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Summer 7-10-1973 The omeH Range and Habitat Preferences of Swamp Rabbits Along a Shell Road in the Intermediate Marsh of Southwestern Louisiana Arthur Benjamin Gould Jr. Louisiana State University and Agricultural and Mechanical College
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Recommended Citation Gould, Arthur Benjamin Jr., "The omeH Range and Habitat Preferences of Swamp Rabbits Along a Shell Road in the Intermediate Marsh of Southwestern Louisiana" (1973). LSU Historical Dissertations and Theses. 8242. https://digitalcommons.lsu.edu/gradschool_disstheses/8242
This Thesis is brought to you for free and open access by the Graduate School at LSU Digital Commons. It has been accepted for inclusion in LSU Historical Dissertations and Theses by an authorized administrator of LSU Digital Commons. For more information, please contact [email protected]. THE HOME RANGE AND HABITAT PREFERENCES OF SWAMP RABBITS ALONG A SHELL ROAD IN THE INTERMEDIATE MARSH OF SOUTHWESTERN LOUISIANA
A Thesis
Submitted to the Graduate Faculty of the Louisiana State University and Agricultural and Mechanical College in partial fulfillment of the requirements for the degree of Master of Science
i n
fhe School of Forestry and Wildlife Management
by
Arthur Benjamin Gould, Jr. B.S., Auburn University, 1969 May, 1974 MANUSCRIPT THESES
Unpublished theses submitted for the Master's and Doctor's
Degrees and deposited in the Louisiana State University Library are available for inspection. Use of any thesis is limited by
the rights of the author. Bibliographical references may be
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A Library which borrows this thesis for use by its clientele
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LOUISIANA STATE UNIVERSITY LIBRARY ACKNOWLEDGEMENTS
I wish +o thank the United States Department of the Interior,
Bureau of Sport Fisheries and Wildlife, and the Louisiana Wild Life and Fisheries Commission, for providing financial assistance through the Louisiana Cooperative Wildlife Research Unit.
Special thanks are extended to Mr. John D. Newsom, Leader of the Louisiana Cooperative Wildlife Research Unit, for his advice and assistance as Project Leader.
For the use ot the facilities at Rockefeller Wildlife Refuge, appreciation is extended to the Louisiana Wild Life and Fisheries
, r nr. + i+l,de noes to the Rockefeller Commission. A special note o g i. TpH Joanen, Research Leader; Mr. Wildlife Refuge personnel. Mr. lea j I M M Rinloa i st• and Mr. Howard Dupuie, Biologist, for their Larry McNease, Biologisi, emu
help and advice throughout this study. , . . nr A W. Palmisano, Assistant Appreciation is extended to Dr. a . • • rxwtprative Wildlife Research Unit, for his Unit Leader, Louisiana Coopera
technical assistance and editorial advice. Thanks are given to Dr.
L. L. Glasgow and Dr. R. B. Hamilton, School of Forestry and Wildlife
, joo Hnrina the preparation of this manusenp Management, for their advic . , +n nr Prentiss E. Schilling, Associate Gratitude is extended to Dr. Prenr.ss . I c+-,+ ; sties, for Statistical advice. Professor of ExperimentaI St • + ro Hurinn many phases of this study, apprecia- For their assistance during many y , 4-,s <- +1irinn+s Tom Hess and Steve tion is extended to fellow graduate students, lom Dubois, and to David Arnoldi for his help with photography. Special thanks are given to Jim Gebhart for his assistance in trap construc tion and many other phases of this study.
Finally, special appreciation is extended to my wife Lynda for her patience and encouragement throughout this study. TABLE OF CONTENTS
Page
TITLE P A G E ...... ,
ACKNOWLEDGEMENTS...... j j
LIST OF T A B L E S ...... v ,
LIST OF F I G U R E S ...... vJ j
ABSTRACT...... j x
I N T R O D U C T I O N ...... ,
Previous W o r k ...... I
LOCATION AND DESCRIPTION OF STUDY AREA ...... 6
Location ...... 5
Description ...... 5
Climate ...... g
METHODS AND MATERIALS ...... 12
T r a p p i n g ...... 12
T a g g i n g ...... 13
Population Estimates ...... 13
Information Obtained from Each Animal ...... 14
Radio Telemetry...... 17
Radio Transmitters...... 17 Radio Receivers and A n t e n n a s ...... 18 Fitting Radio Transmitters ...... 18 Field Testing of Radio Equipment ...... 19 Radio Tracking Procedures ...... 20
Determining Home Range ...... 20
Determining Habitat Preferences ...... 21 Page
RESULTS AND DISCUSSION ...... 23
T r a p p i n g ...... 23
R e s u l t s ...... 23 Discussion...... 24 Accidental Captures ...... 25
Ear Tags and S t r e a m e r s ...... 25
Population Estimates ...... 26
Radio Telemetry...... 28
Transmitter Performance ...... 28 Individual Movements ...... 29
Rabbit 1 3 5 ...... 31 Rabbit 1 3 6 ...... 31 Rabbit 1 2 6 ...... 36 Rabbit 1 5 9 ...... 36 Rabbit 1 8 3 ...... 36 Rabbit 1 3 8 ...... 41 Rabbit 1 6 3 ...... 46 Rabbit 1 0 4 ...... 46 Rabbit 1 7 5 ...... 50 Rabbit 1 2 4 ...... 50 Rabbit 4 ...... 58
Habitat Preference ...... 66
Basic Habitat Types Utilized ...... 66
Preferred Habitat Components ...... 66
D i s c u s s i o n ...... 72
W e i g h t s ...... 72 Population Density ...... 73 Home Ranges ...... 73
SUMMARY ...... lb
A P P E N D I X ...... 77
LITERATURE CITED ...... 79
VITA ...... 82
v l is t of tables Page Tab I e 1. Climatological data for Rockefeller Wildlife Refug^ ^ ^ for 1968 through 1972 ......
2. Monthly climatological data tor R ° cl'e |’®' t o y t through Refuge for the study period from October 1972 through (f May 1973 ......
3. Rabbits caught per trapping®wMdlife Refugerlouisiana habitat types on Rockefel ler W, Idh te Ke g , 22 during October 1972 through May 1973 ......
4. The average home range of swamp ^bb'ts a^ ® } ® rBa, anCe with a polar plan.meter and a »•++!er t ^ ^ + he from data collected wi|dMfe Refuge, intermediate marsh of Rocketeiie ...... 30 Louisiana ...... , raH Inration of observations made on 5. The? number, a is type and l°ca intermediate marsh ?s 1972 through May 1973 ...... LIST OF FIGURES
Figure Page
1. Location of Rockefeller Wildlife Refuge ...... 7
2. Rockefeller Wildlife Refuge showing study area .... 9
3. Rabbit fitted with radio transmitter and ear tag . . . 16
4. The author fitting a rabbit with a radio transmitter. . 16
5. Minimum home range of male rabbit 135, 21-29 October 1972 32
6. Relative movements of male rabbit 135 during a 24-hour period, 26-27 October ...... 33
7. Minimum home range of female rabbit 136, 21-29 October 1972 34
8. Relative movements of female rabbit 136 during a 24- hour period, 26-27 October ...... 35
9. Minimum home range of male rabbit 126, 27 October - 15 December 1972 ...... 37
10. Relative movements of male rabbit 126 during a 24-hour period, 9-10 N o v e m b e r ...... 38
11. Minimum home range of female rabbit 159, 27 October - 15 December 1972 39
12. Relative movements of female rabbit 159 during a 24-hour period, 9-10 Novem b e r ...... 40
13. Minimum home range of male rabbit 183, 19 January - 10 February 1973 42
14. Relative movements of male rabbit 183 during a 24-hour period, 1-2 Fe b r u a r y ...... 43
15. Minimum home range of female rabbit 138, 15-23 February 1973 44
16. Relative movements of female rabbit 138 during a 24-hour period, 15-16 February ...... 45
17. Minimum home range of male rabbit 163, 11-13 March 1973 47
vi i Figure Page
18. Relative movements of male rabbit 163 during a 24-hour period, 11-12 March ...... 48
19. Minimum home range of female rabbit 104, 2 February - 21 March 1973 ...... 49
20. Relative movements of female rabbit 104 during a 24-hour period, 15-16 February ...... 51
21. Relative movements of female rabbit 104 during a 24-hour period, 11-12 March ...... 52
22. Minimum home range of female rabbit 104 during nesting, 21 March - 5 April 1973 ...... 53
23. Minimum home range of male rabbit 175, 30 March - 9 May 1973 ...... 54
24. Relative movements of male rabbit 175 during a 24-hour period, 5-6 Apri I ...... 55
25. Relative movements of male rabbit 175 during a 24-hour period, 12-13 ApriI ...... 56
26. Relative movements of male rabbit 175 during a 24-hour period, 26-27 April ...... 57
27. Minimum home range of male rabbit 124, 13-22 May 1973 . . 59
28. Relative movements of male rabbit 124 during a 24-hour period, 14-15 M a y ...... 60
29. Relative movements of male rabbit 124 during a 24-hour period, 21-22 M a y ...... 61
30. Minimum home range of female rabbit 4 during nesting, I 1-22 May 1973 ...... 62
31. Relative movements of female rabbit 4 during a 24-hour period, 14-15 M a y ...... 63
32. Relative movements of female rabbit 4 during a 24-hour period, 21-22 M a y ...... 65
33. Roseau cane-baccharis-wiregrass habitat type on study area, 21 May 1973 ...... 68
34. Wiregrass-short baccharis habitat type on study area, 21 May 1973 ...... 63
35. High baccharis-wirgrass habitat type on study area, 21 May 1973 ...... 70 vi i i ABSTRACT
The objective of this study was to determine the home range and habitat preferences of swamp rabbits in the intermediate (between brackish and fresh) marsh of southwestern Louisiana.
