Re: [Odonata-l] ecological/behavioural studies
- I thought some of you might be interested in this....
HAPPY THANKSGIVING EVERYONE!
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 interests me greatly, as I did unpublished research on it some time ago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 Paulson & Netta Smith
> 1724 NE 98 St.
> Seattle, WA 98115
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