"They have at least three parakeets."
Translation:Heillä on ainakin kolme undulaattia.
The core meaning is the same (implies the minimum of something), however, there's some difference in the nuance/use. Can't grasp it somehow...
Anyhow, I wouldn't say "Heillä on vähintään kolme undulaattia" if no-one is asking about their parakeets or "Minulla on vähintään kymmenen paitaa," (I have at least ten shirts/blouses), whereas "Tästä kokeesta pitää saada vähintään 30 pistettä" (You have to get at least 30 points on this test) is much better than with "ainakin", but I have no idea why. Maybe it's about certainty or a requirement?
I didn't even know what a "parakeet" was until this course, much less a "budgerigar"... Always thought pet parrots are just called pet parrots in everyday conversations unless the biological species was important.
And this despite my grandmother owning many green and blue parakeets (or волнистые попугайчики as we call them in Russian, literally "wavy parrots" — I guess both that and undulaatti come from the same Latin species name).