Myna of­fence: Why do these birds sound so an­noy­ing?

Whanganui Chronicle - - Nation - Jamie Mor­ton science

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.”

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