Barnard student Lily Perlmutter says:

There’s a guy out [at the Barnard gates] from a labor union with a GIANT blow-up rat with [President of Barnard,] Judith Shapiro’s salary plastered everywhere, and signs asking for better wages. The guy is blowing a whistle and shouting, “JUDY! JUDY!” But there isn’t a crowd of strikers, just this one guy.

Update:
A commenter on this thread posted the following e-mail message from Susan Krause, Director of Human Resources at Barnard, about Tuesday’s demonstration:

We have been informed that the Laborer’s Union expects to organize a protest on Broadway outside the Barnard gates on Tuesday morning, June 20, over the College’s use of a non-unionized contractor on an improvement project at Elliott Hall. Barnard respects the right of the union to express its viewpoint in this way. College administrators have made the point to union leaders that 95 percent of the capital projects at the College over the last decade totaling $56 million have employed union workers. This is the case, even though Barnard is under no obligation to do so. The project in question is small in scale (under $1 million). The College will continue its policy of being a good neighbor and using union workers on its capital projects, when appropriate.