A scientist or scholar who studies bird nests and nesting behavior (now more commonly called an ornithologist).
From Greek 'kalos' (nest) and 'logos' (study) plus the agent suffix '-ist' indicating a person who practices the field. It's an archaic term largely replaced by broader ornithological terminology.
A caliologist represents a kind of scientific specialization we've mostly abandoned—people used to focus deeply on just ONE aspect of birds, but now we'd rather have people study many things.
Complete word intelligence in one call. Free tier — 50 lookups/day.