White stork movements reveal the ecological connectivity between landfills and different habitats

Abstract

Background Connections between habitats are key to a full understanding of anthropic impacts on ecosystems. Freshwater habitats are especially biodiverse, yet depend on exchange with terrestrial habitats. White storks (Ciconia ciconia) are widespread opportunists that often forage in landfills and then visit wetlands, among other habitats. It is well known that white storks ingest contaminants at landfills (such as plastics and antibiotic resistant bacteria), which can be then deposited in other habitats through their faeces and regurgitated pellets. Methods We characterized the role of white storks in habitat connectivity by analyzing GPS data from populations breeding in Germany and wintering from Spain to Morocco. We overlaid GPS tracks on a land-use surface to construct a spatially-explicit network in which nodes were sites, and links were direct flights. We then calculated centrality metrics, identified spatial modules, and quantified overall connections between habitat types. For regional networks in southern Spain and northern Morocco, we built Exponential Random Graph Models (ERGMs) to explain network topologies as a response to node habitat. Results For Spain and Morocco combined, we built a directed spatial network with 114 nodes and 370 valued links. Landfills were the habitat type most connected to others, as measured by direct flights. The relevance of landfills was confirmed in both ERGMs, with significant positive effects of this habitat as a source of flights. In the ERGM for southern Spain, we found significant positive effects of rice fields and salines (solar saltworks) as sinks for flights. By contrast, in the ERGM for northern Morocco, we found a significant positive effect of marshes as a sink for flights. Conclusions These results illustrate how white storks connect landfills with terrestrial and aquatic habitats, some of which are managed for food production. We identified specific interconnected habitat patches across Spain and Morocco that could be used for further studies on biovectoring of pollutants, pathogens and other propagules.

Both environmental conditions and intra- and interspecific interactions influence the movements of a marine predator

“…Such models are analogical to Generalized Linear Models (GLMs) except that they enable hypothesis testing about the processes driving network structure and link formation. These models have been mostly applied in social science, but their properties also make them useful for answering questions related to how and why animals move between locations in the context of movement networks (Fletcher et al, 2011; Jacoby & Freeman, 2016; López-Calderón et al, 2023). Effectively the movement network becomes the response in a regression model, where the predictors are the propensity for nodes (i.e.…”

Winged Resistance: Storks and Gulls Increase Carriage of Antibiotic Resistance by Shifting from Paddy Fields to Landfills

“…The recent change in their foraging behaviour toward more anthropogenic resources (Ramo et al, 2013) makes these bird species interesting models for understanding the impact of human activities on the dispersal of AR at different scales. In addition to long-distance migratory movements, during daily flights gulls and storks often travel between roosting and feeding sites connecting highly polluted systems (where they feed) with wetlands and agricultural habitats (where they rest) (López-Calderón et al, 2023;Martín-Vélez et al, 2020b).…”

“…Artificial methods, mainly using nitrogen and phosphorus application, are employed for fertilization in these agroecosystems, excluding the use of manure (Campos et al, 2010). These paddy fields are a key node of high functional connectivity with other habitat types, including landfills (López-Calderón et al, 2023;Martín-Vélez et al, 2020a, 2020bvan Rees et al, 2021). The Montemarta-Cónica landfill is the largest integrated municipal solid waste treatment centre in Andalusia, managing >620,000 tons per year of waste, including organic matter, packaging, construction, biosanitary waste, and leachate.…”

“…Study site selection was based on GPS tracking data and the use of O. Sacristán-Soriano et al habitat by birds (see (López-Calderón et al, 2023;Martín-Vélez et al, 2020b;van Rees et al, 2021).…”

“…For that purpose, we used two wellmonitored species, white storks (Ciconia ciconia) and lesser blackbacked gulls (Larus fuscus), in the Guadalquivir Basin (SW Spain). Both are known to switch regularly between two major foraging habitats, paddy fields and a nearby landfill (López-Calderón et al, 2023;van Rees et al, 2021). Our work aimed to answer the following questions: i) How does the use of contaminated sites alter the faecal microbiota (composition, diversity, and occurrence of human bacterial pathogens) of two unrelated bird species with different body sizes but similar habitat use?…”