Mystery bird egg

[Con <>]

An interesting puzzle for a rainy day diversion.

Robin has advised some additional details. See below.

The eggs fit none of the Common Myna, Common Starling or Blackbird all of which sometimes build nests in artificial sites.

The nest size and materials tend to eliminate fairy-wrens and thornbills. As Jack observes, the nest location for Grey Shrike-thrush is possible, even likely. But their nests are cup shaped and use items such as bark. White-browed Scrub-wren is somewhat possible but they tend to use a range of materials rather than just grass stems. I am not very familiar with Scrub-wren nests, but don't know of any records of Scrub-wren using artificial nest surfaces. OTOH, the egg fits with those of a Scrub-wren, which are quite variable.

Both Red-browed Finches and Sparrows make largish nests largely constructed of grass so that fits.  The eggs of the Red-browed finch are white. The eggs of the House Sparrow are variable but tend to have a white ground. So that tends to eliminate those two species.

There is a smokey here: the egg (loosely) fits those of several species of cuckoo.

It is possible that the nest was abandoned in response to an attempt at parasitization.

regards

Con

On 10/8/2020 8:24 AM, m("bigpond.com","jandaholland");"> wrote:

Robin, are there any Grey Shrike-thrushes around?  The egg fits the picture in Morecombe’s field guide, and they do have a habit of nesting in old tin cans etc garages.  Regards  Jack Holland

 

From: Robin Eckermann m("eckermann.com.au","robin");"><>
Sent: Thursday, 8 October 2020 8:14 AM
To: Elizabeth Keen m("gmail.com","ejbayly");"> <>
Cc: COG Chatline m("canberrabirds.org.au","canberrabirds");"> <>
Subject: Re: [Canberrabirds] Mystery bird egg

 

Unfortunately no photo of the nest ... but it was quite large (approaching the size of a soccer ball) and composed of loosely woven pieces of grass ... many strands 6” or longer. 

 

On initial inspection, it didn’t even strike me as a completed nest ... more something under construction or abandoned.  I picked it up and took it into the outside light for a closer look. Only then did I discover the small hollow containing the eggs ... but I am uncertain whether this hollow was on the top or side In the original positioning of the nest. 

 

I promptly and carefully put it back onto the bike’s parcel carrier with the hollow on top, and tried to cover the bikes with the tarp that originally covered them. I saw no birds coming to or going from the area in the 3 days prior to discovering the nest ... and despite specifically looking out for them in subsequent days, no sightings thereafter. 

 

Small birds frequenting the garden include superb fairy wrens & brown thornbills ... and also (albeit slightly larger) Eastern yellow robins.

Regards ... Robin

Phone: 02-6161-6161 or 0418-630-555

(sent from iPad)

 

On 8 Oct 2020, at 7:33 am, Elizabeth Keen <> wrote:

Robin, what is the nest like? Cup or dome? What materials? Libby

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