Many people feed wildlife so they can more easily see animals. This is a common purpose of feeding quail, turkey, deer, and backyard songbirds. Some people also feed wildlife to increase the abundance or size of the animals.
Although well meaning, many of these folks are not aware of the potential harm that can be caused by foodstuffs contaminated with mycotoxins, which are toxins produced by fungi. Mycotoxins can be produced in seeds while growing, during handling and storage, and while waiting to be consumed in feeders or on the ground. Many different mycotoxins are produced by several different fungal species. Aflatoxins, produced by Aspergillus fungi, are some of the better-understood and common fungal toxins in seeds, but many other mycotoxins also exist. Stress during growth tends to encourage fungal infection, and therefore mycotoxin production. Some examples of stress during growth include drought, insect damage, and overly wet conditions. Moisture in or around seeds while stored, handled, or fed tends to encourage fungal growth and mycotoxin production.
Mycotoxins are known to negatively affect mammals, birds, and fish. Relatively high levels of some mycotoxins cause acute death, while relatively low levels appear to cause no problems. Intermediate levels can cause several relatively insidious effects, such as liver damage, cancer, anemia, tissue necrosis, immune suppression, decreased milk production, decreased egg production, reduced conception, reduced ovulation, poor fetal development, abortion, reduced feed consumption, reduced feed conversion, and gastrointestinal disturbances.
Susceptibility to various mycotoxins differs among species. For example, adult mallards are killed by levels of aflatoxin that appear to have no effect on adult bobwhite or adult white-tailed deer. However, even bobwhite and deer succumb when aflatoxin levels become high enough. Susceptibility varies with age. Young of most species are generally much more susceptible than adults.
Wildlife probably tend to be less susceptible to mycotoxin poisoning than domesticated animals because wild animals usually consume enough natural foods to dilute any mycotoxins in foods provided by humans. However, due to reduction of natural foods caused by drought, wildlife in southern Oklahoma and northern Texas probably will be attracted to and consume feed provided by humans more than usual this fall and winter. To compound the risk, some of the grain produced this year might have higher levels of mycotoxins due to drought related stresses during seed production.
People who feed wildlife should use the following good management practices to minimize mycotoxin problems.
- Only feed seeds or foodstuffs approved for livestock or human consumption. If unsure about feed quality, either have the feed tested for some locally common mycotoxins, such as aflatoxins, or do not use it.
- Make sure the moisture content of seeds or grain is relatively low, such as, no higher than 13% in corn.
- When possible, avoid placing feed on the ground. Properly designed, covered, hopperstyle feeders with covered troughs should minimize moist feed problems. If feed is placed on the ground, provide only an amount that will be consumed quickly.
- Regularly clean feeders, disposing of any old or moldy feed.
- Regularly move feed locations to minimize mycotoxin and fecal accumulation at feed sites. Many diseases and parasites are transmitted through feces.
- Keep feed dry while stored or waiting to be fed.
With proper management and precautions, feeding wildlife can be an enjoyable practice that does not harm wildlife.