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Do sheep affect distribution and habitat of Asian Houbara Chlamydotis macqueenii?

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We examined whether pastoralism affected the distribution of Asian Houbara Bustard Chlamydotis macqueenii (IUCN Vulnerable) or modified its habitat across 14,500 km2 of the Kyzylkum Desert, Uzbekistan. In this landscape, sheep grazing is constrained by access to water, allowing effects to be examined independent of topography and vegetation community. Across a gradient of sheep density (0–10 to 30–80 individuals km−2) we achieved n = 140 10-km driven transects (total driven 3500 km). On all transects Houbara and sheep were surveyed at least once, and 96 were driven three times with vegetation sampled on four 50 m-long transects along each of these (measuring 7493 shrubs). Houbara distribution and abundance was also recorded at 147 point counts. In Generalised Linear Models that controlled for plant community, neither interpolated sheep density (within 1 km buffers) nor topographic variation affected houbara incidence on transects, or incidence and abundance at point counts. Although subtle effects were found for some palatable shrubs, sheep did not strongly modify shrub composition or structure at landscape scales. At landscape-scales, livestock browsing has not widely degraded these rangelands, which appear sustainably managed or even under-utilised. Pastoralism and houbara conservation may therefore be compatible, although impacts on nesting females require investigation.
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Do sheep affect distribution and habitat of Asian Houbara Chlamydotis
macqueenii?
Maxim A. Koshkin
a
, Nigel J. Collar
b
,
c
, Paul M. Dolman
a
,
*
a
School of Environmental Sciences, University of East Anglia, Norwich NR4 7TJ, UK
b
BirdLife International, Girton Road, Cambridge CB3 0NA, UK
c
School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, UK
article info
Article history:
Received 17 June 2013
Received in revised form
14 January 2014
Accepted 16 January 2014
Available online 7 February 2014
Keywords:
Alhagi pseudalhagi
Artemisia diffusa
Astragalus villosissimus
Calligonum
Chlamydotis undulata
Convolvulus hamadae
Karakul sheep
Kyzylkum
Over-grazing
Pastoralism
Salsola arbuscula
Semi-arid rangelands
Shrub desert
Sustainable management
abstract
We examined whether pastoralism affected the distribution of Asian Houbara Bustard Chlamydotis
macqueenii (IUCN Vulnerable) or modied its habitat across 14,500 km
2
of the Kyzylkum Desert,
Uzbekistan. In this landscape, sheep grazing is constrained by access to water, allowing effects to be
examined independent of topography and vegetation community. Across a gradient of sheep density
(0e10 to 30e80 individuals km
2
) we achieved n¼140 10-km driven transects (total driven
3500 km). On all transects Houbara and sheep were surveyed at least once, and 96 were driven three
times with vegetation sampled on four 50 m-long transects along each of these (measuring 7493
shrubs). Houbara distribution and abundance was also recorded at 147 point counts. In Generalised
Linear Models that controlled for plant community, neither interpolated sheep density (within 1 km
buffers) nor topographic variation affected houbara incidence on transects, or incidence and abun-
danceatpointcounts.Althoughsubtleeffectswerefoundforsomepalatableshrubs,sheepdidnot
strongly modify shrub composition or structure at landscape scales. At landscape-scales, livestock
browsing has not widely degraded these rangelands, which appear sustainably managed or even
under-utilised. Pastoralism and houbara conservation may therefore be compatible, although impacts
on nesting females require investigation.
Ó2014 Elsevier Ltd. All rights reserved.
1. Introduction
In the deserts and semi-arid rangelands of Central Asia, strong
evidence exists for vegetation degradation through over-
exploitation by livestock, notable up to 3 km and detectable up to
5 km around watering points or villages (Behnke et al., 2006;
Coughenour et al., 2006). However, the effects of pastoralism on
rangeland condition at landscape and regional scales remain
ambiguous (Stringer, 2006), since reduced infrastructure and
management capacity in the post-Soviet era has resulted in the
under-utilisation or complete abandonment of some extensive
rangelands remote from settlements (Coughenour et al., 2006;
Shaumarov et al., 2012). We used the opportunity provided by
this variation in sheep density to conduct a quasi-experimental
landscape-scale study of the consequences of livestock browsing
and pastoralism, both for shrub desert condition and for the dis-
tribution of Asian Houbara Bustard Chlamydotis macqueenii (IUCN
Vulnerable).
