occur around most types of fresh water. Certain kinds prefer lakeshores, others are found only along streams, or around springs and in peatlands. Ponds and marshes rich in aquatic vegetation support the most species.

The Odonata and their ancestors are some of the most ancient of insects. They have many primitive features, but also possess many specializations that reflect their aerial and predatory life. The order is divided into three suborders: the Zygoptera (damselflies), the Anisoptera (dragonflies) and the Anisozygoptera, a small group of two species from Asia that is intermediate in appearance between the other two suborders. Damselflies are slimmer, often smaller, and usually fly more slowly than dragonflies. At rest their equal-sized wings are usually held together above the body. Zygoptera means "joined wings". Dragonflies are robust, often fast-flying, with the hindwings broader than the forewings; when perched they hold their wings out away from the body. Anisoptera means "unequal wings". The higher classification of the order is contentious, but the Zygoptera are usually considered the more pleisiomorphic of the two major suborders. They are viewed as a monophyletic sister group of the Anisozygoptera plus Anisoptera in recent phylogenetic studies (Carle 1982, Bechly 1995).

Metamorphosis in odonates is striking but there is no pupal stage. The aquatic larvae are predacious and are armed with an enormously enlarged, hinged labium, which is used as an extendible grasping organ for capturing prey. Larvae are voracious, eating aquatic small crustaceans and even fish. Larvae can be placed in three categories according to their feeding behaviour. Climbers (Zygoptera, Aeshnidae) are streamlined stalkers that live in submerged vegetation. Sprawlers (Macromiidae, Corduliidae and Libellulidae) lie in ambush on the bottom mud and detritus. Burrowers (Gomphidae, Cordulegastridae) cover themselves with sand and mud and await their prey. Larvae go through 10 to 15 instars before emerging as terrestrial adults.

Adults are aerial, visually oriented predators: large, strong-flying insects with large eyes, strong mandibles and spiny legs. Prey is a wide range of flying insects; these are usually captured in flight. Adults are often colourfully patterned and exhibit a wide variety of readily observed behaviour. Mature males patrol the breeding habitats, agressively searching for mates, and may, like birds, defend a territory against other males of the species. These territories limit aggression and prevent undue disturbance of egg-laying females. Sometimes in crowded situations group territories with dominance hierarchies are established.

In the damselflies and many dragonflies development is rapid. Even in the north and at higher elevations in the Montane Cordillera the life cycle takes about a year. Lestes and some Sympetrum species overwinter as diapausing eggs, hatch in the spring and emerge as adults in the summer. Others overwinter as larvae and emerge the following spring or summer, although probably in some species and conditions, the larvae overwinter two years. However, in the larger dragonflies, such as Aeshna or Somatochlora, the short summers of high altitudes and the northern parts of the zone often mean that four or five years are spent in the larval stage. Adults live for about one to two months in this region.

Systematic Review

A systematic checklist of the 78 species (20 of which are potentially endangered, threatened or vulnerable) including their zoogeographic elements, is included as Appendix 1. A brief review of the major taxa of the ecozone with notes on habits is presented below.

FAMILY CALOPTERYGIDAE (JEWELWINGS)
Calopteryx aequabilis represents the Calopterigydae, a family of elegant and colourful damselflies, in the Montane Cordillera. The only population known in the ecozone lives in the outlet stream of Christina Lake, east of Grand Forks. The large-bodied adults are green (females) or blue-green (males) with black-tipped wings. They fly with a beautiful dancing flight along clear streams, where the larvae cling to submerged vegetation.

FAMILY LESTIDAE (SPREADWINGS)
The Lestidae, or spreadwing damselflies, is one of two cosmopolitan genera of Zygoptera. It is a small but widely distributed family in the Montane Cordillera, and there contains only one genus, Lestes, with five species. Most are widespread within North America and the Montane Cordillera zone. Lestes dryas is the only Holarctic member of the family. Lestes adults are metallic green or bronze, but parts of the body become pruinose-grey with age. They characteristically perch with wings half-spread. Females oviposit in tandem with males and eggs are usually placed in plants above the surface of the water. Larvae have unusually elongate labia. Some species are adapted to temporary ponds (see habitat section); in these situations larvae grow rapidly after overwintering as eggs.

Cannings et al. (1980) report on the ecology of three of these species that inhabit a series of lakes on the Chilcotin Plateau that range greatly in salinity and alkalinity. Lestes dryas colonized only the freshest ponds, L. disjunctus occurred in lakes up to medium salinities, and L. congener inhabited the complete range of salinities and occurred in very large numbers even at the highest concentrations (conductivity of 15524 microSiemens). Emergence and mating of the three species were also temporally separate; L. dryas emerged about ten days before L. disjunctus, which preceded L. congener by nine days. The main emergence of L. disjunctus occurred twenty days before the peak of the L. congener emergence.

L. forcipatus was discovered in the Montane Cordillera for the first time in 1998 and is now known from numerous localities in southeastern British Columbia. This species is probably more common than records indicate; it has certainly been overlooked over much of its range because of its similarilty to the common L. disjunctus.

FAMILY COENAGRIONIDAE (POND DAMSELS)
In the Montane Cordillera the Coenagrionidae consists of 6 genera and 15 species. The adults are frequently blue marked with black, but the ground colour may be green, yellow, orange, red or purple. There are often two female colour forms, one of which is similar to the male. Eggs are laid in the tissues of water plants and females may completely submerge for considerable periods during oviposition. The larvae are less elongate and have shorter labia than those of the Lestidae. The genera most often encountered are Enallagma and Ischnura. Enallagma, the common genus of blue and black damselflies, contains seven species in the region, the complete complement found in British Columbia. E. boreale and E. cyathigerum are perhaps the most widespread species in the ecozone. The former fairly swarms around the kettle lakes of the central plateau; the latter is the only Holarctic member of the genus and family. Doerksen (1980) outlined the reproductive behaviour of E. cyathigerum in the ecozone and other localities in British Columbia. E. clausum is typical of alkaline ponds and is the only species of the seven restricted to western North America. In the ecozone E. civile is known only from Bridge Lake on the Cariboo Plateau, where it has been collected only once. Because the status of this population is unknown, and because the species is apparently otherwise absent west of southern Saskatchewan, we have placed the species on the vulnerable list.

