Companies are increasingly forgoing the spring job market, when they would typically be interviewing exiting college seniors, and instead are hiring from a growing pool of interns, shifting hiring patterns and upending recruiting practices. More than 70 percent of hires at large companies such as Facebook, Enterprise Rent-A-Car, and eBay have come from the company’s internship programs, compared to 50 percent or less about 10 years ago. “There was a time when 50 employers came to recruit for interns,” Patricia Rose, director of the career center at the University of Pennsylvania, said. “Now we have 180.” A significant share of the entry-level positions in specific industries such as engineering, graphic design, communications, marketing, and information technology are all internships, according to a Burning Glass Technologies analysis of nearly 215,000 online job postings. This means college students must start acting more decisively while still in school if they wish to land a job in their field upon graduation. “You can’t spend your first couple of summers in college lifeguarding or working as a camp counselor anymore if you have a specific job in mind after graduation,” said Matt Sigelman, the CEO of Burning Glass. “Those typical summer jobs are not going to position you for work after graduation.”