CHANGES IN ESSEX COUNTY AVIFAUNA. 
S. Gilbert Emilio. 
There is a constant though slow change in the avifauna 
of any locality. Though slow and gradual, it is noticeable 
even to constant observers. Dr. Townsend, in the supple¬ 
ment to his “Birds of Essex County,” dwells at some length 
on the changes in the last fifteen years. The writer, how¬ 
ever, has not been a constant observer of Essex County, 
birds for there is a break of fourteen years, during which he 
resided in the West. As a result, his impressions of the 
changes are rather strong. These impressions concern 
about thirty species, nearly half of which seem to have 
increased in numbers, and the other half decreased. In 
some there is a very certain and noticeable change, in others 
the yearly variation or the accident of observation may 
account for the prevailing impression. It may not be ill 
timed to say a word concerning that “accident of obser¬ 
vation,” by which is meant rather the error in determining 
the true state of affairs by the more or less casual obser¬ 
vations of any one individual. The spring meetings of 
our club brought out very clearly to the writer that there 
was variation in individual lists in even the same locality, 
and this must always be considered in dealing with the 
rather hurried observations to which most of us are limited. 
Quite possibly the high-powered binocular is responsible 
for the Iceland Gull records of recent years. I had never 
seen the bird to know it until the early spring of 1921. 
Common Terns are much more abundant, and I think Black 
Ducks and Night Herons can be considered the same; The 
Piping Plover is not yet very common by any means, but 
it is certainly more common than immediately prior to 1907. 
As for the Killdeer, it is a most striking and welcome addi¬ 
tion to our summer residents. A flock of sixteen, probably 
47 