Ischnura is a cosmopolitan genus whose distribution in North America is decidedly southern in character. Two species, I. cervula and I. perparva are occur in the Montane Cordillera Ecozone, and are common in Typha and Scirpus marshes in the south; the former species ranges north to at least 53o. Coenagrion is a predominantly Palaearctic genus with three species ranging across most of boreal North America; C. interrogatum and C. resolutum occur in the ecozone. The former, the most boreal of Nearctic damselflies, is apparently restricted to water bodies with aquatic moss (Cannings and Cannings 1994). The two western Canadian species of Argia are of special interest in the Montane Cordillera. Both Argia emma and A. vivida live in streams, a rather unusual habitat for the Zygoptera of the region. A. emma also develops along lakeshores in southern valleys, and A. vivida is scattered here and there, mostly in the warm rivulets flowing from thermal springs. Both are considered threatened or vulnerable in the area. Pritchard (1982, 1989) , Conrad and Pritchard (1988, 1990) and Conrad (1992) documented the development and behaviour of A. vivida in hotsprings at Banff, Alberta.and Albert Canyon and Halcyon Hotsprings, B.C. Amphiagrion abbreviatum and Nehalennia irene are the sole representatives of their genera in the ecozone. The former is a red and black species inhabiting springs and seeps in the southern valleys; the latter is a tiny blue and metallic green denizen of sedge marshes.

FAMILY AESHNIDAE (DARNERS)
Members of the Aeshnidae are large, swiftly flying dragonflies usually marked with blue, green or yellow. They are represented in the Montane Cordillera by two genera, Aeshna, with 13 species and Anax, with one species. The ecozone supports all species known in western Canada. Adults tirelessly hunt for insects over ponds, lakes and streams, and wander widely in search of prey. When they land, most species rest in a vertical position. Females oviposit in water plants or floating wood above or below the water line. The larvae are slender and sleek, with flattened labia lacking setae. They are rapacious hunters among water plants.

Cannings (1996) keys the species in the region and outlines the biology and distribution of the species of Aeshna. Peters (1998) discusses the ecology of some Aeshna species of British Columbia and presents a key to adults based on wings only. This allows the identification of specimens that have been eaten by birds, a situation often encountered in the field. Six of the 13 Aeshna species are boreal (A. juncea and A. subarctica are Holarctic) and four others are transcontinental in the Transition forests. Three are strictly western in range. A. subarctica, A. sitchensis, A. septentrionalis and A. tuberculifera are peatland obligates in the Montane Cordillera and are found primarily at higher elevations, at least in the south. A. tuberculifera has a very local distribution in the ecozone and is known from only a very few peatland localities; we maintain it on the list of species of management concern. A. interrupta is one of the most widespread species in the area and is found in many habitats from northern peatlands to temporary ponds. It is the characteristic species of grassland ponds. A. constricta is an uncommon species typical of small ponds in the south; its preference for habitats that are often threatened by human development place it on the vulnerable list. Along with A. tuberculifera, the females mimic males in coloration and behaviour; they are also the only species of the genus in our region that regularly lay their eggs above the water in emergent vegetation.

A. californica is remarkable for its springtime flight season. In the south, it may appear as early as the last week of April, emerging with the earliest dragonflies. A species of lowland ponds, it normally disappears by early August, just when many darner species are reaching their peak abundance. Anax junius, the Green Darner, has a southern transcontinental distribution. At least some populations appear to migrate, with spring immigrants moving north in the spring and their offspring flying south in August and September. Other populations are resident.

FAMILY PETALURIDAE (PETALTAILS)
The ancient dragonflies of the Petaluridae flourished in the Jurassic Period at least 150 million years ago, well before the Montane Cordillera region existed. Today, relict populations persist in mountain swamps and seeps in widely scattered regions -- New Zealand, Australia, Chile, Japan, the Appalachian Mountains, and western North America. The single species in the ecozone, Tanypteryx hageni, ranges from California north along the Cascades and Coast Mountains to the north coast of British Columbia. It lives only in the extreme southwest part of the Montane Cordillera Ecozone.

The larva is unlike that of any of our other dragonflies -- it is amphibious. It digs an L-shaped burrow in the mud and moss saturated by the trickling spring water, with the lower, horizontal part of the burrow pointing upstream. Dozens of burrows can be concentrated in a small area. The larvae are mostly nocturnal, coming to the burrow entrance to await their prey. They can breathe air for long periods and often forage well out of the water-filled burrow. Tanypteryx is seldom seen in British Columbia (larvae have never been found in Canada) and because of its apparent rarity, we have placed it on the list of vulnerable species.

FAMILY GOMPHIDAE (CLUBTAILS)
The Gomphidae is a large family that is poorly represented in the Montane Cordillera Ecozone. Only five species in three genera occur; a fourth, monotypic genus, Octogomphus, lives in coastal streams just outside the southwestern edge of the Ecozone. Gomphids are not commonly seen in the zone but when they are encountered, are readily recognized by their widely separated eyes and their green or yellow bodies striped in brown and black. The female lacks an ovipositor and drops the eggs directly into clear streams and along the sandy shores of larger lakes. The larvae burrow in the bottom sediments.

Gomphus graslinellus lives along valley bottom lakeshores in the Okanagan, Shuswap, and Boundary regions, the only part of its Canadian range west of Manitoba. The larvae burrow in the sand and silt along wave-washed shores and the adults bask on the warm beaches. Stylurus olivaceus is closely related and has similar habits and distribution in the ecozone, although it also inhabits the larger, warm rivers such as the Okanagan and Thompson. Ophiogomphus colubrinus is a boreal species, uncommon in the northern streams of the Montane Cordillera. O. occidentis and O. severus are more widespread species that live in both lakes and streams; the former is restricted to lowland areas south of 51oN and the latter ranges well north of the ecozone into the Northwest Territories.

FAMILY CORDULEGASTRIDAE (SPIKETAILS)
Cordulegaster dorsalis is the only representative of the Cordulegastridae in the Montane Cordillera and in British Columbia. It is a large, black and yellow dragonfly, most common on coastal streams, but it is also a rare inhabitant of small streams, especially spring-fed ones, in the Montane Cordillera. Adults patrol these streams, and the female, with a spade-like ovipositor, shoves eggs in the sand and silt of the streambed. The large, squat, hairy larvae bury themselves in the sediment to await their prey. The labium of the larva, with its palps deeply and irregularly toothed, is distinctive.