A total of 12 instrumented rabbits provided data for home range estimates. Four rabbits were followed during the fall, winter and spring. Average home range for males was 10.60 acres and 5.14 acres for females on an area which had a population density of 7.74 rabbits per acre.
The most preferred habitat components were wiregrass with baccharis
less than four feet tall lightly interspersed. Baccharis over four
feet tall with moderately interspersed wiregrass was second, wifh roseau
cane and baccharis over four feet tall lightly interspersed with wire-
grass third. Solid wiregrass stands were the least preferred habitat
type.
Weights of 21 adult males averaged 1831 grams, 27 adult females
averaged 1965 grams, 9 immature females averaged 1472 grams and 4 im
mature males averaged 1601 grams.
Swamp rabbits were generally crepuscular. INTRODUCTI ON
Whether it is called cane-cutter, swamper, or marsh rabbit, the swamp rabbit (Sylvilaqus aquaticus Bachman) is one of the most prized small game species in the areas in which it occurs. Of the estimated 110,000 rabbit hunters in Louisiana, more actually hunt swamp rabbits than cottontails (Sylvilaqus floridanus Allen) because swampers are larger and provide more meat for the table (Collins
1962). Swamp rabbits also provide a long chase proving a challenge to the hunter as well as to his dogs.
With the clearing of bottomland hardwoods and draining and plowing of much of the marsh of southwest Louisiana for rice produc tion and pasture, numbers of swamp rabbits will likely decline. The one limiting factor in agricultural land is adequate cover in areas
where food is available (Sims I960). As more of the marsh is drained,
those areas which remain, such as the spoil levees built to help keep
these areas drained, should be managed so that the maximum number of
rabbits can be maintained. The types of habitat required for swamp
rabbits and the space utilized by each individual rabbit must be
determined in order to efficiently manage this species.
Previous Work
Comparatively little research has been conducted on swamp rabbits
in contrast with the voluminous amount done with cottontail rabbits. 2
However, the two species occupy different ecological niches, and except for recent studies of census techniques (Eberhart, Peterle and
Schofield 1963; Edwards and Eberhart 1967), findings from cottontail studies usually do not apply to swamp rabbits.
Litter size and gestation periods of swamp rabbits have been observed and reported by several investigators. Audubon and Bachman
(1846) reported they "had been told" that the litter size ranged between 4 and 6 young. In a study of swamp rabbits south of Morgan
City, Louisiana, Svihla (1929) found litter sizes to vary from I to
6 young. Hastings (1954), in a study in Louisiana, found litter size
to average 2.94 young, the gestation period to be 28 to 32 days, and
the major breeding season to be from February I to October 15 with
some breeding during the rest of the year. Lowe (1958) found that the
average litter size in Georgia was 2.6 young. Toll (1958), in Missouri,
determined that mean potential litter size was 3.7 by corpora Iutea
count, 2.8 by the number of embryos in utero, and 3.4 by placental scar
counts. Hunt (1959) found that in Texas the gestation period for swamp
rabbits ranged from 39 to 40 days and the litter size averaged 2.83
young. Holler, Baskett and Rogers (1963) found the gestation period
of confined swamp rabbits in Missouri to range from 36 to 38 days, and
mean litter size to be 4.8 young. In Alabama, Hill (1967) found the mean
litter size for first and second conceptions of free rabbits to be 2.863
and 3.176, respectively.
Harrison and Hickie (1931) reported swamp rabbit weights ranging
from 1409 to 2474 grams in Indiana. Hastings (1954) reported weights 3
in Louisiana averaged 4.49 pounds (2240 grams) for adult males,
4.30 pounds (1952 grams) for adult females and a sex ratio of 34 males to 35 females. Toll (1958) reported average weights of males in Missouri to be 4 pounds 8.5 ounces (2057 grams) and females to be 4 pounds 8.3 ounces (2052 grams) with no significant difference between males and females whether young or presumed adults. Lowe
(1958) found mean adult male weights in Georgia to be 1895 grams and mean adult female weights to be 1951 grams. Holten and Toll (I960)
studied winter weights of swamp rabbits in southeastern Missouri and
determined the average weights to be 2235 grams for adult males, 2161
grams for adult females, 2022 grams for juvenile males, and 1954 grams
for juvenile females. Croft (1961), in Louisiana, found the average
weight of adult males to be 65.33 ounces (1803 grams) and 63.34 ounces
(1804 grams) for adult females. Hill (1967) reported mid to late
February weights in Alabama to range from 2722 to 1021 grams and a sex
ratio of 46 percent males to 54 percent females.
Food habits were studied in Louisiana by Svihla (1929) who determined
that each rabbit, on an average, ate half of its weight each day. Smith
(1940) studied the food habits of swamp rabbits in lowland areas of
Oklahoma and found cane to be a preferred food. The food habits of
swamp rabbits in the vicinity of Reel foot Lake, Tennessee were reported
by Calhoun (1941). Bryant (1954) studied penned rabbits in Louisiana
and found pasture grasses and clover to be preferred. Croft (1954)
studied food habits on managed units in Louisiana. Sullivan (1963) 4
and Garner (1969) studied the food habits of rabbits in bottomland hardwoods of Louisiana. Richardson (1963), in Louisiana, studied the daily consumption of confined swamp rabbits and found the average daily consumption to be .53 pounds with soybeans, white clover, dock and giant ragweed being preferred foods.
The home range of swamp rabbits in Georgia was determined by Lowe
(1958) using the beagle chase technique to average 18.9 acres in an area with a population density of 5.6 rabbits per 100 acres. Trapping and beagle chase techniques were used by Toll (1958) and Toll, Baskett and Conaway (I960) in Missouri to determine home range. It was found
from trapping results that the home range for females averaged 5.9
acres, arrived at by the trap squares method, to 2.1 acres by the
minimum home range method. The home range for males, calculated by
the same methods, ranged from 4.6 acres to 1.8 acres. Using the beagle
chase method, minimum home ranges were 5.5 acres for females and 7.9
acres for males.
Other general investigations include Sherman (1939) who reported the
presence of swamp rabbits in South Carolina. Conaway, Baskett and Toll
(I960) reported on embryo resorption. Aye criteria and population
dynamics of the swamp rabbit in Missouri were studied by Martinson,
Holten and Brakhage (1961) using the criterion of epiphyseal closure
and lens weight for age determination and collected rabbits for popula
tion studied. The behavior of confined swamp rabbits was reported by
Marsden and Holler (1964). Farlow (1968) studying parasites in rabbits 5
in Louisiana found only one species of tick (HaemaphysaIis leporis pa Iustri s Packard) and no fleas on rabbits in intermediate marsh hab itat.
