The Little Bustard Tetrax tetrax has a Palaearctic distribution and two geographically separated breeding populations: the western (found in the EU); and eastern (breeding in western and central Asia). It is currently classified as Near Threatened under criterion A on the IUCN Red List, because it is suspected to have undergone a moderately rapid global population decline approaching 30% over three generations. Its global population and range have certainly declined dramatically since the 19th century, with national extinctions in at least 13 countries in Europe and north-west Africa.
The global population (excluding 20,000 individuals in Kazakhstan) was estimated at c.240,000 individuals in the late 1990s (C. Martínez in litt 1999). Spain holds a large proportion of the global population, with an updated estimate of 71,112- 147,763 individuals reported in 2005 (comprising 41,482- 86,195 breeding males, down from 100,000-200,000 males in the 1990s [De Juana and Martínez 1996]) (García de la Morena, et al. 2006).
Data collated recently for a review of the EU Species Action Plan show that the species is still declining across much of its remaining European range (Barov and Derhé 2010; Iñigo & Barov 2010). In Spain, the species declined by at least 20% during 1990-2000 (BirdLife International 2004), although some reports suggest that the decline may have been even greater (e.g. ≥30% over ten years [García de la Morena et al. 2006, De Juana 2009]. Spain’s breeding population has stabilised since then (Del Moral et al. 2010), but declines are still reported for the wintering population in Europe (Barov and Derhé 2010). The species also declined in north-west Africa (mainly Morocco) during 1999-2005 (Alonso & Palacín 2009).
Elsewhere within its range, trends and population sizes are less well known. Eastern populations are said to have increased in recent years, perhaps because the population in the Eurasian steppe belt is thought to have recovered due to an increase in fallow land during the transition process of the former Soviet Union (Gauger 2007). For example, 30% of the population was found breeding on abandoned wheat fields in the late 1990s (Shlyakhtin et al. 2004). Azerbaijan held more than 150,000 individuals during the winter of 2005-2006 (Gauger 2007) and sightings in the winter of 2010 report 25,000 and 50,000-70,000 individuals in Adjinohur valley and Shirvan National Park respectively (Gauger and Heiß 2010). However, it has been suggested that recent and predicted future trends in agriculture in the Eurasian steppe zone, particularly the reclamation of abandoned cereal fields and reduced grazing pressure, may cause populations of most steppe bird species, including the Little Bustard, to decline in the near future (Kamp et al. 2011).
Revised generation length estimates mean that the population trend for this species should now be calculated over a period of 31 years (BirdLife International unpubl. data). If the global population is suspected to be undergoing an overall decline at a rate of 30-49% in 30 years, the global status of Little Bustard would need to be revised to Vulnerable. To re-evaluate its status, more data are needed about the size and trends of populations in the east, particularly from Russia and Central Asia. Ideally, such population estimates should follow standardised reporting so that data are comparable spatially and temporally (i.e. breeding populations estimated through counts of lekking males, multiplied by accurate, reported sex ratios; wintering populations estimated through total number of individuals).
Information on the size and trends of populations in the east, particularly from Russia and Central Asia, are invited.
Alonso, J.C. and Palacín, C. (2009) Probable population decline of the Little Bustard Tetrax tetrax in north-west Africa. Ostrich 80 (3): 165–170.
BirdLife International (2004) Birds in Europe: population estimates, trends and conservation status. Cambridge, UK: BirdLife International.
Barov, B. and Derhé, M. A. (2010) Review of the implementation of species action plans for threatened birds in the European Union 2004-2010 Final Report. BirdLife International for the European Commission.
De Juana, E. (2009) The dramatic decline of the Little Bustard Tetrax tetrax in Extremadura (Spain). Ardeola 56: 119-125.
Del Moral, J. C., Escandell, V., Molina, B., Bermejo, A., and Palomino, D. (Eds.) (2008) SEO/BirdLife monitoring programs 2006. SEO/BirdLife. Madrid.
Del Moral, J. C., Bermejo, A., Molina, B., Escandell, V. and Palomino, D. (Eds.) (2010) SEO/BirdLife monitoring programs in 2008. SEO/BirdLife. Madrid.
García de la Morena, E.L., Bota, G., Ponjoan, A. and Morales, M.B. (2006) El sisón común en España. I Censo Nacional (2005). SEO/BirdLife, Madrid.
Gauger, K. (2007) Occurrence, Ecology and Conservation of wintering Little Bustards Tetrax tetrax in Azerbaijan. Archiv für Naturschutz und Landschaftsforschung 46: 5-27.
Gauger, K., and Heiß, M. (2010) Winter trip 2010: Birdwatching news and bird photography from Transcaucasia. Available at: http://birdingaze.blogspot.com/search?updated-min=2010-01-01T00:00:00%2B01:00&updated-max=2011-01-01T00:00:00%2B01:00&max-results=2. (Accessed: 21December 2011).
Iñigo, A. and Barov, B. (2010). Action plan for the Little Bustard Tetrax tetrax in the European Union. SEO/BirdLife and BirdLife International for the European Commission. http://ec.europa.eu/environment/nature/conservation/wildbirds/action_plans/docs/tetrax_tetrax.pdf
Kamp, J., Urazaliev, R., Donald, P., and Hölzel, N. (2011) Post-Soviet agricultural change predicts future declines after recent recovery in Eurasian steppe bird populations Biological Conservation 144 (11), 2607-2614.
Morales, M.B., Bretagnolle, V. & Arroyo, B.E. (2004) Viability of the endangered Little Bustard Tetrax tetrax population of western France. Biodivers. Conserv. 14: 3135–3150.
Shlyakhtin, G.V., Tabachishin, V.G., Khrustov, A.V., Zavlyalov, E.V. (2004) Ecological segregation of bustards (Otididae) in the north of the Lower Volga Region: evolutionary and adaptive aspects. Russian Journal of Ecology 35, 247–253.