Myna offence: Why do these birds sound so annoying?
If you’ve ever heard a raucous racket cut through the otherwise dulcet birdsong of a New Zealand backyard, there’s a good chance the offender was a myna.
This noisy character, typically found hanging around North Island roadsides, is considered a pest because it feeds on fruit and causes damage to crops.
Annual surveys have shown how their populations are on the rise — to the point they today outnumber even our friendly fantail in urban gardens.
Now a new study shows New Zealand mynas aren’t even playing us the greatest hits their Asian native ranges enjoy, but a dull setlist of harsh screeches and shrieks.
The findings come from Dr Sam Hill, a former Massey University ecologist whose previous focus has been on tu¯¯ı, which, conversely, boast a florid repertoire of more than 300 tunes.
His latest project stemmed from something that struck him while visiting a Nepalese village four years ago.
“I recorded a myna that sang a hugely complex song, which got me wondering why . . . the mynas we have here in New Zealand have such ludicrously simple and noisy ones.”
He now puts this down to a phenomenon called the founder effect — where genetic variation is lost when a new population starts from a small number of individuals.
“Our understanding [from research in] other species was that birds introduced to new areas from their native ranges generally have these founder effects — which lead to genetic bottlenecking, isolation and sometimes inbreeding, and in terms of vocal behaviour, more simple songs.”
For his study, just published in Ibis
— International Journal of Avian
Science, Hill and his colleagues sourced songs from multiple mynas across their native range, which ran from Kazakhstan and Uzbekistan across to India, Nepal and China. They also gathered field recordings from mynas in countries they’d been introduced to — New Zealand, Australia, Oman, South Africa, the United Arab Emirates and the United States.
Next, they assessed 75 individual birds across all ranges to compare the complexity of their songs.
“Our results suggested, as predicted, song complexity was higher in the native areas in a ‘statistically significant’ sense,” Hill said.
“This could be a reflection of their reduced genetic diversity — but this needs more investigation.”