You're lucky your squirrels are smart enough. Mine used to pick every apricot when it was green, take a bite (often just teeth marks because they were so under-ripe) and throw every single one away as inedible.
Moron squirrels - destroyed the entire crop for both of us - how stupid is that? After the second year of growing an apricot just for it's brief blossom I decided that natural selection should have its say (it says the penalty for stupidity is death).
Also you are lucky they are choosing pears - one of the very, very, very few fruit that ripens well off the tree - which is the main reason I grow six types of plums (and twenty types of apples - I hate a soft apple), but shop pears are actually edible - so I only keep the one pear I inherited because I'm not that short of space (and it would be a lot of digging).
Cheers.
PS. If you net the tree for squirrels the wasps will get them. If you stop those the mice will get them, and if you stop the mice the ants will get them. Better to pick them slightly under-ripe, wrap and keep them in a cool drawer - so playing to the pears' strengths.