Dragonfly Migration in North America. Common Green Darner (Anax junius); Dan Jackson

Transcription

1 Dragonfly Migration in North America Common Green Darner (Anax junius); Dan Jackson

2 Dragonfly Migration Observations date back to 19 th century Sun Life Stadium, Miami, FL; Eric Espada Geauga Park, OH Thousands of dragonflies seen moving south in fall

3 Different generations in fall and spring Dragonfly Migration Return north in spring more diffuse Smith Point HawkWatch, Tony Leukering

4 Migrants in North America Common Green Darner (Anax junius); John Abbott Spot-winged Glider (Pantala hymenaea); Dennis Paulson Regular annual migrants Black Saddlebags (Tramea lacerata), John Abbott Wandering Glider (Pantala flavescens), Dennis Paulson Variegated Meadowhawk (Sympetrum corruptum), Celeste Mazzacano

5 Migrants in North America Autumn Meadowhawk (Sympetrum vicinum), Dennis Paulson Band-winged Dragonlet (Erythrodiplax umbrata), Celeste Mazzacano Blue Dasher (Pachydiplax longipennis), Celeste Mazzacano Up to 11 other species may be sporadic, irruptive migrants Twelve-spotted Skimmer (Libellula pulchella), Dennis Paulson Swamp Darner (Epiaeschna heros), Dennis Paulson Painted Skimmer (Libellula semifasciata), Dennis Paulson

6 Common Green Darner Migration Models Wandering Glider Dennis Paulson Dennis Paulson

7 Migration Model: CGD Common Green Darner Common migrant in the east, less so in the West Migrate late July to mid-oct., peak in Sept. Massive swarm may follow passage of cold front Migration may be facultative Dennis Paulson

8 Migration Model: CGD Residents & migrants can inhabit same wetlands but differ in behavior & physiology: Residents: nymphs take one year to complete development, spend winter in diapause Migrants: develop from egg to adult in period of weeks during summer Dennis Paulson

9 Migration Model: CGD 2 size groups = overwintering nymphs (black) and summer cohort (white) Overwintering nymphs take one year to complete development (spend winter in diapause) Summer cohort develops from egg to adult in weeks Trottier, 1971

10 Migration Model: CGD Residents & migrants in same habitat, but larval cohorts develop at different rates Migrants Residents May & Matthews 2008; after Trottier 1971

11 Micro-radio transmitters on 14 CGD Tracking CGD Used light airplane to track migration Wikelski et al. 2006

12 ~25% of body weight Batteries last 12 days Tracking CGD Wikelski et al. 2006

13 Tracking CGD Average advance 20 km (12 mi)/day Movement up to 140 km (87 mi)/day Short-range omnidirectional vs. long-range directional Migrating day followed a colder night Re-oriented to avoid ocean Wikelski et al. 2006

14 CGD Stable Isotope Analysis Ratio of 2 H: 1 H in precipitation varies naturally across northsouth gradient Organisms take in via diet, retain signature in inert tissues

15 CGD Stable Isotope Analysis H 2 :H 1 ratios of individuals collected from Ontario to Veracruz in late August to October ~90% moved south prior to collection Mean distance moved 683 km (425 mi) Members of Atlantic swarms originated largely at inland sites Matthews 2007

16 CGD Stable Isotope Analysis A dragonfly wing isoscape for North America Strong correlation between hydrologic isoscape and wing isotope ratios Collection year had no effect Hobson K., Soto DX, Paulson DR, Wassenaar LI, and Matthews JH. Methods in Ecology and Evolution (2012); Bowen, Waseenaar, and Hobson. Oecologia (2005).

17 CGD Stable Isotope Analysis Used data to develop a wing chitin isoscape map Hobson et al. 2005

18 CGD Stable Isotope Analysis MDP used isoscape map to assess probable origins of CGD specimens captured in the southeast

19 Adult wings in Gulf states CGD Stable Isotope Analysis Adult wings in northern range Much variation in ratio in each month: Wide range of locations of origin Adults moving up from south even in late summer Less variation in ratio in each month: Spring specimens came from south Summer specimens originated in north

20 Migration Model: WG Wandering Glider Widespread, from tropics into North Temperate Zone Regular annual migrant Each generation may breed hundreds to thousands of miles from emergence site Dennis Paulson

21 Migration Model: WG Likely can t overwinter past 40 o N; no winter diapause known for nymphs Breed in temporary pools Develop rapidly to avoid drying Migration may be obligate part of life cycle Dennis Paulson

22 Broad hindwings for gliding Migration Model: WG Fly at high altitudes Can migrate at night, over open water Netta Smith

23 Crossing the Indian Ocean Migration Model: WG Annual circuit may involve up to 4 generations Migration in southern India Millions appear annually After Anderson, 2009

24 Migration Model: WG Annual migratory circuit may involve up to 4 generations Adults usually appear later in summer than CGD May move up Migration in from southern northern India Mexico and southern U.S. Millions appear annually After Elisa Anderson, Peresbarbosa 2009 Rojas

25 Feeding and reproduction can occur along the way Migration Models Celeste Mazzacano Migration start/end points likely widely dispersed

26 Why study dragonfly migration? Regular stops to feed, reproduce? Triggers to move south and north? Genetic isolation? Adaptive advantage? Overwintering grounds? Feed over open water? Sporadic vs. annual migration???? Navigation cues? Southern extent? Diapause vs. migration?

27 Confounding factors Difficult to track Flights are sporadic and unpredictable Variegated Meadowhawk; Dennis Paulson Residents may emerge early; late migrants may overwinter Overwintering adults in south where migrants may be present Black Saddlebags; Dan Jackson

28 Questions? Blue Dasher (Pachydiplax longipennis), Celeste Mazzacano