Top Predators Create Healthy Ecosystems

In an excellent article published yesterday, Jeremy Hance examines three recent studies that underscore how critically important top predators are to healthy ecosystems.  

The first study considers the negative effects that occur when "mesopredators” (e.g., coyotes, raccoons, skunks, baboons, etc.) fill the void left by the disappearance of top or “apex” predators (e.g., wolves, cougars, lions, sharks, etc.).  The second study discusses how the presence of top predators can improve the health of plant communities (e.g., the reintroduction of wolves to Yellowstone led to increased willow and aspen growth).  The third study, the most surprising of the three, looks at how hunting by top predators can “create nutrient hotspots that keep ecosystems rich and varied” (e.g., researchers used a 50-year record of moose kills by wolves on Isle Royale National Park to find that moose corpses create hotspots of forest fertility by enriching the soil with biochemicals).

Hance’s analysis of the three studies leads him to correctly conclude that “it appears that top predators are indispensable to a working ecosystem.” 

The ecological importance of predators is an important component of our wildlife work at NRDC, and it’s an issue we’ve previously blogged about it.  (See other posts by Andrew Wetzler, Dr. Sylvia Fallon, and me.)

Hance’s article and the studies about which he writes are both timely and alarming, as top predators are fast disappearing from the earth.

Cutting research funding for bats: penny-wise and (millions of) dollars foolish

Some pieces of the mysterious puzzle known as white-nose syndrome - the disease that is devastating bat population in the northeastern US - are beginning to fall into place, though as of yet, the picture is still unclear.  Several reports are coming out of Europe that bats have been discovered to harbor the white fungus though without the detrimental effects we see here.  These reports lend support to one of the leading hypotheses on the origin of white-nose syndrome: that the fungus is native to Europe where bats are adapted to coexist with it and that it was accidentally introduced to the US where the bats lack the defenses to withstand infection. 

If this hypothesis is true, it also supports the idea that the spread of white nose syndrome was, at least initially, transmitted by humans.  While it is believed that bats are now transmitting the disease directly to each other, some conservation groups are advocating for the closure of all bat hibernacula on federal land across the US in an attempt to reduce or slow the human-caused spread of the disease which is rapidly making its way toward large colonies of bats including the endangered gray bat and Indiana bat.  Closing bat caves to human activity is one of the few concrete actions that can be taken right now, but the spread of the disease by bats will continue regardless.

What is still needed is further research to better understand the origin, spread and epidemiology of white nose syndrome – both in the bats in the US and those in Europe.  And that research takes money. Unfortunately, the funds that were secured for this type of research by Congress in October would be stripped in the president’s new budget proposal. 

Why should the government care about funding research on bats?  Bats are predators on a number of economically important insects, including corn earworm moths, cotton bollworm moths and tobacco budworm moths, which are important agricultural pests.  A study in southwestern Texas estimated that bats contributed between $121,000 - $1,725,000 in avoided crop loss for cotton in an area of only 10,000 acres. 

We will take this message back to the government as we work to raise the important issue of white-nose syndrome and highlight the research and funding needs in the coming year.  Because when you consider the potential, combined economic cost of crop loss and increased pesticide use that could result from a country-wide loss of bats to white-nose syndrome, funding research that could help prevent or slow the loss of bats could actually be a huge money-saver. 

Image shared by Amyn Kassam via Flick'r.