"They are chickens."
'Sono polli' and 'sono i polli' are both accepted... Are there any rules for the use of articles in Italian? It seems a bit random to me. (Edit: ) In another question, 'Io ho i panini' has only 'I have the sandwiches' as a valid answer; I cannot see why in the present question the article is optional and in 'io ho i panini' it is not...
Thanks for your answer, it does make it more clear. Pity that Duolingo has this inconsistency though...
(io) sono – I am
(noi) siamo – we are
(tu) sei – you (singular) are
(Voi) siete – you (all) are
(Loro) sono – they are
Remember that Pronouns (io, tu, lui, lei, noi, voi, loro) are not always needed in Italian, they are used to add extra emphasis or contrast. If you were to strictly use Pronouns in every sentence and for everything you say, you will sound funny to native Italian speakers.
Also note that sono can mean different things, it all depends on the context!
Duolingo's sets of answers are not always complete, you should 'report a problem' and then note 'my answer should be accepted'. On a side note: strictly speaking, 'gallina' means 'hen' not 'chicken', maybe that is why it is marked as wrong.
"sono" is the verb "essere" which in english is the verb "be" (i am-> io sono etc.) "esse" is another form of "loro", which i think is used when we refer to objects and it is used rarely. When we refer to objects, usually we do not use anythhing, but the verb e.g. sono bicchieri
(i have been learning here italian for about a month, i hope i am not wrong :) )