Threat factors
The international action plan for the great bustard lists 9 threat factors (the global significance of which are given in brackets). Each threat factor differs in importance from one country to the next or from one point in time to the next and very often the impact of one factor is combined with those of others, creating a much larger cumulative effect (e.g. disturbance with collisions, agricultural practices with predation etc.).
- Loss of undisturbed, appropriate habitat with open vegetation (critical) – agricultural intensification (irrigation, chemical plant protection, automation), crop type and pasture / hayfield use patterns and intensity along with afforestation, encroachment by built-up areas and site development all take their toll on the availability of habitats.
- Collision with power lines (high) – on top of direct collisions, power lines also create an aversive effect thereby decreasing habitat availability.
- Destruction of clutches or chicks by agricultural activities (high) - several agricultural practices can directly destroy clutches or the birds themselves (mowing, spraying, cultivating between rows).
- Predation on eggs, chicks and young birds (intermediate) - predation pressure exerted by mammals and birds (mainly corvids). In the Carpathian Basin, the most significant mammalian predators are the red fox, the wild boar and, increasingly, the jackal. As for avian predators, hooded crows and magpies, in certain areas ravens are the main nest predators.
- Disturbance (low) – apart from agricultural practices, other activities can also disturb breeding birds (nature photography, hiking, hunting).
- Food shortage (intermediate) – agrochemicals, agrotechnology and the decrease in precipitation all lead to decrease in invertebrate populations providing staple food sources for bustards.
- Climate change and its impacts (intermediate) - the consequences of extreme weather events (e.g. draught or torrential rains).
- Unusually harsh winter weather (low) - Fleeing from acute food shortage, flocks may move to areas where other threat factors can impact them seriously (predators, hunting, collision with power lines etc.).
- Illegal hunting (low) – May reach significant levels at the eastern parts of the western Palearctic range (Ukraine and Russia).
Of the nine factors listed above, 5 can be traced either directly or indirectly to agricultural activities within the habitat.
Threat factors determine the main actions of a regional conservation plan. Within the Carpathian Basin, the great bustard population is most heavily impacted by collision with power lines, predation, disturbance and agricultural intensification. Implemented between 2016 and 2023, the EU-financed great bustard conservation LIFE programme targets preventive measures for these threat factors.