Date: Mon, 29 Jan 2001 13:35:28 -0500
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From: "Orstan, Aydin" <Aydin.Orstan@CFSAN.FDA.GOV>
Subject: Re: Birds dropping molluscs
>Recently I was able to report on the first cases of landsnail (Helix)
dropping by the Hooded crow in Israel (Triton, 1: 31->32, March 2000).
I haven't seen your paper, so I am assuming that crows break adult Helix
shells this way. Because as is the case with most land snails, juvenile
Helix shells are quite thin & fragile & I would think that a crow wouldn't
have much difficulty breaking open such a shell with its beak, whereas
shells of old adults become quite thick.
From: Henk and Zvia Mienis [mailto:mienis@NETZER.ORG.IL]
Sent: Monday, January 29, 2001 2:14 PM
Subject: Birds dropping molluscs
Dear Sarah and other Conchlers,
I have just read the interesting story of gulls dropping mussels in order to
crack them. As a matter of fact gulls are using this technique the world
over wherever a firm substrate (road, roof, a rocky promontory,etc.) is
available. It is simply an energy saving method to open shells.
Crows are using the same technique in smashing freshwater mussels (Anodonta)
in the Netherlands, marine mussels (Mytilus) at least in the Netherlands and
the United Kingdom and gastropods (Thais) in North America. Recently I was
able to report on the first cases of landsnail (Helix) dropping by the
Hooded crow in Israel (Triton, 1: 31-32, March 2000). Several years ago they
had learned to use that method by breaking pecan nuts in that way.
Henk K. Mienis
National Mollusc Collection
Dept. Evolution, Systematics & Ecology
Hebrew University of Jerusalem
IL-91904 Jerusalem, Israel
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