This study was an attempt to add to the knowledge of swamp rabbits, particularly in the Louisiana coastal marshes. The objec tive was to determine home range and habitat preferences of swamp rabbits in the intermediate marsh of southwestern Louisiana.
Two terms used in this report which need clarification are def i ned as foI lows:
Minimum Home Range: That area utilized by the rabbit during its
normal daily activities.
Maximum Home Range: That area utilized by the rabbit which is
outside its center of activity and is not normally used during
daily activities. 6
LOCATION AND DESCRIPTION OF STUDY AREA
Location
This study was conducted on Rockefeller Wildlife Refuge in
Cameron and Vermilion Parishes, Louisiana (Figure I). Rockefeller
Refuge is about 85,000 acres in'size and is approximately 5-7 miles wide and 35 miles long. It is owned and managed by the Louisiana
Wild Life and Fisheries Commission. It is bounded on the north by the Grand Chenier-Pecan Island stranded beach ridge complex and on the south by the Gulf of Mexico (Joanen and McNease 1970).
Descr i pt ion
The coastal marshes of Louisiana in Cameron and Vermilion Parishes
occupy approximately 760,000 acres and are considered proi r i omarshes.
Early deltaic deposits form a well-defined beach line which borders
the Gulf. The stranded sea rims which were formed during periods of
deposition and by the receding Gulf are called chenieres. These
chenieres and the man-made levees are the only high ground in this
area (O’Neil 1949).
The intermediate or slightly brackish marsh zone is characterized
by wiregrass (Spartina patens (Ait.) Muhl), coco (Scirpus robustus
Pursh), roseau cane (Phragmites communis Trin), hog-cane (Spart i na
cynosuro i des (L.) Roth), and buckbrush (Baccharis halimifolia L.)
(O’Neil 1949). 7 8
The area of Rockefeller Refuge on which this study was conducted was a two-mile long shell covered levee-road in an intermediate marsh
located in western Vermilion Parish (Figure 2). The plants on this area include vast stands of roseau cane, baccharis, and wiregrass.
Along the levee road, these vegetational types were well-defined and
formed four major habitat types. These types consisted of extensive
stands of roseau cane and baccharis over four feet tall with lightly
interspersed wiregrass; baccharis over four feet tall with moderately
interspersed wiregrass; wiregrass with baccharis under four feet tall
lightly interspersed; and vast stands of wiregrass. These types were
located in this order from north to south along the levee-road. The
plants on the road and road shoulders included dock (Rumex sp. L.),
rye grass (LoIi urn sp. L.), clover (Tr i fol i urn sp. L.), da I Ii s grass
(Paspalum di latatum Poiret), and dandelion (Taraxacum o fficinal
Wiggers).
Water areas include a canal approximately 30 to 40 feet wide on
the east side of the levee-road, a small ditch on the west side, and a
lake complex on the western side of the ditch. The water in these
systems is affected by tidal action as well as by rainfall. During
much of the study period, these water areas remained in an almost
flooded condition due to unusually heavy rains and strong southerly
winds which created higher than normal tides.
Climate
The climate of southwestern Louisiana is considered subtropical; k 10
winters are generally mild, but during this study period, the area experienced three snows accompanied by freezing rain and low tempera tures. Temperature averages ranged from a high of 85 F° for Oc+ober
1972 to a low of 40 F° for January 1973. Monthly precipitation ranged from a high of 11.40 inches during April 1973 to a low of 2.52 inches for February 1973. Temperatures and rainfall during the study period as well as yearly averages for 1968-1972 are presented in Tables I and 2. Table I. Climatological data for Rockefeller Wildlife Refuge for 1968 through 1972 a/
Average Temp.______Total Precipitation — Degrees F. — 1nches- 1968 66.9 51.17
1969 68.2 41.99
1970 67.4 56.35
1971 68.9 58.90
1972 68.9 63. 15
0 j -Provided by Rockefeller Wildli fe Refuge
Table 2. Monthly climatological data for Rockefeller Wildlife Refuge for,the study period from October 1972 through May 1973 -
Date Temperature Preci p i taf i on Avg. Max. Avg. Min. Avg. Tota I — Degrees F.— — Inches— Oct. 1972 82 61 72 4.50 Nov. 1972 65 49 57 7.20
Dec. 1972 63 45 54 5.58 Jan. 1973 56 40 48 4.03 Feb. 1973 60 42 51 2.52 Mar. 1973 71 57 64 4.96 Apr. 1973 73 57 65 I I .40 May 1973 81 67 74 5. I 3
b/ Provided by Rockefeller Wildlife Ref uge 12
METHODS AND MATERIALS
Trappi ng
Live-trapping was used to obtain rabbits for population studies and for telemetry work. The traps used were of two types as des cribed by Garner (I960). One type was a factory built weld-wire
live trap made by the National Live Trap Company. This trap had hinged doors on both ends and was 9 by 9 by 32 inches with a sol id center metal trip plate. The other type was made of I by 2 inch welded wire and measured 10 by 10 by 36 inches. The center trip
plate was made from the same material and measured 8 by 6 inches.
A wire was attached to the trip plate, passed through loops on the
top of the trap and was then attached to a wire trigger which held
the single door of the trap open. A coil spring was attached to the
door and then to the outside of the trap so that the door would be held
firmly in place once the trap was tripped.
In order to completely cover the study area, the two types of
traps were placed in an alternating pattern at 100-foot intervals
along the two-mile long levee-road. Each trap site was marked with a
colored marker so that capture sites of individual rabbits would be known
for the duration of the study.
Four baits were tested to determine bait preferences of swamp rabbits.
These baits were carrots, sweet potatoes, Irish potatoes, and apples.
All of the baits except apples were unsatisfactory and very unreliable. 13
During this study, a small piece of apple was placed in front of the door, another small piece was placed just inside of the trap and a large piece was placed at the rear of the single door traps and in the middle of the double-door traps so that the rabbit would be led into the trap.
Tagging
Numbered commercial disc-type (National Band & Tag Company,
Newport, Kentucky) ear-tags were used to identify individual rabbits.
These were placed in a hole in the ear that had been punched with a commercial ear punch. The tag was placed through this hole and an aluminum washer was then attached. A spacer was placed between the ear and the washer before the tag was bent to make it hold, then the spacer was removed. The spacer was used to prevent the tag and the washer from fitting too tightly against the ear (Figure 3).
Colored Saflag streamers made by the Safety Flag Company of
America were also placed between the ear and the washer so that marked animals could be easily identified (Figure 3). Four colors were used so that individuals could be identified as to age and sex. Red was used for adult males, yellow for adult females, orange for immature males, and blue for immature females.
Population Estimates
Colored ear streamers were used to identify marked animals for the
purpose of making population estimates. The entire road on the study
area was driven at 2000 hours on nights when conditions permitted. 14
The number of marked and unmarked rabbits seen along the road and roadside was recorded. Later, a population estimate was made for the study area using Bailey's Modified Petersen Index (Bailey 1951).
Only rabbits that were positively identified as being either marked or unmarked were recorded.
Information Obtained from Each Animal
Upon capture, age and sex were determined by visual inspection of the genitalia. In most cases, the distinction between adults and
immatures was easily recognizable during the early fall trapping period. However, in the late fall and throughout the remainder of the study period, all were recorded as adults.
The weight of each rabbit was determined by putting the animal in a cloth bag and hanging it on a dairy scale. The weight was recorded
to the nearest tenth of a pound. The scale was constantly rechecked for accuracy by using known weights. The weight of the cloth bag and rope was negligible and did not register on the scale. When an individual
was recaptured, the weight was again taken and recorded.
The general condition of each individual was recorded and additional
information such as injuries, physical defects, presence of external
parasites and occurrence of lactation in the females was also recorded
under the heading of general comments. Recaptured individuals were
recorded and the date of the original capture was noted. 15
Figure 3. Rabbit fitted with radio transmitter and ear tag.
