Tuesday, September 6, 2011

Tree Frogs on High

    Tree frogs, aka Northern Pacific Chorus frogs, have been a part of my life from my earliest memories. There were the strident amphibian choruses in spring, rising on the night mists from nearby Hazard Lake. I can still remember being a child, lying in bed,  listening to the frogs lull me to sleep. Though today I live in the middle of a much bigger city than I grew up in, I still hear those frog choruses repeated every March, and am transported back to those early days...

    Tree frogs have two distinct life phases: the spring water phase, where they congregate in wetlands to sing, to breed and to lay eggs. (See our Frog Blogs from March and April 2009). Then there is the lesser-known phase where they migrate out of the wetlands and back to drier, upland areas, where they spend the winter. I’d learned about this from books. What the books didn’t tell me is that somewhere on the march to the overwintering grounds, the frogs seem to like to find a high place to climb and hang out.      

    For example, Nancy took the above picture at one of our favorite local nurseries, Bark and Garden.  While looking at pollinator plants she came across a "Tomato Soup" echinacea.  Her eye was caught by a frog on the topmost flower;  stealthily she adjusted the plant racks, climbed up and captured the shot.

      This brought back more childhood memories.  I remember I was examining  our elderly plum tree, thinking about its tree climbing opportunities.  As I explored one branch in particular, I came eyeball to eyeball with a tree frog.  It was tucked into a crook of branches;  it’s hard to say who was more startled.  I went back into the house and shared this tidbit with my mother, who remarked that frogs do this in the summer, and that’s why they are called tree frogs. 

      I remember some friends who lived out on a wetland off South Bay road.  In summer, the tree frogs left the nearby pond, and climbed up into their tall roses, tucking themselves into the deep red rose buds.  That was quite a thing to see.
    Or my friend Rain, who lives on a wetland near Woodard Bay;  in late summer, there are frogs all over her deck, including one she found living in a dried flower wreath arrangement on the front door.

    One June afternoon a few years ago, Nancy went into her carport shed and stumbled across a Northern Pacific tree frog lurking on top of a shovel handle.   Notice the dark brown color it has.

    A year later just outside the shed, she discovered a deep green Pacific tree frog perched on a hose rack near the moist faucet bib.  

       Just recently, another frog of this species was found suctioned to the outside wall of her mobile home.  She believes it's  the same one she spied several weeks ago in the identical spot, wearing a light green hue.

    It turns out tree frogs have skin full of chromatophores, pigment-containing skin cells that can change color, allowing the frogs to be better camouflaged in their surroundings.  Tree frogs can vary widely in their colors;  notice how the frog on the wall of the mobile has streaks of a pale blue-gray, just like the paint!

       This behavior has caused us Olypollinators  naturalists to kick around various theories as to why they hang out in trees.   One thing  we’ve read says that trees are in fact their preferred habitat, and that the spring ponds are only a brief part of their life cycle. Trees and their leaves have pockets of water, even in summer, which can attract insects;  maybe this is the reason.
    The frog on the echinacea at the nursery was in a fine position to receive the daily spritzes of water from the overhead sprinklers;  maybe that was an attractant?  Or the frog on the wall was near a patch of active pollinator plants, which could provide food?  Or the frog on the shovel handle in the shed was near the one sunny window, which had an active spider web.  Maybe the frog was raiding the web, taking advantage of that food opportunity?
    All these things seem possible.  And it is also true that  animals live in their own world, beyond our knowledge and ultimately, beyond our full understanding.    And that’s one reason we enjoy watching them.

Janet Partlow

Resources: all photos by Nancy Partlow

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