All good ideas from Alison. About the first idea, maybe if golfing fraternity or ball markers could be talked into sponsoring such a study.
I had an intention of writing some of the same ideas. Although I don’t think it has been recorded by corvids, Egyptian Vultures and Black-breasted Buzzards
(instinctively) use stones to break eggs. Maybe corvids being smart, could develop similar ideas.
Philip
From: [
Sent: Thursday, 1 August, 2019 9:46 AM
To: 'shorty'
Cc: 'Geoffrey Dabb'; 'COG Chat'
Subject: RE: [canberrabirds] Ravens and balls, again
We would need to know the proportion of coloured and white balls in the source population to determine whether the birds have a preference or are delivering a random sample, there’s a good project! And are people more likely to spot a coloured
ball than a white one out in the bush?
Interesting additional observations re attempted cracking, soaking and pebbles. I wonder if corvids are responding to a super stimulus in their reaction to roundish white objects which transfers to more prominent targets (see Wikipedia
quoting research on brooding birds which found ‘most birds preferred (eggs) with more exaggerated markings than their own, more saturated versions of their color, and a larger size than their own. Small songbirds which laid light blue grey-dappled eggs preferred
to sit on a bright blue black polka-dotted dummy so large they slid off repeatedly.’). Perhaps this is a partial explanation of how cuckoos get away with depositing larger eggs than those of their host.
Some of the behaviour could also be ‘play’. I have seen groups of Torresian Crows over Uluru dropping, chasing, picking up and repeating the activity with rounded stones, perhaps honing their competitive skills for when one of them finds
a real egg.
Alison
From: shorty <>
Sent: Wednesday, 31 July 2019 6:52 PM
To:
Cc: Geoffrey Dabb <>; COG Chat <>
Subject: Re: [canberrabirds] Ravens and balls, again
Interesting that you both state coloured balls are the preferred ball for the Ravens. Over the last 5 of so Years my local Ravens have mostly bought White balls back to my place with the odd Yellow ball.
They try so hard to crack them open with their beak that i assume they think they are eggs? They even try soaking them in my Birdbath to soften them and when this fails they bury them.
On Wed, Jul 31, 2019 at 1:11 PM <> wrote:
The management of Fairbairn golf course also reports that coloured balls are more popular than white ones with Australian Ravens, and that they lurk in wait for them. Balls are
sometimes dropped on the runway at the adjacent Canberra Airport, perhaps in an attempt to break them open. I also often come across golf balls of all colours in the bush far from any golf course or practice range and assume that ravens are the bearers of
these. Foxes will also gnaw on them, whether before or after they have been transported by ravens I know not.
Alison
From: Geoffrey Dabb <>
Sent: Wednesday, 31 July 2019 11:46 AM
To:
Subject: [canberrabirds] Ravens and balls, again
The usual conversation in the golf shop about whether ravens target orange balls or ‘will take any ball’. Notwithstanding I got a box of new Callaway bright orange
matte finish. Yesterday at Royal Narrabundah at the very first hole a raven flew directly down and took the first (virgin) Callaway orange matte finish back to its pine tree. Thereafter an ordinary white ball was used without incident. I don’t know about
all Canberra courses but Narrabundah and Duntroon are particularly bad for this sort of thing. I believe a small number of orange-fixated resident ravens are the main problem. Certainly white balls are taken occasionally.
