This area chart visualizes the relationship between temperature and bird migration distance, using a light blue filled region beneath a monotone curve. The chart is built with D3 v7, loading CSV data from a GitHub gist, aggregating it by temperature via `d3.rollups` and `d3.mean`, and rendering with SVG. Axes are generated using `d3.axisBottom` and `d3.axisLeft`, while `d3.scaleLinear` maps the data to the plot area.