Mutualistic interactions form the basis for many ecological processes and are often analyzed within the framework of ecological networks. These interactions can be sampled with a range of methods and first analyses of pollination networks sampled with different methods showed differences in common network metrics. However, it is yet unknown if metrics of seed dispersal networks are similarly affected by the sampling method and if different methods detect a complementary set of frugivores. This is necessary to better understand the (dis-)advantages of each method and to identify the role of each frugivore for the seed dispersal process.

Here, we compare seed removal networks based on the observation of 2,189 frugivore visits on ten focal plant species with seed deposition networks constructed by DNA barcoding of plant seeds in 3,094 frugivore scats. We were interested in whether both methods identify the same disperser species and if species-level network metrics of plant species were correlated between network types.

Both methods identified the same avian super-generalist frugivores, which accounted for the highest number of dispersed seeds. However, only with DNA barcoding, we detected elusive but frequent mammalian seed dispersers. The overall networks created by both methods were congruent but the plant species’ degree, their interaction frequency, and their specialization index (d’) differed.

Our study suggests that DNA barcoding of defecated and regurgitated seeds can be used to construct quantitative seed deposition networks similar to those constructed by focal observations. To improve the overall completeness of seed dispersal networks it might be useful to combine both methods to detect interactions by both birds and mammals. Most importantly, the DNA barcoding method provides information on the post-dispersal stage and thus on the qualitative contribution of each frugivore for the plant community thereby linking species interactions to regeneration dynamics of fleshy-fruited plant species.

Short summary:

Along transects, we collected scats of frugivores which contained seeds of the fleshy-fruited plant community in Białowieża Forest, Poland. We used DNA barcoding to identify the frugivore and were thereby able to obtain quantitative seed deposition data.

Further, we used focal observations to catch feeding interactions between fleshy-fruited plant and their frugivore partners.

Additionally, we counted the number of ripe fruits along the transects and determined the crop size of observed plant individuals.

This data package contains data from Schlautmann, Jan; Rehling, Finn; Albrecht, Jörg; Jaroszewicz, Bogdan; Schabo, Dana G. & Farwig, Nina (2021) Observing frugivores or collecting scats: A method comparison to construct quantitative seed dispersal networks, Oikos. Please refer to the readMe.txt file for details on the dataset.