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odd behaviour in palmates

Printed From: Reptiles and Amphibians of the UK
Category: Herpetofauna Native to the UK
Forum Name: Palmate Newt
Forum Description: Forum for all issues concerning Triturus helveticus
URL: http://www.herpetofauna.co.uk/forum/forum_posts.asp?TID=3671
Printed Date: 09 Apr 2020 at 5:07pm
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Topic: odd behaviour in palmates
Posted By: will
Subject: odd behaviour in palmates
Date Posted: 22 May 2011 at 5:45pm
here's something I've not seen before - apologies for the bad photo.  In a heathland pond yesterday around 50 palmates all just below the surface and just milling about.  Maybe they were all enjoying the sun, or hunting for stuff on the surface, but there didn't seem to be much purpose in what they were doing.  Photo shows about 20 of them in a couple of sq m of surface.  Any suggestions what they were doing?  certainly pretty obvious to airborne predators, grass snakes etc...





Replies:
Posted By: Noodles
Date Posted: 22 May 2011 at 11:26pm
Fish behave like this during periods of drought when dissolved oxygen levels are higher in the surface layers. How important dermal oxygen absorbtion is for newts, i do not know. When a pond becomes heavily polluted fish also come to the surface for the same reason. Having said that they also come up to bask in the sunshine on warmer days. Last night (here) was unusually cold, perhaps a little morning bask in the upper layers?
I dunno


Posted By: will
Date Posted: 23 May 2011 at 6:40am
Thanks for the suggestion - the waters looked quite murky and eutrophic / anaerobic (unusual for pond on heathland), so maybe they're forced up to the surface more than they'd like.
Cheers
Will


Posted By: Noodles
Date Posted: 23 May 2011 at 8:50am
I thought it didn't look like your classic whiskey stained water, although i'm sure you're lowland heaths have different soil characteristics. The defensive grouping might also suggest that there is an overriding necessity for this behaviour, with calculated risks!
Cheers 


Posted By: Caleb
Date Posted: 24 May 2011 at 9:24am
Usually when newts need to breathe they just swim to the surface, take a gulp of air then swim back down- I would have thought that this would just happen more often in low oxygen conditions.

Were these mostly males? Male palmates seem to me to be the most sun-loving of the native newts. I've never seen anything like these numbers, though.


Posted By: Noodles
Date Posted: 24 May 2011 at 10:29am
[QUOTE=Caleb]Usually when newts need to breathe they just swim to the surface, take a gulp of air then swim back down

Well that's what i would have thought, but since newts can hibernate underwater absorption of oxygen through the skin may be more important than we perceive. Alternatively if the pool is anaerobic and has remained stagnant for some time the lower layers may cause some form of toxic upset or affect the newts' cutaneous gas exchange (required perhaps in some capacity). Although as you point out Palmates are a surprisingly diurnal species and love a bit sunshine.Cool

Who knows for sure, not I?  

P.S. In the dog days of summer, when the water lies stagnant, fish behave in exactly this way due to depleted oxygen levels and poor water quality. That much is certain.
Cheers 


Posted By: will
Date Posted: 24 May 2011 at 10:44am

Thanks for both your thoughts - there was an even sex ratio, and the newts didn't seem stressed, and on reflection they didn't seem to be gulping air more than usual (which could happen in warm, anaerobic water).  So maybe they were just basking, and opportunistically grabbing insects which happened to get trapped in the surface tension.  However there's no doubt that this strategy would have attracted predators, as I noticed all the ripples some metres away from the bank.  Males also seemed entirely uninterested in courting females, although still in breeding dress, so perhaps they had something else (prey) on their minds. 




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