Why if you touch a birds nest the mother wont come back?

It's a common myth that if a human touches a bird's nest, the mother bird will abandon it and not return. In fact, most birds will not abandon their nests simply because a human has touched them. While some birds may be sensitive to human presence and may temporarily leave the nest if they feel threatened, most will return to continue caring for their young.

Birds have an excellent sense of smell, and they can detect the scent of humans on and around their nests. However, they do not necessarily associate this scent with danger. If a bird does abandon its nest, it is likely due to a combination of factors, not just because it was touched by a human. These factors may include predation, lack of food, or disturbance of the nest site.

If you happen to find a bird's nest, it's best to observe it from a distance and avoid touching it. This will help to minimize any potential stress or disruption to the birds. If you're concerned about the nest or its occupants, you can contact a local wildlife rehabilitator for assistance.