Why Are Japanese Crows So Big?

Crow size depends on the species and the environment they live because different species have varying sizes and body weights. They are native to many countries like Japan and adapt their diet and habitats according to environmental conditions and circumstances.

Why Are Japanese Crows So Big? Japanese crows are usually big because more food sources are available, fewer predators and hunting risks, better genetics, environmental factors, and less competition for resources. Large-billed or Jungle crows are found in Japan and have a longer lifespan than other crows.

Japanese crows are considered larger than many other bird species in different regions because of their physical appearance and weight.

Why are crows so big in Japan?

Crows in Japan are big in size and weight for many reasons. Last year, I visited Japan and noticed big crows compared to the birds in many states of America. Some significant reasons for their larger size are listed here.

More food availability

Japan is a highly developed country with increased urbanization, diversity, and population, which causes more food resources for crows and other birds because these birds can forage food in different places.

The trash cans in Japan are more exposed and not covered with lids, which causes an increase in food availability for these birds. They eat more and have a larger size than other birds.

Better food resources affect their health and size, and it is one of the main reasons for big crows in Japan. They get the nutrients, fats, carbohydrates, and proteins for better growth.

More food sources cause them to eat more and increase their weight compared to birds in other countries or forests where adequate food sources are not available.

They can use their beaks and feet to tear the garbage bags and other food items, as they are intelligent and use cognitive and problem-solving techniques to survive.

Fewer Predators

More predation causes a decrease in their numbers, and they die before reaching adulthood and full size. They face less predation, and there are not many predators of these birds in this country, which helps them reach adulthood and maintain their body weight and size.

Moreover, they are present in large numbers in Japan, and they face predators in group forms, which also adds benefits to dealing with invaders and protecting themselves and their habitat.

The pressure from predators can also affect their growth; therefore, they cannot thrive longer in such places. They do not face much stress from predators, which causes increased body size.


Genetic factors also affect the size of the bird, as some crows have genetically small sizes compared to other birds, no matter how much they eat and where they live.

For example, American crows are genetically bigger in size and weight than carrion crows. Genetic information is passed down from parents to babies as the growth and size vary with their genes.

Crows in Japan are genetically larger than other species in many countries and regions. The genes in these birds affect their beak size, feathers, and tail length, which causes the birds to look big and heavy.

The sizes can vary within the same species, as it is not essential all crows of the same species must have similar body weight and size because other factors affect the growth and size of these birds in different countries. 

Suitable environmental conditions

Environmental factors can affect the body size and weight of different birds, as they have better growth and larger size in a stress-free atmosphere.

The stressful and challenging environment causes the bird to face several problems, and it cannot grow to its full size. The habitat conditions, weather situations, and nesting opportunities are better in Japan, which helps these birds to have big sizes and healthy growth.

There are favorable living conditions for crows in Japan, which is one of the reasons to have a larger size. The circumstances in different regions severely affect the growth and size of these birds, and they cannot survive longer if there is an abrupt change in weather.

Japanese crows do not face such situations; they have healthy, sharp, and intelligent minds and grow to full size in suitable environmental conditions.

Less competition for resources

More competition for basic resources can affect the growth and size of many birds because they need adequate food and safe shelters to grow and forage food for their babies.

Japanese crows do not face much competition for survival resources, such as food, nests, and climate, which results in bigger bodies and healthy weight.

There are more nesting options, diverse food resources, and fewer predator attacks, which causes larger size and more energy in these birds.

The birds with high competition for nesting or habitat areas and other resources remain worried, affecting their growth and genes. The availability of suitable living resources and less competition caused an increased population of crows in Japan. 

Are crows a problem in Japan?

There are many crows in Japan, and they create various problems due to their overpopulation in certain areas. They cause damage to agricultural lands in Japan, such as wheat, rice, peanuts, maize, and many other crops.

Murders of crows can attack a crop field and cause destruction within a few days. Moreover, their movement toward urban areas because of more food sources creates problems for the citizens, as they search the garbage and trash cans and cause a mess around this area.

They build nests in urban areas, such as on trees, window ledges, yards, and other places, and create noise and disturbance for humans.

Their interaction with humans can also cause problems, such as these birds can snatch food and other items from people and irritate them in different ways.

The city management and authorities implement various rules and strategies to restrict these birds and deter them from damaging the properties and fields. However, direct killing, trapping, and relocation are not allowed without a license and permit. 

Which crow species are found in Japan?

Large-billed or Jungle crows are found in Japan with some other crow species, but the large size is associated with jungle crows.

These crows are found in Asia and Japan, as you can find them in the jungles of South Asia and different cities in Japan.

They have large beaks and bigger body structure than many other bird species, which make people think they are big and heavy in weight.

They use their long, sharp beaks to dig holes, bury food, and strike garbage bags to get food. Jungle and Carrion crows are called Karasu in Japan, and different birds migrate toward this country in winter when food resources are limited.

How long do Japanese crows live?

The large-billed or Jungle crows can live long, such as 18-20 years, because they have better food sources, a stress-free and less challenging environment, and fewer predation risks.

However, the average lifespan of Japanese crows can range between 8-12 years if they migrate from other regions because it becomes difficult for these birds to survive if they face severe habitat and climate change.

The lifespan of these birds is estimated from different experiments. Therefore, it can vary within the species, environmental conditions, diseases, and predators in the specific area.

Some Japanese crows can live more than 20 years if they are habitual to their environment and there is no disease or food scarcity around their nesting areas. 

What do crows represent in Japanese culture?

Many cultures have different beliefs related to these birds such as some people believe crows represent bad luck, death, and poor health, while others think they are lucky and bring happy changes in life.

In Japanese culture, crows represent gratitude, good luck, and guidance. They believe these birds are messengers of God and connect them with spirituality.

In some Japanese cultures, people believe that the nest of these birds around their house will bring good luck and protect them from death and omens.

Different stories and myths are famous about crows in Japan, but there is no factual report from scientists regarding these myths and stories.

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