Blackbirds at Christmas

Blackbirds have come back at Christmas      
They always do I have often wondered why,        
Do you know why ?      
In September  crabs are heavy with fruit and      
caterpillars eat fading leaves of  Solomon's Seal         
rivaling mother's lace and paper doilies ,    
angel cakes cooked on Fridays ,standing      
on plates of molded glass.      
There must be a reason,every thing has reason      
should we listen look or learn,maybe that's what        
blackbirds have done, when they return at Christmas.