Breeding populations of the Asian Houbara have declined sub-
stantially across its range, encompassing the Arabian Peninsula
northwards to Central Asia and east to China (BLI, 2012; Riou et al.,
2011). Arab falconers prize both the Asian and the closely related
African Houbara Chlamydotis undulata as their main quarry; in
addition to their cultural signicance, these species have consid-
erable economic value to host countries across range states (Bailey
et al., 1998). Population declines, especially in the Asian species,
have primarily been driven by unregulated hunting throughout the
wintering range (Riou et al., 2011; Tourenq et al., 2005). Reducing
the impacts of hunting on wild populations is fundamental to
ensuring both speciessurvival, but concern has also been
expressed over the deleterious effects of livestock grazing, both
indirectly through deterioration in habitat quality and directly
*Corresponding author. Tel.: þ44 1603 593175.
E-mail address: p.dolman@uea.ac.uk (P.M. Dolman).
Contents lists available at ScienceDirect
Journal of Arid Environments
journal homepage: www.elsevier.com/locate/jaridenv
0140-1963/$ esee front matter Ó2014 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.jaridenv.2014.01.002
Journal of Arid Environments 103 (2014) 53e62
Author's personal copy
through impacts on breeding populations (Lavee, 1988; Le Cuziat
et al., 2005b; Osborne et al., 1997). Management to enhance pro-
ductivity by mitigating habitat deterioration has the potential to
contribute to a sustainable future for these species.
Sheep and goats are thought to affect houbara distribution and
decrease productivity through disturbance of nesting females by
shepherds and their dogs and nest trampling by ocks (Lavee,
1988). The dominant shrub species are palatable to sheep but
also provide houbara with food (Gubin, 2004; Hingrat et al., 2007b)
and concealment (Hingrat et al., 2007a; van Heezik and Seddon,
1999). Therefore, as livestock can reduce shrub biomass, produc-
tivity, density and structure, and alter the plant composition of
shrub desert vegetation (Behnke, 2006; Saiz and Alados, 2012),
pastoralism is also suspected of modifying habitat suitability for
houbara. Numbers of African Houbara increased with distance from
wells (a proxy for nomadic pastoralism and associated human
disturbance) in semi-arid shrub vegetation in the Middle Atlas
Mountains, Morocco, during the breeding season (Le Cuziat et al.,
2005a), suggesting that pastoralism inuences houbara distribu-
tion. However, whether this is through habitat degradation,
disturbance, persecution or a combination of these factors is not
clear. It is also unclear whether ndings concerning the African
Houbara can be assumed to apply to the Asian species, given that
the nature of pastoralism may differ between the continents. In
view of the importance of pastoralism to local livelihoods and the
national economies of semi-arid range states (FAO, 2006; Lindt,
2006), a robust evidence base is clearly needed to inform any ini-
tiatives to mitigate population declines through habitat manage-
ment (Sutherland et al., 2004).
Acknowledging the potential tension between local over-
exploitation and wider under-utilisation of rangelands, we exam-
ined the distribution of Asian Houbara, variation in sheep density
and the structure of desert shrub vegetation in a well-replicated
and extensive study across approximately 14,500 km
2
of poten-
tially suitable habitat in the Kyzylkum Desert in Uzbekistan. Our
aims were (i) to examine whether utilisation of semi-arid shrub
desert by pastoralists affected houbara distribution and abundance
and (ii) to assess the impact of livestock on houbara habitat at
landscape rather than more localised scales, focusing on shrub
structure and relative species composition.
