An investigation of population variation in maze exploration and its predictors in wild Trinidadian guppies (Poecilia reticulata).

Individuals often face unpredictable and harsh environments, presenting them with novel ecological problems. Behaviour can provide an adaptive response in such conditions and where these conditions vary between populations, we may predict development and evolution to shape differences in behaviour such as exploration, innovation, and learning, as well as other traits. Here, we compared in the wild the maze swimming performance of groups of female guppies from two Trinidadian populations that differ in numerous ecological characteristics, the Upper and Lower Aripo river. Compared to Upper Aripo fish, Lower Aripo fish were slower to complete the maze, our measure of propensity to innovate, and scored lower on a combined measure of activity and exploration. More active-exploratory groups were faster to complete the maze, but only in the Lower Aripo. We found no evidence for learning the maze. Our results suggest that activity-exploratory and innovative propensities can vary between populations, as can predictors of innovation. These findings are consistent with high predation risk shaping decreased activity-exploratory propensities, but further population comparisons are required to reliably determine the drivers of the observed population difference. Our results emphasize that individual and population differences in activity-exploration and innovation can be shaped by numerous factors.

Sounds of Indo-Pacific humpback dolphins (Sousa chinensis) in West Hong Kong: a preliminary description.

Vocalizations of Indo-Pacific humpback dolphins (Sousa chinensis) in west Hong Kong waters were described from 12 recordings in 2010. A broadband hydrophone system recorded sounds. Vocalizations were characterized as broadband click trains, burst pulses, and narrowband frequency modulated sounds, including whistles generally similar to those of some other delphinid cetaceans. A comparison of results to previous humpback dolphin sound descriptions for Moreton Bay, Australia found broad similarities except for the apparent absence of "quacks" and "grunts" in the present study, which are of low frequency and thus were possibly masked by anthropogenic and other low frequency noise in the Hong Kong habitat.