Friday, March 5, 2010

Chorus of Spring - Pacific Tree Frogs

While we have had some great late winter weather lately spring still isn't quite here. But March is a magical month of life in nature. Plants begin to grow and our daylight hours are filled with the songs of birds. Another choir of spring also starts to warm up, but this one is at night! Ah, one of my favorite parts of spring. The longer evening hours of warmth lead to that first night where darkness brings on a riot of singing from our hidden but noisy neighbors: the Pacific Tree Frogs!
The Pacific Tree Frog (Hyla regilla) can be found almost anywhere in our region. Woodlands, meadows, pastures, shrubs, small trees, flower gardens, and smack in the middle of your lawn! They often are found even in urban areas quite far from the nearest body of water! Their toes have sticky pads which allow them to climb about on plants with great agility. However they do tend to stay much closer to ground level than most tree frog species, preferring to remain within two feet of the ground most of the time. I have always been fascinated with the care these little creatures use in selecting areas to lay their eggs. The eggs are laid in early March to May in temporary ponds. Why? These temporary ponds are key because their predators such as brown salamanders and bullfrogs do not live or lay their eggs here! These other species require permanent water for their livelihood! By choosing temporary ponds (which will dry up by summer) instead of deep permanent ponds, Pacific Tree Frogs reduce the number of predators that may eat the tadpoles!

So just why do frogs sing? There are actually a wide variety of reasons! Sometimes, frogs sing when they are trying to attract a mate ("Hey there! Come and find ME!"). Sometimes, they sing to mark their territory ("Excuse me, this is MY lily pad!"). Other times, frogs sing because they know the weather is going to change or they even squeak when they are frightened or hurt! But at this time of year what stands out the most is the males call for attracting females. The male frogs are territorial and protect their part of the pond from other males by repeating their two-toned call at night. This call can be heard from as far as a mile or more away and attracts females who hop along to find where the males are hanging out. This loud call is so famous and "perfect" in a sense that even Hollywood has taken notice. The distinctive call of the Pacific Tree Frog is widely used in films for a "tropical" background! Once the eggs have been laid in the temporary pond (attached to a branch or clump of grass) the parents hop back to open forests and other places, leaving the young to fend for themselves. Thus begins the remarkable transformation of an egg to a tadpole and eventually to the young froglet which first grows back legs, then front legs, and then loses the trail to become a froglet. This happens by autumn and young frogs are mature at about one year of age. At that point their main predators are raccoons, herons, mink, bullfrogs, snakes, and other animals.
As March passes along and we get our first warm evenings that last well past dinnertime start keeping an ear open for this spring choir to kick into full swing! While it can be very difficult to spot these little fellows (they cease calling if they feel threatened) you can always sit back and enjoy knowing they are present nearby. Having Pacific Tree Frogs (or any species of frog for that matter) nearby is one of the strongest indications that we have a healthy ecosystem! These little amphibians are one of the first indicators of when an ecosystem is starting to struggle under pressure and we need to keep them happy if the rest of the natural cycle around us is to remain healthy and happy too!


  1. They are alive and well at my house.... and down at my farm... zillions!!! How do the girls ever chose, out of all that great din! Janna

  2. Do the Pacific Northwest tree frogs go back to their place of birth