A 10-year assessment of Asian Houbara Bustard populations: trends in Kazakhstan reveal important regional differences

Abstract

SummaryA sharp decline in the numbers of Asian Houbara Bustard Chlamydotis macqueenii towards the end of the 20 th century raised concerns about the conservation status of this species. Yet due to its large breeding range in the remote steppes and deserts of Central Asia and to its cryptic behaviour, it has been difficult to obtain enough comparable data to make reliable estimates of population trends. Here, we present the results of 10 years of extensive biannual surveys throughout southern Kazakhstan, considered to host the majority of the breeding birds in Asia, and we discuss trends in the Kazakh populations for the first decade of this century. The breeding Houbara population has generally declined over the greater part of Kazakhstan between 2000 and 2009 but with important regional differences. A steep decline was observed in north-east Caspian and Karakum, and a sharp drop followed by a stabilisation occurred in Kyzylkum. Over the same period, estimated densities were stable or increased in the area surrounding Lake Balkash, and increased in the Betpak-Dala region of central Kazakhstan. Autumn surveys showed more variability and revealed little decline overall. It was also clear that Betpak-Dala and Balkash regions hosted the largest populations. Our findings suggest that it is a complex undertaking to assign a level of vulnerability for this species as a whole. Highly variable population trends between regions indicate that threats and pressures are to a considerable extent region-specific, and that conservation measures need to be adjusted locally.

Effects of habitat and land use on breeding season density of male Asian Houbara Chlamydotis macqueenii

“…However, comparison with densities estimated for other Asian Houbara populations is problematic. Most recent studies used driven transects (Tourenq et al 2004(Tourenq et al , 2005Gubin 2008;Riou et al 2011) and each had methodological drawbacks. In Koshkin et al (2014) point counts were found to perform better than transects, at least in the conditions of the southern Kyzylkum.…”

“…Gubin (2008) based multi-annual estimates for several areas in south-western Kazakhstan on numbers of individuals recorded along driven transects within a 200-m survey strip (range of 0.01-0.24 birds/ km 2 ); this may indicate relative abundance among areas, but as detectability was unknown it is not possible to account for undetected birds to estimate density. Although Riou et al (2011) and Tourenq et al (2004Tourenq et al ( , 2005 used distance analysis, distance measurements were not taken and the effective strip width (ESW) is not reported; also, analysis pooled across regions with differing relative abundance resulting in wide uncertainty, and timing and sex composition are not reported. Although more females are detected during driven transects (30 % of adult birds) than on point counts (7 %; Koshkin et al 2014), densities estimated by Riou et al (2011) and Tourenq et al (2004Tourenq et al ( , 2005 will have been underestimated to an unknown extent.…”

“…Although Riou et al (2011) and Tourenq et al (2004Tourenq et al ( , 2005 used distance analysis, distance measurements were not taken and the effective strip width (ESW) is not reported; also, analysis pooled across regions with differing relative abundance resulting in wide uncertainty, and timing and sex composition are not reported. Although more females are detected during driven transects (30 % of adult birds) than on point counts (7 %; Koshkin et al 2014), densities estimated by Riou et al (2011) and Tourenq et al (2004Tourenq et al ( , 2005 will have been underestimated to an unknown extent. Depending on timing, estimates may lie somewhere between an estimate of male numbers (comparable to our male estimate) for survey during incubation (when females are infrequently observed even on driven transects) to an estimate comprising both males and females during brood rearing/post-nesting, closer to, but still likely underestimating, total numbers.…”

“…Poorly regulated and unsustainable hunting and trapping on both migration routes and wintering grounds (Combreau et al 2001) have been blamed for declines in Kazakhstan (Tourenq et al 2004(Tourenq et al , 2005Riou et al 2011), which hosts an estimated 77 % of the global population (Goriup 1997), resulting in Asian Houbara being listed by the International Union for Conservation of Nature (IUCN) as Vulnerable (BirdLife International 2015). Habitat degradation from agricultural intensification and overgrazing, combined with human disturbance, is thought also to be affecting the species in parts of its range (Goriup 1997;Combreau et al 2001Combreau et al , 2002, albeit with little published evidence.…”

“…This estimate, however, extrapolated country-wide numbers from local estimates (Gubin 1992;Mitropolsky et al 1996). Subsequent studies that provided density estimates for several subpopulations in Kazakhstan (Tourenq et al 2004(Tourenq et al , 2005Riou et al 2011) experienced methodological limitations (see ''Discussion''), while for Uzbekistan the two assessments available were considered preliminary and provisional (Launay et al 1997a;Koshkin et al 2014).…”