Ethology and Behavioral Ecology of SireniaHeleneMarsh, Ed. Springer Nature. 2022. i–xvi + 417 pp. <scp>ISBN</scp>: 978–3–030‐90741‐9, <scp>US</scp>$159.99 (Hardcover); <scp>ISBN</scp>: 978–3–030‐90742‐6, <scp>US</scp>$119.00 (<scp>eBook</scp>)

Abstract

It is always difficult, as a professor and student supervisor, to guide students on what texts, books, and articles to read to gain a deeper knowledge on a particular subject. This is especially difficult when most of the existing literature focuses on populations that have been well studied and when there is only scarce information from other populations, many of them in remote areas and/or developing countries. So, my initial thought about this book is that it shows a real effort from the authors and editors to include such information. This book, focusing on the ethology and behavioral ecology of Sirenia, provides a comprehensive coverage of behavior in sirenians and how to study them. It is clear that the editor and authors of the different chapters made a conscious effort to summarize all available information on the sirenian species. Both the editor and authors are experienced researchers and academics, most of them specializing in the study of manatees and dugongs, and they do an excellent job of providing information for some of the least studied species, particularly the African manatee. The book includes eight chapters. The first chapter focuses on behavior, particularly with respect to their feeding behavior and diet, that can be inferred from fossils of extinct Sirenia, presenting hypotheses on how they could have adapted to a fully aquatic environment. The second chapter covers morphological and sensory adaptations found in these animals, reviewing aspects such as thermoregulation, hydrostasis, skeletal pachyosteosclerorosis, and somatosensation and how these systems have contributed to a successful aquatic life and particular behavioral adaptations. This chapter explains in a detailed way the sirenian feeding apparatus as well as the central nervous system, for example, how neuronal aggregations known as Rinderkerne appear to be associated with sensory hairs in sirenians body and faces. Chapter three focuses on diving and foraging behaviors, reviewing the sirenian diving physiology and dive times as well as dietary preferences. It includes types and frequency of plants utilized. The authors explain how it is likely that all manatee species are omnivorous, including in their diet freshwater fish and invertebrates, although this has not yet been confirmed for the Amazonian manatee. I found the section on coprophagy very interesting as the authors explain how this practice may help balance nutritional needs of B-complex vitamins and nitrogen, as well as acting as inoculate of bacterial strains helpful for hindgut fermentation. The fourth chapter reviews information on group size, dispersal, and movement of sirenians in relation to their reproductive and social behaviors. In this chapter, the authors also present information on the mating systems found in Sirenia, including leks and scramble promiscuity, and they explain that it is unclear if these mating systems vary among species in relation to genetic makeup or due to adaptation to different ecological conditions. They also present information on movements in riverine populations of Amazonian and African manatees related to annual flood cycles. The authors do an excellent job in summarizing information on genetic studies the results of which, although not aimed directly at answering questions related to movement or dispersal, support related hypotheses, including natal philopatry in females for most species as well as male-mediated gene flow due to higher dispersal rates for males. Chapter five presents information on migratory patterns and large-scale sirenian movements, reviewing information on how to study these movements and on how physiological characteristics of these species require adaptations in order to undertake long-distance movement related to temperature changes in their habitat. However, environmental selective pressures are varied and numerous across sirenian species, suggesting important variation in large-scale movements in different species, populations, and at the individual level. The authors compiled a very complete and interesting table presenting different studies on environmental drivers of seasonal movements and migration at both the species and population level. Chapter six completes the information on movements in sirenians, focusing on small-scale movements. The authors present information on how GPS tags can provide detailed positions for tagged individuals. Such devices, combined with the more recent use of multisensor biologgers, allow for our further understanding of behavioral changes in relation to particular environmental features found in certain areas. The seventh chapter reviews historical and current interactions between sirenian species and humans. I found this chapter fascinating as it presents archeological and anthropological information about the inclusion of manatees and dugongs in different narratives and myths, due to the similarities in nursing behavior between sirenian females and calves and human females and babies. In addition, there are myths about mermaids in many different cultures in Asia, Oceania, and the Americas. Human-sirenian interactions also include hunting techniques developed by different human groups to catch manatees or dugongs. In this chapter, the authors present evidence on how many of such myths have been included in conservation strategies around manatees, particularly in the Amazon region. The authors present information on behavioral aspects of sirenians that make them more prone to negative interactions with fishing activities and they summarize aspects of habitat change and degradation (noise, seagrass bed destruction, boat traffic) and its effect on different manatee and dugong populations. In the last chapter, the authors present information on how climate change and its consequences (i.e., temperature increase, sea level change, etc.) may affect sirenian species around the world. They emphasize the need to have better assessment of changes occurring in plant community composition to predict potential effects on sirenian population dynamics and reproduction. The authors also present potential stressors, such as harmful algal blooms, that may increase health risks and reduce survival for these animals. I think this book is an important reference for all of those interested in sirenian biology and behavior and should be required reading for any biologist interested in deepening their understanding of these fascinating animals.