FAMILY MACROMIIDAE (CRUISERS)
The Macromiidae are large yellow and black dragonflies inhabiting the rivers and wave-washed shores of lakes, where the adults fly rapidly out over the water. The thorax is encircled between the wings by a distinctive, oblique yellow band. The larvae sprawl on the bottom silt and sand. Their long spider-like legs and the horn-like projection between the eyes are characteristic. The single genus in the Montane Cordillera, Macromia, contains one species, M. magnifica, in the southwestern valleys of the ecozone. In the southern, dry valleys of the area, such as the Okanagan, specimens are pale, with much yellow on the body; in the wetter Shuswap region (and in the coastal forests of the Fraser Valley), the dragonflies are darker. This dark form was described as M. rickeri, but is considered by most to be conspecific with M. magnifica.

FAMILY CORDULIIDAE (EMERALDS)
In the Montane Cordillera the Corduliidae is a family best seen around lakes, boggy streams and peatlands in the mountains or in the north. Nine of 12 species are boreal in distribution. The adults are medium-sized dragonflies, usually with metallic blackish green or brassy bodies. There are three genera in the ecozone: Cordulia shurtleffi is the commonest member of the family; Epitheca canis and E. spinigera, transcontinental in the Transition forests, lay long strands of eggs, sometimes communially, along lakeshores; Somatochlora is the predominant genus with nine species. Somatochlora albicincta and S. cingulata are lake dwellers; S. hudsonica and S. semicircularis live in sedge marshes (the latter is the only Cordilleran species in the family); S. minor and S. walshii inhabit forest and peatland streams; S. franklini, S. forcipata, S. septentrionalis and S. whitehousei are peatland inhabitants.

FAMILY LIBELLULIDAE (SKIMMERS)
The Libellulidae is the largest dragonfly family in the Montane Cordillera, containing four genera and 21 species. The species are most common around ponds, marshy lakeshores and sluggish streams where the adults dart about and spend much time perched horizontally in the sun. Females oviposit alone or in the company of guarding males, and dip the abdomen in the water, releasing the eggs. The larvae, like those of the Corduliidae, move sluggishly or squat on the bottom mud.

Leucorrhinia species are small, black, white-faced dragonflies marked with red or yellow. Five of the six species are boreal and are most prevalent in the mountains or in the north around the marshy shores of lakes in the late spring or early summer. The tiny L. patricia is rare, known from only a few peatland ponds where the larvae live in aquatic moss mats. L. intacta is the anomaly in the genus, preferring cattail marshes in warm valley bottoms. The genus Libellula contains five large, striking species in the Montane Cordillera; most have banded or spotted wings, and in most species, the males sport white, pruinose abdomens. L. quadrimaculata, one of the most widespread dragonflies on the globe, is everywhere, from northern bogs to alkaline ponds. L. pulchella, boldly patterned, lives only in the warmest parts of the southern valleys. Most of this species' habitat has been drained and filled in the past century.

Sympetrum species are mostly small red dragonflies abundant as adults in the late summer and fall. The nine species are especially common in marshy lowland habitats. Unusual in the genus, the colour of S. danae is black and yellow. This species has a wide ecological tolerance, being equally at home in mountain peatlands and lowland marshes. S. vicinum is rare in the Montane Cordillera, and therefore on the list of species of management concern. It flies late, well into November in mild autumns in the south Okanagan Valley. S. costiferum and S. corruptum are typical of saline ponds in the grasslands of the ecozone, and along with the latter, S. madidum and S. pallipes can develop in ephemeral ponds. Cannings (1980b, 1981) described the larva and the ecological preferences of S. madidum on the Chilcotin plateau.

Erythemis collocata is the rarest of all the species in the Ecozone, known only from the old oxbows of the Okanagan River near the north end of Osoyoos Lake at the southern end of the Okanagan Valley.

Zoogeography and Faunal Elements

Species may be grouped with others that share similar distributions to form what can be termed faunal elements. The majority of the 77 species known from the Montane Cordillera Ecozone are restricted to the Nearctic region, although six are holarctic (defined here as species with transcontinental ranges in both North America and Eurasia). Two species (Anax junius and Sympetrum corruptum) are known from eastern Asia but do not have holarctic distributions. This section describes the Nearctic faunal elements pertaining to the ecozone (species with holarctic distributions are also assigned to a North American faunal element).
These faunal elements are:

1. Boreal (26 spp., 34%). Species occurring in the northern spruce (Picea) forests, across the boreal zone from treeline to the southern margin. In general, these species range from the Atlantic Provinces across the northern New England states, Quebec, northern Ontario, parts of the northern tier of mid-western states, the Prairie Provinces north of the Great Plains, and northern British Columbia, often ranging cosiderably southward in the higher mountains and plateaus of the western Cordillera. These species can be further subdivided into:
   1. Widespread Boreal (13 spp., 17%). With ranges as described above. Coenagrion resolutum (Hagen), Enallagma boreale Selys, E. cyathigerum (Charpentier) (also Holarctic), Aeshna eremita Scudder, A. juncea (Linnaeus) (also Holarctic), A. sitchensis Hagen, A. subarctica Walker (also Holarctic), Cordulia shurtleffi Scudder, Somatochlora albicincta (Burmeister), S. franklini (Selys), S. whitehousei Walker, Leucorrhinia hudsonica (Selys), Sympetrum danae (Sulzer) (also Holarctic).

   2. Northern Boreal (4 spp., 5%). Species that are common near the northern treeline but that are virtually absent from the northern contiguous United States and from the southeastern Atlantic Provinces and do not extend far south into the Cordillera. Coenagrion interrogatum (Hagen), Aeshna septentrionalis Burmeister, Somatochlora septentrionalis (Hagen), Leucorrhinia patricia Walker.

   3. Southern Boreal (7 spp., 9%). Species that are uncommon north of 60oN in the West and absent near the Arctic treeline in the East, but range far down the Cordillera and/or into the southeastern Atlantic Provinces and New England states. Some (e.g. Aeshna interrupta Walker) are common on the Great Plains. Nehalennia irene (Hagen), Aeshna interrupta Walker, Ophiogomphus colubrinus Selys, Somatochlora cingulata (Selys), S. minor Calvert, S. walshi (Scudder). Leucorrhinia proxima Calvert.

