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metamorphosis times

Printed From: Reptiles and Amphibians of the UK
Category: Herpetofauna Native to the UK
Forum Name: Great Crested Newt
Forum Description: Forum for all issues concerning Triturus cristatus
URL: http://www.herpetofauna.co.uk/forum/forum_posts.asp?TID=2696
Printed Date: 22 Oct 2019 at 4:41am
Software Version: Web Wiz Forums 11.06 - http://www.webwizforums.com


Topic: metamorphosis times
Posted By: will
Subject: metamorphosis times
Date Posted: 04 Aug 2008 at 10:52am
Hello All

With supposedly drier summers compensated for by earlier egg laying in GCN I was wondering whether anyone has noticed earlier metamorphosis times for GCN in their patches ?

I used to reckon on the beginning of Sept as being peak time for GCN newtlets to appear but at one London site on Sunday August 3rd I turned over a log to find the animals in the photo, including the 3 metamorphs you can see.   What's the earliest date you have for emergence and when do you reckon the bulk of the population has left the water ?

Cheers

Will




Replies:
Posted By: Vicar
Date Posted: 05 Aug 2008 at 8:05am
That's a cracking picture Will ! 
Could we use it on the SARG GCN webpage ? (credited of course!)

I'm the worst person to ask, not really being a Pond-hugger...but, on Saturday night, at a local pond, there were dozens of meta-sized GCN in aquatic phase, all sporting gills, showing no sign of metaphorphosis, with the exception of one animal which was about ready to leave the water.

I imagine that there is a wide distribution concerning the timing of metamorphosis, presumably you found some early leavers?


-------------
Steve Langham - Chairman     mailto:steve@surrey-arg.org.uk">
Surrey Amphibian & Reptile Group


Posted By: will
Date Posted: 05 Aug 2008 at 3:23pm
Thanks Steve

Sure you can use it - just send me a pm with the relevant email address to send the high res image to.

I reckon about 5-10% of this London GCN population's larvae have now metamorphosed, but many hundreds of larvae in this site still fully gilled and no sign of the yellow stripe which runs along the bottom of the tail - indicative of imminent metamorphosis along with gill reduction.

Cheers

Will


Posted By: will
Date Posted: 06 Aug 2008 at 4:45am
Absolutely - good point !


Posted By: will
Date Posted: 13 Jul 2009 at 4:20pm
By way of a follow-up to this topic, I visisted the site above today and managed to catch 180 well grown larvae in about 10cm of water, and to transfer them to a permanent pond closeby (fish free).  As expected at this time of year, they were well grown but generally not close to metamorphosis.  I was therefore very surprised to find what appeared to be a newly metamophosed GCN along with two larger (presumably last year) newtlets under a bin liner close to the pond in question.  This metamorph still had the characteristic gill stubs and light yellow belly which typify newly metamorphosed animals.

I guess earlier metamorphosis times following on from early oviposition compensate for hotter summers, in which ponds will desiccate much earlier.  Has anyone else got early metamorphosis in GCN yet ? (it parallels the early births in Zotooca noted elsewhere)



 


Posted By: Kelly L
Date Posted: 09 Apr 2010 at 6:48pm
Originally posted by will will wrote:

Hello All

With supposedly drier summers compensated for by earlier egg laying in GCN I was wondering whether anyone has noticed earlier metamorphosis times for GCN in their patches ?

I used to reckon on the beginning of Sept as being peak time for GCN newtlets to appear but at one London site on Sunday August 3rd I turned over a log to find the animals in the photo, including the 3 metamorphs you can see.   What's the earliest date you have for emergence and when do you reckon the bulk of the population has left the water ?

Cheers

Will



Thank you for the post.
Hi guys, Im a newbie. Nice to join this forum.


Posted By: will
Date Posted: 14 Apr 2010 at 1:00pm
Hi Kelly

welcome to the forum - and thanks for your thanks re the post!

Will


Posted By: Liz Heard
Date Posted: 29 May 2010 at 12:41pm
wow! amazing pics folks!


i dont know about earlier metamorphosis timings but i can tell you that for the LAST FEW YEARS ive had male cristatus show up, start to crest, defend "territories" etc as early as late NOVEMBER here in GLOS. egg-laying in TC commences many weeks before that of the other species (who arrive at the pond at the "normal" time).

ben


Posted By: will
Date Posted: 21 Jul 2010 at 4:46pm
Here's some vaguely quantitative data based on the site mentioned above.  As usual, the main GCN pond was about to dry out, being reduced to two 'sumps' which each had around 10cm of water in them.  In order to avoid the imminent death of well grown larvae, they were removed to a nearby pond to complete their development.  A total of 1,100 larvae were caught, ranging from 3 to 7cm in length, the majority being 4.5cm.  Of these, about 100 were close to metamorphosis and were left in the sumps, to take their chances.  Around the pond margins 20 metamorphs were found, indicating that at least a few per cent of larvae had already metamorphosed, in spite of the late spring.  Guess it goes to show that some 'catch up' is possible given warm late spring and early summer weather.  Several years of larval rescues have led to torchlight counts of around 100 adults, which is pretty good for London crested newt populations.  Here's a photo of a metamorph with its dried out pond behind it:





Posted By: will
Date Posted: 18 Jul 2014 at 3:44pm
I found my first metamorph of the year at this site today, along with several tens of larvae that were in the 'crawling' phase, with gills receding and skin taking on the marbled slightly rugose look of a terrestrial newlet.  In the 'olden days' - a decade or two ago, I would not expect GCN newtlets til mid August.

So it looks as if the sustained warmth has resulted in plenty of early development at this site (admittedly the pond is unshaded and the water gets very warm).  A few years ago I wondered if early metamorphosis associated with rapidly desiccation of the pond would lead to smaller metamorphs. but this year the full grown larvae and metamorphs look pretty big 6-7cm, so this doesn't seem to be the case.  All of which is good news - it seems that the danger of early desiccation of GCN breeding ponds is, to some degree, offset by the increased growth rate afforded by the early start and the warm water in the pond.




Posted By: GemmaJF
Date Posted: 19 Jul 2014 at 7:11am
Interesting observations Will. 

I suspect there may be a strong link between amphibian metamorph size attained and available food supply. I've seen large well developed animals of several species emerging from relatively tiny but warm ponds. In each case the pond was teaming with inverts.


Posted By: will
Date Posted: 19 Jul 2014 at 9:12am
thanks for that Gemma; I guess you would get a synergistic effect where the warmth that favoured larval development would also favour that of the inverts.  And as the water becomes depleted, the invert soup becomes more concentrated and hence it's easier for the GCN larvae to find a meal (and to snap away at each other, too...)



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