Canada geese: They really exist, they caused a disaster, and they were cleaned up

Recently, the clothing brand "Canada Goose" was criticized and became a hot topic on the Internet. Faced with quality issues such as incorrect embroidery of trademarks, partial thread unravelling, and pungent smell of fabrics, a "replacement clause" of the brand showed that unless otherwise provided by relevant laws, all products sold in specialty stores in mainland China are not returnable.

Just yesterday, Canada Goose issued a statement saying that all products sold in its specialty stores in mainland China can be returned and refunded.

The double standard of "Canada Goose" may have affected the reputation of a kind of bird - after all, "Canada Goose" is not just a brand name, it is a real "goose"! In the animal kingdom, Canada Goose refers to the Canada Goose (Branta canadensis).

"That's me." | USFWS Mountain-Prairie

As a kind of "big goose", Canada geese are extremely powerful - especially in the event of an aircraft collision. Between 1990 and 2012, there were at least 1,403 bird strikes involving Canada geese in the civil aviation industry, and the frequency was related to the local Canada goose population. The most famous bird strike caused a loss of $60 million. This "destructive ability" even prompted New York City to launch a Canada goose cleanup plan...

In December 2016, the film "Sully" was released in China. The protagonist, played by Tom Hanks, remained calm in the face of danger and decisively handled the dangerous situation. He was the last one to leave the plane after confirming that all passengers had evacuated safely. This thrilling emergency landing was based on a real event.

Chesley Sullenberger, the real-life pilot Sully, and Tom Hanks, who played Sully | Ben Allen

On January 15, 2009, at 12:00 PM Eastern Time, an Airbus A320 aircraft with flight number AWE1549 of US Airways took off from an airport in New York State and headed for Charlotte, North Carolina. Soon after takeoff, the aircraft encountered a flock of birds, and both engines failed due to the ingestion of birds. Finally, under the pilot's guidance, the pilot and co-pilot successfully made an emergency landing on the Hudson River. All 155 people on board were rescued.

This is probably the most famous bird strike in human aviation history, also known as the "Hudson Miracle." After several investigations, it was discovered that the bird that could "shoot down" a civil airliner weighing hundreds of tons was the Canada Goose.

"What are you looking at?" | SteveStrummer / wikimedia

Find the culprit

The accident caused at least $60 million in economic losses. Fortunately, no one was killed. But the bird that collided with the plane was obviously not so lucky.

After such a serious bird strike accident, it is crucial to determine the specific type of bird strike, issue early warnings for future aviation operations, and take targeted preventive measures. To this end, researchers from the Smithsonian Institution, Washington and the US Department of Agriculture were invited to participate in the investigation.

In June 2009, researchers published a cover article in Fronties in Ecology and the Environment, a journal of the Ecological Society of America. They obtained nearly 100 tissue, feather and debris samples from the two engines, and through DNA barcoding and feather structure analysis, they pointed out that the bird that collided with flight AWE1549 was a Canada goose.

A flock of Canada geese flying by | Ken Billington / wikimedia

By further measuring the content of stable hydrogen isotopes in feather samples, the researchers also determined that the Canada geese that caused the collision came from a migratory population, rather than a resident population living in New York State.

The murderer is it

Canada geese can be seen everywhere in North America, from Alaska in the north to northern Mexico in the south. They have black heads and necks, white cheeks and throats, and a striking black-and-white contrast. Their bodies are mostly dark gray or brown.

The specific name canadensis in the scientific name comes from the place name, referring to Canada; the genus name Branta comes from Latin, which refers to a kind of goose, namely the genus Brant. Therefore, Canada geese are sometimes also called "Canada geese" | D. Gordon E. Robertson / wikimedia

In winter, populations of Canada geese living in the high latitudes of the north migrate to the south for the winter, while there are also resident populations in the mid-latitudes that do not make long-distance migrations.

Canada geese mainly feed on grasses, plant roots or aquatic plants, and often gather in large groups. They are also well adapted and have been artificially introduced to the United Kingdom, northeastern and central Europe (the nominative subspecies B. c. canadensis), and New Zealand (the subspecies B. c. maxima), forming free-living wild populations.

The "big goose" that grows against the trend

On September 20, 2019, a paper published in the American magazine Science attracted widespread attention. By evaluating the data obtained from the public science project The North American Breeding Bird Survey (BBS), researchers found that since 1970, the number of 303 breeding birds in the United States and Canada has shown a downward trend, with grassland habitat birds showing the highest decline rate, and forest bird populations declining the most. However, the study also pointed out that the number of wetland birds has grown against the trend, and the number of breeding waterfowl populations, including Canada geese, has increased by 56%.

Another study also pointed out that between 1970 and 2012, the population of Canada geese in North America increased from 1.26 million to 5.69 million, a nearly five-fold increase. These increases were mainly contributed by the resident population, whose number soared from 250,000 to 3.85 million, a 15.6-fold increase. The number of migratory populations has been relatively stable since 1990.

Canada geese in a river in Washington state, northwestern United States | Matthew S. Staben / wikimedia

At the same time, between 1990 and 2012, the civil aviation industry was aware of 1,403 bird strikes involving Canada geese, nearly half of which resulted in losses. Between 1990 and 1999, the incidence of bird strikes showed a good correspondence with the increase in the number of resident populations.

Canada geese are large in size, like to move in groups, and are often attracted by food factors in the airport and surrounding environment (especially in open grasslands). As their population increases, they are becoming a major threat to aviation safety and are also the main target of bird strike prevention at many airports.

As the Canada goose population increases, the aviation industry is also developing rapidly. The increasingly "crowded" sky means more "unexpected encounters". Data shows that the number of known bird strikes in the United States has increased sixfold in the past 20 years.

