The six-time Pro Bowl center declined to talk about his injury, but a league source said he had minor elbow surgery.
"I expect to be back real soon," Birk said. "It's nothing major."
Birk can be activated at any time, but he is unsure whether he will be ready for Friday, the official first day of training camp. The Ravens won't rush him back because they know how valuable he is to the team.
"He's just what you're looking for in a center," offensive coordinator Cam Cameron said. "His experience is critical. He just has that personality that brings people together. That's what you need in a center. Centers have to have an 'it' factor that quarterbacks have to have."
Explanation for Kindle's fall?
University of Texas coach Mack Brown said Sergio Kindle's recent fall down two flights of stairs might have been the result of narcolepsy, according to Orangebloods.com.
Kindle, the Ravens' second-round pick who has been hospitalized with a fractured skull, played under Brown at Texas. Brown made his comments at the Big 12 media day Wednesday.
Ravens coach John Harbaugh explained that Kindle fell when he turned the wrong way after waking up in the middle of the night at a friend's house.
Before the Ravens drafted Kindle, there was a report that he took medication for narcolepsy (there are reports that he fell asleep during team meetings) and attention deficit disorder.
After they drafted Kindle, the Ravens were asked about the report that Kindle takes medication for narcolepsy and ADD. At that point, Ravens general manager Ozzie Newsome and director of player personnel Eric DeCosta looked at each other before laughing. "If it was a concern, we probably wouldn't have picked him," DeCosta said at the time.
Narcolepsy is a neurological disorder that affects the control of sleep and wakefulness. Some researchers believe there might be a link between narcolepsy and sleepwalking.
Bad news Bengals
That could become a headache for Marvin Lewis, the Bengals coach and former Ravens defensive coordinator.
Asked if he feels for Lewis, coach John Harbaugh said with a chuckle: "Marvin doesn't need our sympathy. He's not looking for it."
Harbaugh said the move helps the defending AFC North champions. "Obviously, it makes them better," he said. "It's a better Bengals team than it was yesterday."
F. Washington close to return
Ravens cornerback Fabian Washington said he is "very close" to coming off the PUP list.
"I really feel like if the season started tomorrow, I could play football," said Washington, who had offseason surgery to repair a torn anterior cruciate ligament in his left knee. "I'm ready to play, and I'm kind of excited and nervous at the same time."
Washington, who suffered the injury in a 17-15 loss to the Indianapolis Colts on Nov. 22, said he understood the organization's cautious approach. But Washington also said that he's eager to return and prove that he should start along with Domonique Foxworth when the team opens the regular season at the New York Jets on Sept. 13.
"I feel like for me to be the best that I can be, I need as many practices as possible," Washington said. "I think that's at any position, not just because of my knee. For me, I'm one of those guys who can't just turn that switch on. I actually have to practice and get my timing down."
Picking QB No. 3
With Marc Bulger taking the field for the first time this week, the Ravens have begun evaluating who should be their No. 3 quarterback: Troy Smith or John Beck?
Some say it could be a tough choice, but not Cameron.
"It's not as complicated as everybody thinks," Cameron said. "We've got a lot of practice left, a lot of reps in practice. You just watch every drill, watch every practice, watch through the preseason games. It usually clarifies itself and is usually pretty obvious."
Harris' Achilles is sore
Ravens backup cornerback Walt Harris remains on the non-football injury list because he hasn't taken the team's conditioning test. Harris, who agreed to a one-year deal with the Ravens on June 24, said he had soreness in his Achilles tendon.
"Once that comes around, hopefully I will take it again," said Harris, who turns 36 next month. "It's no big deal."
Rookie running back Curtis Steele might have been the most tired Raven after the first couple days of practice.
Part of the reason is that Steele worked hard throughout the practice. Another part of the reason is that Steele is the only tailback to report to camp so far (the first full-team practice is Friday).
"It's a lot of work, but it's worth it," Steele said. "I was warned before I came in, but I wasn't expecting it to be this tough."
The Ravens have spent a fraction of Tuesday's and Wednesday's practice on special teams for good reason. Long snapper Morgan Cox has been the only special teams' player on the field.
The undrafted rookie out of the University of Tennessee spent some time doing drills by himself and got individualized attention from Jerry Rosburg, the team's special teams coordinator and assistant head coach.
"I have enjoyed the time to spend one-on-one with coach Rosburg," Cox said. "He's been helping me a lot, trying to get me ready for when everybody does get here so I can be full speed and go with the rest of the team."
Baltimore Sun reporters Edward Lee, Conor O'Neill and Kaitlyn Carr contributed to this article.