In many areas of the world, rodent damage to field crops causes
severe reduction of the human food supply and increases the risks
of small-farm agriculture. In localized areas, rodents may be a
principal factor limiting crop production; more often, rodents
unobtrusively remove a share of production before harvest--crop
after crop, season after season. Although there are more than
6,000 kinds of rodents, only about 50 can be considered signifi-
cant agricultural pests.

A central difficulty in development of vertebrate damage control
technology has been a tendency to ascribe minor importance to
species and environmental differences and to attempt transfer of
results from the laboratory to field areas where different
species, crops, and environmental factors prevail. Hence, on-site
field testing is requisite to a successful program. In addition,
such an approach affords excellent opportunities for training of
local specialists who will ultimately bear the responsibility for
vertebrate damage control programs in their countries.

Losses to birds are less well documented than those to rodents.
Various species of parrots, parakeets, blackbirds, weavers, doves,
seedeaters, pheasants, and waterfowl are among the types of birds
known to cause damage in agriculture around the world. Actual
losses are difficult to assess because damage is usually concen-
trated in limited areas and, due to the mobility of birds, is
often seasonal, sporadic, and hard to predict.

Research at DWRC and in the field involves evaluation of different
control methods including chemical, physical (such as this sub-
lethal electric barrier), cultural, or other techniques which have
potential for providing positive benefits by reducing vertebrate
damage in agriculture. The species, crop, farming methods, envi-
ronmental factors, and a host of other considerations may influ-
ence the manner in which a particular problem is approached.

The Denver Wildlife Research Center is well equipped with modern
scientific instrumentation, a broad-based technical library, and
linkages to computer systems. These tools provide the capability
for research into many facets of a vertebrate damage problem.

The results of research undertaken by DWRC staff and cooperators
around the world are regularly published in scientific and tech-
nical journals, progress reports, or special publications, often
in the language of the country or countries suffering a particular
pest problem. Nearly 200 publications have resulted from the
international activities of the DWRC since inception of the
program.