What factor largely dictated the successful inland colonization of the Double-crested Cormorant in the Midwest and Plains states?

Answer

The creation of man-made reservoirs and expanded river navigation channels.

The interior distribution is fundamentally tied to large-scale water control projects that created vast, shallow, fish-rich habitats mimicking the open-water feeding grounds used on the coasts.

What factor largely dictated the successful inland colonization of the Double-crested Cormorant in the Midwest and Plains states?
habitatUSavecormorant