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metamorphosis times |
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will
Senior Member Joined: 27 Feb 2007 Location: United Kingdom Status: Offline Points: 1830 |
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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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GemmaJF
Admin Group Joined: 25 Jan 2003 Location: Essex Status: Offline Points: 4359 |
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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.
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will
Senior Member Joined: 27 Feb 2007 Location: United Kingdom Status: Offline Points: 1830 |
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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. |
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will
Senior Member Joined: 27 Feb 2007 Location: United Kingdom Status: Offline Points: 1830 |
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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:
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Liz Heard
Senior Member Joined: 27 Apr 2010 Location: South West Status: Offline Points: 1429 |
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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 |
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will
Senior Member Joined: 27 Feb 2007 Location: United Kingdom Status: Offline Points: 1830 |
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Hi Kelly
welcome to the forum - and thanks for your thanks re the post! Will |
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Kelly L
Member Joined: 09 Apr 2010 Status: Offline Points: 1 |
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Thank you for the post. Hi guys, Im a newbie. Nice to join this forum. |
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will
Senior Member Joined: 27 Feb 2007 Location: United Kingdom Status: Offline Points: 1830 |
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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) |
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will
Senior Member Joined: 27 Feb 2007 Location: United Kingdom Status: Offline Points: 1830 |
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Absolutely - good point !
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will
Senior Member Joined: 27 Feb 2007 Location: United Kingdom Status: Offline Points: 1830 |
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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 |
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