What are you reading?

I'm reading my Dad's letters from the time he went into the Army in1943 till he arrived home in 1945. He was the only survivor of his mortar squad when his unit was overrun in the winter during the Battle of the Bulge. He was trapped in his foxhole for ten days with Germans all around him. He was lucky.
My Vietnam memoir is based on the letters I sent home from my war and that he saved for me. My sister gave me a box with his letters last week.
I'm making notes as there may be another book in me.

How do crows tell each other apart?

With the same black plumage, how do crows tell one another apart? Earlier research has shown that their calls are individually specific, functioning in the same way as human voices. Female crows tend to have higher voices than males, partly due to body size.

Crows also vary in body size and shape and have similarly diverse bills; the tips grow continuously, but the bill shape is stable nearer the base. One crow family that Clark has observed featured a member with a bill shaped almost like a Roman nose, while his mate had a petite, straight bill; their offspring exhibited one or the other.

Clark hypothesizes that, like humans, crows may also be able to recognize individuals by how they move — in their case, fly. One older crow, sitting in her territory at sunset, didn’t respond as other crows winged by overhead, returning home after a day of foraging. That is, until she saw one specific bird fly overhead; she perked up and apparently called a greeting, at which it looked down while in flight and replied, Clark recounted.

“Our recognition of the quality and identity of our social companions uses many sensory modalities,” Clark said. “What we’ve shown is that the black of a crow does vary and has information in it, even though it’s sexually monomorphic.”

https://www.newswise.com/articles/beyond-black-research-explores-the-feather-color-of-american-crows-as-seen-by-crows/?sc=dwhn&user=10024121