"There are very few birds in this forest."
Translation:ngemvamDaq puSqu' bo'Deghmey.
In ngemvamDaq puSqu' bo'Degh the location is extra information and thus the core meaning of this sentence is, "the birds are very few", which gives us the same meaning as, "there are very few birds."
In your other sentence you need an -'e' marker on the end. In ngemvamDaq bIH bo'Degh puSqu''e' the topic is extra information. The core of this sentence is ngemvamDaq bIH which means "they are in this forest". Who is in this forest? "Very few birds, that's who". A more accurate (though more akward in English) way to translate that sentence is, "As for very few birds, they are in this forest." It makes it sound like you are looking for a particular small group of birds and identifying that this forest is where they are located.
None the less, there is overlap in the meaning and the differences are subtle, so for now I have added it as an accepted variation. I may change my mind later as I continue to consider it.
Both are valid. The second is the Englishy way to say it.
This course offers far too many "to be" sentences for translation, almost as if a native English speaker was coming up with sentences based on their native English biases. Perish the thought! Klingon focuses more on normal verbs than on "to be" sentences, and this sentence is one of the refreshing reminders that what counts as an adjective in English is a perfectly ordinary verb in Klingon.
In other words, don't go reaching for a Klingon pronoun every time you see an inflected English "be." First decide if there's a verb to cover it. If the English is "be ," then chances are there's a Klingon verb to cover it. If the English is "be ," then you'll probably need either to use a noun with a syntactic suffix or to recast the sentence entirely.
In English, it is unusual to say that something is few. Instead we like to say that there are few of something. Both are grammatical, but one is much preferred over the other in English. For Klingon it is exactly the opposite. Though both are grammatical, Klingons are much more likely to say puS vay' than vay' puS tu'lu'. Versions based on both those sentences are accepted in this exercise, but we are getting to a point in the course where we are trying to teach you not to always translate literally, but to learn how English and Klingon might express something differently.