The first symbol is a partridge in a pear tree
I found that “according to Greek legend, the first partridge appeared when Daedalus threw his nephew, Perdix, off the sacred hill of Athena in a fit of jealous rage. Supposedly mindful of his fall, the bird does not build its nest in the trees, nor take lofty flights and avoids high places.”Source: Wiki
There are many ways to interpret this symbol. In my view, this particular partridge that is found in a pear tree is a courageous one. On the first day of Christmas, we are asked to gather our courage and aim higher. We are shown that no matter what we are taught about falling and what consequences we drew from our experiences, the notion of fear can be replaced by faith and we must risk and find higher ground.
According to another source, the partridge is Jesus, who appears to us as our guide in our journey on the first day.