On Saturday, February 4, 2023 at 2:36:39 AM UTC+8, David P. wrote:
> Those Window Stickers to Prevent Bird Strikes? There’s a Catch.
> By Catrin Einhorn, Feb. 2, 2023, NY Times
>
> Every year, hundreds of millions of birds die in the U.S. from flying into glass. Combined with other pressures such as habitat lost to development, climate change and hunting by cats, birds have suffered staggering losses in net population. Since 1970, nearly 3 billion birds have disappeared from the U.S. and Canada, scientists have found.
>
> Most strikes occur during the day, according to the American Bird Conservancy, and while people often assume that high-rises are largely to blame, homes and low-rise buildings account for the vast majority of collisions.
>
> Many residents don’t realize that birds are crashing into their windows. The animals may fly away before succumbing to their injuries, or a cat might grab the body before a person discovers it. During the pandemic, reports of bird strikes increased sharply because people were suddenly at home to see or hear more of them.
>
> When used on the outside of glass, the two products they tested increased window avoidance by as much as 47%. Inside, they were ineffective. One was invisible to humans and the other used a pattern of tiny orange and black diamonds.
>
> https://www.nytimes.com/2023/02/02/climate/bird-window-strikes-stickers.html

Reflective sticker will not help prevent crashing. Non-reflective type with the type of color which birds will not crash will be good for them. Lamp post's lights and signboard lights that reflected on building's glass walls will cause birds to crash on glass walls instead.