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The ecology and conservation of the Bog Hawker subarctica WALKER, 1908 (: ) of Latvia

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The ecology and conservation of the Bog Hawker Aeshna subarctica Walker, 1908 (Odonata: Aeshnidae) in Latvia

Mārtiņš Kalniņš

Nature Conservation Agency, Baznīcas iela 7, LV-2150, Sigulda, Siguldas novads, Latvia; e-mail: [email protected]

KALNIŅŠ M. 2012. The ecology and conservation of the BOG Hawker Aeshna subarctica WALKER, 1908 (Odonata: Aeshnidae) in Latvia. – Latvijas Entomologs 51: 40-57.

Abstract: The Bog Hawker or Subarctic Hawker, Aeshna subarctica Walker, 1908, is a declining and already regionally extinct species in some areas in Europe. Published and all known unpublished data have been used to present and analyse its distribution, population size, habitat selection, and conservation status. The distribution of A. subarctica has been mapped using a basic grid of 5x5 km squares in the Baltic grid system. In total, A. subarctica has been recorded from 21 squares and 21 localities occurring sparsely or in small concentrations over a large part of the country apart from its western territories. The majority of the recent localities are situated in northern and southern Latvia. The known pattern of the species’ distribution partly results from the abundance and density of appropriate habitats and possibly a climatic influence. However, this also may be a consequence of an insufficient and uneven odonatological exploration of the country. A. subarctica has mostly been recorded in primary habitats in Latvia, such as raised bogs with bog pools, lakes and lakes within fens and bogs. The flight season of theA . subarctica in Latvia ranges mainly from August to September. The conservation measures are suggested.

Key words: Odonata, Aeshna subarctica, distribution, habitat selection, conservation, Latvia.

Introduction is already regionally extinct in some areas in Europe. In Europe, it currently The Bog Hawker or Subarctic exists mostly in rather localised areas, Hawker, Aeshna subarctica Walker, at individual and scattered localities or 1908, is a circumboreal species, in their small concentrations (Djikstra occurring throughout central and 2006). Available habitats continue northern Europe, Eurasia and Japan to decline due to the drainage of (Dunkle 2000, Djikstra 2006, Paulson wetland areas and climatic changes 2009). However, it is declining and (Raeymaekers 1998, Salmiņa 2010). Latvijas Entomologs 2012, 51: 40-57. 41

Pollution and overgrowth of habitats projection (TKS-1993) of Latvia. The also may threaten the survival of this final map is based on 1:50000 scale species. Therefore, A. subarctica satellite maps available for Latvia, has been classified as Least Concern published in 1999–2000 by the State (LC) species in the European Red Land Service of the Republic of List of (Kalkman et al. Latvia. 2010), and in the European Union The data on habitats (inter alia also as Least Concern species with photo) were collected by the author the decreasing population trend and others in the field. Potential (Kalkman et al. 2010). habitats, such as raised bogs with The aim of this paper is to bog pools and lakes, lakes within summarize the knowledge of fens and bogs and post-excavation the distribution and habitats of peat bogs were examined. Visual A. subarctica in Latvia. This search for imagines and exuviae is not protected in Latvia, but so far was made. Egg laying microhabitat the data on it have not been analysed and substratum was registered when and the species’ current population egg-laying females observed. Data status has not been assessed. on particularly protected nature territories come from the website of the Nature Conservation Agency Methods (Nature Conservation… 2011). The quantitative field data The analysis of distribution on dragonflies exuviae in Lielais and habitat preference is based on: Ķemeru tīrelis Bog were collected in (a) all published data, (b) author’s 16 sampling plots on 16 and 19 July unpublished data collected between 2007. The survey of dragonflies and 1999 and 2010, (c) unpublished data the evaluation of vegetation were collected by entomologists before carried out within a 100 m long and 2011. Both historical and recent data, a 5 m wide transect in each sampling in total 31 records of A. subarctica, plot. The percentage of the coverage of were included in a Microsoft Office different vegetation forms, the impact Access geodatabase prepared by the of trees, the dragonfly species and the author. number of individuals were evaluated The distribution of A. subarctica in each 20 metres in the transect. The has been mapped using a basic grid habitat groups were chosen for the of 5x5 km squares in the Baltic grid arrangement of sampling plots by system on a Transverse Mercator maps at the landscape level, choosing 42 The ecology and conservation of the Bog Hawker Aeshna subarctica ...

