Aflatoxin in Bird Seed
Mixes
The following
information was prepared for the Wild Bird Feeding
Industry by Dr. David Bonter, Project Feeder Watch,
Cornell University Laboratory of Ornithology. It is
reprinted here with Dr. Bonter's
permission.
Recent posts to
birding listserves across North America have raised
concerns about the potential harmful effects of
feeding birds seeds and grains that may be
contaminated with aflatoxin. In response to
numerous requests, following are some comments on
the issue from the Cornell Lab of
Ornithology.
WHAT DO WE KNOW
ABOUT AFLATOXIN?
- Aflatoxins are
produced by fungi that are common and widespread in
nature, Aspergillus parasiticus and A.
flavus.
-The fungi grow
most rapidly in humid environments and can grow on
foods stored in damp conditions.
-Corn and peanuts
are more likely affected than other foods commonly
provided at feeders.
-Research conducted
by Dr. Scott Henke of Texas A&M University
Kingsville found that 17% of the birdseed samples
tested in Texas contained relatively large
amounts of the toxin. His research further suggests
that feeding wild birds foods contaminated with
aflatoxin can be harmful.
SHOULD WE STOP
FEEDING BIRDS BECAUSE OF THE RISKS POSED BY
AFLATOXIN?
-While research
studying the effects of aflatoxin on free-living
birds is scant, evidence suggests that it is not
necessary to abandon bird feeding altogether. Data
from Breeding Bird Surveys, Christmas Bird Counts,
and Project FeederWatch show that populations of
most species that use feeders are stable or
increasing. In fact, a number of common feeder
species have expanded their geographic range in
recent years. An estimated 40-60 million Americans
feed birds and have been doing so for decades. If
aflatoxin-contaminated seeds were negatively
affecting bird populations, we'd see downward
trends in counts of our most common feeder
visitors.
-Providing
supplemental food at feeders likely has little
effect on bird populations (positive or negative),
but the benefits to humans are immeasurable.
Feeding birds has enormous educational value,
providing humans with a window on the natural world
that is important for encouraging people to protect
the environment.
HOW CAN YOU PROTECT
BIRDS FROM AFLATOXIN AND OTHER DANGERS?
The aflatoxin issue
raises the importance of providing a safe
environment for birds. You may follow several
strategies to improve the safety and health of
birds at your feeders:
-Clean your feeders
regularly with a 10% bleach, 90% water solution.
Allow feeders to dry completely before filling with
fresh seed.
-Only provide a
limited supply of food at a time (as much as can be
consumed in a few days).
-Store seed in a
dry place to discourage growth of mold and
fungus.
-Discard any seed
that has become wet.
-Routinely rake the
ground beneath feeders to prevent the build-up of
seed hulls and fecal material that could promote
growth of bacteria and mold.
- Keep your cats
indoors! House cats kill millions of birds each
year.
- Avoid window
collisions (another source of mortality for
millions of birds in the U.S. each year). While
data are lacking about which approach is best,
streamers and silhouettes likely do not
significantly reduce window collisions. We suggest
keeping feeders greater than 30 feet from windows
(so birds are less likely to see the window as a
route through your home). Alternatively, place
feeders less than 3 feet from windows so that birds
leaving the feeders cannot gain enough momentum to
do harm if they hit the window. Consider placing
deer netting over particularly problematic
windows.
-Provide cover near
your feeders so that birds can escape from
predators.
If you are
concerned about the risks aflatoxin may pose to
birds, consider avoiding seed mixes containing corn
and peanuts, as the Aspergillus fungi are most
likely to grow on these food items.
Additional
Information from WBFI
Headquarters
Websites for More
Information on Aflatoxin and Mycotoxins
Link to Cornell
University information on Aflatoxin and Health
Risks:
http://www.ansci.cornell.edu/plants/toxicagents/aflatoxin/aflatoxin.html
Link to University
of Nebraska NebGuide on Aflatoxin and Mycogens:
http://ianrpubs.unl.edu/plantdisease/g1408.htm#top
Link to Council for
Agricultural Science and Technology Interpretive
Summary on Aflatoxin and Mycogens:
http://www.cast-science.org/cast/src/cast_top/htm
WBFI
- 1305 N. Tahoe Trail - Sioux Falls, SD 57110 -
Phone: 888-839-1237 - Fax: 605-275-6697 - E-mail:
info@wbfi.org
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