Today is "Cuckoo Day" - an old English observance marking the migrating birds' return from further south. Since the Evangelist St. Mark has for centuries also been commemorated on this day, the cuckoo became a symbol of St. Mark (along with the more familiar - and much more majestic - lion).
Farther south (where presumably the birds had long since returned) a dog was sacrificed on April 25 as part of the ancient Roman Robigalia festival, focused on protecting the spring and summer crops from mildew. One of ancient Rome's several spring agricultiral festivals, Robigalia featured major (4 horses) and minor (2 horses) chariot races. With triumph of Christianity these races were transformed into the Rogation Procession - the "Greater Litanies," as they came to be known. Ancient peoples appreciated their dependence on the natural seasons and the harvest. The change in religion redirected the focuus of people's prayers to the true Creator God. But that didn't change their dependence on nature or their need for a successful harvest or the value of ritualizing that on traditonal days.
For centuries, the "greater Litanies" were faithfully observed on April 25 (along with the "Lesser Litanies" on the Monday, Tuesday, and Wednesday before Ascension Thursday), until abolished by Paul VI. We hear a lot today - and rightly so - about climate change and its devastating effects. Perhaps a rationalized late 20th-century Roman Liturgy's abandonment of such reminders of our connection - and dependence - on nature wasn't such a smart idea, after all.