the most typical habitats, but transects are concurrent with district names, used by were chosen by ten categories of the author in previous papers (Kalniņš 2007, vegetation developed by the author’s 2008). and as well as by accident. Each transect was run through two times, i.e. back and forth and all exuviae Results were collected. The quantitative field data on Twenty one locality of dragonflies imago were collected in A. subarctica has been recorded Grabatiņš Lake and Meistars Lake. in Latvia so far. Geographical The survey of dragonflies were coordinates are only given for carried out within a transect along several localities, localisation of lake bank. All observed specimens which could be difficult. Vegetation were counted. The length of bank of descriptions concern a zone inhabited Grabatiņš Lake is 300 m, of Meistars by A. subarctica. Lake is 550 m. The areas measured on 1. Lielauce Lake (Auce orthophoto maps, scale 1:10 000 from d.). August of 1949, Aessub: 1 the third cycle (2007-2008) of aerial female was caught (Spuris 1952; photography (Latvian Geospatial 1956). Information about locality Information agency) using Arc GIS (vegetation) was not described in 9 software. Geographical coordinates detail in the original publication, the are only given for several localities, data on vegetation concern its current localisation of which could be composition. The lake is large and difficult. Vegetation descriptions rich in diverse habitats and one part concern a zone inhabited by of lake are fen (~200 ha). The locality A. subarctica. has had PPNT status since 1999. It is situated in the nature reserve “Vīķu Explanations of abbreviations: Aessub purvs” and in the NATURA 2000 area – Aeshna subarctica, PPNT – particularly (site code: LV0504700). protected nature territory, d. – district, vill. – 2. Complex of bog pools S of village. The number of observed imagines or Gārgaļu Lake and at the NE part of collected exuviae of A. subarctica (Aessub) is given after the date of observation and large Lielais Ķemeru tīrelis Bog followed by references or the author of (Tukums d.). Large (~5000 ha) unpublished data, as e.g. (M. Kalniņš). The active raised bog with large regions are named according to the Law complexes of bog pools. Vegetation on administrative territories and populated with Sphagnum cuspidatum and areas (2008). Some of the regional names Sphagnum sp., Eriophorum sp., Latvijas Entomologs 2012, 51: 40-57. 43

Rhynchospora alba, Scheuchzeria with numerous bog pools and small palustris, Ledum palustre, Vaccinium lakes. Vegetation with Sphagnum uliginosum, Calluna vulgaris and cuspidatum and Sphagnum sp., Andromeda polifolia (Table 1). Eriophorum sp., Rhynchospora 06.08.2003, Aessub: 1 female caught alba, Scheuchzeria palustris, Ledum (M. Kalniņš); 18.07.2007, Aessub: 11 palustre, Vaccinium uliginosum, exuviae near five bog pools (Table Calluna vulgaris and Andromeda 1) (M. Kalniņš) (Kalniņš, Medne polifolia. The locality has had PPNT 2007). Since 2006 a project for the status since 1973. It is situated in restoration of the bog’s hydrological the Gauja National Park and in the regime – earlier seriously disturbed NATURA 2000 area (site code: due to drainage – has been carried out LV0200100). resulting in an increased water level 5. Pekšu Lake (Pārgaujas d.). that will certainly improve the habitat A eutrophic lake (~10 ha) with rich conditions for A. subarctica (Ķuze, and diverse vegetation – Phragmites Priede 2008). The locality has had australis, Typha sp., Equisetus sp., PPNT status since 1973. It is situated Menyanthes trifoliate, Nuphar lutea, in the Ķemeri National Park and in Nymphaea sp., Potamogeton sp. the NATURA 2000 area (site code: and others. 09.08.1999, Aessub: 1 LV0200200). individual (M. Kalniņš) (Kalniņš 3. Pakujezers Lake near et al. 2007). The locality has had Ezerkalni (Baldone d.). A PPNT status since 1973. It is situated dyseutrophic lake (~1 ha), bordered in the Gauja National Park and in by a wide (5–10 m) Sphagnum the NATURA 2000 area (site code: zone with Sphagnum cuspidatum, LV0200100). Carex limosa, Eriophorum sp., 6. Grabatiņš Lake in Rhynchospora alba, Calluna vulgaris Grabatpurvs Bog (Krimulda d.). and Andromeda polifolia. 01.06.2008, Active raised bog (~250 ha), with Aessub: 1 exuviae (M. Kalniņš). relative small (~50 ha) open (non- 4. Sudas Bog, SE part, SE owergrown) area and two small from Velna Lake env. near small lakes. Grabatiņš Lake is a dystrophic bog pool (Līgatne d.). 17.06.2006, lake (~0.6 ha), bordered by a narrow Aessub: 2 exuviae (M. Kalniņš); (1–5 m) Sphagnum zone with Carex Sudas Bog, Central part, Salas Lake limosa. 31.07.2005, Aessub: totally env. near small bog pool 19.06.2006, 10 individuals recorded and 3 exuviae Aessub: 1 individual (M. Medne); (R. Bernard, M. Kalniņš). Large (~2600 ha) active raised bog 7. Niedrāju-Pilkas Bog, SW part 44 The ecology and conservation of the Bog Hawker Aeshna subarctica ...

