Tuesday, February 2, 2010

Call of the Ponds

In the frenzy of breeding, some amphibians get confused.

The frogs, toads and newts are heading to the ponds and creeks for their annual breeding. With all the rain we've been getting, these are happy herps. Now is a good time to visit ponds and creeks to witness this seasonal event.

The skewed distribution of rain in California means that some ponds and creeks are wet only in the winter and spring months. If there is rain. As a result, many California amphibians only visit the wet areas for a short period during their hectic breeding season and that is the time you are most likely to see and hear them. Not only is the water a window into their reproductive rituals, but in their frenzy to complete their duties before the rain ends, they seem less sensitive to human curiosity.

A male aquatic-phase newt shows off his black nuptial toes.

The male amphibians usually splash down first and undergo some type of physical transformation to prepare for their upcoming adventures. Male California newts develop smooth skin, swollen limbs and streamlined tails for navigating to their sweethearts in water. They get rough, black tips on their toes, called nuptial pads, to grip the female during mating.

Small in size, the male treefrog pumps a bellow below his chin so that his call can be heard from long distances by female frogs (and people too).

From every pond, creek, ditch, cattle trough and puddle at the Dipper Ranch right now, comes the chorus of male treefrogs. Their two-note (kreek-ik) call, which advertises their fitness for breeding to the female treefrogs, is mostly heard on warm nights, but also on rainy or overcast days. At the height of the breeding season, the treefrogs can't seem to resist calling even during a sunny day. The treefrog chorus will suddenly fall silent as you approach a pond's edge, but soon one frog will start trilling, and not to be outcompeted, the others will quickly join in.

Treefrogs in amplexus. As the female (bottom) releases eggs, the male releases sperm for external fertilization.

Newts in amplexus. Sometimes extra males join in.

Fertilization of eggs is facilitated by amplexus, wherein the male embraces the female from above or behind. In the newts, amplexus occurs as the pair swims slowly and gracefully together around the pond. Surely, this is one of the most peaceful rites of springs to be witnessed at the edge of a pond.

A female newt grasps pond vegetation as an egg mass emerges between her rear legs. Another newt egg mass floats in the water below her belly.

Eggs of each of the amphibian species can be distinguished by their different shapes and sizes. See links below for photos and descriptions. It's worth returning to the ponds and creeks in the next few weeks to witness the hatching of tadpoles and larvae and their transformation into tiny land-hardy frogs and newts.

So gather the family and go visit a pond or stream. Walk right up to the edge of the pond or into shallow waters and squat down to watch the aquatic play. Some activities you might try during your pond-gazing visits:
  • Can you name the different types of frogs, toads and newts?
  • Do you hear different frog calls?
  • Can you see the difference between the males and the females?
  • Can you see different types of eggs?
  • What are the amphibians eating in the pond?
For clues, see the links below for more information and photos.
Peering at you peering at him.

Names of amphibians mentioned in this posting:
  • Sierran treefrog, Pseudacris sierra - formerly called Pacific Treefrog, Pacific chorus frog, Hyla regilla or Pseudacris regilla.
  • California toad - Bufo boreas halophilus
  • California red-legged frog, Rana draytonii
  • Coast range newt, Taricha torosa torosa

4 comments:

  1. I haven't made it to your pages for a while, but it is really worth the trip! Thanks for the good info and great photos.

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  2. I've never seen a newt before - beautiful coloring. I burst out laughing at the frog-on-newt picture!

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  3. Beautiful pictures. I can never seem to get close enough to our frogs to get a good image.

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  4. The California newts are highly toxic and they aren't scared of anything. At night, it's not too hard to get close to the frogs if you move close to the pond edge and then stand still for awhile. They are very cryptic during the day however.

    ReplyDelete

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