In a short aside mentioning Caligula’s penchant for envy towards anyone, Suetonius records that “(he) sent a stronger man to challenge the current King of the Grove”. This Grove turns out to be somewhat different* from the many sacred groves scattered throughout the ancient world. The Romans were not averse to destroying forests for civil or military engineering needs, but they also held piety as one of the highest virtues.
Thus they were the ones to record this act of Gaius Caligula as an insane crime. Given the Roman obsession with auguries, I wonder if anyone made the claim ( in much later years, and under the right Emperor) that this act was a portent of the dreaded year of 4 Emperors to come. The Romans believed that avian auguries were superior to any other for divining matters of state, so perhaps it was overlooked. The practice of bird calling for ritual purposes is still practiced by Tibetan Buddhists today.
* From the revised Robert Graves translation- “In Latin: Rex nemorensis; the priest of Diana at her sacred grove (nemus) near Aricias, south east of Rome. The position was held by an escaped slave, who killed his predecessor and would in turn be killed by his successor”.