Gaudēbant vulturēs, cum cernerent leōnem pugnantem cum aprō, et sē victum atque occīsum dēpastūrōs esse spērābant. Cum autem vīdissent, illōs omissō certāmine pācem et foedus facere, falsī spē dēplōrābant vānam expectātiōnem suam.
SOURCE: This comes from the Latin translation that accompanies Camerarius's edition of the Aesopic corpus; the 1571 edition of Camerarius's Aesop is available at GoogleBooks. This is fable 148 in Camerarius; for other versions, see Perry 338.
READ OUT LOUD. Choose which marked text you prefer to practice with - macrons (above) or accent marks (below) - and read the text out loud until you feel comfortable and confident. Then, try reading the unmarked text at the very bottom. It should be easy for you after practicing with the marked texts. :-)
ACCENT MARKS. Here is the text with accent marks, plus some color-coding for the words of three or more syllables (blue: penultimate stress; red: antepenultimate stress):
Gaudébant vúltures, cum cérnerent leónem pugnántem cum apro, et se victum atque occísum depastúros esse sperábant. Cum autem vidíssent, illos omísso certámine pacem et foedus fácere, falsi spe deplorábant vanam expectatiónem suam.
UNMARKED TEXT. Here is the unmarked text - after practicing with the marked text that you prefer, you should not have any trouble with the unmarked text:
Gaudebant vultures,
cum cernerent
leonem pugnantem cum apro,
et se
victum atque occisum
depasturos esse
sperabant.
Cum autem vidissent,
illos
omisso certamine
pacem et foedus facere,
falsi spe
deplorabant
vanam expectationem suam.
IMAGE. Here's an illustration for the fable (image source) from a 1621 edition of Alciato's emblems - Alciato's version is not quite the same, but it works:
