Nectarines

Question

what has been nibbling my nectarine and how can I get rid of it

Answer 1

There can be birds, rodents and pests that dine on the Nectarine.

Netting can help with birds.
These articles can help you.

https://www.gardeningknowhow.com/edible/fruits/nectarines/spraying-nectarine-trees.htm
https://www.gardeningknowhow.com/edible/fruits/fegen/protect-fruit-tree-birds.htm
https://www.gardeningknowhow.com/edible/fruits/fegen/squirrel-proof-fruit-trees.htm