Whether a pet budgie or cockatoo, birds are not naturally aggressive. When they suddenly bite or shriek, they’re trying to tell you that they’re unhappy about something in their environment. In other cases, the seemingly instant behavior change can be hormonal, which is common in parrots during the breeding season. When you notice a mean attitude in your bird, it’s important to investigate what could be causing the problem. This guide looks at some of the most common reasons as to why your bird is suddenly being aggressive.
Understanding the Signs of Aggression in Pet Birds

To determine whether your bird is in fact acting out, you need to identify the signs of aggression. An aggressive bird will bite, hiss, lunge, scream, and become extremely vocal. They’re also known to puff their feathers and refuse to be handled. While these behaviors are part of aggression, they overlap with many avian health conditions, from fear and anxiety to stress and illness. Some birds display sudden aggression if they haven’t been properly tamed while young. Continuously handling these anxious birds creates stress, and eventually, they will act out by biting and screaming.
If you adopt a feathered companion that has experienced previous trauma, moving into a new environment is a stressful experience that may trigger aggression. Many cockatoo and parrot keepers encounter aggression when their bird only forms a bond with them. Parrots that bond to one person will instinctively “protect” their human as they would defend a bonded partner in the wild. As you can see, there are many reasons for birds to become belligerent.
Stress Can Make a Bird Aggressive

Some pet owners fail to understand the natural behaviors and temperaments of the birds they bring home. There are many avian species that simply don’t like being handled. The more they’re grabbed and touched, the more anxious and stressed they become. Pet birds that don’t enjoy continuous handling include canaries, some types of finches, and African ringnecks.
If you’ve recently changed the cage, moved it, or modified the layout of the room, it may trigger stress. Any disruption to their daily routine and familiarity with their environment leaves them anxious and more likely to act out. Even simple things like new sounds and altering the lighting in the room can affect sensitive birds.
To help your pet transition if you are purchasing a new cage, place the enclosure next to their existing one for a few days. Allow them to climb from their old cage into the new one, and place old toys and accessories inside the new enclosure to encourage familiarity. If you simply want to move the cage, do it gradually by introducing them to the new spot for a short period each day.
Changes in Hormones May Create Territorial Behavior

Most bird keepers report a mean attitude in their pets during breeding seasons. If your feathered friend has seemingly turned on you, determine whether it is mating season. Look for behaviors such as frequent nesting, vocalizing, territoriality, and feather plucking. Fluctuations of testosterone in males and estrogen in females can wreak havoc on avian behavior. If the behavior becomes severe, you might consider spaying or neutering your bird.
But changes in hormones are not only attributed to the breeding season. Tumors and injuries can affect the normal function of the glands responsible for regulating hormones. Birds diagnosed with diabetes and oviduct problems will experience discomfort and behavioral changes.
Look out for accompanying symptoms such as weight loss, puffed feathers, lethargy, and lack of appetite. If your bird is not eating or has diarrhea, it is important to get them to a veterinarian. Female birds that are egg-bound will have a limited time to receive life-saving treatment, so pay careful attention to your pet bird’s demeanor and physical habits.
Fear Leads to Behavioral Changes

One of the leading causes of aggressive behavior in birds is fear. Whether that is attributed to previous trauma, improper handling, or lack of socialization, fearful birds will act out. Some of the circumstances that may cause anxiety include overcrowded cages, being bullied by another bird, being teased, and changes to their environment. The introduction of new pets is also a trigger. When I introduced a new puppy to my chickens, their behavior instantly changed. Despite being safely enclosed, they clucked and lunged at the sight of the puppy. Only through gradual positive reinforcement using treats and teaching the dog to be respectful and gentle around the chickens did they calm down.
If you’ve got a new pet or someone is teasing your pet bird, it’s important to put boundaries in place to protect your avian companion. Some birds are more sensitive than others, and these types of disruptions will create fear.
When to See an Avian Vet

Birds are creatures of habit. They like routine and everything being in the same place because predictability provides security. But even small changes to their home or the onset of illnesses can quickly alter their behaviors from tame and calm to fearful and vocal. Only by carefully assessing changes in the environment or the physical condition of your pet can you understand why they’ve turned into a menace!
If you’ve recently changed their cage, introduced a new pet, or added another pet bird, you can try to improve their mood with positive reinforcement. Introduce more play time and allow them freedom outside of their cage. Start training and look at whether they’re receiving a balanced diet.
Once you’ve implemented these changes with little to no success, it’s time to see a veterinarian. Should you notice accompanying physical symptoms, it’s definitely time to make a trip to your vet.