Figure 4. The author fitting a rabbit with a radio transmitter. 16 17
Radio Telemetry
Sgjjjp Transmitters
Nine transmitters which were purchased from James
Carbondale, Illinois, at a cost of approximately $60.00 per
Were used in this study. These transmitters were equipped wi whiP antennas bent into a loop to fit around the neck of a rabb and each transmitter was coated with dental acrylic y
facturer. Each antenna was protected by a plasfic i 4-K the antenna. plas+»c coated wire which was used to add strenq Tk • f iarae enouqh to f'* ^ e antenna and wire made a loop which was Ju> ll and sma I I °Ver a rabbit’s head and ears. At first, a loath- h t later 3/3“" meta| pop-rivets were used as the attachment dev’
'nch wide copper bands covered with electrical P . . u f a n e then Proved very satisfactory. Each unit was covered wt , leaving only two c°ated with epoxy to make the whole unit waterpro ,
wires exposed for the final solder connection. • ,i0 4 2-volt T w_<- a single 4•*- 'tie power source for the transmitter.- •-i-4-prs ccnsco Mal|ory Duracel battery. During the study when tran, to r battery was connected. unction, they were recovered and a new c . as three tunes Sorne °'f the units were recovered and repaired
nb one unit was repaired four times. D . +he two exposed wires
1 i°r to placing the unit on +he ra 1 ’ were • + > These wire^ Were soldered together thus completing the eircu 18 then coated with Plas-T-Pair(The Rawn Company, Spooner, Wisconsin) to protect the connection from corrosion. The average weight of each completed unit was 58.6 grams which was less than five percent of the body weight of each rabbit fitted with a transmitter.
Radio Receivers and Antennas
The radio receiver used in this study was an AVM Model LA-12 purchased from the AVM Instrument Company, Champaign, Illinois, at a cost of $600.00 and was the same as described by Taylor (1972) and
Bittner (1973). This AVM receiver had a frequency range of 150.800
MHz to 151.075 MHz. The unit was very light, compact and dependable.
It was powered by eight 1.5-volt AA batteries which remained at near full power after 16 to 20 hours of continuous use. With this receiver, a two-element hand-held antenna was used. The ease with which this equipment could be handled and operated certainly made it a desirable choice for this type of study.
Fitting Radio Transmitters
After the final connection had been made and coated, the loop antenna and reinforcing wire were placed over the head of the rabbit. The ends of the copper band were placed over each other until the proper fit for the individual rabbit was attained. A metal pop-rivet was then placed through holes in each end of the copper band and a washer was placed over the end of the rivet next to the rabbit. Once the rivet and washer were in place, the radio was secure and properly fitted (Figures 3 and 4). 19
Field Testing of Radio Equipment
Before each transmitter was coated with tape and epoxy, it was tested to determine the range at which it could be received and at exactly what frequency it could be received best. Each unit was tested at one thousand feet and if the signal received was strong and steady, it was recorded as one thousand feet plus. All but one of the units operated well at this distance. The testing required that each unit be placed on the ground and the required distance be paced off by the author. After a satisfactory test, the unit was taped and coated with epoxy.
When a rabbit of the desired sex and age was captured, the final connection of the transmitter was made by soldering the two exposed wires together. Again, the unit was tested to see if it was working properly. If the unit was functioning as it should, the two wires were coated with Plas-T-Pair and allowed to dry. This drying usually took no more than 15 minutes at which time the unit was again tested.
The unit was then placed on the rabbit and tested again before re leasing the animal. Upon initial release, the unit was tested and then a minimum of 10 hours was allowed to elapse before starting to take fixes on the animal. This time period was used in order to let the rabbit resume its normal behavior pattern after being handled. In many cases, 24 hours elapsed before data collection was initiated for use in determining home range. 20
Radio Tracking Procedures
Two permanent observation points were established for each
radio transmitter in the field from which directional compass bearings
were taken. These observation points were established after each
rabbit fitted with a radio transmitter had been released. The
distance at which each transmitter could be received was determined
north and south of each released rabbit and permanent observation
points were established just within maximum limits for reception. At
one-hour intervals, the direction to each rabbit was determined by
taking the compass bearings of the two fade-out points in the direction
of the rabbit. These two bearings were recorded and the angle formed
was recorded; this angle was then bisected and the direction obtained
was recorded as the direction to the rabbit. Using the bearings thus
obtained from two observation points, triangulation was used to deter
mine the exact location of each rabbit. On a few occasions, visual
observations were used for locating rabbits. A time lapse of no more
than three minutes was required to make the observations, thus helping
to give a very good estimate of the position of each rabbit. In most
cases, there were no more than two rabbits fitted with transmitters in
the field at one time. Several 24-hour sets of data were taken for each
rabbit as long as each transmitter unit continued to operate.
Determining Home Range
Two methods were employed in determining the home range of the
radio equipped rabbits after locations had been plotted. The first 21
method consisted of using a polar pI animeter to determine the home
range by the minimum home range method (Mohr and Stumpf 1966).
This procedure was repeated four times and an average of the four at
tempts was taken to provide the home range estimate. The other method
consisted of comparing the weight of a known area with that of the
area plotted as a home range when each was cut out of the same chart
paper. A Mettler Electronic Balance-Model P-1200 was used to take
these weights. The final home range was then calculated by taking an
average of the two methods for each rabbit.
Determining Habitat Preferences
The preferences of rabbits for certain habitat types was determined
primarily through observations made by the author. The number of rabbits
observed along the roadside in the three major habitat types and their
location were noted when population counts were made as well as during
the time that radio monitoring was taking place. Since only rabbits
along the roadside were noted, there was no differential visibility
among different habitats. An attempt was made to correlate trapping
records within vegetational types to determine habitat preferences, but
there were too many variables (weather, number of traps, different
seasons, etc.) to draw any statistically sound conclusions (Table 3 ). 22
Table 3. Rabbits caught per trapping effort in different habitat types on Rockefeller Wildlife Refuge, Louisiana during October 1972 through May 1973
* Habitat type No. traps No. rabbits rabbi ts/effort
Roseau-bacchari s- wi regrass 100 14 .140
High baccharis- wi regrass 125 17 .136
Short baccharis- wi regrass 135 24 .178
* Trapping data from first two weeks in each habitat type. 23
RESULTS AND DISCUSSION
Trapp i nq
ResuIts
From 6 October 1972 un+i I 14 May 1973, trapping operations were conducted on the study area. A total of 61 rabbits was captured, weighed and examined during this period. Weights for
21 adult males ranged from 1589 to 2225 grams with an average of
1831 grams, a standard deviation of 42.89 and with the 95 percent confidence interval being 1742 to 1921 grams. Twenty-seven females had a weight range of 1452 to 2361 grams with an average of 1965 grams, a standard deviation of 50.40 and with the 95 percent confi dence interval being 1861 to 2069 grams. Few immature rabbits were captured during the study period. The weight of nine immature females ranged from 1134 to 1725 grams with an average of 1472 grams, a standard deviation of 72.32 and with the 95 percent confidence interval being
1302 to 1639 grams. The weight of four immature males ranged from
1226 to 1861 grams with an average of 1601 grams, a standard deviation of 142 and with the 95 percent confidence interval being 1149 to 2153 grams.
While examining each individual rabbit, it was noted that there was a conspicuous absence of ectoparasites. Although the author ex pected to find some ticks and fleas on a number of the rabbits, no ectoparasites were found on any of the animals throughout the study 24
period. Although Farlow (1968) found no fleas and only one species of tick on rabbits in this same marsh habitat, the author observed heavy infestations of fleas and ticks on swamp rabbits in the bottom
land hardwood habitat type in Iberville Parish, Louisiana.
Lactation in the females was noted as late as early November and
then was noted again beginning mid February indicating a very long
breeding season among these rabbits.
Discuss ion
The use of apples as a bait proved very successful during all
seasons in which the study was conducted. It was found that it was ad
visable to pre-bait the area for two days prior to trapping. Even when
new succulent growth was available, the rabbits could be captured readily
by using apples for bait. The use of lead-in fences was considered, but,
in the opinion of the author, was impractical under the conditions which
prevailed.
