Ecological factors influencing group sizes of river dolphins (Inia geoffrensis and Sotalia fluviatilis)

2011 ◽  
Vol 28 (2) ◽  
pp. E124-E142 ◽  
Author(s):  
Catalina Gomez-Salazar ◽  
Fernando Trujillo ◽  
Hal Whitehead
2017 ◽  
Vol 35 (4) ◽  
pp. 1582-1589
Author(s):  
Luzivaldo Castro dos Santos Júnior ◽  
Miriam Marmontel ◽  
Francisco Glauco de Araújo Santos ◽  
Rose Eli Grassi Rici ◽  
Maria Angélica Miglino ◽  
...  

Author(s):  
Evan Hall

Presentation Title: River dolphins globally represent a highly at risk group of mammals. Most river dolphin species inhabit the world’s large rivers, which are also highly populated and heavily utilized. The focus of my research was on the two species of freshwater dolphins that inhabit the Amazon River, the boto (Inia geoffrensis) and the tucuxi (Sotalia fluviatilis). Currently both species are listed by the International Union for Conservation of Nature (IUCN) as ‘Data Defficient’, which means there is currently not enough information known about them to accurately assess whether or not they are endangered. Major gaps in research of these two species currently exist in many basic biological and ecological parameters. The focus of this research was to compare existing data on group size and habitat preference as well as determine the behavioral ecology of the two species of river dolphins. The research was conducted in the Pacaya-Samiria National Reserve, Peru, which has a relatively high density of river dolphins. The reserve consists of many small tributaries, which are relatively understudied and so the conclusions drawn from this research will help guide future research and management decisions in other regions of the Amazon.


Koedoe ◽  
2002 ◽  
Vol 45 (2) ◽  
Author(s):  
D.A. Edge

The Brenton Blue butterfly, Orachrysops niobe (Trimen, 1862) (Lepidoptera:Lycaenidae), is endemic to the southern Cape and is currently listed as Endangered. This study looks at some of the key ecological factors influencing the breeding success of the species—host plant abundance and condition, nectar sources, climate/ microclimate, and vegetation management techniques. The adult butterfly population was monitored over an entire breeding season; host plants were identified and individually monitored; and egg counts were done. This enabled the effects of a number of different management techniques to be evaluated (burning, cutting, physical removal of invasive elements, and combinations thereof). A fivefold increase in the population of O. niobe was observed over the breeding season. This increase was positively correlated to a similar increase in host plant abundance in the areas where cutting and physical removal of invasive elements was practiced. Burning, by contrast, appeared to have a negative impact on host plant and butterfly abundance over the same period. Impacts of other factors such as climate, nectar sources and the natural strength of the second brood are discussed. A hypothesis, of megaherbivore activity as the principal historical disturbance mechanism promoting locally favourable conditions for O. niobe to establish and maintain colonies, is proposed. Recommendations for reserve management and future research are made.


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