This species was originally mainly associated with Eurasian steppe, but it has acclimated to agricultural landscapes (M. Kessler in litt. 2016), and can now be found in open, flat or somewhat rolling landscapes, usually with short sward height and a mixture of preferably low-intensity farmland activities and crops (cereals, vineyards, fodder plants, as well as fallow fields, pastureland and steppic grassland) (J. C. Alonso in litt. 2012, Collar and Garcia 2020). In Iberia, it also occurs in Cork Oak Quercus suber and Holm Oak Q. ilex dehesas, and in olive groves (Collar and Garcia 2020). In Asia, it can also be found in Artemisia and Stipa steppes, mountain foothills and in semi-desert habitats (Gubin 2007 per Kessler and Batbayar 2023). The eastern subspecies inhabits both open steppe and forest steppe, including small forest openings, and using trees as sources of shade and food (Mel’nikov and Popov 2000 per Kessler and Batbayar 2023, Raab et al 2014, M. Kessler in litt. 2016), and are more often found in wet habitats such as river islands and moist meadows (Kozlova 1975, Ponomareva 1986, Goroshko 2002, Goroshko 2008 per Kessler and Batbayar 2023).
Its diet comprises invertebrates, plants and seeds, as well as small vertebrates, including mammals, reptiles, amphibians and birds (Collar and Garcia 2020, Kessler and Batbayar 2023). 
Areas with little or no disturbance and abundant supply of insects are required for successful breeding (Y. Andryushchenko in litt. 1999). Nest sites are selected in grassland, fallow or cereal fields (Rocha et al. 2013) (primarily alfalfa in Central Europe and wheat in Russia, Mongolia and Kazakhstan [M. Kessler in litt. 2016]) in areas of low patch-type diversity, far from human infrastructure, and with good horizontal visibility (Magaña et al. 2010). The eastern subspecies nests primarily in agricultural mosaics, open steppe, and adjacent to forest edge (Kessler 2015), and utilises areas around international borders for both breeding and migratory stopover sites, as well as, possibly, wintering grounds too (Kessler and Batbayar 2023). The species exhibits highly variable migratory behaviour across populations, including obligate winter migrants (majority of Asia), short-distance migrants (Iran), facultative migrants (central European populations) and partial winter and summer migrants with differential migratory pattern by sex (Iberian populations) (Morales et al. 2000, Alonso et al. 2000; Palacín et al. 2009, 2011; Kessler 2022). The species gathers in large wintering flocks in Central Asia (Kessler 2022).

Historically, the species' breeding range extended across the Eurasian steppes, from Portugal all the way to the Pacific coast of Russia and the Korean Peninsula (Kessler 2022, Kessler and Batbayar 2023). Currently, this species breeds in Portugal, Spain, Austria, Germany, Slovakia, Hungary, Serbia, Romania, Türkiye, Russia, Ukraine, Kazakhstan, and China, as well as in Morocco, Iran (West Azerbaijan province [Barati et al. 2015]), western Siberia, western and northern Kazakhstan, and western Mongolia where only isolated populations remain, many of which are at high risk of extinction (Alonso and Palacín 2022, Kessler 2022, Kessler and Batbayar 2023). A reintroduction scheme is currently taking place in the United Kingdom.

The species' range is becoming increasingly disjunct, with rapid declines and population extinctions in parts of eastern and central Europe (Bulgaria, Poland, Moldova, Czechia), and the species is considered at risk of extinction or already extirpated in the majority of areas between west-central Türkiye to Nei Mongol (China) (Palacín and Alonso 2008, Kessler and Collar 2022, Kessler and Batbayar 2023). Over the past half century, the species has only rarely been sighted in Kyrgyzstan, Tajikistan and Azerbaijan, where it once bred (M. Kessler in litt. 2016). Despite occupying a large proportion of the species' range, the population in Central Asia now only represents 1% of the global population (Kessler 2022). 
These declines have been accompanied by a range contraction, due to the disappearance of smaller populations across the species' range, as recently highlighted in Keller et al. (2020). 
Nevertheless, thanks to considerable conservation effort, the species' breeding population has increased in West and East Pannonia, and in Romania, due to the dispersal of the Pannonian populations (Alonso and Palacín 2022, Kessler 2022). 

Most populations of the western subspecies are at least partially migratory, depending on weather conditions, and occur on passage or in winter in Ukraine, Iraq, Kazakhstan and Uzbekistan (Y. Andryushchenko in litt. 1999, 2017; Kessler 2015, 2022; M. Kessler in litt. 2016, K. Ararat in litt. 2023). Birds from northern Central Asia used to overwinter in large numbers in Turkmenistan, as well as Azerbaijan and north-east Iran, but sightings are now rare in these countries, due to the crash of the Central Asian population in the 20^th century (Kessler and Smith 2014). Southern Central Asian breeding grounds in southern and south-eastern Kazakhstan, and areas in Uzbekistan, however, still serve as staging grounds and sometimes as overwintering sites, and these currently hold the largest numbers of Great Bustards during migration (Kessler 2022). The eastern subspecies, which breeds in Mongolia, eastern Russia, and north-east China is fully migratory, spending four months on migratory stopovers and four months on wintering grounds, which used to extend to the Korean Peninsula and can still be found as far south as central China, although more birds are now overwintering in breeding grounds in northern China (Kessler et al. 2013, M. Kessler in litt. 2016, Kessler and Batbayar 2023).

