Publications

Abstract

Understanding cetacean distribution is essential for conservation planning and decision-making, particularly in regions subject to rapid environmental changes. Nevertheless, information on their spatiotemporal distribution is commonly limited, especially from remote areas. Species distribution models (SDMs) are powerful tools, relating species occurrences to environmental variables to predict the species' potential distribution. This study aims at using presence-only SDMs (MaxEnt) to identify suitable habitats for fin whales (Balaenoptera physalus) on their Nordic and Barents Seas feeding grounds. We used spatial-block cross-validation to tune MaxEnt parameters and evaluate model performance using spatially independent testing data. We considered spatial sampling bias correction using four methods. Important environmental variables were distance to shore and sea ice edge, variability of sea surface temperature and sea surface salinity, and depth. Suitable fin whale habitats were predicted along the west coast of Svalbard, between Svalbard and the eastern Norwegian Sea, coastal areas off Iceland and southern East Greenland, and along the Knipovich Ridge to Jan Mayen. Results support that presence-only SDMs are effective tools to predict cetacean habitat suitability, particularly in remote areas like the Arctic Ocean. SDMs constitute a cost-effective method for targeting future surveys and identifying top priority sites for conservation measures.

Abstract

Object categorization is an important cognitive adaptation, quickly providing an animal with relevant and potentially life-saving information. It can be defined as the process whereby objects that are not the same, are nonetheless grouped together according to some defining feature(s) and responded to as if they were the same. In this way, knowledge about one object, behavior or situation can be extrapolated onto another without much cost and effort. Many vertebrates including humans, monkeys, birds and teleosts have been shown to be able to categorize, with abilities varying between species and tasks. This study assessed object categorization skills in the gray bamboo shark Chiloscyllium griseum. Sharks learned to distinguish between the two categories, 'fish' versus 'snail' independently of image features and image type, i.e., black and white drawings, photographs, comics or negative images. Transfer tests indicated that sharks predominantly focused on and categorized the positive stimulus, while disregarding the negative stimulus.