Translation:We like birds, but we also like turtles.
Why is the 'le' used in front of tartarughe and no 'i' in front of uccelli?
it is the use of the indirect object pronoun "ci", which refers "to whom" or "to what" the birds and turtles are pleasing. first person singular would be "mi" instead of "ci".
how can you imply the first person plural from this construction - surely it is just as valid to translate it in the first person singular
You may be thinking of, "Mi piacciono uccelli..." which translates to "Birds are pleasing to me."
In contrast, "Ci piacciono uccelli..." translates to "Birds are pleasing to us." "Ci" can only mean 'to us' in this example, and as you can see 'ci' and 'mi' function as very different pronouns. Hope this helps!