of bog pools complex (Limbaži d.). the NATURA 2000 area (site code: Active raised bog (~500 ha), with LV0000130). open (non-overgrown) bog pools area 10. Kārķu Bog, small (~100 ha). Vegetation with Sphagnum bog pools near Bezdibenis Lake cuspidatum and Sphagnum sp., (Valka d.). Active raised bog Eriophorum sp., Rhynchospora (~300 ha) with one lake and ~60 bog alba, Ledum palustre, Calluna pools. Vegetation with Sphagnum vulgaris. 06.08.2009, Aessub: 17 cuspidatum and Sphagnum sp., exuviae (M. Kalniņš). The locality Eriophorum sp., Rhynchospora alba, has had PPNT status since 1987. It Ledum palustre, Calluna vulgaris and is included in the Northern Vidzeme Andromeda polifolia. 02.08.2005, Biosphere Reserve, in the nature Aessub: totally 1 individual recorded reserve “Niedrāju-Pilkas purvs” and near small complex of bog pools; near in the NATURA 2000 area (site code: lake individuals were not observed LV0509800). (M. Kalniņš). The locality has had 8. Oļļas Bog near Mazezers Lake PPNT status since 1977. It is included (Mazsalaca d.). 01.08.2005, Aessub: in the Northern Vidzeme Biosphere several individuals (R. Bernard). Reserve, in the nature reserve “Kārķu 9. Oļļas Bog near Lejasdīriķi purvs” and in the NATURA 2000 area (Mazsalaca d.). 01.08.2005, Aessub: (site code: LV0515300). 1 exuviae (M. Kalniņš). 11. Taures Bog (Valka d.). Both localities are situated in Partly degraded raised bog by peat large active raised bog (~3000 ha) extracting (~400 ha) and partly active with numerous bog pools and two raised bog (~200 ha) with ~60 bog lakes. Vegetation with Sphagnum pools. Vegetation with Sphagnum cuspidatum and Sphagnum sp., cuspidatum and Sphagnum sp., Eriophorum sp., Rhynchospora Eriophorum sp., Rhynchospora alba, Scheuchzeria palustris, Ledum alba, Scheuchzeria palustris, palustre, Vaccinium uliginosum, Carex lasiocarpa, Ledum palustre, Calluna vulgaris and Andromeda Vaccinium uliginosum, Calluna polifolia. vulgaris and Andromeda polifolia. The distance between localities 15.09.2006, Aessub: 6 individuals No 8 and 9 is 2 km. The localities (including pairs in copula) and 2 have had PPNT status since 1997. It males (M. Kalniņš) (Kalniņš, Medne is included in the Northern Vidzeme 2007). Biosphere Reserve, in the nature 12. Meistars Lake NW reserve zone “Ziemeļu purvi” and in of Mārkalne vill. (Alūksne d.). A Latvijas Entomologs 2012, 51: 40-57. 45

