Thanks to Greg Folkers for sending the link to this report in Emerging Infectious Diseases: Novel Avian Influenza A(H7N9) Virus in Tree Sparrow, Shanghai, China, 2013. The abstract:
In spring 2013, influenza A(H7N9) virus was isolated from an apparently healthy tree sparrow in Chongming Dongping National Forest Park, Shanghai City, China. The entire gene constellation of the virus is similar to that of isolates from humans, highlighting the need to monitor influenza A(H7N9) viruses in different species.
Evidently the Chinese went right into action after the first human H7N9 cases were announced on March 31: Between April 10 and May 15 they took over 2,000 samples from wild birds in Shanghai. Of these, 28 for positive for influenza A and just one was H7N9.