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made of transmilteFequjpped ndmals, most of the locations were dctcrmincd for submerged
alligabrs by recording the position directly above thc point of vertical exit of lhe strongest radio
signal tiom ihe wrter column. In a few c^ses, parlicularly in lhe case of animalswhich left the
resewoir, it was ne€cssary to estimate locations by visual lriangulalion. However it was usuauy
possiblc to plol individual localions with an ac€urfty of approximately alom.
In addition to the adults equipned with radio tr:rnsmitters, four smallor alligators were
cnpturcd by hand or with snare poles usiDg te.chniques described by Chabreck (1963) and Brandl
(1989, l99l). 'Ihese animals were captured bctween 18-20 July 1991, and were fitted with
coloured plastic collars to permit l:llcr visu.l idenlilication. Resightings of thcse .dditional
marked animals were used to furlher documerl alligator movemenl wilhin and emigration from
thc drnwdown reservoir. Recaplures of alligntors rnarked in previous sludies (Murphy 197,
1981; Ilrandt 1989, l99l) were idenlified by tril scutc nolches (Rrandl 1989).
Reproductivc Studies:
Ncsts wore localed during the sumrner of 1991 by visiting arcas of known pasl nesting
and seffching thc rcscNoir shorcline by boat and foot. Once located, nesls were visited at
approximately bimonthly or, when possiblq wcekly intervrls to determine hatching success and
the subsequent f:rte of the young.
Population Numbers:
RNSULTS AND DISCUSSION
ljyeshine counts conducled atter the initiation of the drawdown (Figure 4), were higher
th:ln thosc reported for the same monlhs in 1988 by Brxndt (1989; ligure 4). This may hnve
resultcd from thc continued increase in the population, as documented by that study aod/or may
have heen due to an incrcasc in tbe animals' visibility along thc lake's shoreline which was now
dwoid of vcget^tivc cover. 'fhe same faclors could also havc contributed 1l) an increase m thc
numbcr of rlligntors scen on ierial survey flights during and shorlly after drawdown (July-
November 1991), as compared to the number counted during rhese same monlhs ir prevrous
ycars (Figurc 5; Brnndl 1989). A sharp de.line in numbers or nllisators seen on nighr cyeshine
surveys beiween late July and mid-Seplember 1991, occu(ed during 1l period when oycshinc
counls recorded in previous ye.rs wcro cirher conslant or slighlly incrcrsing (Figure 4). This
declinc could not have been rn arlifacl relnted to the loss of shorcline vegeration and insread,
may havc reflecled thc bcginning ot emigration of alligrtors from the reservoir as will bc
discussed later.
Anrlyses of night eycshinc count datn indicaled thal rhe disrribulion ot alligators in the
reservoir lwo weeks after thc ioitintion of drawdown was significantly different than expected
based o the area ofwater avnilnble in each arn (X'= 11.07, p