small (~2 ha) lake surrounded by and Carex lasiocarpa. 07.08.2005, Sphagnum sp. a transition-mire Aessub: 19 exuviae (M. Kalniņš). vegetation bordering the water table. 16. The NW part of 03.08.2005, Aessub: totally 1 male large Teiči bog (Madona d.). and 2 females (laid eggs) observed 04.07.2004, Aessub: 1 female caught (R. Bernard, M. Kalniņš). (G. Akmentiņš). 13. Palšu Bog, NW of 17. Kurtavas Lake at the Jumurda vill. (Ērgļi d.). Active raised W part of large Teiči bog (Madona bog (~700 ha) with numerous bog d.). 17.08.2006, Aessub: 1 female pools. Vegetation with Sphagnum caught (G. Akmentiņš). cuspidatum and Sphagnum sp., 18. The Central part of Eriophorum sp., Rhynchospora large Teiči bog (Varakļāni d.). 11.– alba and Andromeda polifolia. 27.06.1997 and 20.08-03.09.1997, 11.07.2001, Aessub: 1 female caught “fairly numerous imagines” (Matthes (M. Kalniņš). The locality has had & Matthes 1997), their habitat not PPNT status since 1999. It is included described. in the nature reserve “Palšu purvs” All three localities are situated in and in the NATURA 2000 area (site large active raised bog (~18000 ha) code: LV0526200). with numerous bog pools and 14. Vārnezers Lake SE lakes. Vegetation with Sphagnum of Ineši vill. (Vecpiebalga d.). A cuspidatum and Sphagnum sp., small dystrophic, Brown-water lake Eriophorum sp., Rhynchospora surrounded by a Sphagnum bog, the alba, Scheuchzeria palustris, Ledum water table bordered by a transition palustre, Vaccinium uliginosum, mire mainly with Carex rostrata, Calluna vulgaris and Andromeda C. lasiocarpa and Eriophorum sp. polifolia. In Teiči bogs almost all and Sphagnum cuspidatum. Total kinds of bog vegetation are presented. area ~0.9 ha, open water ~0.1 ha. The distance between localities 07.08.2005, Aessub: 2 teneral No 16 and 17 is 2 km and between females and 18 exuviae (R. Bernard, localities No 16, 17 and 18 is 8 km. M. Kalniņš). Localities have had PPNT status 15. Bezdibenis Lake, E since 1982. They are included in the of Jumurda vill. (Ērgļi d.). A small Teiči Strict Nature Reserve and in (~1.3 ha) dystrophic, Brown-water the NATURA 2000 area (site code: lake surrounded by a Sphagnum bog LV0100500). (~0.4 ha), the water table bordered by 19. Gaiņu Bog S Part a narrow zone of Rhynchospora alba (Līvāni d.). Active raised bog 46 The ecology and conservation of the Bog Hawker Aeshna subarctica ...

(~700 ha) with ~30 bog pools. peaty forest with birch; the water table Vegetation with Sphagnum bounded by Sphagnum mats (2-7 m cuspidatum and Sphagnum sp., broad) with Scheuchzeria palustris, Eriophorum sp., Rhynchospora alba Rhynchospora alba, Andromeda and Carex sp. 25.09.2009, Aessub: 1 polifolia; along the edges of mats, in female caught (G. Akmentiņš). shallow (up to 40 cm) water, a “collar” The locality has had PPNT of Carex limosa (0.3-2 m broad) status since 1977. It is included in the locally with floating Sphagnum; nature reserve “Gaiņu purvs” and in water brownish. 09.07.2002, Aessub: the NATURA 2000 area (site code: 3 exuviae in Lake A, 1 exuviae with LV0525400). teneral female in Lake B (Bernard 20. Two small forest 2003). lakes (A and B), 5.1 km NW of 21. A small lake (90x70 Andrupene, 2.6 km W of the m) NW of Cucuri, S of Rundāni, western shores of the southern part 56°12’42” N 27°50’23” E (Ludza d.). of Viraudas Lake, 56°13’10” N 06.08.2005, Aessub: some individuals 27°20’25-50” E (Rēzekne d.). The (R. Bernard). Lake A is 140x80 m; surrounded by pine forest with addition of spruce and birch); the water table bounded Discussion by narrow Sphagnum mats (0.5-3 m broad, only locally up to 5-7 m) with: Distribution Carex limosa, C. rostrata, C. nigra, C. elata, Scheuchzeria palustris, A. subarctica is a Holarctic Menyanthes trifoliata, Calla widespread (circumboreal) species palustris, Eriophorum angustifolium, with the range extending from 5º E, E. vaginatum, Potentilla palustris, from Belgium, France and Norway Oxycoccus palustris; along one shore up to easternmost Japan. The species Sphagnum mats with peninsulas and also occurs in North America – Alaska bays, with Carex elata at the edge of east to Newfoundland; south to mats and in shallow water next to them Massachusetts, Michigan, Wyoming (accompanied there locally by Calla and Oregon (Dijkstra 2006, Catling palustris); rare Numphaea sp.; water 2003, Discover Life 2011). In Europe, clear with the transparency minimum the species has been recorded between 2 m. The lake B is 100x60 m; eastern France, Italy, Switzerland, surrounded by pine forest with spruce Slovenia and the Bulgaria in the addition an a belt of partly dried pine South and northern Norway, Finland Latvijas Entomologs 2012, 51: 40-57. 47

