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Re: [Odonata-l] ecological/behavioural studies

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  • Kathy &/or Dave Biggs
    I thought some of you might be interested in this.... HAPPY THANKSGIVING EVERYONE! Kathy
    Message 1 of 1 , Nov 25, 2004
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      I thought some of you might be interested in this....
      HAPPY THANKSGIVING EVERYONE!
      Kathy

      Dennis Paulson wrote:

      > This is a follow-up on the very welcome offers of some odonate
      > enthusiasts to help with research.
      >
      > The problem, of course, is that very few people in North America are
      > doing ecological and behavioral studies on odonates! And they may be at
      > universities in places NOT blessed with such enthusiastic volunteers.
      > There are few of them in Washington, they all have their own agendas
      > (rightfully), and I'm sufficiently busy that I can't find much time to
      > direct such volunteers, so it will really be a case of the right time,
      > place, and people to make it work.
      >
      > But here's a suggestion of field research that can be done by anyone
      > anywhere. There is much theoretical interest in polymorphism in female
      > odonates. Adolfo Cordero, Ola Fincke, Mark Forbes, Tom Sherratt, Hans
      > van Gossum and others have published on this, and it's a subject that
      > interests me greatly, as I did unpublished research on it some time ago
      > and have maintained a strong interest in it.
      >
      > Something volunteers could do anywhere is to census female morphs in
      > common odonates in which females come in more than one color. [It goes
      > without saying that you will have to become an expert in identifying
      > the species you study and distinguishing it/them from all similar
      > species.] This polymorphism occurs conspicuously in bluets (Enallagma),
      > dancers (Argia), and forktails (Ischnura) and less conspicuously or in
      > fewer species in some other genera, e.g., sprites (Nehalennia) and
      > spreadwings (Lestes). It also occurs in some darners (Aeshna and
      > Rhionaeschna). Typically one female morph is brown and looks very
      > different from males, the other has some or much blue color and looks
      > more like males. Sometimes it's a bit more complicated, with a green
      > morph thrown in.
      >
      > But they can be censused at or near the water, if you're sure you are
      > dealing with mature females (immatures are duller), either singly, in
      > mated pairs, or both. When good censuses are available for both single
      > females and pairs, some idea of male preference for one or the other
      > morph (or neither) is indicated. The censuses have to be large enough
      > to be statistically significant, and they should be accompanied by all
      > the standard information: locality, habitat, date, time of day, weather
      > conditions. One variable that may influence mate choice is male
      > density, so some idea of male density is also worthwhile to record. A
      > count or estimate of single males along with the female counts would be
      > the best.
      >
      > The genus Ischnura is especially interesting. It has been said that
      > females in the Lilypad Forktail (I. kellicotti) change from orange to
      > blue as they mature, but that would be unique in the genus and needs to
      > be more thoroughly documented. Does anyone have a photo of one of them
      > changing color? Giff Beaton has sent me some information on morph
      > ratios in the field in this species, the first I've seen. Also, color
      > change in the Swift Forktail (I. erratica) is poorly documented. It's
      > most common in the Pacific Northwest, so I have only myself to blame
      > for not understanding this better. And male-like females
      > ("andromorphs") appear to be very rare in some species (e.g., Eastern
      > and Western forktails, I. verticalis and I. perparva), and their
      > frequency needs to be better documented. The frequency of the two
      > morphs, or even their occurrence, in some southwestern species of Argia
      > is poorly known, and even more poorly known as you go deeper into the
      > tropics. It would be of great interest to see if there are geographic
      > trends in polymorphism, something completely unknown.
      >
      > Anyone interested? As it's now the end of the season in the North
      > Temperate Zone, plans could be made for next summer. I should add that
      > this polymorphism is primarily an attribute of north-temperate species
      > and may not occur at all in the South Temperate Zone! It is well known
      > in two Neotropical libellulids, Band-winged and Black-winged dragonlets
      > (Erythrodiplax umbrata and funerea), two more species that could be
      > studied. I should also add that close-focus binoculars are almost a
      > necessity for this sort of research, and I hope most dragonfly
      > enthusiasts use them.
      >
      > Dennis
      > -----
      > Dennis Paulson & Netta Smith
      > 1724 NE 98 St.
      > Seattle, WA 98115
      > 206-528-1382
      >
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