Through the clear large window at the office

Note 159:

At the office table, tucked in a corner,
I was working on a holiday, National Sports Day.
Through the large window,
I saw two birds swoop by in the clear blue sky.
One was bigger than the other that flew close behind.
I wondered if they were a pair,
a couple, as we might call them,
two little bird lovers.
Perhaps the smaller one was the male.
Why does nature design the female to be larger in size,
yet less colorful than her mate?
I grinned at the thought,
then turned back to work.