Batgung

Tadpoles can be found in natural or near-natural environment where there is submerged and emergent (grown above water) vegetations for their protection and food. The water should be shallow - no more than a few inches and preferable stationary, and has access to sunlight to raise its temperture. Their life-span as tadpoles is a week or two and only in the spring when the water temperature is sufficiently warm for development and growth. In Hong Kong, this could mean finding them in the country side or farmland.
I built a backyard fish pond in a new housing development in eastern Canada on land that once was natural environment. Each summer, a dozen or so frogs would sit around the edge of, and facing the pond. They would jump high into the air to catch flying insects that come for water and next dive into the pond. My kids would suspend big and scary spiders by their silk using a stick to feed them. They start to accept your close-up company. After a few years, they never return and I suspect that their natural environment has been sadly permanently lost, plus the use of pesticides (I don't) that I think have serious impacts on their hatching and development.

MrB,

I don't suggest to find tadpoles from nature and bring homes or buy them from Gold Fish market or elsewhere. It's not sure those tadpoles sold in Gold Fish market are foreign species; in case they're grown up and you'll lose interest, and bring back them to nature, the foreign species will influence the local wildlife. Why not take the kids to nature and revisit the wild creatures from time to time, this will be a much better nature education than raising them at home...

Sorry MrB, this isn't the answer you're looking for, but thought I should tell you that after reading about your search for tadpoles the other day, I happened to dream about them last night...  and surprisingly after reading your post today, I remember watching their mating ritual... go figure? LOL

OldTimer, I wonder if the shallow water requirement is specific to colder areas? When I used to go tadpole hunting as a boy, we'd end up at a couple of ponds, both several feet deep. That was in Wales in the UK. In fact there was a different problem there - the frogs would often lay eggs in the large puddles that were left after heavy rain. When the puddle dried up, the eggs died.

Willis, Mr Tall already delights in pointing out the freudian overtones of my interest in tunnels and obelisks. Probably best to keep those dreams about tadpoles to yourself! ;-)

MrB

Uh, MrB, I really don't want to see the list of Google search referrals for our site this month, okay?

I think you're too early, or at least out here in Clearwater Bay, it's too early. We haven't heard the annual chorus begin yet. But we're pretty cool up here, and our temps probably aren't warm enough yet. We have lots of frogs and toads out here--there was a boy who lived here when I first moved here and he had several huge tubs full of water with hanging mossy stuff in them and they were filled with tadpoles--I believe he found the eggs and took them before they hatched. I don't know how many hundreds of little frogs and toads he had over that summer, but it was pretty amazing.

But I still think you're somewhat early. April is a better bet, but I seem to recall them even in the hot months (but I've never paid that close of attention to timing--my seasonal clock gets crazy living in the tropics--same thing when I lived in Hawaii).

M

Okay, MrB, you're going to hate me for this, but I've pretty much had the answers you're seeking all along -- I've got a book titled The Ecology and Biodiversity of Hong Kong, lent to me by a colleague, which has a couple sections on amphibians. To wit:

Many of the 22 species of local frogs and toads breed in April or slightly later during the wet season, but several species have a lengthy breeding period [lucky dogs -- ed.]. The Asian Common Toad, Hong Kong's most abundant and widespread amphibian, starts earlier -- in February -- and continues until May [with, I assume, breaks for tiny cigarettes]. Interestingly, the Brown Wood Frog . . . is at the southern limit of its range in Hong Kong, begins breeding in winter. Tadpoles of a few species of frogs (e.g. the Lesser Spiny Frog) can be seen in all months, but this could reflect slow larval growth during the cooler months rather than year-round breeding.

Most local frogs and toads become inactive at temperatures below 13C, but begin calling and mating activity as temperatures and humidity rise; typically, male Bufo melanostictus are the first to be heard. The reproductive succes of frogs that breed in ponds and marshlands is certainly enhanced by rainfall and rising water levels, and may actually stimulate breeding [sic]. For those species that inhabit streams, however, population size will reflect the interaction of rising temperatures and humidity (that stimulate reproduction) and mortality of tadpoles caused by wet-season spates. In Hong Kong (as elsewhere in Asia where there is a pronounced dry season) rainfall appears to regulate reporductive patterns of most amphibians, but Hong Kong's location on the northern margin of the tropics means that temperature also has some effect on the timing of frog breeding.

and

The Giant Spiny Frog, which can reach over 14 cm body length, is confined to boulder-strewn streams at altitudes exceeding 600 m. Thus far, it has been found only on Tai Mo Shan . . . . The Lesser Spiny Frog, which reaches a length of 8 cm, is also found in rocky forested streams, especially headwater tributaries, and is the most frequently encountered stream frog. Larger forest streams are home to the Hong Kong Cascade Frog. It has a rather flat body and well-developed adhesive discs on the digits that it uses to cling on to rocks in waterfalls and cascades. The tadpoles have a sucker-like mouth, and live in fast flowing water where they graze algae. The Green Cascade Frog has less specialised habits and is more widespread . . . . The uncommon Brown Wood Frog and the rare Big-headed Frog occur only in small slow-flowing forest streams. In lowland and more open conditions, the frogs associated with streams tend to be generalist species that also occur in standing water. . . . The Paddy Frog and especially Gunther's Frog are examples of these habitat generalists. The Three-striped Grass Frog is occasionally encountered along stream margins but is more frequent in marshlands.

