In this research update we summarise articles about research that identifies priority areas for vulture conservation; a cutting-edge study that investigates how Griffon Vultures watch each other to inform flight decisions; a global review of the effects of tracking devices on individual birds; and an article that investigates how farming practices might expose vultures to veterinary drugs.
This study combines information about the distribution and status of all 15 “Old World” vulture species found across Europe, Asia and Africa, and the level of human-caused threats that they face, to identify critical areas for their conservation.
The results showed that the highest priority areas for vulture conservation are in southern and eastern Africa, South Asia and the Iberian Peninsula, and that 80% of these areas are not currently protected by the existing network of reserves.
The study also showed that some species such as the Cinereous Vulture and Bearded Vulture require larger areas for protection than others.
Interestingly, the countries with the largest proportion of priority areas for vulture conservation also spend the most money on preventing and responding to rabies outbreaks (e.g. India, China, Myanmar). The authors therefore suggest that restoring vulture populations in these areas could provide important ecosystem services that regulate rabies and other diseases.
This study provides the first map that identifies top priority areas for vulture conservation and will be a useful guide for implementing the actions of the Multi-species Action Plan to Conserve African-Eurasian Vultures.
Vultures are known to form networks in the sky with individuals watching the movements of other birds to inform their own movement decisions. This improves their foraging efficiency and enables them to arrive quickly at a carcass in large numbers. However, little is known about how vultures use social cues to assess air currents to improve individual flight performance.
The authors of this study equipped five Griffon Vultures with GPS and airspeed loggers at the Rocher des Aigles falconry centre in France, to investigate how birds flying in the same airspace watch each other to make informed decisions about the speed, direction and mode of flight.
Birds that were able to identify the location of thermal updrafts by watching conspecifics were able to quickly adopt higher airspeeds when travelling between thermals, which would be a risky strategy if they were flying alone without the assistance of this “social information”.
The results demonstrate that there are complex combinations of different factors that influence flight speed selection by vultures and that individuals watch each other to gain information about the occurrence of favourable air currents that can inform their movement decisions.
Since it was discovered that accidental poisoning by the veterinary drug diclofenac caused the widespread decline of vultures across Asia, further research has shown that vultures and other scavengers are exposed to a wide range of agricultural veterinary pharmaceuticals, often with harmful effects.
The authors of this study assess the diet and signs of disease in nestlings of Cinereous, Egyptian and Griffon Vultures living in different regions of Spain under contrasting farming intensities: intensive systems with higher use of veterinary drugs (mainly pig and poultry farms) compared to more extensive systems.
Nestlings from central Spain, where farming is more intensive, showed a higher frequency of oral lesions (indicating disease) compared to lower intensity farming areas in southern and northern Spain.
A positive relationship was found between the proportion of nestlings with lesions and the frequency of intensively farmed livestock species (pigs and poultry) in the diet.
The authors encourage further research into the risk of exposure to and harmful effects of veterinary drugs for vultures when feeding on farmland and at supplementary feeding sites which are an increasingly important source of food. They suggest that monitoring the incidence of oral lesions in vultures could be an effective surveillance method that is relatively easy to implement.
Tracking studies can provide important data to inform conservation actions that would not be attainable by other methods (e.g. see this three-decade review on vulture and condor tracking studies).
This comprehensive review of >3,400 primary references investigated long-term patterns of the use of tracking devices to study birds and the reporting of the effects of such devices on individual birds. Of the reviewed studies >1,500 contained information about whether effects of the tracking devices were assessed and reported.
The number of articles on bird tracking increased at 4.4% per year between 1985 and 2017.
The most common primary study topics were migration (20%), foraging (19%), home range and habitat use (15%), survival (9%) and device effects (as a major topic of the study, 6%).
Migration studies have increased in number over time, while studies focusing on the effects of tracking devices decreased significantly from 14% of studies in 1985-89 to 3% in 2015-17.
38% of studies (591/1560) that recorded effects of tracking devices on individual birds reported one or more effects attributable to device deployment or after release or recapture. This proportion declined by 1.4% per year from 71% in 1985 to 61% in 2017.
The proportion of papers that did not explicitly assess the effects of tracking devices increased from 39% in 1985 to 61% in 2017.
The weight of transmitters decreased from 4.1% before 1985 to 3.1% in 1995-199, but with only marginal decreases in the period since.
Most of the main attachment methods were associated with a similar incidence of effects reported, but with invasive (sutured/subcutaneous/body implants) methods incidences were generally high, whereas tail and leg attachment incidences were low.
Effects reported varied in severity from relatively minor (e.g. increased short-term preening following device attachment) to much more serious (e.g. severely compromised locomotion, inability to breed successfully or even mortality caused by lesions and infections associated with device attachment, lower foraging efficiency, increased vulnerability to predators or hunters, increased stress or energy expenditure).
Overall changes in attachment method usage over the 33-year period showed a significant increase in leg and leg-loop harness, and a decrease in back attachment, presumably as the welfare benefits of using leg-loop harnesses have been realised. VCF currently supports the use of leg-loop attachments for vultures in preference to other methods.
The authors call for more systematic documentation of potential effects in peer-reviewed publications to support more rigorous science and to further improve bird welfare.
This research topic is something that we at the Vulture Conservation Foundation consider to be important and we recently conducted a global survey on the effects of raptor and vulture tracking, the preliminary findings of which were presented at the Annual Bearded Vulture Meeting in Cazorla and at the Raptor Research Foundation Annual Conference in South Africa. The survey is still open and we would appreciate your input, survey on the effects of raptor and vulture tracking.We aim for the results to inform best practice guidelines for vulture tracking and tagging.