Birds and Human Industry: A Silent Contest Across Farms and Infrastructure

There are roughly 10,000 bird species worldwide, of which China alone hosts over 1,400 – one of the richest avian diversities on the planet. Yet as bird populations rebound thanks to improved ecology, conflicts between avian activity and human production are escalating. From paddy fields to substations, from orchards to airport runways, different bird species threaten human enterprises in distinct and often surprising ways. Understanding which birds are involved, how they behave, and why they cause damage is the essential first step in recognising the scale of the challenge.

---

I. Agriculture: Who Is Eating Our Harvest?

Agricultural bird damage is a global problem. Approximately 1,200 bird species across 20 families are known to affect crops, and about 2% of these cause significant economic losses. These pest birds strike at different growth stages – from sowing to ripening – and their methods vary widely.

(a) Cereals and field crops

In cereal‑growing regions, the Eurasian tree sparrow (Passer montanus) and the white‑rumped munia (Lonchura striata) are common wheat pests. Sparrows, when food is scarce in early spring, peck at fruit blossoms, sometimes reducing yields in home orchards to zero. In Indonesia, attacks by house sparrows and related species on rice have been reported to cut yields by 30‑50%.

In sub‑Saharan Africa, the red‑billed quelea (Quelea quelea) is arguably the most destructive agricultural pest bird. A single quelea eats about 10 grams of grain per day; a flock of two million birds can consume 20 tonnes daily. The FAO estimates that queleas cause up to $88 million in crop losses every year across Africa.

In northern China, spring‑sown maize often falls victim to pheasants, magpies and crows, which peck through plastic mulch and pull out newly germinated seeds or seedlings. Peanuts suffer the same fate. In Xinjiang, researchers have recorded 49 bird species across 19 families and 10 orders that damage crops – including corn, wheat, rice, grapes, dates, sunflowers and oilseed rape.

(b) Orchards and cash crops

Orchards are among the worst‑hit areas. Over 20 bird species regularly frequent northern Chinese fruit farms, with magpies, sparrows and crows being the most common. In Beijing cherry orchards, the main culprits are magpies, azure‑winged magpies and tree sparrows. Apple orchards in the north face a multispecies threat from magpies, azure‑winged magpies, great tits, hawfinches, sparrows and light‑vented bulbuls.

The magpie is widely regarded as the most “intelligent” orchard pest. According to Beijing fruit growers, magpies learn human schedules, invade orchards only at dawn and dusk when no one is watching, and even display “vengeful” behaviour – pecking a single bite out of every fruit when they feel harassed. Azure‑winged magpies are equally notorious; one grower compared them to “the Monkey King wreaking havoc at the Peach Banquet” – fruit they peck rots within days.

In southern China, light‑vented bulbuls and Japanese white‑eyes are the most common orchard visitors, with bulbuls causing the greatest damage. For grapes, the damaging species shift with latitude: in the south, tits and bulbuls; in the north, sparrows and azure‑winged magpies. In Sichuan pear‑growing areas, the main offenders include azure‑winged magpies, magpies, crows and feral pigeons.

North America faces similar challenges. Red‑winged blackbirds (Agelaius phoeniceus), common grackles (Quiscalus quiscula) and yellow‑headed blackbirds (Xanthocephalus xanthocephalus) are the top sunflower pests. Blackbird damage to sunflowers costs US growers over $15 million annually, with another $15‑25 million lost to mature corn.

(c) Aquaculture

In fish and shrimp farming, herons, cormorants, gulls, ducks, geese and kingfishers are the primary avian threats. Great cormorants are particularly destructive because they forage in flocks, ranging from a few individuals to several hundred, emptying ponds in a matter of hours.

---

II. Power Infrastructure: Hidden Hazards Overhead

Bird‑related faults are now the third leading cause of unplanned power outages – behind only lightning strikes and external damage. Birds of different sizes threaten the grid in fundamentally different ways.

(a) Nesting behaviour

Spring is peak nesting season on transmission towers. Magpies, crows and spotted doves are especially fond of building nests on high‑voltage pylons. The twigs, wire fragments, weeds and other materials they carry back – many of which are conductive or semi‑conductive – can easily bridge live parts and grounded components. Even a single branch lying across two wires may trigger a trip if clearance distances are compromised.

