Create a 3D model of a Black-throated Loon (Gavia arctica). The bird has a long, slender neck and sharp, dark beak. Its head features a black throat, white cheeks, and a dark gray crown. The back is dark gray with subtle feather patterns, while the belly is light grayish-white. The wings are long, narrow, and sleek. The bird’s legs are short and placed far back, with dark webbed feet. Focus on realistic feather texture and subtle color transitions between the dark back and light belly.