Newswise — A study conducted by Professor Joan Real and his team at the UB Conservation Biology Group (EBC-UB) and the Biodiversity Research Institute (IRBio) of the University of Barcelona, in collaboration with the Centre for Advanced Studies of Blanes (CEAB-CSIC) and the University of Seville, has revealed that the disappearance of urban landfills due to new European regulations poses a significant threat to endangered birds like the Egyptian vulture. The study, published in the journal Movement Ecology, concludes that these birds will need to adapt their feeding patterns in order to survive in the future.
The Egyptian vulture, an endangered species
The Egyptian vulture (Neophron percnopterus) is a small vulture species and a globally endangered bird of prey. It is listed as an Endangered Species on the International Union for the Conservation of Nature's Red List. In the Iberian Peninsula, the Egyptian vulture has been experiencing a decline in population for several years, except in certain regions like Catalonia, where its numbers have been gradually increasing.
As a Trans-Saharan migratory species, the Egyptian vulture spends its winters in Mali, Senegal, and Mauritania, and then returns to the Iberian Peninsula during the spring and summer for breeding. Its diet primarily consists of small carrion and deceased animals found in rural areas, particularly carcasses of extensive livestock and wildlife. Due to its feeding habits, the Egyptian vulture serves as an indicator species for the environmental health and plays a crucial role in removing organic remains from ecosystems.
The research team conducted an assessment to investigate the potential impact of landfill closures on the feeding behaviors of Egyptian vultures. They examined how the changes in resource availability, resulting from the closure of landfills, could potentially affect the behavior of these free-ranging birds. By studying these consequences, the team aimed to understand the potential challenges and adaptations that the Egyptian vultures might face in response to the closure of their food sources.
Professor Joan Real, the lead researcher of the project and a member of the UB Department of Evolutionary Biology, Ecology, and Environmental Sciences, highlights that as extensive livestock farming declined and agricultural intensification increased, the Egyptian vulture started utilizing landfills as an alternative food source. This strategy had advantages, such as access to plentiful and predictable food. However, it also posed risks, including potential exposure to toxins and limited acquisition of natural vitamins. This observation underscores the complex trade-offs involved in the vulture's foraging behavior and the need to explore alternative feeding patterns for their long-term survival.
Joan Real raises a concern regarding the increasing dependence of the Egyptian vulture on urban organic waste as a result of changing environmental conditions. However, with the implementation of the European Landfill Waste Directive and the Circular Economy Action Plan, which aim to eliminate landfills and significantly reduce organic waste to prevent adverse effects on human health, the potential impact on endangered species, particularly the Egyptian vulture, remains uncertain. The implications of these measures on the vulture's survival and their ability to find alternative food sources warrant further investigation and consideration to ensure the conservation of this species.
GPS and spatial network models
To gain insights into the space and resource utilization of Egyptian vultures, the research team employed advanced technologies including GPS transmitters. They meticulously tracked sixteen individual birds over a span of three years, aiming to comprehend their spatial movement patterns and food resource utilization. The team also employed innovative analytical techniques, utilizing spatial network-based models. These models allowed them to evaluate the connectivity between crucial food sources based on the movement patterns observed in the tagged birds. This combination of cutting-edge technology and analytical methods provided valuable information about how the vultures navigate their environment and make use of available resources.
According to Catuxa Cerecedo-Iglesias, the first author of the study and a researcher from UB-IRBio, the findings indicate variations in food strategies between breeding and non-breeding Egyptian vultures. Breeding individuals tended to remain within specific areas surrounding their nests, while still having the capability to undertake long-distance journeys and utilize resources from extensive livestock farming and landfills. On the other hand, non-breeding vultures had larger movement ranges but primarily relied on food sources found in landfill areas. These distinctions highlight the different foraging behaviors and resource utilization patterns of breeding and non-breeding Egyptian vultures.
Researcher Catuza Cerecedo-Iglesias emphasizes that one of the key findings of the study is the vulnerability of both breeding and non-breeding Egyptian vultures' food networks to the potential loss of main feeding areas in landfills. These landfills serve as highly predictable and reliable food resources for the vultures. The study underscores the importance of these landfill sites for the vultures' foraging strategies and highlights the potential consequences that the removal of these feeding areas may have on the survival and behavior of the Egyptian vulture population.
The researcher adds that within the context of the anticipated disappearance of landfills in the future, the study unveils that Egyptian vultures would heavily rely on carcasses from extensive livestock farming as their primary food source. However, considering the projected decline in extensive sheep farming, the potential impact of this change on Egyptian vulture populations remains uncertain. The study highlights the need for further investigation and understanding of the potential consequences that the reduction of extensive sheep farming may have on the survival and population dynamics of Egyptian vultures.
Protection of Egyptian vultures in the framework of the circular economy
The study suggests that future environmental policies should focus on expanding the availability of food resources derived from extensive livestock farming. Additionally, efforts should be made to promote the recovery of sheep populations, which have been declining significantly. This would involve allowing the natural abandonment of livestock carcasses in the environment. By adopting such a strategy, not only would it help alleviate the potential food shortage resulting from landfill closures, but it would also contribute to the conservation of endangered species, including the Egyptian vulture. Furthermore, it would serve as a means to preserve sheep farming and the associated pastoral culture. The authors emphasize that this integrated approach would have multiple benefits, addressing ecological concerns while supporting cultural and economic aspects tied to livestock farming.
The authors highlight that in Catalonia, these measures are currently only permitted in certain regions and from a minimum altitude of 1,400 meters. This restricted approach leaves a significant portion of the areas where Egyptian vultures are distributed without sufficient food resources. Therefore, the authors emphasize the importance of expanding the surface area of these feeding zones at lower altitudes and in other regions. By broadening the scope of these measures, more suitable foraging areas can be made available to support the dietary needs of Egyptian vultures across their distribution range. This would be crucial for the conservation of the species and its successful adaptation in different ecological contexts.
The study has received funding from various sources, including the Spanish Ministry of Science and Innovation, Red Eléctrica de España SAU, the Management Service of the Barcelona Provincial Council, Catalunya-La Pedrera, and the organization of the Delta Birding Festival. In addition, it has received support from the Spanish Ministry of Ecological Transition and Demographic Challenge, Ferrovial, the Biodiversity Service of the Catalan Government, the Osona Naturalists Group (GNO), the Calldetenes-Osona Ringing Group (GACO), the Consortium for the Management of Urban Waste of Osona, and a network of dedicated volunteers who contributed to the study. The collaboration and support of these organizations and individuals have been instrumental in the successful execution of the research.
RSS