HAZARDS OF FROGS

     While watching birds on Lake Onalaska, a lake off the Mississippi River in Wisconsin, via a live camera and our home computer screen, I heard the "snoring" courtship calling of leopard frogs in shallow water.  I also saw a great blue heron stealthily stalking on its long legs through those shallows after prey animals to catch and consume.  Step by slow, careful, step, the heron eased forward, occasionally stopping to watch intently for its next victim.  

     Suddenly the great blue thrust its long neck and formidable beak forward and down with lightning speed and grabbed a leopard frog in its bill.  The frog momentarily struggled to get loose, but the heron repeatedly clamped its mandibles on it, quickly killing it.  Then the heron gulped its victim down, whole and head-first.  

     A dramatic scene, and one that shows the hazardous lives frogs, and other small creatures, lead.  No wonder each female frog spawns hundreds of eggs every year.  

     Frogs are preyed on by many kinds of wildlife, including raccoons and mink that forage mostly at night.  Other predators on frogs include cranes, herons, turtles, water snakes and large fish.  Frogs avoid deep water to escape large fish, but then those amphibians are vulnerable to the other predators in shallow water.  And the intriguing courtship croaking of males gives away their presence to predators.  

     I remember one time seeing several handsome green frogs leaping, in panic, out of shallow water and across a mud flat along the shore of a pond.  Within seconds, a large northern water snake slithered rapidly across the same flat, its tongue flicking repeatedly to keep the scent of the fleeing frogs.  

     But frogs have defenses.  They are well-camouflaged when sitting along a shoreline.  They are quick to dive into water and hide under a log, aquatic vegetation or an underwater leaf pack.  And they are prolific, which makes up for losses.

     The fish-like tadpoles are heavily preyed on as well.  Herons, cranes, turtles, water snakes, larger fish and crayfish are some of the critters that prey on tadpoles.  But those polliwogs have safety in large numbers, are camouflaged and sometimes hide under water plants.  

     Some tadpoles, however, are forced into a race against drying pools.  The water dries before those tadpoles are able to grow lungs and legs to escape it, which kills them.

     Frogs and their tadpoles face many dangers.  But they have defenses that allows many of them to survive.  And each female annually spawns hundreds of eggs, which replaces the many losses each year.  Therefore, we can enjoy the charming, intriguing croaking of frogs on lovely, summer evenings.        

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