and Russia, between 45.2º and 61.6º and twenty (3.1 %) in the current N (Dijkstra 2006, Boudot et al. 2009, period (from 1991). However, due Skvorstov 2010). However, the main to limited and diverse intensity of species’ European range is around the odonatological studies in various Baltic Sea (Dijkstra 2006). regions, especially in the past, it is The assessments mentioned impossible to compare the species’ above indicate that the territory of extent of occurrence and occupancy Latvia was and still is an important between the historical period and the component in the European range of current period. A. subarctica. The species has been The species’ extent of occurrence recorded in 21 TKS-squares (5x5 km) theoretically covers the whole in Latvia so far (Fig. 1) that constitute territory of Latvia. However, 2.5 % of the 839 Latvian squares for A. subarctica remains unknown west which data on dragonflies are known of 22°52’ E and only one locality has and 0.8 % of all (2785) squares been recorded in large areas west of covering the territory of the country. 23°30’ E (Fig. 1). This distribution Only one locality (0.3 %) of pattern probably results in part from A. subarctica was recorded in the the diverse intensity of odonatological historical period (before 1991) studies in various regions: they have

Figure 1. Distribution of Aeshna subarctica in Latvia (black 5x5 km squares) and all TKS-1993 squares with records of dragonflies (grey squares) before 2011. The localities are numbered according to the numbering in the text. 48 The ecology and conservation of the Bog Hawker Aeshna subarctica ...

been carried out more intensively in raised bog district which is a part of central and eastern parts than in the a great mires chain extending through West of the country. An analysis of several countries (Fig. 2). Some a potential basis for such a pattern relationship between the distribution has not revealed a clear cause as the of A. subarctica and climatic known distribution of A. subarctica regionalisation (sensu Kalniņa 1995) does not correlate with the delineation has also been recognisable as the of Latvia into physiographic regions majority of known localities (90 %) (sensu Ramans, Zelčs 1995) or are situated in two climatic regions geobotanical regions (sensu Kabucis (Fig. 2). These climatic regions are 1995). However, the richness and characterized by higher humidity abundance of raised bogs, thus (hydrothermal coefficient 1.6–2.4) potential habitats of the species, and a more continental climate in undoubtedly result in greater numbers comparison with other two climatic and concentration of its localities. regions (Kalniņa 1995). This general relationship is especially recognizable from the example of western Latvia, occupied by a large

Figure 2. A distribution of Aeshna subarctica in Latvia (yellow squares) ac- cording to climatic regions (sensu Kalniņa 1995) and mire distribution (mire layer prepared by SIA “Envirotech”, database GIS Latvija 9.2). Latvijas Entomologs 2012, 51: 40-57. 49

