The sonnet was written around the time of spring, which came after a long winter period.
'Cause during the poem, the author wrote that the winter is long and somewhat tiring... And so on, spring is around the corner and the animals we're eating, sleeping. Doing their regular, normal schedule, as well as the plants, with their photosynthesis and all. The poem talks about the outgoing of winter and the arrival of spring.
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- Akamatsu