Thistle seed, often sold as Nyjer seed, is a favorite of finches, but feeding birds often raises concerns about attracting rodents. Rats will consume thistle seed, but whether they target it depends on factors like availability and the presence of other food sources. Understanding the dietary nature of common rat species and how they access food is the first step toward effective mitigation. This article explores the relationship between rats and thistle seed and provides practical advice for minimizing rodent attraction while continuing to feed birds.
Rat Consumption of Thistle Seed
Rats will consume thistle seed, also known as Nyjer, but it is generally not their preferred food source when other options are available. Nyjer is a tiny, black seed high in oil content, which can make it calorically attractive to a wide range of animals. However, because the seed is so small and typically contained within specialized feeders with tiny ports, it presents a challenge for larger mammals to access directly.
The primary issue arises when the seed is spilled or scattered onto the ground beneath the feeder, making it readily available. In an environment where food is scarce, rats will readily consume spilled Nyjer seed. The physical properties of the seed, not the taste, are what typically make it less of a target compared to larger, easier-to-handle seeds like sunflower or cracked corn.
General Rat Dietary Habits
Rats are highly adaptable omnivores, consuming both plant and animal matter based on what is most easily accessible. They thrive in human environments by subsisting on a wide variety of discarded food items, including grains, fruits, vegetables, meat scraps, and garbage. This opportunistic nature means that if a high-calorie food source, such as seed, is present, they will exploit it.
The two main commensal species, the Norway rat (Rattus norvegicus) and the Roof rat (Rattus rattus), exhibit subtle dietary differences. Norway rats tend to prefer cereals, meats, and garbage, and they are ground-dwellers. Roof rats are more agile climbers and often favor seeds, nuts, fruits, and vegetation, making them slightly more inclined to seek out elevated sources of seed. Both species, however, will eat virtually anything, including bird seed, if it offers sufficient nutrition and is easy to obtain.
Identifying Sources of Seed Access
The presence of rats near a thistle feeder is almost always a sign that spilled seed is accumulating on the ground below. Birds feeding on Nyjer seed are often messy and inadvertently knock seed out of the feeder ports or discard shells, creating a pile of food on the patio or lawn. This ground spillage is the single greatest factor attracting rodents to bird feeding areas.
Rats are excellent climbers, but they are more likely to target this easily accessible food on the ground, especially at night when they are most active. Beyond the feeder area, unsecured bird seed storage containers also represent a significant and concentrated food source. Rats can chew through plastic bags and thin plastic containers to access the bounty of seed, which they will then cache or consume on-site.
Methods for Deterring Rats
The most effective strategy for deterring rats centers on eliminating easy access to food on the ground. Regularly cleaning up all spilled seed, hulls, and debris beneath the feeding station removes the primary attraction for rodents. Daily sanitation is a powerful measure to discourage rats from establishing a foraging pattern in the area.
Modifying the feeding setup can further reduce spillage. Using specialized Nyjer feeders, which have small ports that limit the amount of seed dispensed, can minimize waste. Adding a seed tray or catch basin beneath the feeder pole can collect dropped seeds before they hit the ground, and this tray should be emptied nightly.
Feeder placement is another important consideration, as rats are known to climb structures to access food. Feeders should be positioned on a smooth pole equipped with a cone or dome baffle, which physically prevents rats from climbing up to the seed. The pole should also be located at least 8 to 10 feet away from any structure, fence, or tree branch, which rats could use as a jump-off point to bypass the baffle.
Finally, for persistent issues, consider using bird seed products that naturally deter mammals. Bird seed treated with capsaicin, the compound that makes chili peppers spicy, is an option because birds lack the biological receptors that register the heat, while mammals, including rats, find it highly distasteful. Storing all bulk seed in thick metal containers with tight-fitting lids is also necessary to prevent rats from accessing the supply before it even reaches the feeder.