What should we do in such a situation?

It is true that they are large, with adult birds ranging from 55 to 110 cm in length and weighing 1.3 to 6.5 kg | PumpkinSky / wikimedia

Stable isotopes reveal the truth

Since it is difficult to distinguish the migratory and resident populations of Canada geese based on their appearance, and it is also difficult to distinguish them through DNA genetic evidence, scientists have come up with the idea of ​​a natural marker called stable isotope. Isotopes refer to elements with the same number of protons but different numbers of neutrons. Some isotopes of an element are radioactive, while stable isotopes are non-radioactive isotopes.

Precipitation on land changes regularly with latitude, altitude, and distance from the ocean. This change will be reflected in the plants in the corresponding area as a difference in hydrogen isotopes, and the hydrogen isotopes of the animals that eat these plants will be consistent with those in their food.

When animals migrate to another area, the isotope composition of the new food source will gradually affect the original isotope characteristics of the animal tissues as they are metabolized. However, this is a gradual process, and the original isotope characteristics will still be retained for a period of time. Therefore, by measuring the isotope composition in tissues, we can obtain information about the activity areas and migration of animals in a certain period of time.

Canada geese on a lawn with the Canadian Parliament building in the distance | Pierre5018 / wikimedia

The researchers compared the hydrogen stable isotope values ​​of samples obtained from flight AWE1549, the local resident population in New York City, and the migratory population from Labrador, Canada. The results showed that the Canada geese that hit the flight were most similar to the migratory population in Labrador, and were very different from the local resident population in New York City. Therefore, people believe that the Canada geese sucked into the engine in the "Miracle on the Hudson" came from the migratory population.

Therefore, people should adopt different bird strike prevention strategies and corresponding measures according to the different biological characteristics of migratory or resident populations.

It is worth mentioning that the samples used for monitoring in Labrador come from specimens collected by Canadian ornithologist Harold Hanson in his early years. Hanson was committed to studying the geographical variation of Canada geese, so he carried out a large number of systematic specimen collections in the northern breeding grounds and southern wintering grounds of the species. It is these collections at that time that provide valuable reference samples for solving today's problems.

Canada goose chicks | WinterE229 / wikimedia

Canada Goose Cleanup Project

As mentioned above, the number of Canada geese resident flocks has been increasing year by year. However, if we observe it over a longer historical period, we will find something different.

Canada geese have long been a migratory species in North America, and their numbers have fallen to the bottom due to uncontrolled hunting, egg collection, and habitat destruction. Until the early 1900s, records of breeding Canada geese in New York State were rare.

As people's awareness of nature conservation rises, hunting Canada geese begins to be regulated, and the establishment of protected areas provides shelter for the continuation and growth of the population. In places such as the Hudson River Valley and Long Island in New York State, some people have begun to release captive individuals into the wild. By the 1950s and 1960s, government departments also got involved, hoping to increase the number to meet the hunting needs of the people. All these factors combined have led to the growing population of Canada geese in New York State.

Canada geese in and around cities have gradually enjoyed the benefits of living around humans: fewer natural enemies, good living environments such as parks and green spaces, hunters are naturally less likely to hunt in crowded places, and enthusiastic citizens provide additional food sources. These factors have led to a higher survival rate and better reproduction in the resident population.

A family near a city construction site | Oregon Department of Transportation

On the other hand, migratory populations have to endure high mortality rates, predation by natural enemies, the impact of bad weather, and even ambushes by hunters along the way during their long journeys. This may be the reason why the resident population of Canada geese has increased rapidly, while the migratory population has remained relatively stable.

It is estimated that in 2009 there were 20,000 to 25,000 Canada geese resident in New York City; in addition, 1,238 bird strikes of Canada geese were reported between 1990 and 2009, 81% of which involved resident populations.

Therefore, after the AWE1549 flight accident, the relevant departments in New York City immediately launched a removal plan: between June 2009 and 2013, a total of 3,658 Canada geese living within 5 to 7 miles (8.05 to 11.27 kilometers) of the airport were captured alive and then sent to poultry processing plants. The meat produced was donated to people in need by charities.

The good news is that bird strikes did decrease at John F. Kennedy International Airport in New York City and LaGuardia International Airport in New York during the removal program. But that result cannot be attributed entirely to the removal of Canada geese; other bird strike prevention efforts at the airports also played a role.

Bird strike prevention should not be indiscriminate | Daniel D'Auria / flickr

Bird strike prevention is a long and arduous task

118 years ago, on December 17, 1903, the Wright brothers completed the first fully controlled flight in human history, relying on external power, with a heavier-than-air body and staying in the air without landing. The first airplane was born, and humans began to fly independently, officially entering the sky that had been occupied by flying animals represented by birds for hundreds of millions of years.

As the number of human flights increased, unexpected collisions between humans and birds soon began to occur. The first documented bird strike occurred on September 7, 1908, when a pilot named Orville Wright chased a flock of birds over Dayton, Ohio, and killed one of them. Since then, bird strikes have become an unavoidable reality in human aviation.

A helicopter colliding with a crane (above) and a fighter jet colliding with other birds | US military

As the example of Canada geese shows, looking at the existing experience of countries around the world, the primary task of preventing bird strikes (or expanding to wild animals hitting aircraft) is that different airports should take local conditions into consideration and really understand the specific species involved in local bird strikes, so as to identify the species that really pose a threat to flight safety; and on this basis, carry out targeted prevention work such as habitat transformation, expulsion, and even lethal removal. All of this depends on the solid accumulation of basic data, scientific analysis and active disposal and response on a daily basis.

As for setting up layers of bird nets on both sides of the airport runway, indiscriminately intercepting and capturing all birds regardless of size, how much effect can this have in ensuring aviation safety?

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