Geese.
Look at the goose! (one goose)
Look at the geese! (two geese.
No geeses is not a word the correct way to say it is geese eggs
Three geese's nests is the correct plural and possessive
geese, the thing that geeses. and says OMG LOOK AT MY GEESE OMG GEESES!
The plural possessive is geese's. A sentence could be "They found that several of their geese's eggs had been eaten by a fox."
Other animals
geeses
geeses
The word geese implies many, so you don't need it here. You would say the geeses flight was long. That is a special case where there is a word for a plural already.
No, They migrate like all other birds; by flying on their own or in pairs
there are over 20,000 species of invertebrates in Ontario.
The plural of "she" is "they", so the plural of "she had" is "they had".
The plural of 'this' is 'these' and the plural of 'that' is 'those'.