Habitats and populations large and relative large raised bogs with numerous bog pools and lakes A. subarctica inhabits moors (Fig. 3). Eight localities of twenty and bogs with floating peatmoss one locality (38 %, No 2, 4, 7, 8, 9, (Dijkstra 2006). The habitats selected 16, 17, 18) are situated in large raised by A. subarctica in Latvia are mostly bog areas – 2600 and 18000 ha in size primary, i.e. natural. For some and the next four localities (19 %, No dragonfly species, e.g. Nehalennia 10, 11, 13, 19) are situated in large speciosa, this strong preference is raised bog areas – 300 and 700 ha in typical of the species in the core of size, all of them with several dozens its distribution range (cf. Bernard, bog pools at least. The second group Wildermuth 2005). In Latvia, of A. subarctica habitats composed A. subarctica inhabits (1) raised bogs by lakes within fens and bogs – seven with bog pools and lakes and (2) lakes localities (33 %, No 3, 6, 12, 14, 15, within fens and bogs. It seems that the 20, 21), but for two localities (10 %, preference of A. subarctica towards No 1, 5) no accurate data on habitat.

Figure 3. A primary habitat of Aeshna subarctica in Latvia – active raised bog with numerous bog pools and lakes in Niedrāju-Pilkas Bog; locality No. 7 in the text (photo by M. Kalniņš). 50 The ecology and conservation of the Bog Hawker Aeshna subarctica ...

No records in Latvia from secondary Sus scrofa (Bönsel 1999). habitats as post-excavation peat The species composition of pools, although such A. subarctica vegetation at Latvian localities is habitats known from Sweden (Scholl frequently relative poor. Floating 2001). In all cases exuviae’s was Sphagnum cuspidatum is the most found and egg lying was observed in frequent and the most abundant pools ~30-1000 m2. This concurrent representative of the mosses preferred with observations in Czech Republic, for egg lying by A. subarctica (Fig. were the species are occurring in 4). Other Sphagnum species as Sph. small (ca. 50 m2) peat pools and large magellanicum, Sph. rubellum, Sph. (ca. 1000 m2) peat lakes, but most flexuosum, though generally slightly abundant in pools with surface ca. rarer and less abundant, is also 300 m2 (Holuša 2000). However in selected for egg lying by the Bog Germany egg lying and exuviae’s was Hawker. Apart from other typical observed in small pits made by red components of the Bog Hawker’s deers Cervus elaphus and wild boar habitats (for emergence), e.g.

Figure 4. A primary habitat of Aeshna subarctica in Latvia – a bog pool with Sphagnum cuspidatum in Taures Bog; locality No. 11 in the text (photo by M. Kalniņš). Latvijas Entomologs 2012, 51: 40-57. 51

Eriophorum sp., Rhynchospora alba, (Dijkstra 2006). The Latvian dates Scheuchzeria palustris, Andromeda completely correspond to this period polifolia, some rather untypical plant as the earliest record was made on the species occur, such as Carex limosa, 1st June and the latest record on the and C. lasiocarpa. Although Holuša 25th September, but they were most (2000) mentioned, that egg lying in abundant in July and August. Carex paupercule zone were observed and exuviae were found. A. subarctica was not found in Conservation secondary, i.e. partly anthropogenic, habitats in Latvia. However several A. subarctica is declining and post-excavation peaty pools are is already regionally extinct in some visited and appropriate habitats (with areas in Europe. This species belong floating peatmoss etc.) are recorded. to the species sensitive in a longer Thus, such the peaty pools are time-perspective group (Sahlen et al. situated in degraded raised bogs with 2004). In Europe, it currently exists an advanced natural regeneration, mostly in rather localised areas, at should not be excluded a priori, but individual and scattered localities or should also be carefully searched in their small concentrations (Djikstra for A. subarctica. These localities 2006). Available habitat continues may have long-term significance for to decline due to the drainage of A. subarctica as bogs occupy large wetland areas and climatic changes areas and probably always included (Raeymaekers 1998, Sahlen et al. a mosaic of habitats, from active 2004, Salmiņa 2010). Pollution peaty post-excavation places to active and overgrowth of habitats also raised bogs. may threaten the survival of this Due to incomplete data or species. Due to this unfavourable late dates of observations it is conservation status, A. subarctica impossible to reliably assess the size has been classified as Least Concern of the population at many Latvian (LC) species in the European Red localities. However, it seems that List of Dragonflies (Kalkman et al. large populations are rare and small 2010), and in the European Union populations are the most frequent. also as Least Concern species with The flight period ofA . subarctica the decreasing population trend in Europe ranges from the late (Kalkman et al. 2010). In this instance, May till the first late September, although this species are classified as but mainly August and September Least Concern species on a global 52 The ecology and conservation of the Bog Hawker Aeshna subarctica ...

