I think Robert Carrick who studied magpies in the ACT in the 60s found that some males have two females with nests.
From: Philip Veerman [
Sent: Wednesday, 6 August 2014 5:51 PM
To: 'Canberra Birds'
Subject: RE: [canberrabirds] magpie breeding
I happened to go into the ANBG on Anzac day this year and on the eucalypt lawn saw a female magpie in a tree quivering her rear end suggestively. The reaction it got was one of the males promptly flew into the tree and attacked her. I thought that was curious. I did not see a reaction from any other magpies.
From: Barbara Allan [m("bigpond.net.au","allanbm");">]
Sent: Wednesday, 6 August 2014 12:07 PM
Subject: [canberrabirds] magpie breeding
This morning during a chilly dog walk around Hawker ovals, I met two magpies in a eucalypt, she quivering her rear end suggestively. I waited to see the action. Then it became obvious there was another female magpie in a tree opposite, less than 5 m away, and also quivering suggestively. The male pondered for a couple of seconds, then chose the second female and copulated briefly and unceremoniously, thus answering (at least in this one case) Gisela Kaplan’s query as to whether male or female magpies chose their partner. It would have been interesting to see if he also mated with the other female but it was rather too cold to hang about. And Hawker ovals are probably blessed with too many magpies to be sure of future developments. b