t \ fJ i ■ ‘ 
[From The Johns Hopkins University Oiiculars, No. Ill, May, 1894 ] 
. 
THE FAMILY MNIOTILTIDAE IN BALTIMORE 
COUNTY. 
By J. HALL PLEASANTS, Jr| j 
(Abstract of an address delivered before the Baltimore Naturalists’ Field Club, March 
13,1894.) 
Up to the present time, some thirty-three species of warblers have been 
taken in Baltimore County and doubtless this number will be increased by 
future investigation. Of the two hundred and twenty-five, or more, species 
of birds going to make up the avifauna of this region, no family is as largely 
represented as the Mniotiltidae. Yet, with the exception of a few species, 
the average observer is entirely unconscious of the presence here, in im¬ 
mense numbers of these interesting, and for the most part highly colored, 
birds. This can to a certain extent be attributed to their retiring habits 
and diminutive size, few species exceeding six inches in length. If we wish 
to study the members of this group, they must be patiently and carefully 
sought after. They do not thrust themselves upon our attention. Largely 
migratory at this elevation and latitude, the majority pass through the 
county during late spring to their more northern breeding grounds, to re¬ 
turn southward again in early autumn. Many species remain here during 
the summer months to breed, and one, at least, spends the winter occasion¬ 
ally with us. During the periods of migration the warblers are very gener¬ 
ally distributed throughout the county, local conditions, such as differences 
in the flora and topography, playing but a comparatively small part in their 
distribution at this time. In the case of the summer residents, however, 
these factors enter largely into the choice of breeding places. Thus the 
district to the west of the city exhibits numerous peculiarities in its avi¬ 
fauna as Avell as in its geology. Here the blue-winged warbler ( Helmintho - 
phila pinus ), nowhere a common species, has been several times found nesting. 
Many similar cases could be cited. Moreover many species occurring through¬ 
out the entire county are especially abundant in certain sections. There 
also seems to be considerable fluctuation from year to year in the number 
of individuals of some species. 
Migration is generally performed at night, the greater part of the day 
being spent in procuring food. During the first three weeks in May and 
all through September the warbler migration is at its height. Some species 
however, as the Palm Warbler (Dendroica palmarum hypochrysea ), arrive 
much earlier and remain longer than this. 
In the following list the relative abundance, and the length of the stay 
of the various species with us, will be indicated briefly. In the case of a 