Conservation Actions Underway
CITES Appendix I and II, CMS Appendix I and II and CMS MoU for Middle-European Populations in place since 2002 (with the fifth Meeting of the Signatories taking place in September 2023 [CMS 2023]), as well as the CMS Action Plan for the Great Bustard in Asia to be formally adopted in 2024 (Kessler and Batbayar 2023, update from the action plan for east Asian populations [Chan and Goroshko 1998]). EU Wild Birds Directive Annex I, Bern Convention Annex II.
A European action plan was published in 1996 and updated in 2009 (Nagy 2009) and more recently adapted for the Middle-European Populations MoU (Nagy 2018). In addition, a 'Concerted Action' for the species was established among Asian range states in 2017 (Government of Mongolia et al. 2017 per Kessler and Batbayar 2023). An action plan for Morocco was produced in 2016 (IUCN and HCEFLCD 2016) and in Türkiye an action plan was published in 2004 (Doğa Derneği ve T.C. Çevre ve Orman Bakanlığı, Doğa Koruma ve Milli Parklar Genel Müdürlüğü 2004). Agri-environmental and land management programmes have been implemented in Spain, Portugal, Austria, Hungary, Germany, and Serbia.
Monitoring of populations occurs in many range countries, e.g. across the EU and Europe (BirdLife International 2021) and across Türkiye (M.M. Karataş in litt. 2016).

Hunting of the species is prohibited in all the range states of the Middle-European Populations MoU, and range states in Asia (Nagy 2018, Kessler and Batbayar 2023), as well as in the European Union and in Türkiye since 1977. 
Artificial incubation and chick rearing projects have been established in Germany and Hungary since the 1970s. A UK reintroduction project began in 2003 with chicks and eggs imported from the Russian Federation and later eggs from Spain (Dawes 2008, Great Bustard Group 2023) that has established a small population, with first successful nesting and chicks fledging in 2009 (Burnside et al. 2012). A LIFE + project was established in 2010 (European Commission 2021), which continued the release and monitoring of the species, the selection of two new release sites, protection from threats, and establishing agro-environmental schemes and land management advice to farmers, as well as a long-term management strategy. Chicks ceased to be imported in 2022 (N. Collar in litt. 2023), but management is still needed in the form of removing and incubating eggs from nests in fields being harvested and releasing the hatched chicks once the harvest is over (Stubbs 2020, N. Collar in litt. 2023). 
A LIFE Nature project for the species was implemented in Hungary during 2004-2008 with the aim of increasing in-situ protection of the species (Bankovics and Lóránt 2008). Other LIFE projects for the species have been implemented in Spain, Portugal, Germany, Austria and Slovakia (e.g. LIFE Great Bustard 2022). Indeed, continued and intensive conservation actions in the West Pannonian population (Germany, Austria, and Hungary) have led to significant increases in this population, as well as in Romania, due to the dispersal from this increasing West Pannonian population. Using powerline markers and using underground cables instead of over-head powerlines have been shown to reduce mortality in this species (Raab et al. 2012). Accurate distribution maps of the species (e.g. in Spain) is assisting the sensitive development of renewable energy infrastructure (Palacín et al. 2023).

Conservation Actions Proposed
The continued coordination of conservation actions between range states in Asia, where the species is fully migratory, but also uses habitats around international borders is essential, as is the increase in enforcement of sanctions for illegal killing of the species (M. Kessler in litt. 2016, Kessler and Batbayar 2023). Overall, international communication on the species is important (Kessler 2022). Media campaigns should be undertaken to engender pride and concern towards this species, including encouraging volunteering (Kessler and Batbayar 2023).
Conduct nationwide surveys in countries with currently low-quality estimates. Research limiting factors, and investigate its vulnerability to climate change, metapopulation dynamics and the causes of reproductive failure in East Asia (M. Kessler in litt. 2016). Continue research on wintering distribution. Research wintering movements in eastern and south-eastern Anatolia (M.M. Karataş in litt. 2016). 
Protect and manage breeding, wintering and stop-over areas. Identify any remaining breeding sites in Central and East Asia, as well as upgrade existing and establish new protected areas in this region (M. Kessler in litt. 2016). Lek sites over the species' range should be recorded and protected (Kessler and Batbayar 2023). Establish protected areas and strict conservation measures in Morocco, the only African population of the species (J. C. Alonso in litt. 2016).
Implement agri-environment measures for low-intensity farming. The maintenance of biodiversity friendly farming systems (e.g., High Nature Value [HNV]), with a high diversity of land-use types, is essential for the conservation of the species (Palacín et al. 2012). Prevent steppe fires and stubble burning. Re-route or bury overhead cabling at areas in which Great Bustards gather, in order to prevent collisions with powerlines (M. Kessler in litt. 2016). Renewable energy infrastructure should be sited taking into account the landscape scale use by the species and in particular the locations of leks (e.g. in Spain [Palacín et al. 2023]). 
Particular conservation focus should be placed on southern Kazakhstan, as the species occurs there in breeding, passage and wintering seasons, and Uzbekistan, which can host the majority of the species' Central Asian population in winter (Kashkarov et al 2022 per Kessler 2022). Raise public awareness of the population declines and importance of the current key sites.