EDWARDS ET AL.— MAMMAL ABUNDANCE AT FORT HOOD 
5 
Captured animals were anesthetized using ketamine 
hydrochloride (Ketaset at a dosage of 10 mg/kg) or a 
mixture of ketamine hydrochloride, xylazine (Gemini at 
a dosage of 5 mg/kg) and acepromazine maleate 
(PromAce at a dosage of 1 mg/kg) (Pond and O’Gara, 
1996). Immobilized animals were removed from traps, 
weighed, measured, and checked for reproductive con¬ 
dition. Animals then were marked with # 4 monel ear 
tags and released at the site of capture. Voucher speci¬ 
mens were collected during the last quarter of the study 
and deposited in the Angelo State Natural History Col¬ 
lections. All data including species captured, weight, 
measurements, sex, reproductive condition, monel ear 
tag number (left and right ear tags), recapture or first 
time capture, size of trap, trap operablc/inoperable (bait 
removed and/or trap sprung) and Universal Transverse 
Mercator (UTM) coordinates of station were recorded 
on data sheets. 
Capture mean, used as an expression of relative 
abundance, was computed for each transect within each 
sample area from the number of trap nights and number 
of animals caught (McKeever, 1959; Clark, 1972; 
Knowlton, 1972). Total captures per species per transect 
per day were calculated for subsequent analysis. All cap¬ 
ture data were analyzed using the statistical software 
JMP® (SAS Institute Inc., 1995). Repeated measures 
analysis of variance was used to determine if day, transect, 
season, trap size, habitat type, use type (high or low use) 
or any combination of these parameters significantly (P 
0.05) affected captures (i.e., relative abundance). Be¬ 
cause of unbalanced sample sizes caused by inoperable 
traps, sequential sum of squares was utilized. The fol¬ 
lowing assumptions were made with regard to the above 
analyses: 1) traps at each station were in tire same habi¬ 
tat type and 2) at each station an animal had an equal op¬ 
portunity to select each trap size. 
Area analyses involved the comparison of high and 
low use areas within each of the three habitat types 
sampled. Additionally, analyses of capture means among 
habitat types were conducted to determine any differ¬ 
ences in relative abundance of medium-sized mammals. 
Seasonal analyses involved comparisons of capture means 
across the four seasons during which trapping took place. 
Capture means were also compared over the three days 
of surveys, among transects, and among the three sizes 
of live traps. 
Data from spotlight surveys were obtained from 
the Natural Resources Division of Fort Hood. These 
data were collected from nocturnal surveys of white- 
tailed deer and included information on medium-sized 
mammals. Six 24-km transects were surveyed annually 
(August and September) from 1978 to 1996. All data 
were collected following standardized procedures as 
described in Farfarman and DeYoung (1986) and Ralls 
and Eberhardt(1997). 
Presence of medium-sized mammal species de¬ 
tected by spotlight surveys was compared to our data 
determined via trapping. Additional analyses include only 
those data from transects where both live-trapping and 
spotlight surveys were conducted over the same routes. 
Relative abundance was calculated by dividing the num¬ 
ber of individuals of a species observed on spotlight sur¬ 
veys or trapped in live traps by the number of kilometers 
over which surveys or live-trapping were conducted. 
Relative abundance is expressed as the number of indi¬ 
viduals of a species per kilometer. A 14-km section of 
spotlight survey line #1 overlapped the transect on which 
live-trapping stations #1, 3, 5, 7,9, 13, 15, 17, 19,21, 
23,25,27, and 29 of Upl 2 were located. The final 5 km 
of spotlight line #1 overlapped the transect on which live- 
trapping stations #11, 13, 15, 19, and 21 within Rip 2 
were located. Spotlight survey line #2 had a 5-km seg¬ 
ment which overlapped a section of the transect contain¬ 
ing live-trapping stations #13,15,17, and 19 located in 
Rip 1. The initial 5-km of spotlight survey line #3 and an 
8-km segment of line #5 overlapped the transects on 
which live-trapping stations #1, 3, 5,7, and 9 of Sav 2 
and live-trapping stations #1,3,5,7,9,11,13, and 15 of 
Sav 1 were located. Species used in these analyses were 
those documented on sections of spotlight routes that 
overlapped live-trapping transects within the six survey 
areas. No spotlight survey route passed through Upl 1, 
therefore it was excluded from any comparisons. In for- 
mation gained via comparisons between spotlight sur¬ 
veys and live-trapping was used to assess their relative 
effectiveness for monitoring medium-sized mammal 
populations.Results 
Sampling effort using live traps for medium-sized 
mammals totaled 2,945 trap nights. A total ofl49 me¬ 
dium-sized mammals were captured giving a total trap 
success of 5.06%. Nine medium-sized mammal spe¬ 
cies were documented on the base (Fort Hood) as a re- 