I suspect this might help.

Mr Tall

MrB

But I don't think removing a few tadpoles from the wild will do too much harm.

I was suprised to read this. I can't imagine when traveller visiting Tibet using this as an excuse to hunt down Tibetan antelope.
Though this is an exaggerated sample, but the logic is same.

In the good old days, people used same statement on animals like whales, wolves, dingo, sharks e.t.c.

Mathew

Yesterday we completed the tadpole mission, and now share our home with around 10-20 new wriggly friends.

Last week I walked along the course of a stream on Hong Kong island, and noticed a frog in one of the little rock pools. I can't remember having seen one before, and a little further along I heard another frog calling, so I took that as a good sign.

On yesterday's walk I found this happy couple in one of the pools. At first I couldn't see any eggs, so I thought I was too early again. But looking closely there were these two strings of eggs trailing behind. (The start of the video is slowed down so you can see the eggs more clearly).

They were smaller than I remembered, and I didn't expect them to have the mottled pattern (turns out the eggs are black on top, light brown underneath, giving this effect). Since the eggs are in strings like this, we must be looking at a couple of toads, not frogs. (Frogspawn is a mass of individual eggs).

I was also surprised to find several brown, striped fish in the pool. Once I noticed them in one pool, I could see them in several other pools too. They would be useful later on.

It was good to see the spawn, but again it seemed I was too early, and would need to come back later to see tadpoles. But in a pool further down the stream I caught a sudden movement, and bent down for a closer look. It was one of those stripey fish darting at a tadpole - lunch, I guess. We joined in the feast, and netted a few tadpoles to bring home.

MrB

On Saturday afternoon we all took a walk up to where I'd seen the toad in the video above. No sign of the toads, but the small pool was criss-crossed with these strings of spawn - there must be several thousand eggs in all.

As with many things, once you know what to look for, they seem to pop up everywhere. Yesterday we took the girls up to the Wong Nai Chung Reservoir Boating Park to paddle around in one of the boats. In the shallows were more strings of toadspawn, and some tadpoles too.

MrB

PS Oldtimer, the hillsides here have that lovely bright green colour from the fresh growth, and I can see the first traces of mould on our bathroom ceiling. Spring is definitely here!

On Monday I walked up to the stream where we'd found the spawn and tadpoles. I was wondering if the heavy rain over the weekend would have washed them all away, but there are still plenty to be seen. None have started growing legs yet. No signs of adults or spawn either, so I guess we've passed the mating time of year.

Back home I've been hard-pressed to tell you if any tadpoles had survived, as our tank's contents had turned into thick green soup. A quick google of the problem shows the solution is to "replace 20% of the water with fresh water each day until the water is clear, then replace 20% every week or two to keep it clear".

We've been doing that for several days, and I'm happy to report the soup has thinned and the tadpoles are still there. The snails have gone forth and multiplied (several have been rounded up and passed on to a friend with a turtle. Mmm, crunchy!), and the freshwater shrimps have had babies, so the tank is teeming with life at the moment.

The tadpoles are now part of the family, and have to be wished good night by our 2- and 4-year old daughters each night. In fact it's like living with the Waltons, "Goodnight tadpoles, goodnight snails, goodnight baby snails, goodnight shrimps, ..."

And after a request for volunteers, several of the bravest tadpoles were relocated to elder MissB's kindergarten. That was last week, so I hope to hear this week if the children have found them interesting.

MrB

MrB: The adults probably have moved to where the food is, bugs and insects that don't like the cool water of the pond and stream at this time of the season.
Two frogs, who hibernated in my pond, emerged from about a month ago. One has left likely to find his romance. But the other one prefers the good old home and sun-bathes every time the sun shines, with only his head slightly above the water level.
Today, my kids fed him a spider hanging from the tip of the stick. The frog remembered the routine from last year very well. So I guess a frog's memory is longer than that of a goldfish.

The change from having one front leg to losing the tail and turning into a little frog is very quick. I wonder if it's confusing for them? One moment you're swimming around under water with a tail, then a day or so later you've got legs and want to spend all your time climbing around in the open air.

Three have changed into frogs so far (their body is less than 1cm long):

Their single goal is to climb out of the tank:

So we've instituted a high-tech security barrier to keep them safe - an old pair of MrsB's tights are now stretched across the top of the tank! But it's clearly time to take them back to their stream in the next few days.

MrB

The stream is full of tadpoles again, so late March / early April seems to be primetime for tadpoles in western Hong Kong.