   4. Western Boreal (2 spp., 3%). Species not found east of Hudson Bay. Somatochlora hudsonica (Selys), Leucorrhinia borealis Hagen.

2. Transition (17 spp., 22%). Species generally most common in the southern boreal forests and adjacent montane forests in the West and mixed and deciduous forests in the East. Calopteryx aequabilis, Enallagma ebrium (Hagen), E. hageni (Walsh), Aeshna canadensis Walker, A. constricta Say, A. tuberculifera Walker, A. umbrosa Walker, Gomphus graslinellus Walsh, Epitheca canis MacLachlan, E. spinigera (Selys), Somatochlora forcipata (Scudder), Leucorrhinia glacialis Hagen, L. intacta (Hagen), Libellula julia Uhler, Sympetrum costiferum (Hagen), S. internum Montgomery, S. obtrusum (Hagen).

3. Cordilleran (12 spp., 16%). Species confined to the western mountains and their intervening valleys and plateaus. Argia emma Kennedy, A. vivida Hagen, Ischnura cervula Selys, Aeshna californica Calvert, A. palmata Hagen, Tanypteryx hageni (Selys), Ophiogomphus occidentis Hagen, Stylurus olivaceus (Selys), Cordulegaster dorsalis Hagen, Macromia magnifica MacLachlan, Somatochlora semicircularis (Selys), Libellula forensis Hagen

4. Western (9 spp., 12%). Species confined to west of the 100th meridian but otherwise ranging widely in North America. Amphiagrion abbreviatum (Selys), Enallagma clausum Morse, Ischnura perparva Selys, A. multicolor Hagen Ophiogomphus severus Hagen, Erythemis collocata (Hagen), Sympetrum madidum (Hagen), S. occidentale Bartenev, S. pallipes (Hagen).

5. Austral (6spp., 8%). Species ranging across the continent south of the boreal forests, often extending into Transition areas but with most of the range in the United States. Enallagma carunculatum Morse, E. civile (Hagen), Anax junius (Drury), Libellula lydia Drury, L. pulchella Drury, Sympetrum vicinum (Hagen).

6. Widespread (6 spp., 8%). Species with broad distributions in North America, from north to south and east to west, overlapping several of the other elements listed. These species range into boreal regions to varying degrees. Lestes congener Hagen, L. disjunctus Selys, L. unguiculatus Hagen, L. dryas Kirby (also Holarctic), Libellula quadrimaculata Linnaeus (also Holarctic), Sympetrum corruptum (Hagen).

The faunal elements are thus represented in the Montane Cordillera Ecozone as follows:

Twenty-five species of Boreal origin (32%) are recorded. Of these, 13 (17%) are Widespread Boreal, 7 (9%) are Southern Boreal, 4 (5%) are Northern Boreal and 2 (3%) are Western Boreal. Transition species total 17 species (22%) and there are 13 (XX20%) Cordilleran species. Nine species (1XX0%) are Western, 6 (9%) are Austral and 6(XX7%) are Widespread according to our definitions.

Six species -- Lestes dryas, Enallagma cyathigerum, Aeshna juncea, A. subarctica, Libellula quadrimaculata, and Sympetrum danae -- are holarctic, ranging around the Northern Hemisphere. It is most likely that these species have had such wide distributions since before the last glacial age. In contrast to the situation in some other insect groups, there is no evidence that the Beringian glacial refugium influenced the distribution of Montane Cordilleran Odonata. The only odonate with a Beringian distribution, Somatochlora sahlbergi Tryböm, does not range south of the central Yukon (Cannings and Cannings 1997). There, however, it hybridizes with two congeners widespread in the Montane Cordillera: S. albicincta and S. hudsonica (Cannings and Cannings 1985).

Farther north in the Cordillera, 70 percent of 33 species in the Yukon are of Boreal origin (Cannings and Cannings 1997); in the Montane Cordillera this boreal component is reduced to 34 percent. This reduction is the result of the strong influence of more southerly faunas, since all but one (Somatochlora kennedyi Walker) of the Yukon’s boreal species range south into the Montane Cordillera. Nineteen species in the Boreal element of the Montane Cordillera range south of 51oN along the mountains and plateaus of the Cordillera: Coenagrion resolutum, Enallagma boreale, E. cyathigerum, Nehalennia irene, Aeshna eremita, A. interrupta, A. juncea, A. sitchensis, A. subarctica, Cordulia shurtleffi, Somatochlora albicincta, S. cingulata, S. hudsonica, S. minor, S. walshii, Leucorrhinia borealis, L. hudsonica, L. proxima, and Sympetrum danae. These also could be termed boreomontane species. In contrast, six species of the Boreal element are rare as far south as even the northern parts of the Montane Cordillera: Coenagrion interrogatum, Aeshna septentrionalis, Ophiogomphus colubrinus, Somatochlora septentrionalis, S. whitehousei, and Leucorrhinia patricia. Except for Aeshna septentrionalis, these species are also sparsely distributed further to the north relative to their numbers east of the Cordillera. Their rarity in the west is probably more related to habitat scarcity rather than to limited post-glacial colonization.

Since the last glacial age, the Montane Cordillera has been recolonized by Odonata from at least two southern refugia: one in what is now the southeastern United States and another in the intermontane Cordillera south of Canada. The putative species pairs Somatochlora albicincta/ S. hudsonica and Leucorrhinia hudsonica/ L. borealis have distribution patterns that suggest this history. S. albicincta and L. hudsonica are boreal species with transcontinental ranges. Presumably they inhabited the southeastern refugium and recolonized the Montane Cordillera from the east and north, following the early retreat of the continental ice sheet east of the Rocky Mountains. S. hudsonica and L. borealis have similar distributions but do not range east of Hudson’s Bay, indicating that they recolonized the Cordillera from the south.

The Cypress Hills of southeastern Alberta and southwestern Saskatchewan are, for many species from diverse groups, an outlier of the Montane Cordillera. The upper plateau of the Cypress Hills was never glaciated and the surrounding territory became free of ice very early. The forested hills were soon repopulated by western montane taxa, rather than taxa from the eastern boreal forests. Lodgepole pine (Pinus contorta), Northern (Red-shafted) Flicker (Colaptes auratus cafer), Townsend's Warbler (Dendroica townsendi) The Cordilleran Odonata are represented there by Aeshna palmata.

