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

Abstract

Landscape-scale habitat and land use influences on Asian Houbara Chlamydotis macqueenii (IUCN Vulnerable) remain unstudied, while estimating numbers of this cryptic, low-density, over-hunted species is challenging. In spring 2013, male houbara were recorded at 231 point counts, conducted twice, across a gradient of sheep density and shrub assemblages within 14,300 km 2 of the Kyzylkum Desert, Uzbekistan. Four sets of models related male abundance to: (1) vegetation structure (shrub height and substrate); (2) shrub assemblage; (3) shrub species composition (multidimensional scaling); (4) remote-sensed derived land cover (GLOBCOVER, 4 variables). Each set also incorporated measures of landscape rugosity and sheep density. For each set, multi-model inference was applied to generalised linear mixed models of visit-specific counts that included important detectability covariates and point ID as random effects. Vegetation structure received strongest support, followed by shrub species composition and shrub assemblage, with weakest support for the GLOBCOVER model set. Male houbara numbers were greater with lower mean shrub height, more gravel and flatter surfaces, but were unaffected by sheep density. Male density (mean 0.14 km -2 ) estimated by distance analysis differed substantially among shrub assemblages, being highest in vegetation dominated by Salsola rigida, high in areas of S. arbuscula and Astragalus, respectively, lower in Artemisia and lowest in Calligonum. The study area was estimated to hold 1824 males (CI 1645(CI -2030. The spatial distribution of relative male houbara abundance, predicted from vegetation structure models, had the strongest correspondence with observed numbers in both model calibration and the subsequent year's data. We found no effect of pastoralism on male distribution, but potential effects on nesting females are unknown. Density differences among shrub communities suggest extrapolation to estimate country-or range-wide population size must take into account vegetation composition.

Effects of habitat and livestock on nest productivity of the Asian houbara Chlamydotis macqueenii in Bukhara Province, Uzbekistan

“…& Second, independent evidence indicates that the relative density of captive-bred individuals in the Bukhara breeding population is likely to be low. To date, <280 birds a year have been released by EBBCC in our study area, annually representing some 7.5 % of the extant population (1886 males and presumably a similar number of females: Koshkin et al 2016). These birds were either 1-year-olds released in spring or 4-month-olds released in August; few 1-year-old females and none of the males would have bred in the year of release, and both they and the August releases then experienced high over-winter mortality such that only 10.8 % returned to the breeding grounds the following year (Burnside et al 2016).…”

“…Thus, adult female recruits may have numbered fewer than 15-20 per year. & Third, released birds exhibit strong site fidelity: maximum natal dispersal distance of 9 satellite-tracked captive-bred birds that survived to complete their first return migration (see Burnside et al 2016) was 51.1 km, median 27.4 km, upper quartile 36.3 km (RJB, unpublished data). Thus, while birds of EBBCC origin may recruit into our study population if they survive, locally sourced stock released in Navoiy (breeding centre approximately 150 km from the centre of our study area) or Kazakhstan (country border at least 250 km away) are very unlikely to do so.…”

“…are unknown. As repeated industrial-scale reinforcement has the potential to compromise the integrity of populations, supplementation should seek to minimise impacts, both by maintaining the highest possible integrity of releases (Combreau et al 2005) and through management to minimise the relative numbers required to be released (Burnside et al 2016). To assist in this, opportunities for alternative in situ conservation measures clearly need to be explored.…”

“…Asian houbara (hereafter 'houbara') breed across a wide range of landscapes and vegetation types, varying with drainage, landform and substrate, from consolidated sands to clay saltpans (Gubin 2004), and differing in shrub height and composition (Koshkin et al 2014(Koshkin et al , 2016. Nest success of wild houbara has been quantified (Combreau and Launay 1999;Combreau et al 2002;Lavee 1988) and nest micro-site selection investigated (Aghanajafizadeh et al 2012;Yang et al 2003), but whether productivity varies with habitat differences or livestock levels remains unknown.…”

“…In Morocco and Fuerteventura, breeding African houbaras avoid major roads, human settlements and sheep camps (Carrascal et al 2008;Hingrat et al 2008;Le Cuziat et al 2005a), but whether productivity is influenced by these anthropogenic factors has not been examined. Although the numbers and distribution of male houbara showed no response to low and moderate sheep densities in the southern Kyzylkum, Uzbekistan (Koshkin et al 2014(Koshkin et al , 2016, livestock impacts on nesting are unknown.…”