U.S. turbines kill 234,000 birds per year on average. When a bird flies into a patch of air immediately after a blade tip has passed by, the sudden drop in pressure can reportedly rupture its lungs, a condition known as "barotrauma." There are several solutions proposed but the problem is still so large that the only solution that is found to work is stopping the wind turbine when migratory birds come into the areas of the wind farm, using a radar that can detect an incoming large number of birds. Some of the proposed solutions are:

Safer locations - The simplest way to keep birds and bats away from wind turbines is to not build wind turbines where lots of birds and bats are known to fly. It's not always that simple, though, since many of the open, treeless expanses that attract birds and bats are also prime locations for harvesting wind.

Ultrasonic 'boom boxes' - Birds are mostly visual animals, but since bats use echolocation to navigate, sound might offer a way to repel them from wind farms. That's the idea behind ultrasonic "boom boxes," which can be attached to turbines and emit continuous, high-frequency sounds between 20 and 100 kilohertz.

New colors – painting of only one turbine with black paint has given a very promising result according to some researches.

Radar and GPS – detecting large number of migratory birds when reaching wind farms to prevent collision by stopping the wind turbine.

Restraint – is a sensor that can tell when something hits a wind turbine blade, giving operators a chance to prevent more collisions by shutting turbines down.

This project is about building a new system that can repel birds from entering wind farms which prevents collisions using an effective visual technique. This is done by installing an insignificant (lightest weight) and very flexible material like fabric or a sealed plastic bag filled with a safe, lightest gas like Helium on the very tip of the three turbine blades to create more surface area from the top view to maximize the sight for birds that will prevent them from approaching the area where the turbine blade rotates. Meaning as the wind blows perpendicular to the blades, the three installed materials are forced to be perpendicular to the turbine blades or parallel to the wind and as the turbine blades rotate, each of them also rotate along with each of the blades being in position parallel to the wind. Since they are very flexible as each of the materials reaches the turbine tower stand, they fold at the moment of contact and regain their shape instantly after contact with the tower stand. This system does not affect the efficiency of the turbines because they are insignificant (in weight) and do not alter the aerodynamic because the will be behind the turbines at all time. Based on some recent research results, in order to maximize the visual effectiveness to keep away the birds only one of the materials is painted black.

https://hackaday.io/project/176730-new-bird-repellent-wind-turbine-invention