2. Methods
2.1. Study area
The study area (39.34e40.56
N 62.21e65.20
E, altitude 170e
400 m above sea level) was located in the Bukhara District of
Uzbekistan, within the Kyzylkum Desert of the southern Central
Asian desert ecoregion (Olson et al., 2001)(Fig. 1). The climate is
characterised by variably cold winters (mean monthly tempera-
tures 0e5
C, but often reaching 25
C), hot summers, and an
annual precipitation of 125e170 mm, mostly during winter and
Fig. 1. Study area within Bukhara District, Uzbekistan, showing distribution of desert plant communities within it, following Rachkovskaya (1995). In the map inset, Bukhara District
is shown in black.
M.A. Koshkin et al. / Journal of Arid Environments 103 (2014) 53e6254
Author's personal copy
spring (as snow and rain). The landscape is predominantly at, with
undulating terrain, bounded by mountain ranges to the north and
east. Variations in topography, geomorphology, drainage and soil
result in areas with distinctly different shrub-desert communities,
all dominated by drought-resistant and or halophytic shrubs.
Following Rachkovskaya (1995), we classied these plant com-
munities as: (a) Artemisia(4400 km
2
), located on gypseous soils on
a piedmont slope at 200e400 m elevation intersected by wadis,
dominated by Artemisia diffusa; (b) Salsola(3500 km
2
), on halo-
phytic soils dominated by Salsola arbuscula,Salsola gemmascens and
Salsola rigida; (c) Astragalus(1860 km
2
) on semi-consolidated
sands, dominated by Astragalus villosissimus and Convolvulus
hamadae but also containing Salsola spp. and A. diffusa; and (d)
Calligonum(4730 km
2
) on areas of weakly consolidated sands,
supporting a diverse shrub community typied by Calligonum spp.
Owing to logistical difculties surveys were not continued in an
extensive area (7700 km
2
) of unconsolidated dunes to the west of
the study area that supported White Saxaul Haloxylon persicum
subforest with abundant Sandy Acacia Ammodendron conollyi;
however, no houbara and few pastoralists were detected during
pilot work in this habitat. Ephemeral plants occurred sparsely
throughout all plant communities; additionally a thin ground cover
of grasses and or Carex occurred in spring on gypseous soils and
semi-consolidated sands (Artemisia and Astragalus vegetation
respectively).
The south-east of the study area borders irrigated croplands and
permanent settlements (Fig. 1), but the study area itself is
unpopulated except by seasonal pastoralists, who graze Karakul
sheep and smaller numbers of goats. These are brought into the
desert for lambing during the spring (AprileJune), coinciding with
the breeding and nesting season of Asian Houbara, when ephem-
eral plants and some perennial shrubs provide high-quality fodder;
they are removed to irrigated areas and the vicinity of canals and
settlements during June. During the spring period most of the
sheep are managed out of seasonal camps, comprising a watering
point and either small clay huts or mobile caravans, and often
holding several hundred sheep each. In addition to spring grazing,
limited areas of Artemisia vegetation are utilised throughout the
year by pastoralists from piedmont villages (Kalata, Dzhangeldy,
Shuruk, Ayakagytma); thus grazing impacts were expected to be
greatest in this plant community. Sheep distribution during spring
is therefore limited by the distribution of functional wells or to
areas to which water can be transported; this leaves extensive areas
of desert relatively unutilised, and permitted us to examine the
effects of sheep density independently of plant community.
2.2. Sampling of sheep, houbara density and vegetation
In Central Asia, the localised impacts of sheep grazing on semi-
arid vegetation are detectable by remote sensing up to 3.5e5km
from settlements, and to a lesser distance around wells (Behnke
et al., 2006; Coughenour et al., 2006). In our study area, in addi-
tion to localised degradation in the immediate vicinity of watering
points or sheep camps, where palatable shrubs are absent and
unpalatable Peganum harmala can be dominant, sheep density also
varied at landscape scales. Shrub desert within 10e20 km of the
cropland and settlement boundary contained numerous seasonal
sheep camps, with a mean distance between camps of 2.3 km,
SD ¼1.2, such that all intervening desert was subjected to grazing.
Further from settlements or permanent water the density of camps
was lower, and in the remotest areas few pastoralists were
encountered. We used this landscape-scale variation in the live-
stock density to relate houbara presence/abundance and shrub
desert composition to sheep density, stratied across plant
communities.
