According to the Yellow Book, Purple Martins are present in good numbers
through the end of August then quickly group up and head off south, with
only very small numbers left in  September and October, then not showing up
again until March.

 

I've had a Purple Martin house up for three seasons now and my observations
have been very close to the Yellow Book, at least until this year.  I live
beside Sinepuxent Bay, just south of Ocean City, and my community has many
Purple Martin houses.  All of them this year were empty, with no local
activity, from mid July.  My question is, could the brutal temperatures
during that part of July have led to nesting failures or other causes fort
the birds to leave at such an early date?

 

Norm Saunders