From 10,000 to 8,000 years before present, following the retreat of the Cordilleran glaciers, the climate became warmer in the ecozone than it is today (Hebda 1995). Presumably, although there is no fossil evidence, southern, warm-adapted species ranged more widely to the north than they do at present. Disjunct, present-day populations in isolated, unusually warm habitats offer evidence for these former distributions. For example, Ischnura damula is now restricted in the Cordillera to the Liard River Hot Springs in the Boreal Cordillera Ecozone; further east and south, its nearest population is in southern Saskatchewan. Argia vivida, in a genus known for its Neotropical origins (Pritchard 1991), is largely associated with geothermally heated streams in the ecozone (Pritchard 1982). It, too, perhaps, was more widespread during the warmer hypsithermal period and has subsequently been restricted to warm sites (Pritchard 1989).

Patterns of distribution between the Pacific Maritime and the Montane Cordillera ecozones require more study. In Washington State, several species considered completely coastal in British Columbia, such as Ishnura erratica, Sympetrum illotum and Pachydiplax longipennis, also occur east of the Cascade Mountains. The Columbia River Valley may have acted as a corridor for these coastal species to range inland. In addition, a number of interior species such as Archilestes californica McLachlan, Erpetogomphus compositus Hagen, and Gomphus lynnae Paulson do not range north of the Columbia Basin in central Washington. This area is the northern limit of distribution of many plants and animals. In contrast, Argia emma is locally common in the lower Fraser River Valley of British Columbia on the western side of the Coast Mountains. It has apparently colonized this area by using the Fraser River Valley as a conduit from the Interior valleys of the Montane Cordillera Ecozone. It is not known from coastal habitats in Washington State, although it is common east of the Cascades.

Dragonfly Habitat in The Montane Cordillera

The general aquatic habitats available to dragonflies in the Ecozone are listed below, with the distinctive species associated with each.

1. Large lakes (wave-washed shores with little vegetation):
   In southern lakes, there is a distinctive fauna found in lakes with wave-washed shores with little vegetation: Argia emma, Enallagma carunculatum (in Scirpus beds), E. ebrium, Aeshna umbrosa, Gomphus graslinellus, Ophiogomphus severus, and Macromia magnifica. There are many large, deep lakes north of the southern valleys, but because of the cold, oligotrophic nature of these water bodies, dragonflies are restricted to shallow waters in sheltered bays, where the fauna resembles that found in small lakes and ponds.

2. Small lakes and ponds (floating, but little emergent vegetation):
   A wide variety of small lakes and ponds are present, and an equally diverse array of Odonata: Enallagma ebrium, E. hageni, Aeshna canadensis, A. eremita, A. multicolor, A. palmata, A. tuberculifera, A. umbrosa, Cordulia shurtleffi, Somatochlora albicincta, S. cingulata, Leucorrhinia glacialis, L. hudsonica, L. proxima, Libellula julia, L. lydia, and Sympetrum vicinum.

3. Alkaline lakes:
   These occur primarily in the dry, warm southern valleys and plateaus. None of the fauna is restricted to these unusual habitats, but these species are able to live here despite the often high salinity, and their life histories enable them to take advantage of the ephemeral nature of the shallower lakes and ponds. Enallagma clausum, E. boreale, Lestes congener, L. unguiculatus, Sympetrum corruptum, and S. costiferum.

4. Cattail/bulrush marshes (including margins of lakes and ponds):
   Lestes congener, Lestes disjunctus, Lestes dryas, L. forcipatus, L. unguiculatus, Enallagma carunculatum, E. cyathigerum, Ischnura cervula, I. perparva, Aeshna californica, A. canadensis, A. constricta, A. interrupta, A. multicolor, A. palmata, Anax junius, Erythemis collocata, Leucorrhinia intacta, Libellula forensis, L. lydia, L. pulchella, L. quadrimaculata, Sympetrum costiferum, S. danae, S. internum, S. obtrusum, S. occidentale, and S. pallipes.

5. Sedge marshes:
   Lestes congener, L. disjunctus, L. dryas, L. forcipatus, Coenagrion resolutum, Enallagma boreale, E. cyathigerum, Nehalennia irene, Aeshna interrupta, A. juncea, A. palmata, Somatochlora hudsonica, S. semicircularis, Libellula quadrimaculata, Leucorrhinia borealis, L. hudsonica, Sympetrum internum, and S. obtrusum.

6. Ephemeral ponds:
   In addition to some saline ponds that dry up in summer, fresher ephemeral waters support the following species. Some of these species overwinter as diapausing eggs in the dry pond basin. Lestes dryas, L. unguiculatus, Sympetrum corruptum, S. madidum, and S. pallipes.

7. Small peatland ponds with aquatic moss:
   Coenagrion interrogatum, Aeshna septentrionalis, A. subarctica, and Somatochlora septentrionalis.

8. Shallow sedge/moss fens:
   Enallagma boreale, Coenagrion resolutum, Nehalennia irene, Aeshna sitchensis, Somatochlora franklini, S. semicircularis, S. whitehousei, and Leucorrhinia patricia.

9. Streams:
   Odonata are not normally found in the cold streams of mountainous areas. The following species of flowing waters are generally restricted to the warmer slow-flowing, southern lowland streams or montane streams that drain lake basins, beaver ponds or peatlands. Calopteryx aequabilis, Argia emma, Ophiogomphus occidentis, Stylurus olivaceus, Macromia magnifica, and M. rickeri are restricted to the southern valleys. Aeshna umbrosa and Ophiogomphus severus are more widespread and also live in lakes. Somatochlora forcipata is restricted to the Rocky Mountains, S. minor and S. walshii are more widespread in small montane streams. Ophiogomphus colubrinus has been found only in warm rivers north of 5330’N.

10. Springs and shallow seeps:
    Some of the more uncommon species of Odonata are associated with small springs and shallow seeps. Amphiagrion abbreviatum is widespread in such habitats in the southern part of the Ecozone. Argia vivida is, for the most part, restricted to hot springs in the mountains, although it occurs in small, spring-fed streams in the southern Okanagan Valley. Cordulegaster dorsalis, which is found in many warm streams draining lakes on the west side of the Coast Mountains, but in the Montane Cordillera has only been found in spring-fed streams. Tanypteryx hageni is a relict of a primitive family whose larvae are mostly amphibious. This species lives in mossy seepages in the mountains where the larvae burrow in the mud.

