Rare Dragonflies of British Columbia

H WILDLIFE IN BRITIS COLUMBIAAT RISK Rare Dragonﬂies of British Columbia British Columbia is home to species of dragonflies; of these are considered rare or potentially at risk. Ministry of Sustainable Resource Management Ministry of Water, Land and Air Protection support the most species. The aquatic thorax (damselflies) or by the top of larvae are predacious and are armed the head (dragonflies) with the with an enormous hinged labium claspers at the tip of his abdomen. The (sort of a lower lip), which is used female loops the end of her abdomen ven though dragonflies are predomi- as an extendible grasping tool for up to the base of the male’s abdomen, nantly a tropical group, and even capturing prey. Larvae are voracious, where the sperm is stored and trans- though they are one of the smaller eating small aquatic insects, crus- ferred. The Odonata are the only insects Einsect orders, British Columbia is taceans and even fish. Larvae can be that mate in this “wheel position.” home to 87 species, roughly 40 percent of divided into three categories accord- The female lays the eggs once they the Canadian total. Twenty-three species ing to their feeding strategy: climbers are fertilized. All damselflies and some are considered rare or potentially at risk stalk through vegetation; sprawlers dragonflies (mainly the darners in the and have been placed on the provincial ambush prey while sitting on bottom family Aeshnidae) have a knifelike Red and Blue lists. In this brochure we sediments or debris; and burrowers egg-laying structure, called an ovipos- look at the nine Red-listed species. wait under cover itor, at the tip of the abdomen. They The Odonata of sand and mud. lay their eggs in plant tissue of various Introducing dragonflies After 10 to 15 sorts. In many species, the male often he insect order Odonata and their moults, the full- retains his hold on the female while (Greek for “toothed jaws”) ancestors are grown larva crawls she lays her eggs, guarding her from contains the groups of insects out of the water other males who may attempt to mate Tknown as the dragonflies and some of the up a plant stalk or with her. Some female damselflies damselflies; however, we also use most ancient some other sup- actually crawl below the water surface the name “dragonflies” to refer to port. The skin on to escape the attentions of males, the whole order. The Odonata is a of insects – its back splits open remaining there for over an hour to small order of about 5000 named fossil records and the adult lay their eggs. They can take a film of species and 23 families worldwide. dragonfly squeezes air down with them, trapped in the The Odonata and their ancestors go back more out. The newly- hairs on their body. Species lacking are some of the most ancient of than emerged dragonfly ovipositors usually just dip the tip of insects. Fossil records go back to pumps blood into the abdomen into the water and wash more than 300 million years ago, million years. its wing veins and off the eggs,which then sink to the bottom. predating dinosaurs by more than the wings expand. For many of the damselflies and 100 million years and birds by some 150 Gradually the body hardens, and some dragonflies in million. Dragonflies have many primi- after an hour or so the dragonfly The most the province, the tive features, but also possess many can fly. It leaves behind the life cycle takes about specializations that reflect their aerial empty larval skin, or exuvia. serious stress a year. Spreadwing and predatory lifestyle. The order is Adults are aerial, visually ori- on dragonfly damselflies (Lestes) divided into two suborders in British ented predators: they are large, and some meadow- Columbia: the damselflies or Zygoptera strong-flying insects with huge populations hawks (Sypetrum) (“joined wings”) and the true dragonflies eyes, strong mandibles and spiny has been the overwinter as eggs, or Anisoptera (“unequal wings”). Dam- legs. They prey on a wide range hatch in the spring selflies are slimmer, usually smaller and of flying insects, which are usu- elimination and emerge as ad- fly more slowly than dragonflies. At rest, ally captured in flight. Adults are or alteration ults in the summer. their equal-sized wings are usually held often colourfully patterned and Others overwinter together above the body. Dragonflies are exhibit a wide variety of behav- of their as larvae and em- robust and often fast-flying. Their hind- iours. Mature males patrol the freshwater erge the following wings are broader than their forewings breeding habitats, aggressively spring or summer, and, when perched, they hold their searching for mates and may, habitats. and some, under wings out away from the body. like birds, defend a territory certain conditions, Dragonflies live in and around against other males. will overwinter two years. The larval most types of fresh water. Ponds and When a male is ready to mate, he