Houbara and sheep were simultaneously surveyed along 140 10-
km driven transects, during the period of houbara display and
breeding, from mid-March to mid-June 2012. Numbers of 10-km
transects were similar among three of the four plant commu-
nities sampled (Artemisia,n¼39; Salsola,n¼41; Astragalus,
n¼34), but Calligonum (n ¼26) vegetation received lower sam-
pling effort owing to the rougher terrain and denser vegetation.
Given that sheep and goats were both browsing shrub vegetation in
the same way, that goats were always found in mixed ocks with
sheep dominating, and that it was impracticable to separate them
reliably when counting distant ocks, we combined observations of
both species for analysis and hereafter refer to both as sheep.
Transects were at least 2 km apart and were arranged so as not
to cross plant community boundaries. We aimed to drive each
transect once in each of the three periods 22 Marche22 April, 4
Maye5 June and 7e19 June. Owing to time restrictions, 96 transects
were run three times, 18 twice and 26 once, totalling 3500 km.
Surveys were restricted to 2e3 hours after sunrise and before
sunset, when houbara are most active (Combreau and Launay,
1996). Sheep were out in the desert from early in the morning till
sunset and did not return to camps or wells during the day,
sometimes for 2 days. A vehicle with one driver and one observer
was driven off-road at an average speed of 15 km/h, scanning with
the naked eye for houbara and sheep. For each houbara or houbara
group observed we recorded a GPS waypoint of the detection on
the transect line, distance (measured using a laser range-nder
effective up to approximately 1.2 km), angle from transect line
(using a compass) and number of individuals; where possible, in-
dividuals were sexed (by plumage and morphological features) and
aged (adult or juvenile, dened as young of the year). Flying birds
often could not be sexed but were included in the density analysis
as they were considered to have ushed from the ground at the
approach of the vehicle; perpendicular distance was measured to
the equivalent location on the ground. For each sheep ock, the
number of individuals was counted (using binoculars), and the
perpendicular distance from the transect line to the ock centre,
following Buckland et al. (2001), was measured by laser range-
nder. All sheep camps located during survey work in the study
area were mapped using a hand-held GPS.
Houbara were also surveyed at 147 point counts (that were at
least 3 km apart), conducted during 14 Aprile5 June (of which 38
were repeated once), stratied across plant communities (Arte-
misia,n¼43; Salsola,n¼52; Astragalus,n¼42; Calligonum,
n¼10). Point counts lasted 30 minutes and were conducted within
2e3 hours after sunrise and before sunset using telescope and
binoculars. For each houbara observed, we recorded: sex, age,
number of individuals and the radial distance from the observer
(measured by laser range-nder, except for a few
observations >1200 m which had to be estimated by eye owing to
strong heat haze and bearing against bright sun). The few houbara
seen ying were usually moving in response to interactions with
other houbara (usually moving short distances and still visible on
landing) and were therefore included in the distance analysis.
Species composition and structure of shrub vegetation were
measured on 96 of the 10-km transects during the nal transect
round, between 3 and 19 June, after any effects of spring browsing
on fresh growth had accumulated. Vegetation was recorded at four
locations spaced along each 10-km transect; and Houbara survey
was then discontinued for the rst 500 m of driving after sampling
vegetation. At each location, a 50 m line intercept transect was
conducted, following Rich et al. (2005), recording the species,
height (measured with a ruler to 1 cm accuracy) and diameter of
each shrub touching the line. Shrub height was used in further
analysis as an index of shrub volume, as it was strongly correlated
with diameter (r¼0.592, p¼0.001). Recorded frequency of shrubs
M.A. Koshkin et al. / Journal of Arid Environments 103 (2014) 53e62 55
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(number per 50 m) increases with greater shrub density, but also
with greater size of individual shrubs that are thus more likely to
intercept a line placed at xed distance from their rooting point; it
should therefore be considered an index of shrub cover. Shrub
species were identied from Gintzburger et al. (2003), and vali-
dated by two botanists with extensive experience of the Kyzylkum.
