As the weather gets cooler, I have been getting quite a few people reaching out to see what they should be doing with tadpoles that were caught over the summer. Here are some answers to the most common questions I have received.
When will my tadpole transform into a frog?
If the tadpole has not started metamorphosis by end of summer/ early fall; it is quite possible that the frog will stay a tadpole over the winter.
What causes the tadpoles to morph into a frog?
It is thought that the two main factors in the tadpoles development are water temperature and food availability.
- Water Temperature too cold -> can slow the rate of development
- Surplus food -> can delay metamorphosis
In labs, tadpoles who spent the time in low temperature water with short food supply were the most likely to wait until after winter to become frogs; however in the wild, the early change to cold water with short food supply were known to metamorphose before winter. It is now thought that the tadpoles are choosing to stay a tadpole over winter instead of completing metamorphosis.
What are the tadpoles outlook if they stay tadpoles over winter?
Tadpoles may have a better chance of survival if they delay metamorphosis. As a tadpole in winter, they need less oxygen to survive which is helpful when there is a layer of ice which is blocking the air from the water surface causing a low-oxygen water condition that could cause a frog to suffocate. Tadpoles who delay turning into frogs may have a distinct advantage on land as well. By delaying metamorphosis until the following spring, tadpoles will be larger and better suited for competing for on-land resources.
What to do with remaining tadpoles that have not metamorphosed?
If you know where it was originally caught:
- You can continue caring for it, however you will need to be prepared with a tank set-up in case it morphs before the lake/pond is thawed.
- You can return it to the pond/lake it was originally caught from
If you do not know where it was originally from you will need to set-up a tank that will allow it to transform from a tadpole to a frog and then continue hand raising it through its life. Please do NOT transfer frogs from an unknown area to your pond/yard. This can unknowingly spread diseases and invasive species.
- University of Edinburgh – Tadpoles’ survival in winter explained
- What do tadpoles Eat – Over-wintering Tadpoles
- Natural Areas Notebook – What’s under the ice? Wow! Winter Tadpoles!
- Northern Woodlands – Tadpoles of Winter