Changing Climate, Changing Behaviors

That the earth’s climate is changing has become a well established fact, but determining exactly how these changes will effect ecosystems is still an area of active research.  Within this scope of research, how climate change will effect animal behavior is a particularly understudied topic.  But, a recent presentation at the 2013 Animal Behavior Society conference gave an interesting example of just that.  The information presented was on where the Pantless Tree Frog (Dendropsophus ebraccatus) decides to lay its eggs.  This species, which is found throughout Central America, sometimes lays its eggs on the underside of leaves and at other times lays them in the water.  Each location has advantages and disadvantages.  Laying eggs in water mean that they are pretty much guaranteed to sty moist, but there are predators in the water that eat frogs eggs, so more clutches fail due to predation.  Laying eggs on leaves exposes the eggs to much lower rates of predation, but if the eggs dry out they die.  Generally, conditions in the range of the Pantless Tree Frog are quite rainy and so the frogs choose the option of avoiding predation and they lay their eggs on leaves.

However, as the climate has changed rain storms have become more and more sporadic over the last 4 decades, and are likely to become even more so in the future.  This has meant that Pantless Tree Frogs are having to lay their eggs in water to prevent them from drying out.  However, this leaves them open to the greater predation rates.  When predation rates go up on a species, the population level of that species usually finds a new equilibrium level that is lower than before the predation rates rose.  And smaller populations are classically more vulnerable to be reduced further by natural disasters like floods or droughts, and experience higher likelihoods of extinction.

In this way, the Pantless Tree Frog is an excellent example of how changes in an animals’ behavior, in this case in response to climate change, can have important conservation implications.