UK Newt larvae still in ponds?

[colin]

Hi All,

Last night I went to survey a pond one last time for the year.

Essentially, it is a new Great Crested Newt site I found earlier in the year and has a good population of smooth and palmates also.

Unfortunetly, I didnt find any GCN larvae... I am asuming that they have all left the water. But to my surprise there were approximately 35 - 40 larvae from smooths and palmates. Some of which would only have been 10mm long, if that!

I do understand that some larvae will overwinter but from my records of larvae seen over the summer in this pond it looks like about 25% of what i have counted is going to overwinter.

Anyone got any information on this or any ideas???

The pond is pH 7.2, approx 30 feet by 8 feet wide and about 12 - 24" deep but with a large silt layer. Invertebrate populations seem very healthy as does plant life. One part of the pond is heavily shaded but the rest will get sunlight throughout the day.

also spotted two adult frogs, two adult toads, 2 of this years frogs and 2 subadult palmates.

Cheers
Colin

 

[caleb]

Colin,

It is unusual to find that many larvae in the water this late in the year. Also, GCNs are usually the last to leave, in my experience.

Do you know when the newts started breeding in this pond? They started pretty late this year where I am (near Durham), though I've not been out to check for larvae recently.

Is this pond near Glasgow, as your profile suggests? Your local herp recorder would probably be interested if it is, are there aren't many known GCN sites in Scotland.

Griffiths' book suggests that a percentage of smooth and palmate larvae overwinter- I can't remember the exact figure, but I remember being surprised how large it was (10% perhaps?)

It's also possible that this is a population with a high rate of neoteny...

It sounds like it would be worthy of investigation over the winter and into next spring, in any case!

 

[alan]

I would estimate that the proportion of T.vulgaris larvae in my pond which overwinter probably approaches 10%. My pond is deep (4 feet in the centre) and heavily vegetated so it's hard to be sure since when the water temperature falls, they tend to retreat deeper. I've always been of the opinion that these larvae tend to represent the later spawners in a particular year. No evidence of neoteny in this population, they just morph earlier the following year. Good survival strategy if you ask me.

 

[william]

that's what happened to me because when i was fishing out some goldfish for a friend last week i found a number of newt larvae in the water weed. i've no idea what species they are although they are probably smooth newts. the pond is probably 2 foot at the deepest and is choked with weeds and lilies it gets all but the earliest morning sun.

pleased to find them with goldfish

 

[colin]

Thanks for the quick replies...

caleb, I should have said that I am the regional recorder for my area. I am a member of the local ARG and countryside ranger so luckily i get to do this as part of my job

As far as know there are about 4 sites within 10 miles of me that have GCNs. Glasgow is the nearest big town to me but I'm about 10 miles south and in a different council area.

That aside, i also expected just to get GCN larvae and was surprised, especially at how small some were.

I dont know exactly when they started but they were spawning in May when i first found the pond. I have set aside time in October and Novemember to re-check the area.

Alan & William,

What size were the newt larvae you found? I just feel that these larve are very small. i did find last year' slarve in some bog pools earlier this year (April) but they were about 4-5cm

thanks again
C

 

[jeffrey]

Colin do you think the long summer and higher temperatures we have experienced might have led to extra matings?

The only time I was in your area I was on a rugby tour with the school I attended, we stayed in East Kilbride and played at several local schools including Airdrie where we played in a foot of snow. We were not lucky enough to see any local flora and fauna die to the weather, if I get up that way again I will pay better attention.

Jeff

 

[alan]

The late larvae I find are big, it's just like they don't quite make it before the winter, so decide to sit it out until the Spring.

 

[william]

same with mine

 

[justin]

i visited my favourite pond the other day to see many great crested larvae in it i think it is due to the mild weather we had during jan feb then all of a sudden very cold weather which might have caused them to breed later on .i no the weather upset my pond at home and they left to come back later on in april the weather is very worrying this year hope it gets better next year

 

[morg]

All this pond watching spurred me on to check my garden ponds, and for a change, my largest[although still small] pond has no sign of larvae ready to overwinter.
I think though, that this maybe due to an adult female T cristatus that is still living aquatically possibly eating them.
The other two ponds do contain T vulgaris larvae[large] still, and I also saw 1 well developed T cristatus in my medium sized pond.

 

[benjamin]

In my garden pond there is an adult female smooth newt who came to the pond in the begging of april and has not left it since, is it possible for adults to live all year in ponds.

 

[morg]

It is unusual as most newts leave the water for a terrestrial life after breeding season, but I have found adult newts in my ponds mid winter when clearing leaves and excess plants etc

 

[colin]

Update 23rd October 2004-

Looks like at least 20 - 30 newts will be overwintering as larvae in my dad's pond.

I was visiting yesterday and although the overnight temperature had been as low as 1 or 2 degC the day temp rose to about 10 and there were quite a lot of larvae lying near the top of the water on leaves etc.

This has encouraged me to visit the original pond i reported on again and aim to do so this week.... hopefully see some cristatus

 

[caleb]

There were still quite a few palmate larvae about round here (Durham) when I was out a couple of weeks ago.

By the way, a quick method to tell if a newt larva is close to metamorphosis- lift it out of the water. If it thrashes about like a fish, it's got a way to go, if it walks, it's nearly there (this method was published in the BHS Bulletin a few years ago).

 

[sergé]

Adults can indeed return to the water before the winter. Males (especially of palmate newts) do it (field research in the Netherlands has showed it). They are then first there when the females arrive next spring. But also females can do so. It seems there are different strategies to make sure the species survives...but it probably depends also on the type of pond and the food availability.

 

[william]

there are now no larvae left in my pond, i don't know how much the few goldfish had to do with that though

 

[benjamin]

Colin, how well developed are the 10mm larvae?

 

[colin]

just front legs... look a lot like a couple of week old larvae do normally... I am taking water sample next time to get lab tested, that may show up anything???

 

[benjamin]

This pond does seem a little bit peculiar. Is there a nearby factory, could the newts be genetically isolated in any way?