Date:         Mon, 29 Jan 2001 22:25:52 +0200
Reply-To:     Conchologists of America List <CONCH-L@LISTSERV.UGA.EDU>
Sender:       Conchologists of America List <CONCH-L@LISTSERV.UGA.EDU>
From:         Henk and Zvia Mienis <mienis@NETZER.ORG.IL>
Subject:      Re: Birds dropping molluscs
Content-Type: multipart/alternative;

Indeed they are breaking the adult shells in this way. Juvenile shells are swallowed by crows with the shells as their crushed remains are often found in the faeces of crows. Henk.
  ----- Original Message ----- 
  From: Orstan, Aydin 
  To: CONCH-L@LISTSERV.UGA.EDU 
  Sent: Monday, January 29, 2001 8:35 PM
  Subject: Re: Birds dropping molluscs


  Henk,
   
  >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.
   
  Aydin ?rstan
    -----Original Message-----
    From: Henk and Zvia Mienis [mailto:mienis@NETZER.ORG.IL]
    Sent: Monday, January 29, 2001 2:14 PM
    To: CONCH-L@LISTSERV.UGA.EDU
    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
    E-mail: mienis@netzer.org.il

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