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| Gib Point http://www.lbcarchive.co.uk/forum/viewtopic.php?f=20&t=12831 |
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| Author: | Edmund Mackrill [ Mon Aug 23, 2010 8:30 am ] |
| Post subject: | Gib Point |
Chris has given me the results of his weekly Reserve count for yesterday - Sunday 22nd. Common Blue Damselfly - still a few on most ponds Blue tailed Damselfly - Something of an increase with 20+ Emerald Damselfly - 2 m Small Red-eyed Damselfly - c80 m and c40 f including 37 pairs in tandem. This represents a huge increase from the less than 10 that have been present since the July 25th 'explosion'. Could this be the appearance of individuals from the eggs that were laid on and around July 25th?? Chris asks for any and all comments from our Odonata experts. Ruddy Darter - 9 Common Darter - common Migrant Hawker - common Emperor Dragonfly - 4m 2f with both females ovipositing. These were both blue bodied individuals. |
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| Author: | Nick Tribe [ Wed Aug 25, 2010 8:41 pm ] |
| Post subject: | Re: Gib Point |
Re the small red-eyed damselfly query, I'll give it a go....... No British species is capable of development that rapidly. Corbet and Brooks (Dragonflies 2008 Collins) identify 3 life cycles for British odonata. Type 1 - Spring species that over-winter at the last stage of larval development. Eggs develop about one month after laying. Often show synchronous emergence. Type 2 - Summer species that overwinter at a late, but not the last, stage of larval development, typically emerging later than Type 1 with non-synchronised emergence. Type 3 - obligatory univoltine (have a 1 year lifecycle) species that typically overwinter as an egg with rapid (2-3 month) larval development The book does not state which Type this species belongs to but it would appear to be either Type 2 or 3. By contrast (large) red-eyed damselfly is listed as a Type 1 species. Hope this helps Nick |
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| Author: | Stephen Routledge [ Sat Aug 28, 2010 8:45 pm ] |
| Post subject: | Re: Gib Point |
Hi Ed, As Nick has said in his post,Small red-eyed Damselfly is a Univoltine species,which usually emerges after one year,the explosion in numbers may be due to one of two things,further immigration or warmer water temperatures helping further individuals to emerge,it could easily be the former,as so far this year,it has been a very good year for damselfly immigration. Regards Steve. |
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| Author: | Edmund Mackrill [ Sat Aug 28, 2010 10:07 pm ] |
| Post subject: | Re: Gib Point |
Thanks for the replies Nick and Steve. Chris and I have noticed how closely linked the emergence/visibility of Small Red-eyeds is with warm humid weather. Both the days on which the highest numbers have been recorded have been very warm and humid - the warmest and most humid for weeks in fact. They are also much more prone to disappear 'in an instant' if the sun goes in. So given that they are difinitely univoltine we would say that it is the weather conditions that have caused these sudden increases in numbers. We will certainly continue to monitor and observe. |
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