Both types of traps proved to be effective. The traps made by the
author needed minor but constant repairs due to damage by animals such as
raccoons (Procyon lotor L.), opossums (Didelphis virginiana L.), and
armadillos (Dasypus novemcinctus L.). These animals broke trip wires and
occasionally trip plates and doors were bent and broken. Mink (Mustela
vison Schreber) predation was a major problem which arose during trapping
operations and it occurred on trapped rabbits as well as on those which
had been ear tagged or fitted with radio transmitters and released. In
the opinion of the author, however, there was not a high degree of diff
erential vulnerability between tagged animals and non-tagged animals, but 25
it was easier to notice predation on individuals which had been marked. In most cases, only a smaI I amount of fur and the ear tag or radio transmitter was found after a rabbit had been killed. There was a high mink population on the levee-road due partially to abnormally high water conditions during most of the study period. Predation seemed higher in areas composed of baccharis over four feet tall with moderately
interspersed wiregrass, the reason for which was not determined.
Accidental Captures
Several animals other than swamp rabbits were captured during the
764 trap-night trapping period. These included 15 opossums, 10 raccoons,
4 nutria (Myocaster coypus Molina), 4 armadiIlos, one 4-foot all igator
(Alligator mississipiensis Daudin). one Clapper Rail (RalI us longirostris
Boddaert), one Brown Trasher (Toxostoma rufum L.), and one mink.
It was thought by the author that the raccoons and opossums were
attracted by the bait and that the others, except for the mink, wandered
into traps set in their paths. It was assumed the mink entered a trap
because of the rabbit smell associated with it.
Ear Tags and Streamers
The use of numbered commercial metal ear tags proved very
satisfactory in most cases. When ear tags were fitted too tightly,
the ear became infected and a portion of the ear, as well as the ear
tag, was lost. This happened very infrequently until the latter part
of the study, however, and was not considered to be a major problem. 26
The Saflag streamers lasted well and, in some cases, streamers attached at the beginning of the study were still in good condition at the end of the study. Orange was the color most easily seen with red being next most easily seen, then yellow and blue.
Population Estimates
Visual counts were made to estimate populations at approximately
2000 hours on nights that were clear and cool, when there was little wind. These conditions seemed to be the best for maximum numbers of rabbits to be using the levee-road and for maximum visibility of the ear streamers on the rabbits. Bailey's Modified Petersen Index
indicated a population for the study area of 131.4 rabbits with a standard deviation of 9.54. The 95 percent confidence interval placed around the population mean was 110.94 to 151.56 animals. The area on which population counts were made was two miles long, averaged 70 feet wide and had 16.96 acres. The estimate for rabbits per acre on the study area was 7.74 with the 95 percent confidence interval being 6.54 to 8.95 rabbits.
It should be understood that the rabbit population estimate provided here is maximum. Even though all rabbits enumerated were within the 70 foot strip along the shell road this does not imply that their home ranges were restricted to that area. Reference to the
figures delineating home ranges as established by radio telemetry shows extensive use by rabbits of the wiregrass marsh adjacent to the shell road. In reality the shell road, which is the only high 27
ground in the vicinity of the study area, probably serves as an area of concentration, and the indicated population density is much higher than the true density.
The estimates were made from 24 November 1972 until 22 March
1973. At that time, the author felt the loss of ear tags and the loss of rabbits to predation reached a level where accurate estimates could no longer be made. The maximum number of tagged rabbits in the field at one time was 45 and it became increasingly difficult to keep that number marked. Density of the vegetation along the roadside also presented a problem since it became increasingly difficult to determine whether or not rabbits seen were marked or unmarked. Due to these conditions, population estimates were discontinued. 28
Radio Telemetry
Transmitter Performance Performance of the radio transmitters proved to be a mayor n+,v transmitters would not obstacle throughout the study. requ. _ . „ , ;n+hree instances, stopped operating function a full week and in thr , „hbit. One transmitter continued same day they were attached to a r • a of two months and two days to operate satisfactorily for a perio , . . j the transmitter iri l led by a mink and tfie at which time the rabbit was , . The primary source of was recovered still operating but dam 9 rnroof n inside the waterprooi trouble seemed to be moisture conden rorroded. • r |n most c q s o s f epoxy coating. The battery connocti - the unit mixture or corrosion -as noted In many cases, however, no mo +h problem ■ • n-,ttery life seemed not was still not functioning. months i++er which functioned over since the battery on the transm ^ 0rigina1 4.2- as opposed to i was checked and registered 4. vo J j on rabbits n transmitters were placed volt rating. During the fall, hfor ,ever useful data to be obtamel. h+iined. fr°ur °*
and four functioned long•a d enougdata in the -inter and four of save provided six transmitters provided data
data in the spring. arj0d considerably. WhilG The range of each individual +rnn.>m +0 one- . xxint ranges m ' observation po'n1» using a 40-foof .all tower as an vation points , raseS, while using o b s . half mile were obtained. In mo> - . jhe only ,,00 feet were obtained. on the ground, ranges from 800 ° 29
exception to these ranges was one transmitter which could only be received at a maximum of 400 feet.
Individual Movements
Minimum home range was calculated for rabbits fitted with radio transmitters (Table 4). The average size of the home range for six male rabbits was 10.60 acres with a standard deviation of 3.48 and a
95 percent confidence interval of 1.74 to 19.64 acres. The average home range for six females was 5.14 acres with a standard deviation of 1.12 and a 95 percent confidence interval of 2.26 to 8.02 acres.
There was a significant difference between the home ranges of male
and female rabbits. Among the males there was a significant difference
in home ranges but there was no significant difference among home ranges
of the females. There was no significant difference in home ranges due
to season and no significant difference between the sexes among the
seasons. Adverse weather conditions restricted the movements of one
male rabbit from the average of 10,60 acres to 1.22 acres during
freezing rain, snow and high winds. Two nesting females also had very
restricted home ranges in the spring. Their home ranges were .52 and
3.87 acres as opposed to the average for females of 5.14 acres.
The movements of individual rabbits during 24-hour periods for
which they were monitored were plotted and are presented in the discus
sion on individual animals. Periods of greatest movement varied among
individual animals, but a general trend toward crepuscular activity was
noted. 30
Table 4 . The home ranges of swamp rabbits as deter „ |gnce from polar planimeter and a Mettler E ec . +he jnter- data collected October 1972 to ay R fuge Louisiana mediate marsh of Rockefeller Wildlife Retug
Age Home Range,--- and Average^ Rabb i t No. No. Planimeter___MejiLeL-— Sex F i X65 -acreb- 12.81 13.13 12.48 22.75 AM 135 29 9 24.60 20.90 5.12 IM 126 71 50 5.39 4.84 8.45 AF 136 29 9 8.83 8.07 IF 159 71 50 2.63 2.70 2.55 1.15 AM 163 25 3 1 .22 1.09 6.84 AM 183 23 7.13 45 6.55 6.06 AF 1 38 8 6.30 31 5.82 AF 48 104 100 7.25 7.50 7.00 17.02 AM 175 40 17.88 75 16.16 .52 AM 10 .51 124 75 .53 3.87 AF 14 4.12 104 26 3.63 AF 4 75 12 10.60 for males Average 5.14 for females Average 31
A detailed summary of the observations for each rabbit is
presented here to enable the reader to better interpret individual
home range and daily movements.
Rabbit 135. This adult male which weighed 1905 grams was in
good physical condition and was captured 21 October 1972. It was
fitted with a radio transmitter weighing 57.6 grams which remained
functional for only one week. In the only 24-hour period during
which its movements were followed, the temperature ranged from
50 to 64 F° and the weather was overcast with intermittent rain.
The minimum home range was calculated from 29 readings (Table 4)
and a map was drawn from these readings (Figure 5). Its greatest movement was from 1500 hours to 0400 hours with periods of little
activity between these hours (Figure 6).
