Magpies staking a claim

["Philip Veerman" <>]

There are two factors, they are territorial all year, so will defend a nest site in readiness for the next breeding, before there is any breeding activity. A nest site could also be a roost site worth defending. That could be what you are seeing.

 

From The GBS Report: the species has Rank: 1, Breeding Rank: 1, meaning it has more records and more Breeding records than any other species, so a big sample size. Having said that, they will start some behaviour that looks like nest building before starting nest building. Yesterday I watched two by my back door both pick up the same grassy twig and run about with it for a little while before dropping it:

 

Australian Magpie Gymnorhina tibicen

This is the most consistently present species. It is well suited to suburbs (Jones 2002). In a short study Davey (1995) demonstrated how dense the population of this species can be in Canberra. It is conspicuous, bold and abundant. It feeds on invertebrates on lawns and open ground. They will become tame and accept hand feeding. They vigorously attack most raptors at all times and will also chase other birds. This is the only species that has been recorded from every site and is the one recorded and breeding on the most charts. Only seven out of 1316 charts have not included this species, five of those are from Sites 73 & 219. Its omnipresence makes the annual variation quite noticeable, even though the amplitude is minimal. There is a slight dip in numbers from July to September, then a rise to November. From November to July it is almost constant. This spring dip is probably due to the count being down slightly when females are on nests. The long-term abundance has barely perceptible changes, although overall a small increase. This species demonstrates best, the closeness of the average A value in the two graphs. In the breeding season some individuals are very aggressive in defence of their nest and they will swoop at people. Mostly this is annoying or gives a fright, sometimes this results in injury to people. Although they aggressively defend their nests, they do not defend dependent young.

 

Nest building commences and peaks in July and is finished by October. Nests with eggs or young commence in July, peaks in September and is finished by January. First dependent young in September, peaking in November and last in May. There are many records that appear to show a complete breeding event and the duration is generally close to 15 weeks. The frequency of breeding has been quite stable over the years (was very low in Year 2).

 

Graphs on page: 103, Rank: 1, Breeding Rank: 1, Breeding graph on page: 107, A = 2.71793, F = 99.47%, W = 52.0, R = 84.861%, G = 3.20.

-----Original Message-----
From: Megan Mears [
Sent: Thursday, 23 May 2013 5:26 PM
To: COG Chatline
Subject: [canberrabirds] Magpies staking a claim

Hi, I'm wondering how early magpies prepare for breeding. Last spring some bred in a tree near my work and this year I have seen a pair sitting close to that nest, at various times, over the last few weeks. It's a deciduous tree so easy to spot birds in. Could this be the breeding pair staking their claim already, or perhaps random magpies hanging about? All knowledge, hunches and idle speculation welcome!

Megan