Magpie-larks nest-building delays...

[Martin Butterfield <>]

Robin 

I have looked at a set of GBS records I still have on my computer and of the 143 sheets with NB for Magpie Lark 4 sheets report 5 consecutive weeks with NB.  One of these then reports, after an interval of three weeks, a second go for 2 weeks.  In another case the string of 5 consecutive weeks follows 1 week of NB and then a gap of 1 week.  There are a further 4 sheets with NB recorded for 4 consecutive weeks.  

Of course it may be the activity commenced on the last day of the 1st week of the sequence and ended on the first day of the final week reducing the actual build periods to 3 weeks and 2 days and 2 weeks and 2 days respectively but that would be an unlikely coincidence if it occurred in every case.

That is of course a very superficial glance at the data but it would take a lot of effort to nut out the full story behind each event.  However I think it allows 

me to conclude is that your birds are probably more industrious than the average but it is not an unprecedented level of activity.  

In terms of the birds investment of time and energy I suspect for some species (not, of course Magpie-larks) larger amounts of energy and possibly similar amounts of time are devoted to migrating to breeding grounds.  The biological imperative to breed is a powerful thing!

Martin Butterfield

http://franmart.blogspot.com.au/

On Sat, 9 Nov 2019 at 13:32, Robin Hide <> wrote:

Thanks Philip.

My question was perhaps a little ambiguous- I was referring specifically to the time involved  in constructing a  single nest (or in the case of the Campbell St. pair, two abandoned, half-constructed. nests and starting on a third).

More than 4 weeks working every day constructing a single nest seemed to me like a major time investment?.

Robin

 

 

From: Philip Veerman
Sent: Friday, 8 November 2019 1:34 PM
To: Robin Hide; 'Canberra Birds'
Subject: RE: [canberrabirds] Magpie-larks nest-building delays...

 

Hello Robin,

 

From The GBS Report:

 

Magpie-lark Grallina cyanoleuca

This bold and confiding bird is well adapted to the suburban and even urban environments. Some will accept

hand feeding. Some individuals will attack people when nesting but they are not as bad as Australian

Magpies. They often display aggression towards Australian Magpies (which ignore them). Adult males, adult

females and the juveniles are each easily distinguished by the pied pattern of the head. They are among our

most regular species, present all year and with a consistent small amplitude monthly pattern. This is probably

because the species maintains permanent evenly spaced territories. From a minimum in October they rise

smoothly to a maximum in March, then decline smoothly again. This is only minor variation and is due to two

factors. The spring drop reflects some birds moving away from garden areas for breeding or lowered counts

if birds are undetected when on nests. The autumn rise reflects new young birds in the population becoming

independent and the birds forming flocks and being counted in larger aggregations (though at fewer sites).

Single observations of over 20 birds (sometimes up to 100) are mostly during autumn and early winter. Long term

numbers have had a smooth to undulating increase. Being a widespread species, this trend is across

the board. It has clearly been contributed to by Site 230 that has habitat to support large groups.

Breeding records have fluctuated but there is a strong increasing trend. The breeding period is long, there are

many records that suggest double brooding. A full breeding event appears to take up 19 weeks. One record

contained breeding data for two events continuously for 23 weeks. Some nest building starts in early August

but mostly they start in September, mostly activities at nest have finished by end of January. Dependent

young from late November, peaks in January, finishes in late March.

Graphs on page: 101, Rank: 5, Breeding Rank: 4, Breeding graph on page: 106, A = 2.02629, F = 98.28%,

W = 52.0, R = 73.612%, G = 2.75.

 

 

Note that the breeding graph (page 106) answers your question. So in quick answer to: Is this unusually protracted?  No.

 

Philip

 

From: Robin Hide [m("anu.edu.au","robin.hide");" target="_blank">]
Sent: Friday, 8 November, 2019 1:18 PM
To: Canberra Birds (m("canberrabirds.org.au","canberrabirds");" target="_blank">)
Subject: [canberrabirds] Magpie-larks nest-building delays...

 

Is the nest-building of Magpie-larks usually a long-drawn out affair?

 

I’ve been watching off and on since early October the activities of two pairs of Magpie-larks in neighbouring Ainslie streets  - Paterson and Campbell Streets.

 

The Paterson St nest- in a Celtis australis street tree- was well under way on the 7^th of October.- with both birds ferrying wet mud from the gutter on a shed next door to us and flying constantly across our garden.

 

The half built nest looked like this on Oct 7:

 

 

 

They have continued working on it since - and were hard at work still this morning (8 Nov., 4 weeks later) with the nest wall a few cms taller now.

 

Over the same period, the Campbell Street pair (a bare 200 m away) have started and abandoned two nests (far left and far right in ths photo below) , and are now working on a third one -all on the same branch of a Quercus lusitanica street tree.

 

 

 

Is this unusually protracted?

 

Robin Hide