Right, devoid of any later loanwords, this would be a ModIr version:
Mise an t-earrach a ghreadann ón ngréin
Mise an faolán a chanann don ré (
or don ghealach, but ré/gréin have a nice half-rhyme thing going)
Mise an nathair a chosnaíonn an síNote 1: "earrach" as a word for falcon didn't make it into Modern Irish. The two normal words we have are
fabhcún (< AN faukun > ModE falcon) and less accurately/often
seabhac (< OE heafoc > ModE hawk). Earrach would most likely be confused with "spring" here. Could you use
iolar "eagle" here, a pure Old Irish word?
Note 2: "ón ngréin" is using a Dative form of the word "grian", which is now mostly lost in speech/writing - if you don't want it "ón ngrian" will suffice.
Note 3: "faolán" literally means "little wolf". I've never seen "mac tíre glic", and frankly find it a little unbelievable as a term (sorry

). Little wolf is one of the alternative names Wikipedia (such a reliable source lol) supplies for coyote, hence its inclusion here.
Note 3: "dumha sí" is accepted as fairy mound, but in reality it means "mound mound" - the síthe are technically the mounds not the fairies themselves, whom are called Aos Sí "people of the mound".
Now, since I love Old Irish, here's one for you in good old Sengoídelc:
Am int errach benas ón gréin
Am in fáelén canas dond éscu (
or dond ré)
Am ind nathair con-oí a síd