Fåglarna äter upp alla jordgubbar.
The birds eat all the strawberries.
Why not jordgubbarna? Wouldn't this sentence just mean "The birds eat all strawberries?"
With "alla" + noun, you can use either definite of indefinite form. Using the definite puts a little more emphasis on some specific strawberries.
Do you know how it compares to English? Are "all the strawberries" and "all strawberries" used in the same way as in Swedish?
Magnus, here's my take on this as a native speaker of American English:
"All strawberries contain fruit sugar." The statement declares that is true of every single strawberry in the world – without exception.
"All the strawberries contain fruit sugar." This is a more modest statement about a specified set of strawberries and does not pretend to be true of every strawberry in the world.
As for the Duo item, I would probably never say:
"The birds eat all strawberries."
For me, the definite article is obligatory: "The birds eat all the strawberries."
Hope that helps.
Is that really the case when "alla" actually refers to all of a subset of something (as in this case) rather actually all of something? As a native Swedish speaker I would certainly go for "Fåglarna äter upp alla jordgubbarna" and find the translation "Fåglarna äter upp alla jordgubbar" somewhat awkward.
Using a search engine to find some examples I get "Alla kanaler från Sveriges radio", where the indefinite form is used and the expression actually mean all channels and "Vi svarar gärna på alla frågor", where they actually answer all question (well at least they say they do..). On the other hand "Är alla klapparna öppnade men plomberingarna fortfarande obrutna?" use definite form and talks about a subset of all Christmas presents ("klappar"), rather than all Christmas presents (in the entire world). Similarly, the birds presumably do not eat all strawberries in existence, but "only" all the strawberries at some location.
I actually think both Fåglarna äter upp alla jordgubbarna and Fåglarna äter upp alla jordgubbar are totally fine in Swedish. There might be a slight difference in implication but it's very small. Fåglarna äter upp alla jordgubbar might imply alla jordgubbarna i jordgubbslandet but it doesn't imply 'all strawberries in existence'.
In practice, both are definitely used. Also try some sentences like: Var har du gjort av alla pengar(na)? Vem har tagit alla …? Var har du alla …? E.g. Var har du alla medaljer? implies 'all your medals', not 'all medals in existence', and if anything, I think that sounds slightly better than Var har du alla medaljerna? for the most likely scenario.
I'm only guessing, but I think the emphasis is on the birds in this case. If you wanted to stress that it's the strawberries that are being eaten, then jordgubbarna makes more sense. I think using jordgubbar like this is treating it like a mass noun, instead of a countable one, whereas fåglarna is the countable noun, that it's the birds that are eating the strawberries, not the strawberries being eaten by the birds. I hope that helps, and I also hope there's some truth to it, too. Remember, this is mere speculation.