Observations were made at the Damm Farm on 102 days in the two-year
period beginning in Autumn, 1954; observations were concentrated in
the period from May to October although some observations were made in
every month, January and February excepted. Field work was done
chiefly in daylight hours but a few trips were made to the study area
at night.
Routine handling of each turtle captured at the Damm Farm consisted
of: marking, weighing and measuring turtle; recording the exact place
of capture, body temperature and environmental temperature; and,
recording miscellaneous items such as the presence of ectoparasites,
injuries, distinctive markings, and in some instances, the approximate
age of the turtle.
Excursions on the Damm Farm were made on foot in 1954 and 1955, and,
in 1956, on horseback. By using a horse, more ground could be covered
per unit of time, a better view could be obtained of immediate
surroundings, and, cattle on the area, being accustomed to horses, did
not become agitated as they would when unmounted persons were nearby.
The entire study area could not be inspected thoroughly in a single
day. It was usually more profitable to find and mark turtles along
fences, in ravines, or in other open areas, and subsequently to follow
their movements away from these areas by means of trailing threads.
Turtles could be observed from a distance through binoculars.
Cultivated areas were regularly scanned with binoculars but turtles
were seldom seen there. Behavior was observed by sitting motionless on
rock fences or in a blind on top of a stepladder.
No box turtles were removed from the study area. Specimens obtained in
other areas were used for studies of growth, reproduction, and food
habits. Measurements, weights, and data concerning temperature and
ectoparasites were obtained from specimens collected elsewhere as well
as from individuals on study areas.
Turtles were obtained by hand-collecting and in unbaited traps; the
number captured in a single day ranged from 12 to none. Traps, like
those used by Packard (1956:9) for tree squirrels, were set in the
mouths of burrows and dens, or--with leads to channel animals into the
trap--along ravines and rock fences. Traps set in the open were
covered to prevent death of turtles from overheating in direct
sunlight. Live-trapping provided much valuable data, although quail,
rabbits, opossums, and box turtles were caught with about equal
frequency in the traps.
Turtles were marked by notching the marginal scutes of the carapace by
means of a hacksaw blade, following the code system described by Cagle
(1939). Notches, one eighth to one quarter of an inch deep and wide
could be cut more quickly than filed and were more evident than
drilled holes which often became plugged with soil and obscured.
Hatchlings and juveniles were notched with a sharp knife.
Movements of individual turtles were studied by means of a
turtle-trailing device--similar to the kind first described by Breder
(1927) and later modified by Stickel (1950:355-356)--a tin can, cut to
fit the shell of a turtle, with an axle that bore a spool of thread
(Pl. 27, Fig. 1). The device was taped to the turtle; the free end of
the thread was tied to a stationary object. Thread payed out from the
spool through a guide-loop and marked the course of the turtle as it
moved away from the starting point. Because of its great strength and
elasticity (as compared to cotton), nylon sewing thread was used in
trailers. Ordinarily, turtles were unable to break the thread if it
became snarled or was expended. Cattle frequently tangled the thread
and displaced it but did not often break it. Ordinary spools were cut
down on a lathe so they would hold 600 to 800 yards of thread.
Turtle-trailing provided an accurate record of where and how far a
turtle had traveled, and to a lesser extent, the sort of activity in
which the turtle had been engaged (evidence of feeding, forms, or
trial nest holes). Trailers seemed not to alter the normal activity of
turtles.
Prominent landmarks were rare or wanting in most places on the
pasture. Locations of captures (or reference points in the movements
of trailer-turtles) were determined by triangulation with a Brunton
compass, using trees along fences as known points of reference. Rough
maps were made in the field and used later, along with compass
readings and measurements, to make a more precise record of movements
and captures on a large map (scale, 100 feet to one inch) of the study
area. Mapped points of capture in grassy areas were accurate within
ten to twenty feet; points of capture in areas where landmarks were
nearby were nearly exact. Areas were measured with a planimeter;
distances traveled by individuals were measured with a cartometer.
Turtles were measured in the field to the nearest millimeter with
large wooden calipers (of the type used by shoe salesmen) and a clear
plastic ruler. Measurements in the laboratory, especially in studies
of growth, were made, to the nearest tenth of a millimeter with dial
calipers. Measurements made on each specimen examined in the field
were: length of carapace, width of carapace, length of plastron (sum
of lengths of forelobe and hind lobe), width of plastron (at hinge),
and height. All measurements were made in a straight line. A spring
scale of 500 gram capacity, used in the field, gave weights accurately
within three grams. A triple-beam balance was used in the laboratory.
Unless otherwise noted, measurements are expressed in millimeters and
weights are expressed in grams.
Body temperatures were taken by means of a quick-reading Schultheis
thermometer inserted into the distal portion of the large intestine
with the bulb directed ventrally to avoid puncturing the bladder. Body
temperature of turtles were altered little or not at all in the few
seconds the turtles were held and no attempt was made (except for
small juveniles) to insulate them from the warmth of my hands. Data
recorded with body temperature were: air temperature (in shade,
approximately one inch from turtle); ground temperature (or water
temperature); behavior of turtle; weather conditions; nature of
vegetation or other cover; and, time of day. Unless otherwise noted,
temperatures are expressed in degrees Centigrade.
A maximum-minimum thermometer was installed near the buildings at the
Damm Farm. Notes on general weather conditions were made on each visit
to the study area. Additional climatological data were obtained from
the U. S. Weather Stations in Topeka and Lawrence, from records at the
Reservation, and from official bulletins of the U. S. Weather Bureau.
Stomachs and gonads were removed and preserved by standard techniques
soon after specimens were killed. The dates given to gonads were, in
all instances, the dates when the specimens were killed. Eggs were
prepared for incubation in the manner described by Legler (1956).
Females laying or containing eggs used in studies of incubation were
preserved for further studies and comparison with young hatched from
the eggs. Histological preparations were fixed in ten per cent
formalin or Bouin's fluid, embedded in paraffin, and stained with
hematoxalin and eosin.