First, I compliment you on your keen observations. I hope
you have time to continue watching this particular crow. Second, there
are reports in the literature that describes the behaviour you have
witness first hand (e.g. The Food Storage Behaviour of the Northwestern
Crow by P.C. James & N.A.M. Verbeek 1983 in Behaviour; also see Recovery
of Cached Food by Torresian Crow by Andrew Ley, Australian Bird Watcher
in which other Australian reference are given). Currently, I am collecting
references on caching behaviour in birds for an upcoming article in the
Interpretive Birding Bulletin. If you are interested I'll let you know
when it gets written.
In general, many corvid species will cache food including crows,
butcherbirds, nutcrackers, rooks, etc. Also many small passerines will
also store food. However, in your case, I am not sure why the crow would
store plastic items which can't be mistaken for food, or could they?
It would be nice to find out if the individual in question was a juvenile.
If so, the behaviour you observed could have been a form of "practicing"
an interesting possibility.
On Tue, 4 Nov 1997, Syd Curtis wrote:
> Crows Corvus orru, ubiquitous in suburban Brisbane, now accept we hominids
> as harmless, though they keep at a greater distance than say magpies. On a
> recent early morning walk (5.30 am), I watched a crow foraging in a heap
> of leaf and bark litter in the gutter opposite me.
> It tossed aside a piece of bark, rummaged among the leaves and picked up a
> small white object and placed it on the concrete kerbing. It placed a
> second one beside the first then picked up both, flew about 4 metres to a
> small garden bed around an ornamental shrub on the footpath, and placed
> them on the ground. The crow excavated a small hole in the heaped up
> grass-clippings and soil of the bed, inserted its treasures and carefully
> covered them over. It picked up another small object from beside the bed
> and placed it on top. The bird's behaviour was similar to that of a dog
> burying a bone ... allowing for the difference in technique necessitated by
> beak instead of paws in the excavation.
> The crow then flew to the top of a power pole some 30 metres away and
> stayed there. I examined the garden bed. I could discern no sign of the
> crow's activities and could not identify any particular object as the one
> placed on top, which I assume was simply camouflage. However, as I had
> carefully noted where the crow had buried the objects I was able
> immediately to unearth them: two pieces of broken hard plastic, each about
> 50 x 15 mm and a few mm thick, which I replaced and covered over again.
> Without binoculars, I was unable to determine whether the crow had dark or
> light eyes.
> Is this sort of Corvid behaviour discussed in the literature? Or has it
> been, on this list? (I subscribed only recently.) Any comments?
> Syd Curtis (at Hawthorne in Brisbane, 04.11.97)
> H Syd Curtis