The use of fertilizers in gardens and lawns is common practice to promote plant health, but it introduces a potential hazard for local avian life. Homeowners often observe birds foraging on treated lawns, raising concerns that these treatments may be ingested. Ground-feeding species are naturally drawn to these areas, and while the interaction is often accidental, the chemical ingredients within these products can pose significant health risks.
Why Birds Interact with Fertilizer
Birds generally do not seek out fertilizer as food, but they often consume it inadvertently due to their foraging habits. Ground-feeding birds like robins rely on sight to locate seeds, grit, or insects in the soil and grass. Granular fertilizer pellets, especially slow-release varieties, can easily be mistaken for seeds or grit, which birds require to grind food in their gizzards.
The risk of accidental ingestion is much higher with granular formulas, which remain on the surface after application, unlike liquid fertilizers that absorb quickly. Birds may also be attracted to the treated area not by the fertilizer, but by the promise of prey. They hunt for insects and grubs near the soil surface, and if these invertebrates have been exposed to the treatment, the birds can suffer secondary poisoning.
Toxic Components and Health Risks
The danger of fertilizer to birds depends highly on its chemical composition, as basic nutrients and added pesticides present distinct threats. In standard N-P-K (Nitrogen-Phosphorus-Potassium) fertilizers, the primary danger comes from the high concentration of mineral salts, such as sodium chloride. Ingesting these salts can lead to severe salt poisoning, causing intense dehydration, digestive tract burns, and potentially resulting in renal failure.
Another serious risk comes from urea-based fertilizers, where excessive levels can result in urea intoxication. This leads to neurological symptoms such as disorientation, weakness, and seizures, while also affecting the digestive system. However, the most severe threat is posed by “weed-and-feed” products, which combine fertilizer with herbicides or insecticides.
These additives can contain highly toxic compounds like neonicotinoids, a class of systemic insecticides. Neonicotinoids are particularly harmful because they poison the entire food chain; even a single treated seed can be lethal to a small songbird. Other neurotoxic agents, such as organophosphates and carbamates, attack a bird’s nervous system, often resulting in rapid illness or death. Even organic fertilizers, while free of synthetic toxins, carry risks like pathogens or digestive blockage if consumed in large amounts.
Practical Prevention Methods
Homeowners can significantly mitigate the risk to birds by altering application methods and product choices. The most effective action is to thoroughly water in any granular fertilizer immediately after spreading it. This process dissolves the granules and washes them into the soil, drastically reducing their availability on the surface where birds forage.
Selecting the right product is also an important preventative measure. Organic options generally pose a lower toxicity risk than synthetic blends containing chemical pesticides. It is advisable to avoid combination “weed-and-feed” products entirely, as the integrated insecticides are the main source of severe neurotoxicity.
During and immediately after application, clear away any spilled or unused fertilizer, as residual product is easily accessed by wildlife. Applying fertilizer when birds are less active, such as outside of the peak spring nesting season, can also reduce exposure. If a lawn must be fertilized, using physical deterrents like temporary netting or providing alternative feeding stations can redirect birds away from the treated zone until the product is absorbed.