A D3.js-powered SVG landscape features a sky, sun, land, trees, and birds, with animated gradients simulating a 24-hour day-night cycle. The scene is constructed entirely via the SVG DOM API, using `createSVGElement` and `setAttribute` to build paths, gradients, and groups. Birds are cloned and transformed with CSS `scale` and `rotate`, while the sun and horizon colors animate through `animate` elements with timed `values` arrays.