Feisty House Sparrows: Why Are They So Aggressive?

House sparrows are one of the easiest birds to locate and identify. From grocery parking lots to city parks to rural farms, house sparrows have taken up residence and thrive near human establishments. 

Interestingly enough, the house sparrow is a bird we love to hate (at least here in the United States). In the birding world, mention of house sparrows often brings up disdain and even anger. What about these little birds causes such an uproar, and is it justified? 

Perhaps it has to do with their invasiveness coupled with their aggressive behavior. On the other hand, humans tend to glorify what is rare and disregard what is common. No matter your stance, it’s important to understand house sparrow behavior, including their aggression and ecological impacts. 

House Sparrow Overview 

The house sparrow (Passer domesticus), also known as the English sparrow, is one of the most common birds in the world. They are distributed across most of North America, except northern Canada and Alaska. They are native to northern Africa and Eurasia and were introduced to North America in the 1850s. 

It isn’t an exaggeration to say that everyone in the United States (and much of the world) has seen a English sparrow, whether they knew the species by name or not. Male English sparrows are easier to distinguish than the females due to their black bib, grey head, and chestnut nape. The females are light grey-brown with indistinct markings on their head and back. 

English sparrows stay close to humans and have come to depend on human influences for survival. Their common name, house sparrow, describes this relationship as they readily nest in man-made structures. This species, classified as an Old World Sparrow, has lived near humans and fed on our grains for thousands of years. As our ancestors moved, so did the house sparrow. When we settled in an area, they did too. 

Because of their close association with civilization, house sparrows avoid uninhabited areas, such as forests, grasslands, wilderness areas, and deserts. 

Invasive Status 

English sparrows were purposely introduced to the United States as a natural pest control. While they rely on insects and larvae to feed their young, the English sparrow’s diet consists mostly of grains and weed seeds. 

There also seemed to be nostalgic homesickness among the settlers that further enticed the introduction of the house sparrow. In England and other parts of Europe, this bird was (and is) a familiar sight, especially in city areas. Whereas, in the United States, the newly structured cities lacked the presence of the once-loved English sparrow. In the beginning, they were a welcome sight to the settlers. 

However, house sparrows spread rapidly and established themselves in farms and cities across North America. They are considered agricultural pests as they feed on ripening seed heads in grain fields and eat large quantities of farm animal grain. 

To add insult to injury, English sparrows fiercely defend nest sites. They aggressively push or remove native species from the area.

They also compete with native bird species for trophic resources, as they form large flocks that can dominate an area. 

Due to their invasive status, English sparrows can be legally euthanized in the United States. European starlings also share this exception.

House Sparrow Aggression 

House sparrows take the concept of “only the strongest survive” to an uncomfortable and harsh reality. Their brutal survival tactics make them highly unpopular among birders in the United States.

Both male and female English sparrows aggressively defend nest sites. If another bird species nests nearby, they will enter the nest and peck the eggs or kill the young. If an adult bird stays in the nest to defend their young, the house sparrow will also kill the adult by pecking them to death. 

English sparrows prefer to nest in cavities made by other birds, but will also nest in birdhouses and crevices in man-made structures. As such, they compete with other cavity nesters in rural and urban areas, such as eastern bluebirds, tree swallows, chickadees, and purple martins. These are the native bird species most affected by house sparrows. 

The aggressive tactics of English sparrows have contributed to the decline of eastern bluebirds. However, they should not be entirely blamed for the decrease in eastern bluebirds. Agriculture, city development, and deforestation have also played a major role in displacing native bird species.

Why Are They So Aggressive?

The aggressive behavior of English sparrows influences flock dynamics. They have a pecking order similar to chickens, and skirmishes often break out to establish dominance and rank. 

Interestingly, intersex aggression is rare, and displays of dominance are usually only between the same sex (male to male and female to female). While it isn’t common, it is not unusual for a female English sparrow to claim another sparrow’s nest and even kill her young. 

Because of these intense interactions, a male English sparrow will spend about 60% of their time perched near their nesting site to defend their territory. It appears that the male sparrows are more bonded to their nesting site than their mate. Even if their nests are removed in an attempt to dissuade the house sparrows, the male house sparrow will quickly rebuild. 

House Sparrow Nesting Problems 

Check out this house sparrow control page if you’re having issues with house sparrows nesting in your bird boxes. You’ll find information about the next box hole size, as well as passive and active house sparrow control methods. 

Should We Hate House/English Sparrows? 

It’s easy to understand why birders have such a disdain for English sparrows. This is especially true for those who have witnessed English sparrows kill native birds in their bird boxes. 

Here in the United States, most informational resources will guide you on how to “control” house sparrow populations and why they are such a “nuisance bird.” Interestingly, in other parts of the world, house sparrows are well-loved. 

Globally, English sparrow populations are declining. This has led to the creation of ‘World Sparrow Day’ to celebrate and protect house sparrows. 

It is up to you how you feel about English sparrows. I choose to see them as an opportunistic and adaptable species with harsh survival tactics. I do not think this makes them a “bad” bird, but simply one that challenges our human morality, as it should. It is also interesting to consider the response of other countries whose house sparrow populations are declining and how that may influence our American understanding of this “civilized” bird.