Gray Catbird
Catbirds are aggressive backyard birds and their name hints a little bit about their behaviour. These birds make cat-like noises to scare off predators and other birds while they are hiding in bushes.
American Robin
American Robin can been seen in your backyard all year round. They usually puff up their red breast and signing loudly. The common aggressive behaviours of the American Robin are posturing and signing to protect their territory.
Blue Jay
Though Blue Jay looks sweet, but they are one of the most aggressive birds. Blue Jays can even mimic the call of intimidating birds such as hawks to scare off other birds.
Starlings
One of the bird species that most bird observers dislike is the starling. They are the sky rats of the birding world, according to some people. Sarlings have a tendency scare native species in the area.
House sparrow
These little songbirds are invasive species, just like starlings, and they harm native bird species. Similar to this, they plunder food supplies, damage eggs, steal nesting places, and even attack or kill other birds.
Crows
They have a reputation for being aggressive birds and you will them carry out mobbing behaviour which includes squawking and dive-bombing attacks.
Brown-headed cowbird
Actually, they are referred to as parasitic birds. In other words, they lay their eggs in other bird species' nests. Eating eggs and murdering baby birds in bird nests to replace them with their own is their primary cause of aggressiveness.