August 9, 2023

One of the objectives of the LIFE for falcons projects is addressing the primary anthropogenic threats in the project’s Special Protection Areas where the Saker falcon has been recorded. One of the threats is accidental poisoning by pesticides used in agriculture. The Habitat Foundation conducted research on the use of pesticides in Romania and Bulgaria, developed mitigation measures and provided practical alternative solutions to the key stakeholders. In Bulgaria, Romania and other in countries in their vicinity, different examples exist of excessive use of pesticides in the past that still have consequences on soil, animals and humans.

The report of the study on the excessive use of pesticides is available here: Excessive use of pesticides.

Summary

It is well known that raptors are sensitive to certain pesticides. Many pesticides are not or only partially broken down, and thus persist throughout the food chain. The toxic chemicals and their derivative metabolites are stored in for instance liver and fatty tissues, and bioaccumulate further up the food web. Top predators and scavengers are therefore often exposed to high levels of a diversity of pesticides. Also, the Saker Falcon (Falco cherrug), a raptor of mainly open grasslands and feeding on small rodents and birds, may therefore be subjected to high concentrations of pesticides.

Raptors, like the Saker falcon, are indirectly poisoned with pesticides through their prey, small mammals. Although small mammals may be directly sprayed with pesticides when they are residing in or near crop fields, the exposure pathway is usually through the ingestion of contaminated food. Granivorous and omnivorous mammal species may for instance eat seeds that are coated with pesticides. However, exposure may also be indirect, through eating contaminated (insect) prey or drinking contaminated water. The importance of the exposure of small mammals to toxic compounds in combination with bioaccumulative properties of these compounds can hardly be overstated. Small mammals serve as prey for many predatory mammals and birds, thus exposing these species to the same chemicals.

Interestingly, the development of new types of pesticides that are not lethal to small mammals may enhance exposure of predatory species. Chronic exposure of small mammals can affect physiological processes and their behavior, making them easy prey for predators. Thus, predators may preferentially prey on individuals that are suffering from the effects of pesticides.

At the same time, predators are also heavily impacted by rodenticides, i.e. pesticides that target rodents and aim to kill them as quickly as possible. A recent review compiled the evidence for the effects of rodenticides on secondary and tertiary consumers. Rodenticides are usually anticoagulants that not only affect rodents, but also other mammals and birds. They are often lethal after secondary exposure, but may also cause sublethal effects, such as impaired mobility or anemia. Anticoagulants are also very likely to cause population declines in predatory and scavenger species.

Even when a complete mechanistic understanding of how pesticides affect birds is lacking, negative impacts have become apparent. For instance, although neonicotinoids have been suggested to have direct effects on birds and mammals, the mechanisms are largely unclear. Yet, large-scale impacts on populations of many bird species in the Netherlands have been shown. Hence, even when direct effects of pesticides on individual birds appear to be absent, or the mechanisms are unclear, longer-term negative impacts may nevertheless exist. This is particularly relevant when considering the use of pesticides based on risk assessments by the European Food Safety Authority, which do not evaluate these kinds of physiological and behavioral impacts.

A recent survey suggested that a diverse set of 71 different active substances are likely to be used in Bulgaria as ingredients in pesticides sold under various brand names. These 71 substances comprise 32 BRPs, i.e. chemicals that are not permitted under EU-legislation but may still be permitted under federal law or are used illegally. Many of the 71 substances are moderately to highly toxic to mammals and/or birds at high acute or lower chronic doses.

In Romania, neonicotinoids (neurotoxic insecticides) are used until today, even though the European Commission fully banned neonicotinoids (neurotoxic insecticides) in 2018. The excessive use of these insecticides is particularly damaging for Romanian beekeepers, while they are also used to fields of sunflower, corn and colza, all crops highly attractive to pollinators. These practices have led to an enormous rate of bee colony losses.

Not only animals are affected by pesticides. Based on the World Health Organisation’s Mortality Database, it is estimated that about 385 million cases of acute pesticide poisoning (APP) occur annually world-wide, including around 11,000 fatalities. Based on a worldwide farming population of approximately 860 million, this means that about 44% of farmers are poisoned by pesticides every year. There is robust evidence that APP is an ongoing major global public health challenge. There is a need to recognize the high burden of non-fatal acute pesticide poisoning, particularly on farmers and farm workers.

The report gives some examples of alternatives to the use of pesticides. There have always been alternatives but it isn’t easy to convince farmers to change the products they use. The mentions a study that gives information on strategies for raising awareness of the adverse effects of pesticide products, both at the food consumer and farmer levels.