Q. Consider the following: Biopesticides Pesticides Mosquito Repellants Chemical Fertilizers Which among the above have significantly contributed to the decreasing population of “Birds’?
Answer: Only 2 & 4
Notes: Among the options listed, the use of pesticides and chemical fertilizers is believed to have contributed to the decreasing population of birds.

1. Pesticides: Certain pesticides, particularly organophosphates and neonicotinoids, have been linked to harmful effects on birds. These chemicals are used to control pests and insects in agriculture, but they can also have unintended consequences for non-target species like birds. Birds may ingest these pesticides directly when they consume treated seeds or insects, or indirectly when they eat contaminated prey. Pesticides can lead to decreased reproductive success, developmental abnormalities, and even mortality in bird populations.
2. Chemical Fertilizers: Chemical fertilizers, such as nitrogen and phosphorus-based fertilizers, are commonly used to enhance crop yields. However, their overuse and runoff can lead to water pollution, which can negatively impact aquatic ecosystems that birds depend on for food and habitat. Additionally, the excessive nutrient load can alter the composition of plant communities, affecting the availability of food sources for birds.

Biopesticides and mosquito repellents are generally considered to have lower impacts on birds compared to traditional chemical pesticides. Biopesticides are derived from natural sources and are designed to target specific pests while having minimal effects on non-target organisms, including birds. Similarly, mosquito repellents are typically applied directly to human skin and not to areas where birds are directly exposed.

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