What is wildlife strike

Wildlife strike refers to a collision between an aircraft in flight or moving on the ground and one or more wild animals. Although the term encompasses any species — mammals such as hares, foxes and rabbits, and occasionally reptiles such as tortoises — birds account for approximately 95% of all recorded events. For this reason, the phenomenon is also commonly referred to as bird strike.

Wildlife strike has accompanied the history of aviation from its very beginnings: since humans first took to the air, aircraft and wildlife have shared the same environment, with outcomes ranging from negligible consequences to catastrophic accidents.

 

The physics of impact

The severity of a wildlife strike depends essentially on three factors: the mass of the animal (or animals, in the case of flocks), the speed of the aircraft, and the part struck. The kinetic energy released on impact is proportional to the mass and the square of the velocity, according to the well-known formula E=½mv².

To illustrate the scale: a European Herring Gull (Larus argentatus) weighing approximately one kilogram, struck by an aircraft travelling at 300 km/h, generates an impact energy equivalent to a 100 kg weight in free fall from a height of 10 metres. If the impact involves the engines, bird ingestion can seriously impair their operation, potentially causing shutdown — a particularly critical eventuality during take-off and landing, when the margin for manoeuvre is minimal.

 

When and where strikes occur

The large majority of strikes — approximately 75% according to ICAO data — occur within the aerodrome or in its immediate vicinity, during the take-off, approach and landing phases. Similarly, more than 90% of events occur below 3,500 feet above ground level according to ICAO data, confirming the critical nature of low-altitude operations.

75%
Strikes at or near the aerodrome (ICAO)
>90%
Below 3,500 ft AGL (ICAO)

From a seasonal perspective, the period of highest risk coincides with the months of May through August, when two factors combine: the intensification of spring migratory movements and the presence of inexperienced fledglings. Within the daily cycle, the most critical moments are dawn and dusk, when many species are most active in their movements.

 

The situation in Italy

Italy has ecological and geographical characteristics that make the wildlife strike phenomenon particularly significant. The country hosts more than 550 bird species, approximately 270 of which breed regularly, ranking Italy among the richest in avian biodiversity in Europe. This richness is attributable to the country’s geographical position — a natural bridge between Europe and Africa — and to the variety of habitats present: coastlines, wetlands, agricultural plains, hills and mountains.

In addition to this resident avifauna, Italy plays a crucial role as a migratory corridor. Every year approximately 2.1 billion Passeriformes and related species cross the Mediterranean twice — in spring and in autumn — together with large-bodied birds such as storks (Ciconia ciconia), wild geese, herons and numerous raptor species. This massive flow inevitably traverses Italian airspace, increasing the risk of collisions.

 

The global dimension of the problem

Wildlife strike is not an exclusively Italian problem. Worldwide, from 1912 to the present, collisions with wildlife have caused approximately 1,000 fatalities and the destruction of more than 750 aircraft, according to the database maintained by Avisure and Richard Dolbeer. In the United States alone, more than 20,000 strikes are reported annually, although fewer than 5% cause actual aircraft damage.

These figures, while significant, likely represent an underestimate: many minor strikes go unreported, and in more than half of cases the species involved is not identified. It is precisely to address this gap that taxonomic identification of biological remains assumes fundamental importance.

 

Why species identification matters

Identification at species level — not merely at group level such as “gull” or “raptor” — is a key element of effective risk management. Knowing exactly which species are involved in strikes makes it possible to:

  • Habitat management: design targeted environmental management measures to reduce the attractiveness of aerodromes to the most problematic species, acting on vegetation, food resources, and nesting or roosting sites.
  • Risk modelling (Bird Avoidance Model): build predictive models based on historical time series to anticipate the periods, times of day and flight paths posing the greatest risk for each species.
  • Aeronautical design: define resistance standards for engines, windscreens and other critical components based on the mean body mass of species actually involved in strikes.

⚠️ NOTE: In Italy, more than 50% of strikes still involve unidentified species. To address this shortcoming, the Italian Birdstrike Identification Center (I.B.I.C.) has been established — a specialised scientific laboratory operating under a convention between ENAC and the Department of Earth Sciences of the University of Turin — with the aim of identifying approximately 90% of submitted samples to species level.