Analysis of trends in species occurrence and abundance

Draining of wetlands
The most serious historic anthropogenic stress on dragonfly populations has been the alteration of their freshwater habitats. Most destructive has been the draining and filling of marshes. For example, only about 15% of Okanagan Valley wetlands remain. South of Penticton, most of this was the result of the completion of the Okanagan River flood control channel in 1957. None of the marshes and associated wet meadows that once occupied extensive parts of the western Okanagan Valley bottom at Penticton still exist; the last remnants were filled in 1990. This has not eliminated any species from the region, but it has surely reduced the populations of many species, including Enallagma boreale, E. cyathigerum, E. ebrium, Ischnura cervula, I. perparva, Aeshna californica, A. constricta, A. interrupta, A. multicolor, A. canadensis, Somatochlora semicircularis, Erythemis collocata, Libellula forensis, L. pulchella, Leucorrhinia intacta, Sympetrum corruptum, S. costiferum, S. danae, S. internum, S. madidum, S. obtrusum, S. occidentale, S. pallipes, S. vicinum and others. The channelling and diking of the Okanagan River for most of its length between Penticton and Osoyoos Lake has eliminated much habitat for Argia emma, Ophiogomphus occidentis, Stylurus olivaceus and Macromia magnifica.

Flooding of wetlands
Large hydroelectric and flood control dams have destroyed many lowland wetlands in the Montane Cordillera -- 175 000 hectares flooded in the Peace system, 91 000 hecatares in the Nechako, and 102 000 hectares in the Columbia system, including the Columbia, Canoe, Pend d'Oreille, and Kootenay Rivers (Cannings and Cannings 1996). These reservoirs have eliminated populations of almost all dragonfly species on the ecozone list. Dams not only inundate wetlands, lakes and streams upstream but completely alter the natural flow regime downstream. Since Montana's Libby Dam eliminated the spring freshet of the Kootenay River through the Creston Valley, the large marshes that remain along the river are now artificially maintained in a series of diked impoundments, and their insect communities are undoubtedly different from those before the dam was built.

Hundreds of smaller, high elevation dams built to supply water to lowland communities have flooded peatlands, ponds, shallow lakes and slow streams, creating larger lake habitat and causing a reduction in odonate diversity. This habitat loss has eliminated populations of dragonflies such as Coenagrion interrogatum, Aeshna sitchensis, A. subarctica, Somatochlora minor, S. franklini, and many others and, assuming shorelines lack extensive marshy or peatland edges, replaced them with a few species characteristic of montane lakeshores: Aeshna eremita, Aeshna umbrosa, and Somatochlora albicincta.

Fish introductions
Fish are major predators of odonate larvae (Corbet 1999, Hilton 1987), and the energetic programs to release sport fish into almost 2,000 lakes in the Montane Cordillera (many originally fish-free) (S. Billings, pers. comm.) must have had a significant effect on both the abundance of Odonata and the composition of the communities in these lakes. There are some data available to document this supposition. Species of Enallagma that have escape responses specifically adapted to life in a fishless environment are at risk when confronted by fish. When faced with a fish predator, these species move in ways that increase their vulnerability to predation (McPeek 1990). In an experimental study in North Carolina, ten times as many dragonfly larvae were found within fish exclusion cages as outside them (Morin 1984). The poisoning of aquatic communities to prepare lakes for sport fish introductions also has likely had a significant impact on dragonfly populations.

The aquatic communities of many systems that historically contained fish have also been altered by the purposeful or accidental introduction of non-native fish species. In the Columbia watershed, 16 species, a full 37 percent of the entire fish fauna, are introduced. Some of these species not only eat many odonate larvae, but also alter the habitat structure. Carp (Carpinus carpio) were introduced into the mainstem lakes of the Okanagan in 1917 and subsequently destroyed or reduced much of the native aquatic vegetation, including Lemna and Potamogeton (Brooks 1973).

Lakeshore modification
Especially in the southern valleys, destruction of natural lakeshore, mostly for housing and swimming beaches, has reduced habitat available for many lake dwellers, including Gomphus graslinellus, Ophiogomphus occidentis and Macromia magnifica.

Livestock disturbance
Many species breeding in small, often temporary ponds or spring-fed streams in grasslands and dry forest have been adversely affected by cattle that trample and pollute these habitats. Argia vivida is especially vulnerable to these effects; outside of hotsprings, it is known from only a handful of tiny spring-fed streams in South Okanagan rangelands, all of which are potentially affected by the activities of cattle or horses.

Hot springs development
Hot springs are almost always modified by humans. In the Montane Cordillera Argia vivida is largely restricted to the outlet streams of hot springs and the small populations are vulnerable. The species has almost certainly been extirpated from some of the developed springs around Banff and Radium.

Logging
Although there is little evidence to back up the assumption, the extensive logging that has affected hundreds of streams in the ecozone has probably reduced the populations of dragonflies such as Calopteryx aqequabilis, Cordulegaster dorsalis, Somatochlora minor and S. walshii. Logging and associated road building can result in streams with less stable flows, warmer water temperatures, and higher silt loads, all of which negatively affect dragonfly larvae. Logging has also likely affected the community structure in peatlands, marshes and lakes, especially at higher elevations.

Climate change
Climate change will drastically affect present Odonata distributions as lowland waters dry and water in general becomes scarcer (Hebda 1997). Hebda (1995) outlines the characteristics of several ecozone localities in the drier and warmer periods that prevailed between 10,000 and 7000 years ago. A significant component of the diversity of Odonata in the ecozone lives in grassland ponds and marshes and small lakes in the lowlands. Presumably, many of these habitats will disappear in any drying trend. Whether dragonfly populations will be able to shift northwards or to higher altitudes if suitable water bodies develop there is unknown, but the relatively strong powers of dispersal of many species, at least, should be a major factor in their survival. The affect of climate change on the extensive dragonfly populations in montane and northern peatlands is unknown, but similar problems will probably exist.

Recommendations for Future Inventory, Research and Monitoring

Odonata inventory in the Montane Cordillera has been extensive but not systematic. Even in the southern valleys, much more work is necessary. A comprehensive inventory in 1997 in the Okanagan basin (the best collected area in the zone) greatly increased our knowledge of the abundance and distribution of many species (Cannings 1998). In doing so, however, it revealed how much additional effort is needed to give a more precise idea of dragonfly distribution throughout the zone. For example, the known range of Coenagrion interrogatum was extended from Heckman Pass, Tweedsmuir Park, on the extreme western boundary of the Ecozone south to the Okanagan Highlands; four localities for the species were discovered in the Okanagan. It is clear that the distribution of this species in the zone remains poorly known. The number of localities for some uncommon lowland species was also increased significantly; for example, Argia vivida localities increased from three to eight and Argia emma from five to 16.

