196 



REESE 





Fig. 5 a, A burrow of the coconut crab, Birgus latro. Note the partially shredded 

 coconut and above it the fiber at the entrance to the burrow: b. Land crabs Coenobita 

 perlatus are active scavengers. They are abundant on Ikuren Island. [Photographs by 

 E. S. Reese.] 



edge, the entire sequence of events has not been 

 observed. There are a number of questionable accounts in 

 the literature. It is important to note that the broken line 

 on old nuts found in the forest always passes through one 

 of the eyes. This is not true of the clean break made by a 

 man with a machette. Rats can gain access to nuts by 

 gnawing through the tough fiber and into the soft eye of 

 the nut. Rats do not shred the fiber from the nut, and, 

 therefore, nuts opened by rats are readily distinguishable 

 from those opened by crabs. Rats can gnaw into green 



nuts in the crown of the tree. Coenobita are unable to 

 open coconuts and must rely on what is left by Birgus and 

 rats. 



The population of coconut crabs on Ikuren Island was 

 studied periodically from 1960 to 1976 using tagging 

 recapture methods by Reese, Helfman, and their col- 

 leagues. These data will be part of a monograph on Birgus 

 latro which is in preparation. The population size on 

 Ikuren ranged from a low of 300 crabs estimated in April 

 of an exceedingly dry season to a high of about 1200 to 