— bbit l36‘ This adu'+ female weighed 1814 grams when captured
on 21 October 1972 and was in good physical condition. The radio
transmitter attached to this animal weighed 57.2 grams and functioned
for only one week. It was observed at the same time as rabbit 135.
It was not lactating at the time of capture. The minimum home
range was calculated from 29 readings (Table 4) and a map was drawn
from these readings (Figure 7). Its greatest movement was from
1000 hours to 1400 hours and then from 1700 hours to 1500 hours
with periods of seemingly little activity between these hours
(Figure 8). ro 6;M J138. J LTL j 62 fc!2- 1 1 500- I 1 1 1 1 1 1 1 1 1 1 1 1
400-
— 300-
>
I s 200-
100
1900 2200 5100 0400 0700 TOi30 1300 1600 / T9 /
TTVFm ^ * ■> - Figure 6. Relative movements of male rabbit 135 during a 24-hour period, 26-27 October. Arrows Indicate sunrise and sunset. »ather cloudy, tneperature 50-^4 decrees Fahrenheit. V/4 £ 62 1 5 0 0 - 1 1 1
400-
C V t_
0 3 0 0 . t ; > f -
E3 § 2 0 0 - e! co i—i
100- 1 1900 22 00 01 00 "3 7 00 0700 1000 1300 1600 / s, 1900 m T t Figure 8. Relative movements of female rabbit 136 during a 2^-hour period, 26-2? October. Arrows indicate sunrise and sunset. 'feather clotidy, temperature 50-6A decrees Fahrenheit. 36
Rabbit 126. This immature male, weighing 1861 grams, was captured on 27 October 1972 and was in good physical condition.
It was fitted with a radio transmitter weighing 55.6 grams which
functioned for about four weeks. It was followed for one full
24-hour period 9-10 November and for several other shorter periods
which were shortened due to heavy rains and high winds. During
the 24-hour monitoring, the temperature was 52 to 78 F° and the
weather was partly cloudy and windy. The minimum home range was
calculated from 71 readings (Table 4) and a map was drawn from
these readings (Figue 9). In this particular case, the minimum
home range may approach the maximum home range due to some movements
outside of the center of major activity. Its greatest periods of
movement were from 0200 hours to 0500 hours and from 0700 hours
to 1600 hours (Figure 10).
Rabbit 159. This immature female, weighing 1725 grams, was
captured on 27 October 1972 and was in good condition. It was fitted
with a radio transmitter weighing 57.9 grams which functioned for
about four weeks. It was followed at the same time as rabbit 126.
The minimum home range was calculated from 71 readings (Table 4)
and a map was drawn from these readings (Figure II). Its greatest
periods of movement were from 0300 hours to 0800 hours and from
1200 hours to 1700 hours (Figure 12).
Rabbit 183. This adult male, weighing 2225 grams, was captured
on 19 January 1973 and was in good physical condition at the time of 37 CO Figure 10. Relative movements of male rabbit 126 during a 24-hour period, 9-10 November. Arrows indicate sunrise and sunset. I. eat her partly cloudy, temperature 52-73 degrees Fahrenheit. 39 Figure 12. Relative movements of female rabbit 159 during a 24-hour period, ;-10 November. Arrows indicate sunrise and sunset. Weather partly cloudy, temperature 52-?9 degrees Fahrenheit. 41
capture. It was fitted with a radio transmitter weighing 57.9 grams which functioned for about three weeks at which time the rabbit was found to have a broken leg and was killed by the author.
It was followed for one 24-hour period on 1-2 February 1973, at which time the temperature was 44 to 69 F° and the weather was cloudy to partly cloudy. Additional readings were taken during periods of freezing rain, snow and high winds resulting in II hours of complete inactivity. The minimum home range was calculated from 45 readings
(Table 4) and a map was drawn from these readings (Figure 13).
Its periods of greatest movement were from 1500 hours to 2100 hours and from 2300 hours to 0800 hours (Figure 14).
Rabbit 138. This adult female, which weighed 2088 grams, was captured on 15 February 1973 and was in good physical condition.
It was fitted with a radio transmitter weighing 61.5 grams which functioned for about two weeks at which time the rabbit was killed by a mink. It was followed for one 24-hour period on 15-16 February at which time the temperature was 37 to 60 F° and the weather was clear and sunny, lhe minimum home range was calculated from 31 readings (Table 4) and a map was drawn from these readings (Figure 15)
Its period of greatest movement extended throughout much of the
24-hour period with several periods of seemingly little activity spaced between 2100 hours and 0900 hours (Figure 16). 42
Figure 13. Minimum home rani’e of Tile rabbit 183, 19 January, 10 Feb ruary 1Q73. Figure 14. Relative movements of rrale rabbit 183 during a 24-hour period, 1-2 February. Arrows indicate sunrise and sunset, '.leather cloudy, temperature 44-69 degrees Fahrenheit. 44
46
Rabbit 163. This adult male, weighing I860 grams, was captured on II March 1973 and was in good physical condition.
It was fitted with a radio transmitter weighing 61.5 grams which functioned for about two days at which time the rabbit was recaptured and the radio removed. It was followed for one 24-hour period on
11-12 March at which time the temperature was 57 to 79 F° and the weather was clear. The minimum home range was calculated from 25 readings (Table 4) and a map was drawn from these readings (Figure 17).
Its period of greatest movement was from 1600 hours to M O O hours with
intermittent periods of rest and no activity being recorded from
100 hours to 1500 hours (Figure 18).
Rabbit 104. This adult female, weighing 1589 grams and
captured on 2 February 1973, was the only rabbit to be followed
from one season to the next (winter to spring). It was also the
only female to be followed from normal activity to activity associated
with nesting and care for its young. It was fitted with a radio
transmitter weighing 62.0 grams which functioned for two months
and two days at which time the rabbit was killed by a mink. It was
followed for two full 24-hour periods, however, on 15-16 February and
11-12 March at which times the temperature ranged from 37 to 60 and
57 to 79 F°, respectively. The weather was clear during both 24-hour
periods. Other periods of surveillance led to 100 readings from
which the minimum home range was calculated (Table 4) and a map
was drawn (Figure 19). During the 15-16 February 24-hour monitoring, 47 DISTANCK TRAVELED (feet) • ... ; i - - a le ra b b i* 1 i i 1 i* b b ra le a - - i ; ... • i se and s s d n a e is r n u s e t a iic n L ..-.set Weat ear, temperature 57-79 i i e r h a P s e e r g ie 9 7 - 7 5 e r u t a r e p m e t , r a le c r e th a e W . uri g in r lu a 2 4 - h o u r p e r io d , 1 1 - 1 2 M u r e h . . h e r u M 2 1 - 1 1 , d io r e p r u o h - 4 2 ro s Arrow Figure 19. Minimum home ran^o of female rabbit 10^, 2 February- 21 March 1971. 50
the greatest period of movement was from 1900 hours to 1000 hours with periods of reduced activity interspersed (Figure 20).
The greatest movement during the 11-12 March monitoring was from 1900 hours to 0500 hours (Figure 21). Twenty-six readings were used to calculate a minimum home range during nesting activities (Table 4) and a map was drawn from these readings (Figure 22).
Rabbit 175. This adult male, weighing 1816 grams, was captured on 50 March 1973 and was in good condition. It was fitted with a
radio transmitter weighing 58.0 grams which functioned for slightly
over one month. It was followed for three 24-hour periods on 5-6
April, 12-13 April and 26-27 April at which times the temperature
was 47 to 64, 51 to 72 and 57 to 84 F°, respectively. The weather
during these periods was cloudy to partly cloudy. The minimum home
range was calculated from 75 readings (Table 4) and a map was drawn
from these readings (Figure 23). During the 24-hour monitoring on
5-6 April, the periods of greatest movement were from 0100 hours
to 0400 hours and from 1000 hours to 1200 hours (Figure 24). The
period of greatest movement during the 24-hour monitoring on 12-13
April extended from 1400 hours to 0400 hours with a peak at 2000 hours
(Figure 25). Less activity was noted during the 24-hour monitoring
on 26-27 April with a peak at 0300 hours (Figure 26).
