In this month’s research update we summarise articles on Egyptian vulture migration bottlenecks along the Eastern Flyway between Europe, the Middle East and Africa; the impacts of traffic on vulture feeding patterns in a natural park in Spain; and two articles that investigate the impacts of vultures feeding on human-derived waste at rubbish dumps in South America and Spain.
Identifying critical migratory bottlenecks and high-use areas for an endangered migratory soaring bird across three continents. Buechley et al. 2018. Journal of Avian Biology
The authors of this study used remote-tracking technology to study the migration routes of 45 individual Egyptian vultures over a total of 75 complete migrations that traversed three continents along the Red Sea Flyway. The vultures were trapped and fitted with satellite transmitters in the Balkans (Bulgaria, Greece, Former Yugoslav Republic of Macedonia, and Albania), the Middle East (Turkey and Armenia), and Africa (Ethiopia and Djibouti).
The vultures showed a high degree of individual variation in the duration (12 – 95 days) and distance (3,302 – 11,974 km) of their spring and autumn migrations, but the linear distance between start and end points was similar for immatures (3,289 km) and adults (3,332 km). Immatures, however, migrated less efficiently than adults, taking less direct routes and having to cover greater distances.
The most important migratory bottlenecks were located in the south-eastern Red Sea coast and the Bab-el-Mandeb Strait (Saudi Arabia, Yemen, Djibouti), the Suez Canal zone (Egypt), and the Gulf of Iskenderun (Turkey), as shown in the map below. Importantly, none of these areas were covered by protected areas and <13% of the high-use areas along the migration routes were protected. The authors provide clear guidelines to address these concerning gaps in the protected area network and conservation investment.
Tourism in protected areas: Disentangling road and traffic effects on intra-guild scavenging processes. Donazar et al. 2018. Science of the Total Environment
The authors of this study used camera traps placed at 130 experimentally placed carcasses to examine how road proximity and traffic intensity influenced patterns of resource use in the avian scavenger guild in Bardenas Reales of Navarra Protected Natural Park in northern Spain.
Eurasian griffon and Egyptian vultures were frequently observed at the carcasses together with five species of facultative scavenger species such as crows and black and red kites. The results showed that number of species present at the carcasses and the probability that the carcasses would be consumed decreased if they were closer to roads and on days when the traffic was heaviest. It was also apparent that griffon vultures altered their attendance patterns to avoid maximum traffic levels.
These findings demonstrate that while protected areas are important for conserving vultures and other scavengers, they must be managed sensitively to avoid unintentional negative impacts of tourism.
More massive but potentially less healthy: black vultures feeding in rubbish dumps differed in clinical and biochemical parameters with wild feeding birds. Plaza & Lambertucci, 2018. PeerJ
This study investigated the potential effects on the health of [American] black vultures (Coragyps atratus) when they frequently feed on rubbish dumps. The authors compared health parameters of 94 adult black vultures from two different sites in North Western Patagonia, a rubbish dump and the wild steppe.
These findings highlight the important role that vultures play in consuming waste at the same time as illustrating how susceptible they can be to the negative impacts of human-derived environmental toxins.
Assessing the applicability of stable isotope analysis to determine the contribution of landfills to vultures’ diet. Tauler-Ametller et al. 2018. PLoS ONE.
Related to the previous study, these authors also investigated the diet of vultures feeding at rubbish dumps, using conventional methods (i.e. visual identification of food items collected at nests) and stable isotope analysis (SIA) of nestling feathers feathers to study the diet of Egyptian vultures in the north-east Iberian Peninsula.
Although the results from the two methods differed in some ways, the authors suggest that stable isotope analysis could be used to distinguish between Egyptian vultures that rely on human waste at landfills and those that rely on a supply of domestic livestock and wild species.
The results showed that the diets of some breeding pairs of Egyptian vultures consisted of 50% of food derived from landfills, and that a higher degree of “humanization” of their territories resulted in higher levels of isotopes related to food sources derived from human waste.
This study once again illustrates the close relationship between vultures and human-derived waste and land management practices, and also provides a promising new method for studying this important topic.