162 
TENTH REPORT. 
AN ECOLOGICAL STUDY OF THE BIRDS OF THE YPSILANTI 
BAYOU. 
Max Minor Peet. 
The observations included in this paper cover a period of six years and 
were made entirely by the writer. The area worked consists of about sixty 
acres, known as “the bayou” lying to the west and southwest of the Ypsi- 
lanti Highland Cemetery. This area includes a wide variety of conditions, 
embracing as it does, the cemetery proper, with its steep slopes, a large bayou 
with a stretch of flood-plain, and the river. Observations were made through- 
out the entire year and under all conditions of weather. In this small terri- 
tory all the environments which are usually spread over many square miles 
are brought together and are easily accessible. For this reason the place 
is particularly rich in bird and plant life. In fact, the complete list includes 
all the common and most of the rare birds to be found in Washtenaw County. 
The bayou alone offers exceptional opportunities for study from an eco- 
logical standpoint, because of the variety of conditions and the fact that it 
is practically free from changes due to man. It is further favorable in that 
it lies directly in a line of migration, the Huron River valley being well- 
known as a path for these birds. 
The results h re presented are the outcome of an attempt to compile a 
list of the birds found at the bayou together with the habitat relations of 
each species. Food, nesting sites and protection are the chief factors to be 
considered in such an investigation. 
It is an established fact that the flora of a region is dependant upon the 
environmental conditions. That birds of a limited area are dependant on 
the plant life of that particular area' I will attempt to show in the body of 
the paper. But since the plant life is dependant on the physiography of 
the region, which is the “resultant of the geological formations and the agen- 
cies at work modifying them,” it must change as the physiography changes. 
Therefore the bird life being dependant on the vegetation will also experience 
a similar change. The interrelations existing between the birds and plants 
and the environmental conditions are more clearly seen by considering 
the physiography in its dynamic or unstable condition. A knowledge of 
the changing conditions is therefore necessary to explain the distribution 
of the bird life in this region. In view of this fact the area was divided up 
into stations each representing a definite habitat. The change taking place 
in each station with the seasons necessitates dealing with each period sep- 
arately. Each habitat will be divided into four seasonal divisions beginning 
with spring. The divisions are based upon the migration records of the 
commoner species, and are as follows: March 1st to June 1st, spring; June 1st 
to Aug. 15th, summer; Aug. 15th to Nov. 1st, fall; Nov. 1st to March 1st, 
winter. The food of the principal species was determined both by stomach 
examinations and observations in the field. Observations on the relative 
abundance of available food were also made, and will be considered with 
the food habits. The nomenclature of the A. 0. Lb is used and Britton and 
Brown’s botany for the plant life. 
I wish to thank Dr. Hinsdale of Ann Arbor for his kind offer to bird s u dents 
