No, they shouldn't just kill the birds, but it was an incredible lack of forethought to remove one species and not consider the possible ramifications. That no one considered what the cats fed on or what might feed on them, or any other ways the cats influenced the ecosystem there, is ridiculous.
One would think we'd be beyond such idiocy nowadays and that at the least all of the above would've been considered before removing the cats, even if the choice was made to do so and risk the consequences. I don't think anyone even considered the possible consequences (although what I read implied they did)...they just removed the offending felines and then acted shocked when the cats food sources flourished with their primary (only?) predator gone.
