In this month’s research update we summarize articles on the wildlife poisoning in Greece; the breeding success of Egyptian vultures in Bulgaria; the prevalence of rodenticides in non-target predators and scavengers in Finland; and the role of bathing in restoring Cape vulture feather shape and strength.     

Animal mortality and illegal poison bait use in Greece. Ntemiri et al. 2018. Environmental Monitoring and Assessment.

This study analyses the use of poison baits to kill animals across Greece between 2000 and 2016, during which a total of 1015 poisoning incidents in rural areas that killed a minimum of 3248 animals were recorded. 

Avian scavenger species, especially vultures, were most frequently killed by secondary poisoning (30% of wildlife fatalities), while shepherd dogs accounted for 66.4% of domestic animal fatalities.  

Although in 58.7% of investigated cases the motives for poisoning were unknown, for the remaining cases multiple factors, often working in synergy, were the main reasons for poisoned bait use: control of predators (mainly foxes); retaliatory actions between stakeholders (e.g. hunters vs livestock farmers); and control of crop-damaging species. Conflicts between different stakeholders were the most common cause of poison use, for multiple complex reasons.

Although poisoned baits were often not found, toxicological analyses of poisoned animals revealed that a wide range of chemicals were used, including agricultural pesticides such as carbamates and organophosphates. Methomyl was the most common substance used, detected in 54.2% of analysed samples, and an increase in the use of potassium cyanide over the course of the study period was recorded.  

The majority (72 %) of incidents were recorded outside protected areas, with a concentration in the north of the country, probably due to the greater abundance of large predators, and on the island of Crete, possibly due to better monitoring procedures. 73.4 % of the cases were not reported to relevant authorities.

This thorough research demonstrates the prevalence of poisoning in Greece and the potential impact on wild and domestic animals. The authors call for an integrated and collaborative national anti-poisoning strategy, which the VCF’s recently-launched Balkan Anti-Poisoning Project will contribute to.

In this month’s research update we summarise research articles on wind farm impacts on migratory birds; a state-of-the-art detection system for reducing bird collisions with wind turbines; the first record of a tracked Egyptian vulture being hunted and traded in West Africa; and the potential negative impacts for scavengers as apex predator populations recover.     

Impact of wind farms on soaring bird populations at a migratory bottleneck. Martin et al. 2018. European Journal of Wildlife Research

The authors of this study examined monthly migratory soaring bird abundance in relation to long-term mortality rates at 21 wind farms located near the Strait of Gibraltar – the most important migratory bottleneck in Western Europe and also an important region for wind energy generation in Spain. A previous study by some of the same authors revealed that the collision rate of birds with wind turbines in this region was among the highest ever recorded for raptors, with griffon vultures being the most frequently killed species.  

Although monthly bird abundance was not directly related to the number of fatalities over the year, mortality rates peaked in the late summer and early autumn, coinciding with the peak autumn migration period. Griffon vultures were the most commonly killed species, with 416 recorded fatalities in the 9-year study period. A second mortality peak occurred in the breeding season, when a higher proportion of adult birds were killed. 

The authors suggest that the number of fatalities during autumn migration constitute only a small proportion (1%) of the total migrating population, and that most of the deaths are of juveniles; but that fatalities during the breeding season represent a substantial proportion (6%) of the local breeding population, with population-level impacts being likely at the local scale. [It is worth noting that the wind farms closest to the Strait, where mortalities of migrants might be expected to be higher, were not included in the analysis – Fig. 1 below]

Vultures are particularly susceptible to collisions with wind turbines due to their large size, limited manoeuvrability and tendency for wind farms to be located where they occur in high densities (often due to favourable topography and wind currents).  It is therefore essential that new methods for reducing bird collisions at wind farms are developed, as discussed in the next article.