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The odd behaviour thread!
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GemmaJF View Drop Down
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    Posted: 01 Oct 2014 at 9:42am
Things often get mentioned in passing on other threads but I thought I would start a specific thread for behaviours observed but not always explained in the literature.

The idea being people can report a behaviour they have seen, others can confirm if they have seen it also, and perhaps someone will even provide a possible explanation for it!

So my first one, newt, frog and toad tadpoles 'lining up' around the  edge of a pond before thunderstorms. Seen it several times and with captive tadpoles in trays in the past I could even predict a storm was on its way! Anyone else see this? Any idea why they do it or how they know a thunderstorm is brewing?
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GemmaJF View Drop Down
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Points: 4359 		Post Options Post Options   Thanks (0) Thanks(0)   Quote GemmaJF Quote  Post ReplyReply Direct Link To This Post Posted: 01 Oct 2014 at 9:44am
The next one, toad tadpoles shoaling, anyone else seen the massive swirls of toad tadpoles moving in a coordinated way on a hot summer day in lakes?
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will View Drop Down
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Points: 1830 		Post Options Post Options   Thanks (0) Thanks(0)   Quote will Quote  Post ReplyReply Direct Link To This Post Posted: 01 Oct 2014 at 10:44am
good idea! no idea about the tadpoles lining up - (sounds like little compass needles orienting in a magnetic field produced by thunderstorm activity?? - a complete guess).

I have seen toad taddies shoaling - several of the lakes in Epping Forest spring to mind. it makes sense, given that they are distasteful and also I guess from a 'selfish herd' principle, though. It's always fascinating how the shoal 'knows' where it is going, as with flocks of starlings etc.

I guess we could add lizard foot waving to the thread, too, except that we have discussed this at length before.

I've noticed adult newts with their heads arched upwards out of water on thundery/rainy nights during the breeding season, apparently just 'enjoying' the rain...
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AGILIS View Drop Down
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magnetic tad-poles keith
   LOCAL ICYNICAL CELTIC ECO WARRIOR AND FAILED DRUID
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Liz Heard View Drop Down
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Points: 1429 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Liz Heard Quote  Post ReplyReply Direct Link To This Post Posted: 04 Oct 2014 at 2:33pm
Good idea for a thread.

Yes, i've seen toad tadpoles shoaling too - and they did it just like fish or starlings, all moving as one in a mesmeric flowing cloud. Fantastic!
But why is it necessary when they are off the menu for so many creatures?
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will View Drop Down
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Points: 1830 		Post Options Post Options   Thanks (0) Thanks(0)   Quote will Quote  Post ReplyReply Direct Link To This Post Posted: 04 Oct 2014 at 3:07pm
Hi Ben

good Q.  I think they shoal because a single toadpole is vulnerable to being ingested and chewed up by a fish - even if it is subsequently rejected by the predator.  There must be a selective advantage to being part of a shoal.  It might a)intimidate a predator such as a smallish fish b) make it statistically less likely that you will be eaten (the selfish herd principle) and c) that a predator, having had a distasteful experience, will remember (at least in the short term) that the idea of snacking on the constituents of a big, obvious shoal of tadpoles is not a good idea.  I seem to remember studies have shown that the shoals are often made up of siblings, which would add a 'selfish gene' dimension as well - ie the maximum number of copies of the parents' genes are left behind if their offpsring shoal rather than live separate lives, for the reasons given earlier.
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GemmaJF View Drop Down
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Points: 4359 		Post Options Post Options   Thanks (0) Thanks(0)   Quote GemmaJF Quote  Post ReplyReply Direct Link To This Post Posted: 04 Oct 2014 at 4:36pm
I think your points make sense Will, I have seen shoaling in lakes definitely supporting fish.

I did wonder too when observing it whether it could disturb nutrients on the lake bottom and provide food. Perhaps a handy side benefit of the behaviour. I didn't know the shoals are often made up of siblings. I always thought catching tadpoles to stock a new pond was better than taking spawn because it gave a cross-section of the gene pool, netting them out of a shoal might not be such a good idea if that is the aim!
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GemmaJF View Drop Down
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Points: 4359 		Post Options Post Options   Thanks (0) Thanks(0)   Quote GemmaJF Quote  Post ReplyReply Direct Link To This Post Posted: 04 Oct 2014 at 4:49pm
Was doing a bit a dig around and came across this:


Which also gives thermoregulation advantage as a possible reason for shoaling

Not sure why I don't have the book in my collection but handy it is online!
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will View Drop Down
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Points: 1830 		Post Options Post Options   Thanks (0) Thanks(0)   Quote will Quote  Post ReplyReply Direct Link To This Post Posted: 04 Oct 2014 at 5:39pm
interesting reference; I hadn't considered the stirring up nutrients bit or that it might help with thermoregulation, but both seem plausible.  Newly hatched frog tadpoles do gather at the centre of the disintegrating spawn mass which may help with warming up before they go their separate ways.  As genetic analysis gets ever easier it may be possible to tell in the field if a shoal of common toad taddies is comprised of kin or mixed parentage, I suppose.
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Caleb View Drop Down
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Points: 660 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Caleb Quote  Post ReplyReply Direct Link To This Post Posted: 06 Oct 2014 at 11:59am
Originally posted by GemmaJF GemmaJF wrote:

Not sure why I don't have the book in my collection

Maybe cos it's alarmingly expensive? That's my reason, anyway.

Kentwood Wells' 'Ecology & Behaviour of Amphibians' has a big section on tadpole aggregations.

One thing he mentions that's not been mentioned yet is the possibility of tadpole shoals being able to physically displace competing species when feeding. Another is 'nutritional benefits derived from the feces of other individuals'. 

He also quotes this study on common toads:

which suggests that they're more likely to shoal with their siblings and/or in the presence of fish.


Edited by Caleb - 06 Oct 2014 at 11:59am
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