Capacidades cognoscitivas, estrategias de forrajeo y estructura social: el caso de los mamíferos acuáticos

There are several hypotheses that explain brain size differences, like the developmental hypothesis, the foraging hypothesis and the social brain hypothesis. They have been successfully developed/tested in some terrestrial taxa, however, no attempt has been done to test them in aquatic mammals. I reviewed previously published data in order to validate those hypotheses. Morphological, reproductive and social aspects of 66 aquatic mammal species, belong to the Orders Cetacea, Sirenia and Carnivora, were reviewed and correlated with their encephalization quotient (EQ). Relative brain size did not show a strong correlation with gestation duration nor sociability indexes (r<0.05). Nevertheless, filtering and herbivorous species showed EQ lower than those animalivorous species. Aquatic mammals show morphometric adaptations to their special habitat, and alometric studies should be taken with caution. Furthermore, the study of the mammal’s behavior in wildlife could be more difficult in water than in land. It is necessary to develop a frame of satisfactory explanations which integrates social, ecological, energetic and lifestory aspects in order to identify evolutionary aspects that drive the size brain selection in aquatic mammals.Existen varias hipótesis que explican las diferencias en el tamaño cerebral, y que han sido desarrolladas y comprobadas en diversos taxa del reino animal. Entre ellas se encuentran la hipótesis embrionaria, la hipótesis del forrajeo y la hipótesis del cerebro social. No obstante, hasta ahora no se ha intentado comprobarlas en mamíferos acuáticos. Este trabajo pretendió validar cada una de estas hipótesis usando datos previamente publicados. Se revisaron aspectos morfológicos, reproductivos y sociales de 66 especies de mamíferos acuáticos, incluyendo los órdenes Cetacea, Sirenia y Carnivora y se correlacionaron con sus coeficientes de encefalización (EQ). El tamaño relativo del cerebro en mamíferos acuáticos no presentó una correlación estadísticamente fuerte con el tiempo de gestación ni con los índices de sociabilidad (r<0.05). No obstante, se encontró que las especies filtradoras y herbívoras tuvieron EQ menores que las especies animalívoras. Los mamíferos acuáticos presentan adaptaciones morfométricas al hábitat que ocupan, por lo que los estudios alométricos que han sido exitosos en animales terrestres deben ser tomados con cautela al ser aplicados a animales acuáticos. Adicionalmente, el estudio del comportamiento en vida silvestre de estas especies, principalmente en relación a la socialización, es más difícil de desarrollar que en el caso de la mayoría de animales terrestres. Es necesario desarrollar un marco de explicaciones satisfactorio que permita integrar todos los factores sociales, ecológicos, energéticos y de historia de vida de las especies a fin de identificar los mecanismos evolutivos que operan en la selección del tamaño cerebral en mamíferos acuáticos

Interacciones entre crías de manatí amazónico en Perú: Un caso de estudio

Trichechus inunguis is an endemic species of the Amazon, which inhabits mainly in lakes and calm rivers. The objective of this study case was to describe the social behaviour of two female-orphaned calves, of T. inunguis in captivity. They were kept in the same pool at the facilities of the Amazon Rescue Center (ARC, Iquitos, Peruvian Amazon). Between February and October 2011, the individuals were observed during day and night times, completing 352 hours of observation. Through ad libitum observation of the individuals, we developed a catalogue of social behaviors that includes descriptions of 93 behaviours, classified in eight behavioural categories.. The frequency of behaviours was assessed by instantaneous sampling (for states) and continuous recording (for events). Manatees displayed mainly social behaviours, and the most frequent interaction was the simultaneous starting of the same behaviour by both individuals. Most of social behaviours occurred during the day, but ‘group resting’ was recorded mostly at night. ‘synchronized breathing’ and ‘group feeding’ did not have temporary variation between days or between daytimes. Regarding the use of the space, the majority of interactions occurred in shaded places. This study revealed strong interactions between confined calves, suggesting that social activity may play an important role in their learning process. © 2016, Universidad Nacional de Colombia. All rights reserved

