"Er schaut den Vögeln zu."
Übersetzung:He watches the birds.
I had that answer as well but it was not accepted. I reported it on 14-09-2015
Es wurde nicht akzeptiert, weil "Er schaut den Vögeln zu." eben "He watches the birds." bedeutet und nicht "He looks at the birds." (das wäre eher so etwas wie "Er betrachtet die Vögel.", "Er sieht (sich) die Vögel an." oder "Er schaut auf die Vögel.").
It wasn't accepted because it isn't a correct translation.
In English the difference between looking and watching is very small. Also google translate gives "looking" as the prefered translation for "schauen" https://translate.google.nl/#de/en/schauen
And watching is translated by google to: Aufpassen. https://translate.google.nl/#en/de/watching
Don't trust Google too much, it will usually only give you one translation without regard for context (at least it seems that way judging by your examples).
"Schauen" can be translated to "(to) look" (see how Google picks a not very general context for no real reason?), but in Duolingo's German sentence the verb is a form of "zuschauen". Don't overlook those little seperable prefixes!
However, as far as I know there still is a difference between "(to) look (at, on, ...)" and "(to) watch", namely that "(to) watch" (in this context) means "(to) look for a (longer) period of time", while "(to) look" can describe an action at a single point in time (feel free to correct me if this is inaccurate). I'd say that the difference between "zuschauen" and "schauen / sehen (auf, zu ...)" is similar in this context.
Lastly, "(to) watch (out)" can indeed be translated to "aufpassen", but only in entirely different contexts (e.g "Watch out!" - "Pass auf!" or "Could you watch the children for a minute?" - "Könntest du kurz auf die Kinder aufpassen?").
@FreekVerkerk "It is good not to trust other people too much":
"Zuschauen" is definitely more like "(to) watch", in particular watching people, animals or just some event in general (however, for watching television, a movie or a sports game and so on we'd just use "schauen / sehen", which can describe both a single action and refer to a longer activity). In this case I would imagine "him" sitting on a bench in a park or somewhere and really watching the birds for some time. "Schauen + zu (or auf)" (which should not be confused with "zuschauen" even though it's easy to for learners) is moslty short in my opinion ("Er schaut zu den Vögeln." - "He looks at / over to the birds.").
The word "Vogel (m)" does not describe a woman in German, but it can mean "idiot" (e.g. "Du bist so ein Vogel, ey!" - "Man, you're such a tit!").
No, I'm not a moderator. I think you can usually recognise them by a coloured ring around their avatar, at the very least on the forums they moderate.
It is good not to trust other people too much, you are correct jjd1123 :) I can agree with you that 'looking" is something short and "watching" takes more time. Like the German: "auspassen". You look at a woman (for a moment, and you watch television (for hours). Ok, that is the English part. But that should be a translation of the German sentence. "Er schaut den vogel zu" Is that more like "looking to a woman for a minute" (max) or "watching television" for hours? Birds watching, indeed some people can watch birds for hours, but for me it has more similarity with watching a woman (also called a bird in slang English) . Are you a moderator here?
Bei der Übersetzungshilfe ist "schaut .. zu " explizit mit "looks on bzw. ist looking on" angegeben!!!
"(To) look on" für sich alleine heißt "zuschauen", ohne Objekt (z. B. bei einem Spiel oder generell einem Ereignis). Wenn man etwas oder jemandem zuschaut, wäre das auf Englisch eher "(to) watch sth. or so.". "He looks at the birds." wäre auf Englisch korrekt, hieße aber eher "Er schaut / sieht die Vögel an." oder "Er schaut / sieht zu den Vögeln." etc.
Wenn sich jemand das Verhalten ansieht (genauer hinsieht) und weniger zuschaut, wäre ebenfalls to look at korrekt, oder?