Assessing the value of feathered workers
Birds perform a multitude of services that contribute to our well-being
Published: June 24, 2011
What are birds worth? A few species cause economic damage — they harm
crops, property, or livestock; they disperse weed seeds; they make
noise and leave droppings — but considered at the ecosystem level, the
services provided by birds are overwhelmingly positive.
According to an article in a recent issue of The Auk,
the journal of the American Ornithologists’ Union, birds deliver food;
they offer inspiration for art and music and recreational opportunities
through birdwatching; they control pests and remove carcasses; and they
pollinate, disperse seeds, cycle nutrients, and perform other essential
services. Much science needs to be done to assign dollar values to all
such services, yet the authors cite several eye-opening case studies:
• Experiments in Jamaica showed that insect-eating birds boosted income by $310 per hectare per year on a mid-elevation farm.
Scientists in Stockholm, home to one of the largest oak forests in
Europe, estimated the cost of replacing the acorn-dispersal services of
just one pair of Eurasian Jays at about $4,035 if acorns were seeded
and about $22,560 if saplings were planted.
• In the U.S., the
Forest Service is planting whitebark pine seedlings to replace trees
lost to blister rust and outbreaks of native pine beetles. The cost of
the restoration — a minimum of $2,190 per hectare — represents the
value of seed-dispersal services performed by Clark’s Nutcrackers.
And when populations of three species of vulture crashed in India,
numbers of feral dogs and other scavengers skyrocketed and diseases
spread to humans and domestic livestock. Health costs attributable to
the loss of the vultures’ services totaled a staggering $34 billion
between 1993 and 2006.
“We know that birds are important
ecologically,” the authors write. “The challenge is to quantify that
importance in terms that are currently meaningful to humans.”