Primer registro de la ballena de aleta Balaenoptera physalus para el Caribe mexicano

Background. Until 2015, the aquatic mammals biodiversity in the Mexican Caribbean was unknown, but was in that year when 18 species were confirmed to be distribute in this region, none of them a Rorcual species. Goals. The aim of this work is to report the first sighting of a Balaenopteridae whale in the Mexican Caribbean. Methods. CONANP patrolling activities at the National Park Isla Contoy were conduced. Results On 2th August 2018, a stranded-live whale was found. The animal was identified as a ~18m (in length)  fin whale Balaenoptera physalus (Linnaeus, 1758). Conclusions. This note is the first confirmed record of this species in the Mexican Caribbean increasing the list of confirmed aquatic mammal species distributed in this region.Antecedentes. Hasta 2015 la biodiversidad de los mamíferos acuáticos en el Caribe mexicano era desconocida, pero en ese año se confirmó la distribución de 18 especies en esta región, ninguna de ellas una especie Rorcual. Objetivos. El objetivo de este trabajo es reportar el primer avistamiento de una ballena Balaenopteridae en el Caribe mexicano. Métodos. Se llevaron a cabo actividades de patrullaje de la CONANP en el Parque Nacional Isla Contoy. Resultados. El 2 de agosto de 2018, se encontró una ballena varada la cual se identificó como una ballena de aleta Balaenoptera physalus con una longitud de 18 m. Conclusiones. Esta nota es el primer registro confirmado de esta especie en el Caribe mexicano y aumenta la lista de especies confirmadas de mamíferos acuáticos distribuidas en esta región.&nbsp

Seasonality of habitat use, mortality and reproduction of the vulnerable antillean manatee trichechus manatus manatus in the orinoco river, Colombia: Implications for conservation

The Vulnerable Antillean manatee Trichechus manatus manatus (Mammalia, Sirenia) is threatened by hunting, entanglement in fishing nets and habitat degradation but most knowledge of the species comes from coastal and estuarine populations. We therefore studied an Antillean manatee population located >1,100 km from the Caribbean coast, in the Orinoco River of Colombia, during 20012005. To verify the occurrence of the manatee and to investigate its habitat use throughout the annual hydrological cycle, we carried out surveys for manatees and manatee feeding signs over c. 40 km of the Orinoco River, between El Burro and Bachaco. We made 870 sightings in 1,003 hours of observation, and found 69 feeding areas in 776 hours of surveys. From 82 interviews in a total of 28 locations in Venezuela and Colombia we compiled 90 reports of manatees injured or killed in the Orinoco during 19802004. Both habitat use by the manatee and anthropogenic impacts on the species vary with the annual hydrological cycle. Reproduction appears to occur during the low water period in restricted areas that retain deep water. Improved knowledge of the dynamics of manatee migration and regulation of human activities, especially those related to use of nets and boat traffic, are required for conservation of the Antillean manatee in this freshwater habitat. © Fauna & Flora International 2009

Aquatic mammals from the Mexican Caribbean; a review

We present a review of the aquatic mammal species occurring in the Mexican Caribbean. Several published sources were reviewed to find information about aquatic mammals reported for the Mexican Caribbean. Additionally, we consulted 29 national and international collections and museums. Based on documents, collections, direct records and local news, we analyzed 18 confirmed species of aquatic mammals for the study area [Tursiops truncatus, Stenella clymene, S. frontalis, S. longirostris, Steno bredanensis, Grampus griseus, Globicephala macrorhynchus, Peponocephala electra; Pseudorca crassidens, Orcinus orca, Physeter macrocephalus, Kogia breviceps, K. sima, Ziphius cavirostris, Mesoplodon europaeus, Trichechus manatus manatus, Lontra longicaudis annectens and Monachus tropicalis (extinct)]. In order to gather solid baseline information that enhances efficient long-term management, regular and systematic population censuses of the aquatic mammal community are recommended. We recommend the use of the Mexican Caribbean area as a separate unit of management and conservation, differently as has been included in the macro region Gulf of Mexico/Mexican Caribbean

