Dear colleagues, We are now pleased to share with you our most recent papers on dolphins in Golfo Dulce (Costa Rica), just published in Journal of Mammalogy. We continue exploring the key aspect involved in the ecology of dolphins coexisting in a very discrete habitat, in this case when modelling the ecological niche of cetaceans. Please don't think twice to ask for a print in case you cannot access the paper by subscription. *Habitat partitioning mediates the coexistence of sympatric dolphins in a tropical fjord-like embayment* Lenin Oviedo, Marc Fernández, David Herra-Miranda, Juan Diego Pacheco-Polanco, Claudia J Hernández-Camacho, David Aurioles-Gamboa Bottlenose dolphins (*Tursiops truncatus*) and pantropical spotted dolphins (*Stenella attenuata*) co-occur in Golfo Dulce, a fjord-like embayment located in the southern Pacific coast of Costa Rica. We evaluated if spatial overlap by these dolphin species is associated with similar environmental requirements. Presence-only models based on niche theory were constructed by contrasting a set of spatial locations with the responses of the target species to abiotic ecogeographical variables (EGVs: depth, slope, distance to rivers, distance to 200 m isobath, mean sea surface temperature, and variation in sea surface temperature). Models were cross-validated with levels of discrimination that ranged from acceptable to excellent based on the area under the curve assessment (*T. truncatus*, rainy season: 0.76, dry season: 0.83; *S. attenuata*, rainy season: 0.84, dry season: 0.89). Both dolphin species occur in Golfo Dulce year-round; the lack of seasonality documented previously was supported by the models. Species distribution models showed no spatial overlap, with differences in EGVs affecting their distribution (*T. truncatus*: distance to river + distance to 200 m isobath, *S. attenuata*: depth + sea surface temperature). We argue that the coexistence of both predators in Golfo Dulce is linked to habitat heterogeneity, where critical habitats are spatially differentiated. The lack of fine-scale spatial overlap, along with influential abiotic variables, highlights a process of coexistence for dolphins that are sympatric at the scale of Golfo Dulce, but within the Gulf there is fine-scale allopatry. *----------------------------------------------* *Lenin Oviedo Research Associate Centro de Investigación de Cetáceos CEIC-Costa Rica*