Augury is the practice of reading a bird's appearance, flight patterns, or population numbers in an effort to portend future events. These events can't portray anything specific, such as the exact timing of an occurrence, but they can offer you insight on what's to come through their various omens.
Many signs you will come to discover online are blatantly misinterpreted, such as a crow being an omen of death. Much like a black cat symbolizing bad luck, this merely is old superstition from the days of Salem. In omens, color association is not always an accurate way of determining a sign to be positive or negative, so please try to dispel any previous notion of an omen's simplicity.
Augury is a practice that mostly relies on intuition, but there are common associations across different cultures that will reflect the following meanings in different species of bird.
Buzzard: Obstacles, Difficulties
Crows/Ravens: Truth, Good passage, Protection
Dove: Love, Happiness
Eagle: Power, Might
Goose (if calling): Danger
*Geese naturally migrate every season so you will undoubtedly hear their calls. The omen of danger is not necessarily pertaining to you as it is the upcoming winter months. The same can apply with any other omen, so do not be worried every time you see a group fly of geese over you. An individual goose calling from the neck of the woods would be a more accurate representation of a negative sign than a typical migration.*
Hawks: Good luck, Noble path
Hummingbird: Achieving impossibility, Lightheartedness
Magpie: Bad luck, Death
If more than one: Good luck
Owls: Wisdom, Prophecy, Bad fortune, Death (especially if seen over a home)
Pigeon (White): Impending engagement
Quail: Good fortune
Robin: Good fortune if outside your home
Rooster: Good luck if heard while thinking of a crush
Seagull: Happy travels
Stork: Good fortune, but always listen for calls of distress
Swallow: Renewal, Revival
Wagtail: Good luck
Wren: Good fortune
Bird following you: Guardianship, Protection
Bird flying into home: Bad luck
Bird flying into window: Obstacles
More than one bird flying into a window: Danger (this is more from personal experience than anything official, but it could mean something unflattering is living in your home, as it did with me)
Basic Numerology comprehension can also play a role in Augury, as there may be multiple birds of the same species in a given area. A pair of birds like cardinals could hint at a romantic message, while a solitary bird could reflect a more personal message. If there is a surplus of birds, perhaps it is sending a message of social or societal circumstance.
Flight patterns also play an active role in Augury. The four cardinal directions each list the basic associations in which your message may consist of. However, this may require the use of a compass if you do not know a layout offhandedly.
North: strength, earth, vitality
East: intellect, air, learning
South: passion, fire, motivation
West: intuition, water, emotion
To discern a message from a naturally occurring event or migration, try to observe for abnormal bird behavior. This may appear through calls of alarm or an unnatural silence in a typically busy area. You may also notice an unusual bird species in a place where they are not commonly spotted. These are all basic examples of what to look for since these bird behaviors are outside of the typical eating, nesting, and breeding mentality.
You could similarly take a deeper look into Augury by observing shape formation, left-to-right flight pattern shifts and forward-to-backward flight pattern shifts.
Ultimately, one shouldn't worry about seeing a bad omen as much as they should be cautious of what happens next. If one willingly looks into the possibilities of the future, they mustn't come to fear it. No future is set in stone, and has the opportunity to change with every new step taken. With that said, I hope this article helps provide insight on a less commonly used method of divination.