° m* P ] • BAKtK. Tfo 5u«/W;y of Stow* hy /hmi^ls 91 



\'<w SoOTb Wales, shows that a specimen of the Crested Piffcon Mtypttupx 



lotfwttx) had its "stomach Idled With coarse quarts gravel", the Australian 

 Spur -winged Plover (f.ohibyx novae -hoihuduw) had a "small quantity r-i 

 nttid and a number of pebbles", a Blank-fronted Hon Ft el I Cti&radriin 

 i\ic!c)wf>s) bud ''small pebbles and mud", and Iwo specimen*, of llie White- 

 headed Siilr {fifwmti&pvt Inuocephatus) hid small and coarse utwrU 

 prhMcs The largest quantity was loimd in a single specimen of the Straw - 

 necked fbis {Thrcskiorms j^i'ifci'/|u), whitli Mad m jfW stomach fourteen 

 pebbles ranging up to one ij turner ounce in weight- Perhaps of equal interest 

 j^. that tliree specimens of lite Australian White Ibis ( I hrtsktor w-S ntolucrir) 

 contained 16, 42 and 18 'yahriie stones' of a ire>bu-r*iri' crayfish, and a Music 

 lJuek (tihmrfl tehnhi) had two "yabbiv stones' with sand and gravel. 



Finally there aie record* of domestic ummaK and animals Hcfjft tjl ?*«» w 

 having stones found in their stomachs »fttl death, and ahhoit^li ibis may 

 be won by of mention, the reasons tor ibis unnui be considered with Ihtae 

 animals living under natural rondition*. W. J Beal iW-O mentions that 

 bogs kept in an enclosed area, when slaughtered, were luund to liWT* in the 

 Stomachs of several, enough pebbles each to Till |be two Iipii».1v oi a man. 

 and there were smaller C|udn4 iticrs in some instances, 



Reasons (or Sfone-SwollowinA 



Many theories have been advanced to explain this peculiar phenomenon; 

 N^ute have prompted definite, investigation into the life histories Ot the 

 animals, wink others have attempted to explain l\ in connection with the 

 digestive structure, and a few have promoted reason:; without having given 

 thought to their possibilities. 



W. H. \Vjc&4 (1908) disru$v$ v»"*" of these iheories in Wis paper "Pebble 

 Swallowing Animals", and, with matter published on tins subject since, the 

 theory can be placed in the following order: 



(a) A>; ballast. 



(b) Accidental. 



(c) Swallowed with food attached, e.p,. sen anemones, spawn. 



(d) A heady in the food swallowed,, ic fish, err, 

 (c) (Sasim. 'chewing gum'. 



(t) Trituration ot food. 



(a) As balfasl. 



This theory, that stone* were swallowed by very fat seal- as Iwllasl (A J. 

 Harrison. J8S7 > io allow litem lo sink into deeper water* W,ii llie opinion of 

 the sealers of ('ape. Colony, and alhO the co<l-fishers of Newfoundland. Thev 

 referred to llie seals' stomachs as 'fcJatlast Bags'. A similar account uppeai? 

 in the Report on Zoology of the Challenger Expedition (\V. Turner, 1887), 

 stating that sailors considered ihe teals lo swallow stones to enable them to 

 dive loi (bhj and they ro'dH dfag$*r££ ihe stones at will and so sutlace a#ain. 



In a pamphlet published by the Ret. Canon Ormvinigg of St. John's, 

 Launccston, about 1872 (quoted by F. l-ewis, 1916) it h stated tlm before 

 a youoy Mutton-bird could take lo the water, it had to Uke in 'ballast' to 

 enable it to get properly balanced 



A. J. Campbell (1900), dealing with the life history of the Muti oil-bird, 

 states, "before ihe young birds Follow their parent* to the sea, they devour 

 a quantity of *and or gravel; the popular belief is that they ballast them- 

 selves. ^0 that if thrown into the water fifty would not drown". 



Tr is worthy of note that although ihe quantity of stones swallowed by 

 the various animals outlined in this p-iper appears to he considerable, then 

 Weight compared with the weight of the animal itself w-ould not make an 

 appreciable difference to the stability of it? movements. Also, it Ira* been 