Rabbit 124. This adult male, weighing 2178 grams, was captured
Vj"i 53 54 I
58
on 13 May 1973 and was in good physical condition. It was fitted with a radio transmitter weighing 61.5 grams which continued to function for about one month. It was followed for two 24-hour periods on 14-15 May and 21-22 May 1973 at which times the temperature was
61 to 80 and 71 to 88 F°, respectively and the weather was partly cloudy. The minimum home range was calculated from 75 readings
(Table 4) and a map was drawn from these readings (Figure 27).
In this particular case, the minimum home range may approach the maximum home range due to movements far from the center of major activity. The greatest movement during the 24-hour monitoring on
14-15 May extended from 0700 hours until 0100 hours with periods of reduced activity interspersed (Figure 28). During the 24-hour monitoring on 21-22 May, the greatest movement was from 1700 hours to 2000 hours and from 0300 hours to 1300 hours (Figure 29).
Rabbit 4 . This adult female, weighing 2088 grams, was captured on II May 1973 and was lactating heavily when captured. It was fitted with a radio transmitter weighing 62.0 grams which functioned for about one month. It was followed for two 24-hour periods at the same time as rabbit 124. The minimum home range was calculated from 75 readings (Table 4) and a map was drawn from these readings
(Figure 30). The period of greatest movement during the 24-hour monitoring on 14-15 May was from 2000 hours to 2100 hours with a
lesser peak from 0600 to 0800 hours (Figure 31). The peak of activity 59
I’icure 2 . M inLmum homo ran^e of' male rabbit 12V, 15 May-22 May l')7i. oo> cn Figure 23. R elative movements of male rabbit 124 during a 24-hour period, 21-22 ’ lay. Arrows indicate sunrise and sunset, ’.feather partly cloudy, temperature 61-76 degrees Fahrenheit. 62
Figure 30. Minimum home range of female rabbit 4 during nesting, 11-22 May 1973.
64
for the 24-hour period on 21-22 May was at 2100 hours with a lesser peak at 0900 hours (Figure 32). C7> VJI _ , oo roia-i-P -icr-ernents of female rabbit 4 during a 24-hour period, 21-22 'ay. Arrows indicate 'i.urs > . 1 ' anc»-sunset. '.leather partly cloudy, temperature 70-80 degrees Fahrenheit. 66
Habitat Preference
Sasic Habitat Types Utilized^ .hpre are four major habitat types utilized On the study area, there .+ Thp firs+ type is composed of roseau cane )y the swamp rabbits. The , et tall with wiregrass lightly interspersed and baccharis over four feet ta , . x ,; m n r^<;c with b6cch3ris (Figure 33). The second type is compose h liahtly (Figure 34). The third under four feet tall interspersed lightly r feet tall with wiregrass type is composed of baccharis over c. « , The fourth type is almost moderately interspersed < '9ure * |jza+;on by rabbits , Each of these types had some utilizat entirely wiregrass. tac for food. either for resting, escape or nesting cover,
Preferred Habitat Component.^ . ,| +h0 author observed rabbits during all Throuqh the study d' r 1 ' anted „ „f the habitat types. Concerted h°UrS ° f ^ ‘laV 7 7 h7 " p l r i e d that population estimates were made, efforts were made during j+ + type was like- . n access within each habitat YP The general trend of trappi utilized to some A i though each habitat type was ut.hz wise noted (Table 3). of th0 observations, that degree, it is felt by the author, «« ,, h+,y interspersed the preferred habitat components are wiregrass .
, ,t fall, in the opinion of the author, baccharis under four fee for rabbits . . | | of the major components neces y habitat typo provides all o ., al, Qf the n l+ is sufficiently dense to provide all to live and rear young. _11DD|y. There . . , a varied and continuous food supply, cover needed, and it provides a 67
Figure 33. Roseau cane-baccharis-wiregrass habitat type on study area , 21 May 1973.
Figure 34. Wiregrass-short baccharis habitat type on study area, 21 May 1973. 68 69
Figure 36. High baccharis-wiregrass habitat type on study area , 21 May 1973. 70 71
also seemed +o be less predation on trapped animals as well as rabbits which had been marked and released in this type. Baccharis over four feet tall with moderately interspersed wiregrass seemed to be the second most favored type, with roseau cane-baccharis and wiregrass being the third and solid wiregrass stands being the least preferred. 72
D i scuss ion
Weights
The weights of the rabbits in the marsh habitat, as obtained by the author, differed only slightly with those obtained by other investigators in Louisiana even though they were working in bottom land hardwoods. The average weights found in this study were 1831 grams for adult males, 1965 grams for adult females, 1601 grams for immature males, and 1472 grams for immature females as compared with
Hastings (1954) who found the average weights of adult males to be
2240 grams and adult females to be 1952 grams and Croft (1961) who found adult male average weights to be 1803 grams and adult female average weights to be 1804 grams. The weights in this study are also similar to weights obtained by investigators in Georgia and Alabama.
Lowe (1958) in Georgia found weights of males to average 1895 grams
and female weights to average 1951 grams, while Hill (1967) in Alabama
found average weights to vary from 2722 to 1021 grams. The weights
in Indiana as reported by Harrison (1931) and in Missouri by Toll (1958)
and Ho I ten and Toll (I960) are somewhat heavier than those in this re
port. The Indiana weights varied from 1409 to 2474 grams. The Missouri
average weights as reported by Toll (1958) were 2057 grams for adult
males and 2052 grams for adult females, while Holten and Toll (I960)
reported average winter weights of adult males to be 2235 grams, adult
females to be 2161 grams, immature males to be 2022 grams and immature 73
females to be 1954 grams.
Population Density
The indicated population density in the marsh habitat where this study was conducted is much higher than those reported for bottomland hardwood areas in Louisiana and Georgia. There were 7.74 rabbits per acre in the marsh habitat compared to one rabbit per 6.2 acres and one rabbit per 5.7 acres reported by Bryant (1954) in
Louisiana and 5.6 rabbits per 100 acres reported by Lowe (1958)
in Georgia. However, as previously stated, the indicated population density is probably much higher than the true density. Consequently, this study may project the false impression that intermediate marsh
supports many times the number of rabbits than is supported by bottom
land hardwood habitat.
Home Ranges
Average home range for males In marsh habitat was 10.60 acres and
5.14 acres for females. Although the home ranges of a I I rabbits were
centered around the levee-road on the study area, there was much more
movement out into the marsh proper than was expected. Much of each
day’s activity was normally spent on the levee-road but at various
and irregular times each rabbit ventured out into the almost solid
stands of wiregrass which were generally flooded. Some of these trips
away from the road system accounted for greatly increased estimates of
the home ranges of male rabbits number 126 and 124, 22.75 acres and 74
17.02 acres, respectively.
Average home range for females in bottomland hardwoods in
Missouri as reported by TolI (1958) and TolI, Baskett and Conaway
(I960) was 5.9 acres calculated for females by the minimum home range method and average home range for males was 4.6 acres calculated by the same method. Home ranges for the females in the present study and those calculated by the minimum home range method in the Missouri studies were very similar, but home ranges for the males varied greatly. Lowe (1958) in bottomland hardwoods in Georgia found average home range of swamp rabbits to be 18.9 acres which is much larger than those in the other studies, but the beagle chase method was used exclusively and may account for the larger average home range in the opinion of this writer. 75
SUMMARY
From 6 October 1972 to 22 May 1973, a study was conducted on swamp rabbits on Rockefeller Wildlife Refuge, Cameron and Vermilion
Parishes, Louisiana. The objective of this study was to determine the home range and habitat preferences of swamp rabbits in the
intermediate marsh.
Hinged-door traps baited with apples were used to live-trap rabbits for population studies and radio telemetry work. A total of
12 rabbits provided data for home range estimates. Radio transmitters
functioned from I day to 62 days. The average minimum home range for males was 10.60 acres and 5.14 acres for females on an area with a
population density of 7.74 rabbits per acre.
The most preferred habitat components were wiregrass with baccharis
less than four feet tall lightly interspersed. Baccharis over four
feet tall with moderately interspersed wiregrass was second, with
roseau cane and baccharis over four feet tall with lightly interspersed
wiregrass third. Solid wiregrass stands were the least preferred habi
tat type.