An inventory in the Columbia-Kootenay region in 1998-99 (Cannings et al. 2000) increased the species list for the southeastern part of the ecozone from 57to 66 and added three species new to British Columbia (Calopteryx aequabilis, Lestes forcipatus and Somatochlora forcipata). The ranges of several other species ( including Coenagrion interrogatum, Cordulegaster dorsalis, Gomphus graslinellus, and Sympetrum vicinum were significantly extended into the southeastern part of the province.

Outside the Okanagan drainage (Cannings 1998), the Kootenays (Cannings et al. 2000) and Becher's Prairie on the Chilcotin Plateau (Cannings and Cannings 1987), no formal inventories have been made anywhere in the zone. High priorities for future inventories are the species-rich, lowland valleys of the Kootenay and Thompson regions. For clarifying the ranges of northern species, intensive work in the Cariboo, Omineca, Selkirk, Purcell and Rocky Mountains; the Bulkley Valley, and the Babine Upland is critical.

A few species are known from adjacent areas and may occur within the zone. Tramea lacerata, Pantala hymenaea, and P. flavescens, all well known for their wide-ranging flights, are recorded from central Washington State; the first two have been recorded as wanderers on the south coast of British Columbia (Cannings 1988, 1997). To the north, Somatochlora kennedyi is known from the Taiga Plains in northeastern British Columbia and from the Boreal Cordillera in extreme southern Yukon, and is almost certain to occur at the northern limits of the Montane Cordillera Ecozone.

Increased inventory efforts would especially improve our knowledge of the species that range widely across the zone but are known from few localities: for example, Lestes forcipatus, Aeshna tuberculifera, A. septentrionalis, Ophiogomphus colubrinus, Cordulegaster dorsalis, Somatochlora cingulata, S. septentrionalis, and Leucorrhinia patricia. Other species, such as Calopteryx aequabilis, are known from only one locality within the ecozone and their status needs to be elucidated. West of Manitoba, Somatochlora forcipata is known from only four sites, including one in Banff National Park (Walker and Corbet 1975). In the Montane Cordillera, Enallagma civile is recorded only from Bridge Lake in south-central British Columbia; otherwise it is not known west of Swift Current, Saskatchewan (Cannings and Stuart 1977). The extent of the range of Tanypteryx hageni along the mountains at the southwestern edge of the zone needs to be studied.

No studies examining the effects of human activity in the environment (e.g. siltation and elevated temperatures in streams in logged areas or the effect of dams on dragonfly populations) have been undertaken in the ecozone, and no long-term monitoring studies are in place that could detect changes in species composition and abundance of dragonfly populations. Although recent inventories have increased our knowledge of the habitat requirements of a number of species, our understanding of the needs of most species remains rudimentary, and more ecological studies would be of enormous benefit.

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Appendix 1: Checklist of Montane Cordillera Odonata -- 77 species
* Species of management concern: endangered, threatened or vulnerable.
(H) Holarctic in distribution.

FAMILY CALOPTERYGIDAE (JEWELWINGS) (1 species)
*Calopteryx aequabilis Say. Transition

FAMILY LESTIDAE (SPREADWINGS) (4 species)
Lestes congener Hagen. Widespread
Lestes disjunctus Selys. Widespread
Lestes dryas Kirby. Widespread (H)
*Lestes forcipatus Rambur. Austral
Lestes unguiculatus Hagen. Widespread

FAMILY COENAGRIONIDAE (POND DAMSELS) (15 species)
Amphiagrion abbreviatum (Selys). Western
*Argia emma Kennedy. Cordilleran
*Argia vivida Hagen. Cordilleran
Coenagrion interrogatum (Hagen). Northern Boreal
Coenagrion resolutum (Hagen). Widespread Boreal
Enallagma boreale Selys. Widespread Boreal
Enallagma carunculatum Morse. Austral
*Enallagma civile (Hagen). Austral
Enallagma clausum Morse. Western
Enallagma cyathigerum (Charp.). Widespread Boreal (H)
Enallagma ebrium (Hagen). Transition
Enallagma hageni (Walsh). Transition
Ischnura cervula Selys. Cordilleran
Ischnura perparva Selys. Western
Nehalennia irene (Hagen). Southern Boreal

FAMILY AESHNIDAE (DARNERS) (14 species)
Aeshna californica Calvert. Cordilleran
Aeshna canadensis Walker. Transition
*Aeshna constricta Say. Transition
Aeshna eremita Scudder. Widespread Boreal
Aeshna interrupta Walker. Southern Boreal
Aeshna juncea (Linnaeus). Widespread Boreal (H)
Aeshna multicolor Hagen. Western
Aeshna palmata Hagen. Cordilleran
*Aeshna septentrionalis Burmeister. Northern Boreal
Aeshna sitchensis Hagen. Widespread Boreal
Aeshna subarctica Walker. Widespread Boreal (H)
*Aeshna tuberculifera Walker. Transition
Aeshna umbrosa Walker. Transition
Anax junius (Drury). Austral (also in parts of Asia. . . and Oceana)

FAMILY PETALURIDAE (PETALTAILS) (1 species)
*Tanypteryx hageni (Selys). Cordilleran

FAMILY GOMPHIDAE (CLUBTAILS) (5 species)
*Gomphus graslinellus Walsh. Transition
*Ophiogomphus colubrinus Selys. Southern Boreal
Ophiogomphus occidentis Hagen. Cordilleran
Ophiogomphus severus Hagen. Western
*Stylurus olivaceus (Selys). Cordilleran

FAMILY CORDULEGASTRIDAE (SPIKETAILS) (1 species)
Cordulegaster dorsalis Hagen. Cordilleran

FAMILY MACROMIIDAE (CRUISERS) (1 species)
*Macromia magnifica MacLachlan. Cordilleran

