Read the following passage carefully:
Long before the Shaanxi Wildlife Sanctuary was officially established by government decree in 1990, ornithologist Dr. Haruki Takahashi had already taken decisive action to save the endangered Crested Ibis. In 1988, prior to the sanctuary's formal inauguration, Takahashi initiated a pioneering captive breeding program at the Beijing Zoo. This breakthrough built upon his earlier field research in 1981, when he had personally located and recorded the last known wild nesting pair in the Qinling Mountains. Encouraged by that 1981 sighting, Takahashi drafted a comprehensive habitat preservation proposal in 1985, urging regional authorities to restrict logging in core nesting zones.
Based on the passage, arrange the following events in chronological order from earliest to latest.
- 1Takahashi located and recorded the last known wild nesting pair of Crested Ibises.
- 2Takahashi drafted a comprehensive habitat preservation proposal.
- 3Takahashi initiated a captive breeding program at the Beijing Zoo.
- 4The Shaanxi Wildlife Sanctuary was officially established by government decree.