stages can last four or five years for marshes rich in aquatic vegetation grasps a female by the front of the the larger dragonflies, such as darners (Aeshna) or emeralds (Somatochlora), many of which live in cold mountain or northern waters where summers are short. In British Columbia, adult dragonflies live for about one to two months. The larva of the Olive Clubtail burrows in the sand and silt of rivers and lakes in the warmest valleys Where do they live of the southern interior. in British Columbia? wetlands in the province – 175 000 populations are vulnerable and this ifferent dragonfly species have differ- hectares flooded in the Peace River damselfly has almost certainly been ent habitat requirements. Some system, 91 000 ha in the Nechako extirpated from some developed tolerate only a narrow range of con- system and 102 000 ha in the Colum- springs, such as those at Radium. Dditions, whereas others live in a wide bia system. These reservoirs have Many species breeding in small, range of ecosystems. Some key habitat eliminated populations of almost all often temporary ponds or spring-fed types in British Columbia that have dragonfly species on the provincial streams in grasslands and dry forest distinctive dragonfly faunas are: large, list. Dams not only inundate wetlands, have been adversely affected by cattle warm lakes; small lakes and ponds with lakes and streams upstream, but also that trample and pollute these habitats. floating vegetation; alkaline (saline) completely alter the natural flow The Vivid Dancer is especially vulner- lakes; cattail and bulrush marshes; sedge regime downstream. Since Montana’s able to these effects, since outside of marshes; warm creeks and rivers (e.g., Libby Dam eliminated the spring hot springs it is known from only a those that drain lakes); small springs and freshet of the Kootenay River through handful of tiny, spring-fed streams in seeps; temporary ponds; bog and fen the Creston Valley, the large marshes Interior rangelands, all of which are ponds; and shallow sedge-moss fens. that remain along the river are potentially affected by the activities of (Bogs are acidic peatlands low in nutri- now artificially maintained in a series cattle or horses. ents and dominated by sphagnum moss- of dyked impoundments. These are Logging and associated road build- es. Fens are richer, less acidic peatlands drained periodically and their dragon- ing can result in streams with less dominated by sedges, grasses and non- fly communities are undoubtedly stable flows, warmer water tempera- sphagnum mosses.) different from those that existed tures and higher silt loads, all of which before the dam was built. negatively affect dragonfly larvae. Why are dragonflies at risk? Hundreds of smaller, high-elevation Logging has also likely affected the com- he most serious stress on dragonfly dams built to supply water to lowland munity structure in peatlands, marshes populations has been the elimination communities have flooded peatlands, and lakes, especially at higher elevations. or alteration of their freshwater ponds, shallow lakes and slow streams. Fish are major predators of dragonfly Thabitats. Most destructive has been They have eliminated the drag- larvae, so the energetic the draining and filling of marshes. onflies of these diverse ecosys- Detailed programs to release sport Many of the richest marshes and ponds tems, replacing them with a few fish into a large number are associated with flat floodplains, and of the more common, ubiqui- and of lakes in British Col- these wetlands are often sacrificed to tous species characteristic of focussed umbia (many originally road and railway construction, commer- montane lakeshores. fish-free) must have had a cial and residential development and Many natural lakeshores inventories significant effect on both intensive agriculture. For example, only have been destroyed, mostly for of species the abundance of Odon- about 15 percent of Okanagan Valley housing and swimming beach- ata and the composition wetlands remain and most of those left es, reducing the habitat avail- and their of the communities in have been significantly altered by water able for many lake dwelling habitats these lakes. The poisoning flow changes. The channelling and dyk- dragonflies, particularly in the of aquatic communities ing of the Okanagan River for most of its warm southern valleys. are urgently to preparelakes for sport length between Penticton and Osoyoos Humans almost always needed. fish introductions in past Lake has eliminated much habitat for a modify hot springs. In British years also likely had a sig- number of Red- and Blue-listed species. Columbia, the Vivid Dancer, Argia nificant impact on dragonfly populations. Large hydroelectric and flood-control vivida, is largely restricted to the out- The aquatic communities of many dams have destroyed many lowland let streams of hot springs.

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