scale, their Mediterranean population the structure of vegetation caused are under threat, due to their marginal by an increased load of nutrients and sometimes relict distribution in from deforested or agriculturally the region, and because of the fact used surroundings, aerial influx and that A. subarctica is very sensitive to recreational activities (e.g., angling), global warming and the desiccation (c) overgrowth of habitats (Riservato of breeding habitats (Riservato et al. et al. 2009, Termaat et al. 2010). 2009). In Latvia, 13 of 21 known The main factors and processes localities have an official conservation currently threatening A. subarctica status (PPNT) (Fig. 5). Nature constitute: (a) drying out of habitats management plans are prepared (or in as a result of drainage, extreme process) for five PPNT (nature reserve weather events and climatic changes “Vīķu purvs”, Ķemeri National Park, (global warming), (b) changes in Gauja National Park, nature reserve

12%

32%

28%

16% 0% 0% 12%

Figure 5. The current (January 2011) official conservation status of localities inhabited by Aeshna subarctica in Latvia. Red – strict nature reserve, green – nature reserve, orange – national park, blue – biosphere reserve, grey – locali- ties without conservation status; 0% – nature park & protected landscape area. Latvijas Entomologs 2012, 51: 40-57. 53

“Palšu purvs” Teiči Strict Nature size of every population is necessary Reserve) which cover 8 localities. and a long-term monitoring of this A. subarctica is not included in these size is required at least for major plans (Nature Conservation… 2011). Latvian populations. The following conservation Habitat and site-based actions. measures are suggested for Priority must be given to the full A. subarctica in Latvia: conservation of best localities by their Policy. The species should be integration in officially protected included into Regulations of the territories. At the same time, a Cabinet of Ministers concerning the complete assessment of factors and list of specially protected species processes currently threatening and species with exploitation A. subarctica should be prepared for limits (Regulations… 2000). The each locality and, where it is needed, dataset of the species’ localities for detailed conservation measures governmental institutions should be should be planned. imported to “OZOLS”, i.e. the Nature Species-based actions, such as data management information system local reintroduction or establishing funded by the European Regional new localities are currently Development Fund and developed unnecessary in Latvia, but should by the Nature Conservation Agency be recommended as scientific (Nature Conservation… 2011). At the and practical nature conservation same time there is an urgent need to experience. improve the nature management plans for PPNTs and to include requirements concerning A. subarctica into these Acknowledgements plans. Research. The search for species This work has been supported at old locality and intensive search in part by the European Social Fund for new localities is needed both within the project “Support for in western Latvia and near known Doctoral Studies at University of localities in other territories. As the Latvia”. habitats suitable for A. subarctica are I am greatly indebted to Guntis widespread in Latvia and the habitat Akmentiņš (the Entomological conditions at old localities have not Society of Latvia & Nature changed significantly (Pakalne 2008), Conservation Agency, Ļaudona, the Bog Hawker probably occurs at Latvia), Dr. Rafal Bernard more localities. Assessment of the (Department of General Zoology, 54 The ecology and conservation of the Bog Hawker Aeshna subarctica ...

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Table 1. The mean percentage of the coverage of water and vegetation structures in sampling plots and number of founded exuviae in Lielais Ķemeru tīrelis Bog in 2007. Sampling plot No. Open water with Sphagnum mosses Water sunken Sphagnum mosses Wet Hummocks of Sphagnum mosses Sphagnum mosses with Eriophorum sp. Sphagnum mosses with Rhynchospora alba and Scheuchzeria palustris Sphagnum mosses with Carex limosa Ledum palustre and Vaccinium uliginosum Calluna vulgaris and Andromeda polifolia High sedges Carex sp. Trees Exuviae

K4 24 13 20 3 1 8 0 3 28 0 1 1 K6 0 42 36 2 2 9 0 0 9 0 0 1 K8 21 5 24 3 9 24 0 0 14 0 0 1 K9 26 1 9 2 2 44 0 1 15 0 0 3 K12 20 19 18 5 4 14 0 0 20 0 1 5 Average 18 16 21 3 4 20 0 1 17 0 Total 11