Birds get constipated when it rains.
I’ve come to the conclusion that rain causes constipation in birds.
My very scientific observation has shown that on sunny days, there is usually at least one spot of bird crap on one of the vehicles outside. This shows that the birds digestive systems are functioning normally.
On rainy days, no bird crap. ergo, birds get constipated when it rains.
Must be something to do with rain-soaked worms…