We also have moreporks here (at least on the mainland, not sure about Tassie. They are also called mopokes. Both names are onomatopoeic of their mournful call.
Some of them are non-rhotic and some aren't.
Actually I heard an American today on the radio pronounce 'environmental' non-rhotically. Even an Aussie wouldn't do that. It was weird. What kind of US accent would that be? The pronunciation was something like 'envionmental' or even 'eviomennal.'
Now that's a word that I have never heard before, i.e., rhotic, which may be surprising since I had seven years of formal studies in Koine'. Furthermore, it is not in my *Webster's New World Dictionary of American English* (1988 edition). The nearest to it was rhotacism. But, I Googled it and that took me to a new website on using English that appears to be a resource for future reference.
However, now that I know what rhotic and non-rhotic mean, an observation or two on your American radio speaker. There are several sections of the USA where rhotacism and related manifestations of mispronuciations are common. The most common section so charged is the Deep South (Mississippi, Alabama and Georgia in particular). The particular flaw that you described might have come from some one raised in particular sections of New York City or north New Jersey. I have frequently heard some one from the latter speak of his State as New Joisey.
While there are quite a number of examples that might be drawn from the South, one that I like to use as an illustration is "like." If a Southerner ever asks you "What do you 'like'?", it is more than likely that he is asking you what is that you need, i.e., "What do you 'lack'?"