Heavy poaching in prime habitat: the conservation status of the West Indian manatee in Nicaragua

Jiménez, Ignacio

doi:10.1017/s0030605302000492

Cited by 29 publications

(25 citation statements)

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“…Furthemore Colmenero and Hoz (1986), Jiménez (2002), Horikoshi-Beckett and Schulte (2006) reported more crepuscular and nocturnal activity in manatees, probably in response to less human activity overnight. It is likely since in this study the manatees were exposed to a public environment enclosure, the result is that there is more diurnal activity as opposed to night activity.…”

Section: Discussionmentioning

confidence: 95%

Circadian and ultradian activity rhythms in manatee (Trichechus manatus manatus) in captivity

Holguin-Medina

Araújo

Alcaraz-Romero

et al. 2015

Biological Rhythm Research

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In this study, we show temporal organization of activity patterns in larger temporal series recording. The objective of this study was to determine the temporal pattern of the rest-activity rhythm in manatee (T. manatus manatus) in captivity. Activity recordings were programmed from August (2010) to September (2011) with actimetry devices, and behavior recordings were conducted in dry and rainy seasons. We showed that the marine manatee presents a complex temporal organization, in which the activity-rest rhythm comprises several frequencies with a predominant circadian component and multiple ultradian components. Our results indicate that the animals were more active during the day with respect to the night. The temporal organization of this cycle entails multiple frequencies that include ultradian rhythms, which may be expressions generated by physiological needs, like a food availability and thermoregulatory requirements. These patterns should be taken into consideration for future studies of biological rhythms in manatee.

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Section: Discussionmentioning

confidence: 95%

Circadian and ultradian activity rhythms in manatee (Trichechus manatus manatus) in captivity

Holguin-Medina

Araújo

Alcaraz-Romero

et al. 2015

Biological Rhythm Research

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“…The resting behavior also increased during the afternoon. Manatees have been described as arrhythmic (Hartman 1979;Reynolds, 1981), although in areas with marked human activity, they seem to be more active at dawn, dusk and during nighttime (Colmenero and Hoz 1986;Jiménez 1999;Jiménez 2002;Horikoshi-Becket and Shulte 2006). While studying animals in captivity, Holguin et al (2015) found a circadian cycle of the resting behavior, with manatees being more active during the day, which is consistent with other studies of manatees in captivity (Hénaut et al 2010, Kikuchi et al 2010.…”

Section: Discussionmentioning

confidence: 99%

Habitat use by the Antillean manatee (Trichechus manatus) during an extreme dry season in an urban lake in Tabasco, Mexico

