For further information concerning the Northwestern crows see:
Zach, R., 1978. Selection and dropping of Whelks by Northwestern crows.
Behaviour, 67: 134-148.
Zach, R., 1979. Shell dropping: decision-making and optimal foraging in
Northwestern crows. Behaviour, 68: 106-117.

For literature concerning shell dropping in Great Britain & Ireland:
Whiteley, J.D., Pritchard, J.S. & Slater, P.J.B., 1990. Strategies of mussel
dropping by Carrion crows Corvus c. corone. Bird Study, 37: 12-17.
Berrow, S.D., 1991. Predation by the Hooded crow Corvus corone cornix on
freshwater pearl mussels Margaritifera margaritifera. Irish Nat. J., 23:
492-493.
Berrow, S.D., Kelly, T.C. & Myers, A.A., 1992. The diet of coastal breeding
Hooded crows Corvus corone cornix. Ecography, 15: 337-346.

Dito in Israel + related articles:
Mienis, H.K., 1980. New records of predation on snails by the Hooded crow in
Israel. Levantina, 28: 331-332.
Mienis, H.K., 1993. A change in the nut-cracking technique used by Hooded
crows in Kibbutz Netzer Sereni, Israel. Bull. Ornithol. Soc. Middle East,
30: 29.
Mienis, H.K., 2000. Landsnail dropping by the Hooded crow in Israel. Triton,
1: 31-32.

Regards,
Henk K. Mienis
----- Original Message -----
From: Peter Egerton <[log in to unmask]>
To: <[log in to unmask]>
Sent: Tuesday, January 30, 2001 12:54 AM
Subject: Re: Interesting article


> Here in BC the Northwestern Crows eat bivalves by dropping them on
> the roads, sidewalks, rocks, whatever's a hard surface. There have
> been studies done regarding this behavior and it's quite the thing
> to watch. It's also a great way to collect shells...a few times I've
> seen a crow drop one and run over and nabbed it (they often take a
> few drops before the shell breaks). I've also narrowly escaped being
> the accidental target of these drops as well. Quite entertaining!
>
> Peter Egerton,
> Vancouver, Canada
>
>