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Witcombe Reservoir

Printed From: Reptiles and Amphibians of the UK
Category: General
Forum Name: Reporting
Forum Description: Report garden sightings and field days
URL: http://www.herpetofauna.co.uk/forum/forum_posts.asp?TID=5325
Printed Date: 04 Aug 2020 at 3:57pm
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Topic: Witcombe Reservoir
Posted By: Liz Heard
Subject: Witcombe Reservoir
Date Posted: 01 Jun 2020 at 12:35pm
Hello all

Just thought I’d share this as I thought it was an impressive spectacle. The black line represents countless toad tadpoles resting/feeding along the margin of one of the lakes at Witcombe Reservoirs.
Although the concentrations varied a bit (never less than numerous though!), it extended unbroken for around 200 metres - the entire length of the northern boundary.

You won’t be surprised to learn that the location is quite far from any significant roads!

Cheers
Ben




Replies:
Posted By: chubsta
Date Posted: 03 Jun 2020 at 3:10pm
wow!

must be a good population in the area, hopefully many will survive.

is there any way of differentiating toad and frog tadpoles?


Posted By: Liz Heard
Date Posted: 03 Jun 2020 at 6:38pm
Yes, by appearance, behaviour and timing.
Although both start out dark, it isn’t long before frog tadpoles become brown in colour (with attractive ‘speckles’ if you look closely). Toad tadpoles however, remain black.
Once you’ve got your eye in, you can also tell by looking at the tail which is shorter with a more blunt tip in ‘toadpoles’.
If the pond has fish and/or you see lots of tadpoles swimming about boldly in open water (or even congregating/shoaling en masse as above), then they are toad.
Frog tadpoles tend to become more secretive as they grow (and their numbers diminish), hiding still among vegetation or in the mud at the bottom of the pond.
Of course, toad tadpoles generally hatch later than frog too.


Posted By: GemmaJF
Date Posted: 06 Jun 2020 at 12:19pm
Thanks for sharing, that is quite a sight! I find toad tadpoles fascinating in behaviour, on several occasions now I've observed 'shoaling' which is amazing to see. Still seems to be much speculation on why they do it, though I like the idea it creates a vortex that brings up nutrients from silt at the bottom of water bodies.


Posted By: Liz Heard
Date Posted: 10 Jun 2020 at 2:42pm
Hi Gemma

Yes, there's this on the Froglife website, but it seems at odds with my sighting which was one long continuous congregation rather than distinct separate groupings.

https://www.froglife.org/2018/05/31/croaking-science-kin-recognition/" rel="nofollow - https://www.froglife.org/2018/05/31/croaking-science-kin-recognition/


Posted By: GemmaJF
Date Posted: 10 Jun 2020 at 7:49pm
Seen it at several sites, each time a single swirling mass rather than groups. One of the smaller ponds made it reasonably easy to estimate the mass was likely to include the majority of toad tadpoles present, so though the research on the tadpoles being closely related is interesting, it is also somewhat at odds with my own observations.


Posted By: Liz Heard
Date Posted: 11 Jun 2020 at 1:30pm
Originally posted by GemmaJF GemmaJF wrote:

I like the idea it creates a vortex that brings up nutrients from silt at the bottom of water bodies.


Me too though there was no silt where the tadpoles were at the above location. Only gently sloping bare concrete with what looked possibly like minor algal growth in the thin lines between the sectioning.

The numbers were fewest beneath, and in the shadowing just either side of, the jetty in the first pic (where it will have been colder). Here, the tadpoles remained roughly in line with the others, but were more in flux and swimming around.
Like you, on occasion elsewhere I've observed great clouds of toadpoles swimming and swirling in close formation like fish. This has been at, or very close to, the surface of steep sided and quite deep ponds. Can't say I noticed the water becoming any cloudier in their wake though!



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