Not all birds on towers pose equal danger. As Dr. Li Ning, a migratory bird researcher at Nanjing Forestry University, notes: “Small birds like magpies and sparrows are generally not a threat to power lines, but large migratory birds – especially herons and egrets – are much more hazardous.”

(b) Guano contamination

The droppings of large birds are another major concern. Grey herons, great egrets and night herons produce faeces rich in uric acid, which is highly conductive. When deposited on porcelain insulators, the waste reduces insulation performance and triggers flashovers – surface discharges that can cause line trips. In February 2006, a 500‑kV line in Yangzhou, Jiangsu, tripped due to a flashover; subsequent investigation traced the cause to droppings from little egrets.

(c) Body‑span short circuits

Large birds – such as Oriental storks (Ciconiiformes), northern goshawks and golden eagles (Accipitriformes) – have wingspans that can simultaneously touch two different phase conductors or a conductor and an earthed structure, creating an instantaneous short circuit. In Hunan Province, researchers identified 13 bird species that are most frequently implicated in grid faults, out of the province’s 463 recorded species.

Jiangsu Electric Power Company has produced China’s first “grid bird activity and fault distribution map”, which systematically analyses 11 years of bird‑related incidents and zones transmission corridors into four risk levels. Behind this map lies a growing reality: as the environment improves, more birds are choosing high, sturdy pylons as their preferred nesting sites.

(d) Electrocution and collision

In Nepal, black kites (Milvus migrans) and house crows (Corvus splendens) are the species most often electrocuted, while collisions are more common among Himalayan swifts (Apus nipalensis) and common mynas (Acridotheres tristis). Rock pigeons (Columba livia) are also frequently killed by electrocution. Globally, power infrastructure has been confirmed to contribute to population declines in 14 threatened bird species, including the critically endangered great Indian bustard (Ardeotis nigriceps).

---

III. Aviation Safety: An Unbearable Weight in the Sky

Bird strikes are a persistent challenge for global aviation. According to US Federal Aviation Administration (FAA) data, 88 aircraft were lost to bird strikes between 1990 and 2024. In the United States alone, annual losses from bird and bat strikes are estimated at $400 million; for commercial aviation worldwide, the figure reaches $1.2 billion.

(a) Species diversity in strikes

In 2024, 410 bird species were recorded as striking civilian aircraft in the US. From 1990 to 2023, 651 species were confirmed to have been involved in strikes, of which 331 were reported to have caused damage.

Hawks, eagles and vultures account for the highest proportion of strikes (28%), followed by passerines (27%) and shorebirds (18%). Turkey vultures, hawks and New World vultures are responsible for 14.6% of strikes involving piston‑engine aircraft.

(b) The decisive role of body mass

The severity of strike damage correlates strongly with bird size – each additional 100 grams of body weight increases the probability of damage by 1.27%. Gulls and waterfowl (ducks, geese, swans) are especially dangerous due to their bulk. In August 2019, a Ural Airlines A321 struck a flock of gulls shortly after take‑off from Moscow, causing dual‑engine failure and an emergency landing in a cornfield. In 1960, Eastern Air Lines Flight 375 crashed after hitting a flock of European starlings (each weighing about 80 grams), killing 62 people.

(c) Bird congregations around airports

The ecological environment around airports often attracts large numbers of birds. Pigeons, gulls and waterfowl – species that have adapted to human‑modified landscapes – are high‑risk strike species because they forage near runways and waste dumps. Fiji Airways once grounded four Boeing 737 aircraft due to bird‑strike damage, with estimated losses of $19.2 million. Nigerian airlines lose at least 20 billion naira (approximately $15 million) annually to bird strikes.

---

IV. Closing Perspective

From sparrows nibbling grain in the field, to magpies building nests atop high‑voltage towers, to ducks colliding with aircraft at 10,000 metres – the impact of birds on human society extends far beyond the idyllic image of “birdsong and blossoms”. Different species intersect with human industry in completely different ways: some feed directly on crops, some disrupt infrastructure through nesting, and others meet high‑speed machines during migration.

It is worth noting that the label “pest” is inherently relative – the same species can be beneficial or harmful depending on time, place and context. Of the roughly 1,200 bird species globally that can affect agriculture, only a small minority cause serious economic losses. Understanding their identities, distributions and behaviours is not about simplistically branding a species as “harmful”; it is about building a more rational, nuanced appreciation of the complex and ever‑shifting relationship between humans and nature.