Hello, there is a nest in the area (on someone’s property) where I was invited to do the mitzvas shiluach hakan. Is it a bitul asseh if I don’t want to do it because I feel that since I don’t need the eggs I am causing pain to the animal needlessly. I noted that the Chasam Sofer Orach Chaim #100 brings down many sides to this issue. Can I comfortably not do this mitzvah or should I do it?
You should definitely do it! The minhag is that we do the mitzva even if we don’t need the eggs, but simply because it is a mitzva that Hashem commanded us to do. What you can do is send away the mother bird, you don’t have to grab it with your hand, and even if you take a stick and scare it away, until it actually flies away from the nest, that is enough. Then pick up the eggs with a plastic glove, not for sanitary reasons, but if you wear a glove, the eggs will not get a human smell, and the mother will be willing to return to the nest. After you have acquired the eggs, you can put them back, and be mafkir them and it is even possible for someone else to merit to do the mitzva. As a side point, the mitzva is only with the mother bird, and it is the mother that is on the bird from sundown until sunrise.
See Shleach Tshalach – Dini Shiluach Haken 12 in the name of R’ Eliyashiv zt”l and ybchl:ch R’ C. Kanievsky shlit”a, also see halacha 14.