A bar chart displays the average migration distance for birds, grouped by region. The visualization uses a sample dataset loaded from a GitHub gist, with the computation of regional averages handled by `d3.rollups` and `d3.mean`. The SVG rendering employs `d3.scaleBand` for the categorical x-axis and `d3.scaleLinear` for the continuous y-axis, with axes generated via `d3.axisBottom` and `d3.axisLeft`. The bars are drawn as SVG rectangles in steel blue, and the chart updates with an animation on data load.