Esther Sebastián-González, postdoc researcher presents her paper ‘Waterbird seed‐dispersal networks are similarly nested but less modular than those of frugivorous birds, and not driven by functional traits’, and show us how waterbirds paved her road into ecology.

Esther Sebastián-González in a fieldwork trip in Mongolia (Author JM Pérez-García)
Esther Sebastián-González in a fieldwork trip in Mongolia (Author JM Pérez-García)

About the paper

Frugivorous animals and plants with fleshy fruits are largely known to benefit from each other. This happens when the seeds of the plants survive after passing through the animal´s gut and get dispersed, increasing their chances of producing a new plant, while animals get food. However, not all animals can disperse all the fruit species in an ecosystem, as the larger seeds can only be swallowed by the larger animal species.

Group of flying Northern shovelers (Spatula clypeata). Northern shovelers have been found to disperse many different seeds via gut passage (Author Sándor Borza)
Group of flying Northern shovelers (Spatula clypeata). Northern shovelers have been found to disperse many different seeds via gut passage (Author Sándor Borza)

In our paper, we study a largely unnoticed seed dispersal interaction: that provided by waterbirds. We used waterbird diet studies from four European wetlands and 10 duck and rallid species dispersing 88 different plants lacking a fleshy fruit. Despite the morphological and ecological differences these birds have, a network analysis revealed no consistent differences in the plants they were dispersing. Previous work found that frugivorous birds may split into groups of similar species that disperse similar plants. We found that waterbirds such as dabbling ducks, diving ducks, coots and moorhens have similar roles as seed dispersers within a wetland, despite being very different in their behaviour and morphology. Available functional traits did not explain the roles of different birds or the plants they disperse in the networks of interactions. However, when we consider the vital role waterbirds have in spreading plants to new places, some bird species undergo longer migrations or move more frequently, and others move at different times of the year and in different directions, so each has a unique role to play in long-distance seed dispersal.

About the research

Group of male and female mallards (Anas platyrhynchos). Mallards have been found to disperse many different seeds via gut passage (Author: Nicky Petkov)
Group of male and female mallards (Anas platyrhynchos). Mallards have been found to disperse many different seeds via gut passage (Author: Nicky Petkov)

This paper adds to the growing evidence about the important role that waterbirds play in dispersing both aquatic and terrestrial seeds via gut passage. Their long-distance migrations can have outstanding consequences for helping plants to track climate change, or for the spread of invasive species. Ours is the first network analysis for the seed dispersal of non-frugivorous birds. Given the broad variety of plants dispersed by waterbirds, and the few scientists with the naturalist know-how to identify all the seeds they eat, finding datasets of sufficient quality was a considerable challenge. Defining the spatial limits of a suitable study area is also more complicated than for frugivore studies, given waterbirds complex patterns of movement, which may fly daily over tens of kilometres between different feeding and roosting sites.

Most of the plant species dispersed by waterbirds have long been assumed to lack a mechanism for long-distance dispersal. Critically, we are yet to identify the traits that predict which plants are dispersed by waterbird endozoochory, and this is a priority for future research. Other future aims are to sample more complete waterbird communities, including shorebirds, gulls and piscivorous birds (which secondarily disperse seeds inside, or attached to, their prey) such as herons, to compare the role each species has as a plant vector and assess the structure of these broader seed dispersal networks. We also hope to compare the suite of terrestrial plants dispersed by waterbirds with those dispersed by ungulates and corvids in the same landscape. Finally, we plan to sample the resident waterbird species throughout the annual cycle, to assess temporal dynamics in the seed dispersal networks.

About the author

I am a postdoctoral researcher with a curious mind. My PhD work was on waterbirds, but since then my research has broadly covered areas of ecology, zoology, conservation biology and ornithology from different perspectives and covering several study systems worldwide. I have focused on understanding the factors driving the structure of terrestrial animal communities (mostly, but not exclusively, birds) and how habitat and interactions among species influence them at local and macroecological scales. I am interested in understanding community ecology from both a theoretical (e.g. hypothesis testing) and an applied (i.e. conservation and management) point of view. In my free time, I love hiking, traveling, reading, cooking, dancing and playing with my little kid.

You can find more about me in my personal webpage.

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