Yes, black widow poison can kill chickens. Black widow spiders are venomous, and their venom is a neurotoxin that can cause paralysis and death. Chickens are relatively small animals, and they do not have a high tolerance for toxins. Even a small amount of black widow venom can be fatal to a chicken.
If you have chickens, it is important to be aware of the dangers of black widow spiders. These spiders are often found in dark, secluded areas, such as under logs and rocks. If you see a black widow spider, do not attempt to handle it. Instead, contact a pest control professional.