Ecological Niche Modeling of Three Species of Stenella Dolphins in the Caribbean Basin, With Application to the Seaflower Biosphere Reserve

Dolphins of the genus Stenella occur in pelagic waters of both tropical and warm-temperate oceans. Three species, the Atlantic spotted dolphin (Stenella frontalis), the pantropical spotted dolphin (S. attenuata), and the spinner dolphin (S. longirostris) are abundant worldwide, but in the Caribbean Basin they have been poorly studied and information on their distribution patterns is scarce. Specifically, in Colombia’s remote Seaflower Biosphere Reserve (SFBR) S. attenuata has been reported occasionally, but S. frontalis and S. longirostris have never been recorded before. To address this information gap, an ecological niche modeling approach was used to determine the potential distribution patterns of these three dolphin species in the region. Records of these species for the Caribbean Basin were compiled, including both published and unpublished data. Environmental information, including bathymetry, bathymetric slope, distance to shore, sea surface temperature, sea surface salinity, and chlorophyll-a concentration was gathered from public databases (MARSPEC and Bio-ORACLE) in raster format. The maximum entropy algorithm (Maxent) for modeling species’ geographic distributions with presence-only data was used. After filtering the data, 210 records of S. attenuata, 204 of S. frontalis, and 80 of S. longirostris were used to run models. The best configuration for each model was chosen based on the ΔAICc criterion. For all three species, the final ecological niche models returned AUC test values higher than 0.8, indicating satisfactory model performance. The resulting potential distribution maps suggested that areas closest to continental shorelines of the Caribbean Basin and surrounding islands had the highest environmental suitability for all species (>70%). All models reported high environmental suitability for S. attenuata and S. longirostris in the SFBR, mainly in the southernmost part surrounding San Andrés and Providence Archipelago. Assessment of niche overlap from the predictions of species distributions using the similarity statistic and pairwise map overlap indicated that S. frontalis and S. longirostris had niches slightly more similar in comparison to S. attenuata. As this was a first effort to fill a gap in our understanding of the distribution of species in the genus Stenella in the Caribbean Basin, further studies are necessary using both niche modeling and biological/ecological approaches

Magníficos villanos

Invasive alien species (IAS) are considered the second greatest threat to biodiversity after habitat loss; and therefore, they need to be controlled promptly to avoid irreversible damages to the ecosystems and loss of species. However, this is not an easy task when the IAS is also a charismatic animal. Here, I analyze the case of the invasive hippos in the Magdalena River basin (Colombia) as an example of an IAS charisma. The charisma of this mega-mammal may have affected the Colombian people’s perceptions and attitudes toward its management, and ultimately delayed or prevented control implementation. A transdisciplinary approach considering both biological and non-biological aspects of hippo’s management in Colombia is critical in solving this environmental dilemma.Las especies exóticas invasoras (EEIs) son consideradas la segunda mayor amenaza para la biodiversidad después de la pérdida de hábitat; y por lo tanto, deben ser controladas con celeridad para evitar daños irreversibles a los ecosistemas y pérdida de especies. Sin embargo, esta no es una tarea fácil cuando la EEI resulta además ser un animal carismático. Aquí analizo el caso de los hipopótamos invasores en la cuenca del río Magdalena (Colombia) como ejemplo de EEI carismática. El carisma de este mega-mamífero podría haber afectado las percepciones y actitudes de la sociedad colombiana con respecto a su manejo y, en última instancia, retrasar o impedir la implementación del control efectivo de la población. Para resolver este dilema ambiental es fundamental abordarlo desde un enfoque transdisciplinario, que considere los muy diversos aspectos biológicos y no biológicos del manejo del hipopótamo en Colombia

Ecología, comportamiento y uso de hábitat de manatíes en la Bahía de Chetumal

Chetumal, Quintana Roo, México : El Colegio de la Frontera Sur, 2010