Complex sentence: During breeding season, birds such as herons and egrets look for sticks to build their nests, and in some cases when there is a shortage of sticks in marshy areas where bird and reptile habitats overlap, the search can become extremely competitive.
Split into simpler sentences: During breeding season, birds such as herons and egrets look for sticks to build their nests. Sometimes there is a shortage of sticks in the marshy areas where these birds and reptiles overlap, and therefore the search becomes extremely competitive.