Fertilizers are commonly used in gardens and agricultural fields to help plants grow. However, some types of fertilizers can be harmful to birds if consumed. Understanding which fertilizers are potentially toxic to birds and taking steps to use them safely can help protect local bird populations.
How fertilizers can harm birds
Some chemical fertilizers contain ingredients that are highly toxic to birds, even in small amounts. Birds may eat granular fertilizer spread on lawns or fields, mistaking the granules for food or grit. They may also ingest fertilizers, pesticides, or herbicides that have made their way into water sources.
Two types of fertilizer ingredients are particularly hazardous to birds:
Nitrogen-based fertilizers
Fertilizers high in nitrogen like ammonium nitrate, ammonium sulfate, and urea are acutely toxic to birds. When ingested, the nitrogen compounds break down into ammonia. Ammonia burns and damages tissues, especially in the mouth, throat, and digestive tract. Birds that swallow high levels of nitrogen fertilizers often die within hours or days from internal chemical burns or kidney failure.
Metal salts
Some micronutrient fertilizers contain heavy metal salts like zinc, copper, nickel, cobalt, and manganese. These metals can accumulate in birds’ tissues when consumed over time. High accumulation leads to poisoning, causing problems like weak bones, suppressed growth, and damage to organs like the kidneys.
Which birds are most vulnerable?
All birds are susceptible to fertilizer poisoning. However, some types of birds are more likely to directly ingest fertilizers in significant amounts:
- Waterfowl and wading birds – These birds feed in areas where fertilizer runoff collects in ponds and wetlands. Consuming contaminated water can cause toxicity over time.
- Seedeaters – Birds like doves, quail, finches, and sparrows scavenge on the ground and could mistake fertilizer pellets for edible seeds.
- Scavengers – Crows, gulls, vultures, and chickens will opportunistically eat almost anything they find, increasing chances of accidentally ingesting fertilizers.
Young birds may also be more vulnerable than adults. Chicks have less-developed digestive systems and weaker immune defenses to deal with toxins.
Ways fertilizers harm birds indirectly
Aside from direct toxicity, fertilizers can impact birds in their habitats and food chains:
- Habitat loss – Excess fertilizers in ponds and wetlands promote algae blooms that deplete oxygen, killing fish and aquatic insects birds rely on.
- Food chain effects – Chemicals like nitrogen and metals bioaccumulate, becoming more concentrated as they move up the food chain from plants to insects to birds. Even small doses can become toxic over time.
- Reproductive issues – Metals like manganese can disrupt hormones and reproduction in birds. Possible effects include smaller eggs, lower hatching success, and developmental abnormalities.
These indirect effects make birds weaker over time and more prone to illness, starvation, and predation.
Fertilizer toxicity signs in birds
Look for these signs that birds may have been poisoned by ingesting fertilizers:
- Lethargy, weakness, unable to fly or stand
- Ruffled, unkempt feathers
- Mouth or throat irritation indicated by head shaking or gaping beak
- Vomiting or diarrhea
- Trouble breathing
- Tremors or seizures
- Sudden unexplained death of multiple birds in an area
Protecting birds from fertilizer risks
Here are some tips to use fertilizers safely around birds:
- Avoid fertilizers with ammonium nitrate, ammonium sulfate, zinc, or copper salts which are highly toxic.
- Read product labels thoroughly and follow all environmental precautions.
- Use organic natural fertilizers like compost or bone meal when possible.
- Apply only recommended fertilizer amounts – excess can easily wash into waterways.
- Rake any scattered pellets back into soil – don’t allow them to accumulate on bare ground.
- Avoid spreading fertilizer where birds are actively feeding.
- Wait until rain is forecasted to apply fertilizers, which will help wash more into soil.
- Create wildlife-friendly wetland buffer zones around ponds and streams.
Being vigilant about properly applying fertilizers, as well as providing birds safe, chemical-free habitat and food alternatives, will go a long way towards protecting backyard and migratory birds.
Conclusion
Some chemical fertilizers, especially those high in nitrogen or certain metals, are highly toxic to birds. All birds are vulnerable if they directly ingest enough fertilizer. However, birds like waterfowl and seedeaters are most at risk of consuming dangerous amounts while feeding. Carefully following application directions, choosing more natural organic options, and keeping fertilizers away from feeding areas and waterways can help reduce the risks. Staying alert to any signs of fertilizer poisoning in local birds is also important to respond quickly. With proper precautions, gardens and bird-friendly habitats can co-exist in harmony.