REMOVAL OF EGGS 
209 
just prior to her visit, and there was no trace of the 
fosterer’s missing egg near the nest, beside which 
the Cuckoo had remained for an exceptionally 
long time. The obvious conclusion is that she 
had swallow r ed the fosterer’s egg. But what is so 
curious is that the only tw r o occasions when the 
Cuckoo w r as seen to spend a long period by the 
nest Avas when the dupe’s eggs were incubated. 
One is tempted to wonder whether the Cuckoo was 
aware of it and deliberately set out to cool the eggs 
and so check their incubation ! 
p 