Ramírez-Jiménez

Olivera‐Gómez

Cueva³

2017

Therya

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There are three important manatee areas in Mexico: the coasts of the State of Quintana Roo; the freshwater systems within the lower basin of the Grijalva-Usumacinta rivers, which host the largest manatee population; and the rivers of central and southern Veracruz. The Antillean manatee (Trichechus manatus manatus) is a threatened species throughout its range. In the Grijalva-Usumacinta region, two of the current threats to manatees are the effects of extremely dry periods and geographical isolation. The objective of the study was to evaluate the behavior and habitat use of the landlocked manatee population inhabiting Laguna de las Ilusiones, Villahermosa, Tabasco, under fortuitous dry conditions, to conduct an evaluation and implement a monitoring plan for landlocked manatees. In this work, we gathered information on the differential use of the lake, and on whether this use is related to the known habitat characteristics that govern the distribution of manatees. Using VHF tags, we followed the activities of four manatees (three females and one male) to characterize and quantify four behaviors, namely feeding, resting, exploring, and traveling, between April and August 2007. We built Kernel polygons for the 25, 50, 75, and 95 % of the utilization distribution (UD). We modeled the habitat using a binary logistic regression and explored the association between the tagged manatees using Cole's simple coefficient of association. Manatees were concentrated mainly to the northeast of the lake. The best feeding logistic model included depth, distance to the the shore, tree cover, and wind speed (Table 1), and yielded differences between periods (H = 9.85, P = 0.007, Figure 5). The logistic models fit poorly for resting, exploring, and traveling (Table 1). The resting model included distance to the the shore, tree cover, and company, and yielded differences between periods (H = 6.68, P = 0.035). Traveling included depth, cloud cover, and human activities, and yielded differences between periods (H = 7.55, P = 0.023). Exploration included depth and company, and did not differ between periods (H = 1.55, P = 0.461). We had the opportunity to assess these behaviors under dry conditions, and our findings are not necessarily applicable to the rainy season. The northern portion of the lake is an embayment connected to the central zone by a 50 m-wide shallow channel, which limited the movement of manatees. Higher food availability and stress avoidance might make manatees choose this area. Feeding was better modeled by the habitat characteristics included in the study. Feeding increased slightly in the evenings. Exploring and traveling were the behavior types observed most frequently in manatees; maybe they were moving across food patches or known areas. Manatee social encounters are reported as short-term and sporadic, but in this study manatees were observed in groups during nearly half of the observation time. When the availability of grasses and aquatic plants is low, manatees increase their consumption of other food items li...

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“…During low tides and the dry season in Venezuela and Costa Rica, they often take refuge in holes or channels in the rivers that range from 6 to 12 m in depth (O'Shea et al, 1988;Smethurst & Nietschmann, 1999). Anecdotal observations suggest that manatees in Nicaragua rest in quiet, sheltered, deep water during most of the day, leaving to feed only during the night, early morning, and late afternoon (Jiménez, 2002). In Belize, resting behavior has been correlated with the presence of a "resting hole" (CSS & K. LaCommare, unpub.…”

Section: Introductionmentioning

confidence: 97%

Characterization of Resting Holes and Their Use by the Antillean Manatee (<I>Trichechus manatus manatus</I>) in the Drowned Cayes, Belize

Bacchus¹,

Dunbar²,

Self‐Sullivan³

2009

aquatic mammals

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In the Drowned Cayes area of Belize, manatees (Trichechus manatus manatus) are commonly observed resting in depressions in the substrate, locally referred to as manatee resting holes. To understand why manatees prefer locations with resting holes, the physical and environmental attributes of the depressions were characterized and diurnal and nocturnal use by manatees at four resting hole sites were documented over two summers. Twelve resting hole sites were compared with 20 non-resting hole sites in the Drowned Cayes, using water depth, substrate type, vegetation, water velocity, salinity, and water temperature. Four resting holes were chosen for repeated diurnal and nocturnal observations, during which sea and weather conditions were recorded in addition to the presence/absence of manatees. Resting holes were significantly deeper and had slower surface water velocity than areas without resting holes. A total of 168 point scans were conducted over 55 d, resulting in 39 manatee sightings over two summers. There was a significant difference in the number of sightings between research years and between day and night scans. Given the large number of resting holes in the Drowned Cayes, many of which are in sheltered areas with slow currents, it is possible that manatees select these spots based on the tranquility of the water and environment. The combination of slow currents, protection from waves, low numbers of boats, and nearby seagrass beds would make these ideal resting areas. These findings have implications for the conservation of important manatee habitat.

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Heavy poaching in prime habitat: the conservation status of the West Indian manatee in Nicaragua

Cited by 29 publications

References 0 publications

Circadian and ultradian activity rhythms in manatee (Trichechus manatus manatus) in captivity

Circadian and ultradian activity rhythms in manatee (Trichechus manatus manatus) in captivity

Habitat use by the Antillean manatee (Trichechus manatus) during an extreme dry season in an urban lake in Tabasco, Mexico

Characterization of Resting Holes and Their Use by the Antillean Manatee (<I>Trichechus manatus manatus</I>) in the Drowned Cayes, Belize

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