Average live weight for 21 adult males was 1831 grams, 1965 grams
for 27 adult females, 1472 grams for 9 immature females and 1601 grams
for 4 immature males.
Population estimates for the study area, calculated by Bailey's
Modified Petersen Index, was 131.4 rabbits with 7.74 rabbits per acre. 76
bb,ts on the area was generally crepuscular,
” t0f+hera nt of variation the c e m e n t of any _ a nreat amount or va but there was a greai i I i nri I V I dU3 I S • individual and also among all 77
APPENDIX Table 5' {^the^ntermedtate^mareh^o^Rockef e^er^W^d iTf^Refuge^' LouU!ana^ October 1972 throuah Mav 1973
Number Number of Number of To+a 1 Number Rabb i t Observat i ons Observations Number of of of Visual Observat i ons On Levee-road In Marsh ’'lumber Radio Fixes 16 29 0 13 135 29 37 0 24 126 71 71 9 0 20 136 29 29 29 0 42 159 71 71 10 25 U 15 163 25 39 6 45 39 6 183 o 14 17 138 31 31 28 5 72 104 10 0 95 39 2 36 175 75 73 19 73 2 56 124 75 9 24 2 104 26 24 26 0 49 4 75 75 79
LITERATURE CITED
Audubon, J.J., and J. Bachman. 1846. Quadrupeds of North America 1:287-291.
Bailey, N.T.J. 1951. On estimating the size of mobile populations from recapture data. Biometrika. 38 (pts. 3-4):293-306.
Bittner, S.R. 1973. Wild turkey food-habit, movements, and popu lations on Winter Quarters Hunting Club, Tensas Parish, Louisiana. Unpub. master’s thesis. La. State Univ., Baton Rouge. 87p.
Bryant, R.L. 1954. Population studies and food habits of cotton tails and swamp rabbits in southeastern Louisiana. Unpub. master’s thesis. La. State Univ., Baton Rouge. 66p.
Calhoun, J.B. 1941. Distribution and food habits of mammals in the vicinity of Reelfoot Biological Station. Journ. Tenn. Acad. Sci. 6:177-185, 207-225.
Collins, J .0. 1962. Louisiana rabbit hunting: Improvement through management. La. Wild Life and Fish. Comm. Wildl Ed. Bull. No. 26. 7p.
Conaway, C.H., T.S. Baskett, and J.E. Toll. I960. Embryo resorption in the swamp rabbit. Journ. Wildl. Manaqe. 24(2):197-202.
Croft, R.L. 1961. The value of food plots to cottontail and swamp rabbits in Louisiana. Unpub. master's thesis. La. State Uriiv., Baton Rouge. 61 p.
Edwards, W., and L. Eberhart. 1967. Estimating cottontail abundance from livetrapping data. Journ. Wildl. Manaqe. 31(2):87-95. a
Eberhart,_L., T. Peterle and R. Schofield. 1963. Problems in a rabbit population study. Wildl. Mono. 10. 5lp.
Farlow J.E 1968. Seasonal distribution of some arthropod para- !! +S ° rabbits in Louisiana. Unpub. master's thesis. La. State Univ., Baton Rouge. 55p. 80
Garner, G.W. 1969. Short-term succession ot vegetation following habitat manipulation of bottomland hardwoods for swamp rabbits in Louisiana. Unpub. master's thesis. La. State Univ., Baton Rouge. 181p.
Harrison, T. and P.F. Hickie. 1931. Indiana's swamp rabbit. Journ. Mammol. 12:319-320.
Hastings, E.F. 1954. Life history studies of cottontail and swamp rabbits in Louisiana. Unpub. master's thesis. La. State Univ., Baton Rouge. 85p.
Hamilton, W.J. 1955. Croprophagy in the swamp rabbit. Journ. Mammol. 36:303-304.
Hill, E.P., III. 1967. Notes on the life history of the swamp rabbit in Alabama. Proc. 21st Annu. Conf. S.E. Assoc. Game and Fish Comm. p. 118-123.
Holler, N.R., T.S. Baskett and J.P. Rogers. 1963. Reproduction in confined swamp rabbits. Journ. Wildl. Manage. 27(2):179— 183.
Holton, J.W. and J.E. Toll. I960. Winter weights of juvenile and adult swamp rabbits in southeastern Missouri. Journ. Wi Idl . Manage. 24(2):229-230.
Hunt, T.P. 1959. Breeding habits of the swamp rabbit with notes on its life history. Journ. Mammol. 40:82-91.
Joanen, T. and L. McNease. 1970. A telemetric study of nesting female alligators on Rockefeller Refuge, Louisiana. Proc. 24th Annu. Conf. S.E. Assoc. Game and Fish Comm. p. 92-120.
Lowe, C.E. 1958. Ecology of the swamp rabbit in Georgia. Journ. MammoI. 39:I 16- I 27.
Marsden, H.M. and N.R. Holler. 1964. Social behavoir in confined populations of the cotton fail and the swamp rabbit. Wildl. Mono. 13. 39p.
Martinson, R.K., J.W. Holton and G.K. Brakhage. 1961 . Age criteria and population dynamics of the swamp rabbit in Missouri. Journ. Wildl. Manage. 25(3):271-281.
Mohr, C.O. and W.A. Stumpf. 1966. Comparison of methods for cal culating areas of animal activity. Journ. Wildl. Manaqe. 30(2):293-304.
O'Neil, T. 1949. The muskrat in the Louisiana coastal marshes. Pub. Fed. Aid Sec. La. Dept, of Wild Life and Fisheries. I52p. 81
Richardson, L.V. 1963. Food preferences and nu+r' + '^ con^ " + of selected plants fed cottontail and swamp rabbits. Unpub. master’s thesis. La. State Umv., Baton Rouge. 77p.
Sherman, F. 1939. The swamp rabb it (Sy I vi I a.q.us aquat i cus aauati cus) in South Carolina. Journ. MammoI. 20.259.
Sims, J. I960. The rabbit in Louisiana. Fed. Aid Proj. VJ-29R. * La. Wild Life and Fish. Comm. 11P•
Smith C C 1940. Notes on the food and parasites of the rabbits of ; lowland area in Oklahoma. Journ. WMdl. Manage. 4:429-431. c ... A n |966 Food preferences of swamp rabbits for selected SU " p l a n t J ^ ’un i u ^ ’master's thesis. La. State Univ., Baton Rouge. 53p. Svihla, R.D. 1929. Habits of Sylvnasus afflaticus WttoraMs. Journ. MammoI. 10:315-519. T i r W 1972 A telemetric study of the red fox in agricul TaV °trir=; ;reas of southeast Louisiana Unpub. a s t e r ’s thesis. La. State Univ., Baton Rouge. lOZp.
T o n J E. 1958. Life history of the swamp rabbit. Unpub. master's ’thesis. Univ. Mo., Columbia. Glp.
T .| , r T s Baskett and C.H. Conaway. I960. Home range, ’reproduction and foods of the swamp rabbits ,n Missouri. Amor. Midi. Natur. 63 ( 2 ):598-4 I 2. 82
VITA
Arthur Benjamin Gould, Jr., was born in Cullman, Alabama, on
13 December 1946. He attended public school in Cullman, Alabama, and was graduated from Cullman High School in May 1965.
From September 1965 to June 1969, he attended Auburn Uni versity, Auburn, Alabama. He received a Bachelor of Science degree in Biological Sciences majoring in Wildlife Biology from Auburn
University in June 1969.
In October 1969, he entered the United States Army. In August
19/1, he was discharged from the Army and entered the Graduate School of Louisiana State University. He is currently a candidate for the degree of Master of Science in Game Management. EXAMINATION AND THESIS REPORT
Candidate: Arthur Benjamin Gould, Jr.
Major Field: W ild life
Title of Thesis: The Home Range And Habitat Preferences Of Swamp Rabbits Along A Shell Road In The Intermediate Marsh Of Southwestern Louisiana Approved:
of ^e^^^uate'^^iool
EXAMINING COMMITTEE.
Date of Examination:
July 10. 1973