Late Tadpoles

[Jürgen Gebhart]

Found some Tadpoles today at first I had no idea what they are.

Later I found a small Jumper

Looks like Bombina variegata

I found some more tadpoles, much smaller as the first, some without legs.

Looks like a Bufo bufo or calamita (I know it`s a hell of a pic)

I found them never that late in the year, strange, isn`t it?

[Mario Riedling]

Hi,

over here in south-western Germany amphibians had lots of problem with the dry spring.
B. variegata and B. viridis found their first vernal ponds on the 17th of May after some heavy rain falls. But after May it was too dry again so many tadpoles had to deal with a lack of water and crowding effects. Most tadpoles died due to these two reasons.
We also had couple late ones, especially when it comes to metamorphosis. But your examples are unbelievably late!

Regards,
Mario

[miguel santos]

In the south of the Nederlands you can still find tadpoles from alyttes and bombina. The ones from alyttes will survive the winter (even bellow ice ), but the ones from bombina will not develop any more
. If they don't metamorphose before fall they will not survive. As for the second tadpode it is indeed quite late for it.

[Bobby Bok]

Indeed quite late! Laura and I had a similar experience two weeks ago when we found several tadpoles and fresh metamorphs from Bombina somewhere near Munich. Your little bufo is a small calamita (dorsal stripe).

[Jeroen Speybroeck]

the ones from bombina will not develop any more. If they don't metamorphose before fall they will not survive

Where did you get this?

[miguel santos]

from two sources:
- Herpetofauna van Limburg, Verspreiding en ecologie van amfibieën en reptielen in de periode 1908-2009, Natuur historisch genootschap in Limburg 2009.
On page 133 it is writen : (in Dutch) "It has been observed in Wahlwiller that larvae that are still in the water in September never metamorphose due to the fall in temperature, they all end up dying"
AND from asking arround in the field. I live in less the 10 Km from 4 habatits where Bombinas live and I often seen Larva in September/October and even last year with almost no frost not one single larva metamorfose after that period. I also know the man that manages the area in Wahlwiller and he confirmed this earlyer to me.
That is at least the situation under the present Dutch climate.
Greetings,
Miguel

[Jeroen Speybroeck]

Thanks. I wonder if this holds true throughout the species' range...

[miguel santos]

I wonder if there are any records of overwintering larvae for this species? Do their cusins in Italy or Greece produce larvae through fall?
they are more mountain related down there and I supose their live cycle is a bit like the ones in central Europe or is that not the case?

[Bobby Bok]

I can imagine it is somewhat similar at least in Greece or Italy. Most often the places they inhabit (shallow puddles next to bigger streams or slow-flowing parts of the streams) are characterized by heavy rainfall in autumn/winter forming raging torrents and rapids. In summer 2010 I visited a place for Bombina (variegata) pachypus in Liguria (with Jeroen a.o.), the same place in autumn 2013 was a massive river and offered no refuge for any amphibian larvae at all.

[Jeroen Speybroeck]

Something to check in "The Handbuch", but tagging along with the expressed reasoning, wintering larvae of Bombina bombina seem quite a bit more plausible, although they too tend to breed in habitats known for strong water level fluctuation (but not so much changing current velocities).

I have some difficulty in getting the hang of what truly separates the breeding habitat of Bombina variegata and Alytes obstetricans. Would you say the latter breeds generally in deeper (less likely to freeze) water bodies in Central and more N Europe? To my mind, they can both occupy similar sunny, shallow, poorly vegetated waters, offering equal chance for wintering larvae to both species. Also, do they share the same water bodies in NL? I recall a German quarry where both co-occur, but I'm not sure if the larvae coexist in the same water. Surely, a consequence of the too limited attention I tend to pay to tadpoles.