FAMILY CORDULIIDAE (EMERALDS) (13 species)
Cordulia shurtleffi Scudder. Widespread Boreal
*Epitheca canis MacLachlan. Transition
Epitheca spinigera (Selys). Transition
Somatochlora albicincta (Burmeister)Widespread Boreal
*Somatochlora cingulata (Selys). Southern Boreal
*Somatochlora forcipata (Scudder). Transition
Somatochlora franklini (Selys). Widespread Boreal
Somatochlora hudsonica (Selys). Western Boreal
Somatochlora minor Calvert. Southern Boreal
Somatochlora semicircularis (Selys). Cordilleran
*Somatochlora septentrionalis (Hagen)Northern Boreal
Somatochlora walshi (Scudder). Southern Boreal
Somatochlora whitehousei Walker. Widespread Boreal

FAMILY LIBELLULIDAE (SKIMMERS) (21 species)
*Erythemis collocata (Hagen). Western
Leucorrhinia borealis Hagen. Western Boreal
Leucorrhinia glacialis Hagen. Transition
Leucorrhinia hudsonica (Selys). Widespread Boreal
Leucorrhinia intacta (Hagen). Transition
Leucorrhinia patricia Walker. Northern Boreal
Leucorrhinia proxima Calvert. Southern Boreal
Libellula forensis Hagen. Cordilleran
Libellula julia Uhler. Transition
Libellula lydia Drury. Austral
*Libellula pulchella Drury. Austral
Libellula quadrimaculata Linnaeus. Widespread (H)
Sympetrum corruptum (Hagen). Widespread (also in far eastern Russia)
Sympetrum costiferum (Hagen). Transition
Sympetrum danae (Sulzer). Widespread Boreal (H)
Sympetrum internum Montgomery. Transition
Sympetrum madidum (Hagen). Western
Sympetrum obtrusum (Hagen). Transition
Sympetrum occidentale Bartenev. Western
Sympetrum pallipes (Hagen). Western
*Sympetrum vicinum (Hagen). Austral

What are Dragonflies and Damselflies?

Dragonflies and damselflies, in the Order Odonata, are some of the most ancient of insects. They have many primitive features, but also possess many specializations that reflect their aerial and predatory life. Damselflies are slimmer, often smaller, and usually fly more slowly than dragonflies. At rest their equal-sized wings are usually held together above the body. Dragonflies are robust, often fast-flying, with the hindwings broader than the forewings; when perched they hold their wings out away from the body. Metamorphosis in odonates is striking but there is no pupal stage. The aquatic larvae are predacious and are armed with an enormously enlarged, hinged labium, which is used as an extendible grasping organ for capturing prey. Larvae are voracious, eating aquatic small crustaceans and even fish. Adults are aerial, visually oriented predators: large, strong-flying insects with large eyes, strong mandibles and spiny legs.

Where do I find Dragonflies and Damselflies?

Dragonflies and damselflies are aquatic insects. The larvae live in ponds, marshes, peatlands, streams and lakes. Climbers (e.g., damselflies, darners) are streamlined stalkers that live in submerged vegetation. Sprawlers (river cruisers, emeralds, and skimmers) lie in ambush on the bottom mud and detritus. Burrowers (clubtails, spiketails) cover themselves with sand and mud on the bottom and ambush their prey.

Adults can spend much of the time away from water, hunting their insect prey in sunny, open areas. When they are ready to breed, they return to the water. There, males patrol the breeding habitats, agressively searching for mates, and may, like birds, defend a territory against other males of the species. Females visit the breeding area periodically to mate and lay eggs. Because they are drawn to the breeding sites, and because they are easy to watch there, these places are ideal for dragonfly study.

What is the Dragonfly and Damselfly species diversity of the Montane Cordillera Ecozone?

• 77 species known
• all species native
• about 4 more species expected
• 20 species potentially rare or threatened
• 38% of all Canadian species

What species are at risk?

Twenty species are considered rare, based on collections in museums. However, with increased collecting, some of these (e.g. the Sweetflag Spreadwing (Lestes forcipatus), the Black-tipped Darner (Aeshna tuberculifera) and the Lake Emerald (Somatochlora cingulata)) will turn out to be more widespread than we once believed. Others, such as the Vivid Dancer (Argia vivida) live in restricted habitats that are threatened by human-caused development and so are more likely to be at risk, even if more populations are discovered.

What are the human impacts on Dragonflies and Damselflies?

The greatest impacts are the destruction and degradation of the aquatic habitats of dragonflies, especially by draining and filling. These changes have eliminated populations of almost all dragonfly species on the ecozone list. Large hydroelectric and flood control dams not only inundate wetlands, lakes and streams upstream but completely alter the natural flow regime downstream. Hundreds of smaller, high elevation dams built to supply water to lowland communities have flooded peatlands, ponds, shallow lakes and slow streams, creating larger lake habitat and causing a reduction in odonate diversity. Other negative affects come from the introduction of fish into originally fish-free lakes, destruction of natural lakeshores, disturbance of fragile pond and stream habitats by livestock, and the siltation and temperature increases in streams caused by logging and associated road building.

Trends in dragonfly populations

• Case History 1 -- Alteration of warm springs habitats
  Hot springs are almost always modified by humans. In the Montane Cordillera Ecozone, the damselfly Argia vivida (Vivid Dancer) is largely restricted to the outlet streams of hot springs and the small populations are vulnerable. The species has almost certainly been extirpated from some of the developed springs around Banff and Radium. A few tiny populations in streams flowing from cool springs in the South Okanagan are threatened by trampling by cattle.

• Case History 2 -- Draining and filling of wetlands
  Flat, valley bottom lands occupied by wetlands are at a premium in mountainous regions, and marshes and ponds have been drained and filled for building and agriculture. For example, only about 15% of the valley bottom marshes of the Okanagan Valley remain. South of Penticton, most of this was the result of the completion of the Okanagan River flood control channel in 1957. None of the marshes and associated wet meadows that once occupied extensive parts of the western Okanagan Valley bottom at Penticton still exist; the last remnants were filled in 1990. This has not eliminated any species from the region, but it has surely reduced the populations of many species, including Enallagma boreale, E. ebrium, Ischnura cervula, A. constricta, A. multicolor, Somatochlora semicircularis, Erythemis collocata, L. pulchella, Leucorrhinia intacta, S. madidum, S. vicinum and others. The channelling and diking of the Okanagan River for most of its length between Penticton and Osoyoos Lake has eliminated much habitat for Argia emma, Ophiogomphus occidentis, Stylurus olivaceus and Macromia magnifica

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