Off-topic mystery

Hi all,

Slightly off topic but hopefully someone can help.

I have a metal-framed vinyl swimming pool, 3m diameter that I set up for the
kids in the back yard every summer.

On Monday I found a dead Noisy Miner in the pool.

On Tuesday another.

Today, a dead kookaburra.

8 years or so with no drowned birds, then 3 in 3 days.

I cannot think of any plausible explanation for this expect coincidence. Any
ideas?

Paul.