2012 COURSE DATES: AUGUST 4 – 17, 2012 - Sirenian International

Captive Female Manatee Social Behavior 137
(Orlando, Florida). Generally, manatees were housed in human-made enclosures
approximately 3 m in depth and oval in shape. The exception was HSWSP, which is
a naturally occurring spring that covers approximately 0.2 ha and reaches depths of
13.5 m. Manatees (n ¼ 20) at all facilities were viewed from an underwater
observation area or from above the enclosure. We estimated the volume of water
for HSWSP from the dimensions of the exhibit. The other three facilities provided us
with aquarium volumes. Water volumes at each facility are as follows: HSWSP (1.1
10 7 L [9 manatees]), Sea World (1.4 10 6 L [6 manatees]), Epcot (760,000 L
[2 manatees]), and Lowry Park Zoo (470,000 L [3 manatees]).
Behavioral Observations
Manatees were watched continuously for 180 min over 3 days around
feeding times. The time duration was selected because there were constraints
at the facilities that prevented longer observation periods including operating
hours, interference in observations when visitor numbers were high, and
logistical issues. Observations were made at the four facilities with 20 individuals
for a total of 36 hr. No adult males were observed for this study, but three
juvenile male manatees were observed. One male was at Lowry Park Zoo
and two were at Sea World. All three males were with females. During the
3 hr of continuous observations for all interactions, we recorded all aggressive
and non-aggressive contacts between manatees (sender–receiver) and spatial
displacement by manatees [Martin and Bateson, 1993]. Aggressive interactions were
defined as contacts in which the sender’s head touched the receiver with some
momentum or caused physical movement of the receiver. Displacement was occurred
when one manatee (sender) caused another manatee (receiver) to move from its
location without contact because of the presence or movement of the sender.
Displacements were rare and not considered in the analysis. Other aggressive
interactions occurred when the sender’s tail hit the receiver with force as it swam
away. Non-aggressive interactions that might be affiliative in nature included all
other contacts (head to different body parts, body to different body parts, fin to
different body parts, and tail to different body parts without force). Incidental
contacts transpired when an animal brushed against another animal. These contacts
were not included in the analysis.
Manatees at all facilities were fed 25–100 heads of romaine lettuce
depending on the number of manatees in the aquarium (one head weighs
approximately 488 grams; V. Burke, head keeper at Lowry Park Zoo,
personal communication). Feeding occurred three to four times a day at regular
intervals. Three observational periods were defined as pre-feeding, during-feeding,
and post-feeding. The pre-feeding period occurred during the first 60 min of
observations before the handlers provisioned any food. The feeding period occurred
when the manatees were feeding and post-feeding was defined as when 10% or less of
the food remained (heads and leaves combined). The number of heads of lettuce
(or leaf equivalents) that remained in the aquarium were counted and recorded every
5 min. Feeding periods lasted approximately 1 hr. Supplemental foods such as
carrots, kale, and apples were sometimes provided to manatees by the aquarium
staff, but not included in the determination of feeding or non-feeding observational
periods.