Birds and jets

Apparently a flock of birds took down a jet in New York City.  Everyone survived due to the skill and heroic efforts of the pilot, who landed the jet in the Hudson River.  But the engines suffered catastrophic failure.  How could this happen?  According to the article, jet engines are vigorously tested with real birds of all conceivable types (yeck).

In the physical tests, the engines are revved to full power inside a test facility and absorb various kinds of birds, from those the size of sparrows to those the size of herons, one at a time. (The birds are already dead.) The engines also ingest multiple birds meant to simulate a collision with a flock...

So could this flock have consisted of birds they hadn't tested? I wonder if they considered rubber chickens.