Within the study area, shrub composition is broadly homogeneous
over large areas owing to the combined effects of landform and
substrate (clay foothills, saline outwash plain, areas of accumulated
sand: Fig. 1), and density is also consistent over scales greater than
10 km; four line intercepts were therefore considered sufcient to
represent vegetation on each transect. For analysis, data from the
four line intercepts were pooled for each 10 km driven transect
(providing the mean number or height of each species per 200 m).
2.3. Analysis
2.3.1. Distance analysis of sheep and houbara density
Sheep and houbara densities were estimated by distance anal-
ysis conducted in DISTANCE 6.0. For sheep, distance transects were
two-sided (sampling fraction 1.0) and for the (highly cryptic)
houbara the sampling fraction on distance transects was estimated
to be 0.7 (owing to reduced search capacity on the drivers side of
the vehicle); for houbara on point counts the sampling fraction was
specied as 1.0. For those distance transects driven three times
(n¼96) similar numbers of houbara groups were observed per
transect among each of the three survey periods (generalised linear
model with Poisson error, controlling for transect ID: period,
X
2
¼1.807, p¼0.405; transect ID, X
2
¼44.697, p¼0.180). Repeat
surveys were considered as replicate observations and were used to
calculate transect-specic mean densities.
For both line transects and point counts, Uniform, Half-normal
and Hazard-rate detection functions, examining both cosine and
polynomial adjustments (simple or hermite), were tted following
Buckland et al. (2001). The detection model with the lowest Akaike
Information Criterion adjusted for nite sample size (AICc) was
selected; when there were two or more best competing models
(with
D
AICc <2), model-averaging was undertaken in DISTANCE,
with variance estimated by bootstrapping (600 iterations). On
transects, birds were detected to a maximum distance of 1000 m
(mean ¼207 m, SD 166), and perpendicular distances of all ob-
servations were measured by laser range-nder. Separate sets of
models were examined after truncation of either 5% or 10% of the
most distant observations, following Buckland et al. (2001), and
whichever provided the narrowest condence intervals to density
was selected. For point counts, displaying males could be detected
beyond 2 km. However, observations were truncated at 1000 m to
use only those with radial distance conrmed by laser range-nder,
as error in distance estimates makes density estimates unreliable
(Buckland et al., 2001). In predicting density, the mean observed
group size was used if the regression of group size against
perpendicular distance was p>0.15; otherwise adjusted group size
was used.
The null hypothesis that densities (of sheep and houbara) were
similar among the four plant communities was tested by Analysis of
Variance performed on point count and transect-specic density
estimates, with plant community treated as a xed effect.
2.3.2. Effects of sheep density on houbara
To examine the effects of sheep density on houbara incidence
and local density we constructed a series of Generalised Linear
Models (GLMs). The rst of these compared characteristics of lo-
cations at which houbara were observed on distance transects to
those of random points, in a used-available design (Manly et al.,
2002) with binomial error and log link. We excluded four
individuals recorded on the second or third transect round which
occurred within 1.5 km of a previous observation, to avoid any
pseudoreplication by individual. Random points were generated
within a polygon enclosing all driven transects (buffered by 5 km),
and excluding unsuitable areas (drainage marsh and mountains),
conducted in ArcMap 10.1. The second GLM examined incidence at
point counts (0: absence both visits, 1: presence on one or more
visits) with binomial error and log link, controlling for number of
repeat surveys (1 or 2) as a covariate. The third considered abun-
dance at point counts (number of individuals observed within 1 km
radius or, for points with two visits, the maximum count on a single
visit), again controlling for number of visits, with negative binomial
error and log link (as models with Poisson error were over-
dispersed).
Sheep density information was available for the driven tran-
sects. To allow sheep density to be estimated for other locations
(including point counts and random points), we assigned transect-
specic sheep values to transect centroids, and created an inter-
polated surface by Inverse Distance Weighting (with 500 m raster
resolution) using ArcMap 10.1. Mean sheep density was then
extracted from 1 km radius buffers around each location (obser-
vations on transects, random points and point counts). Interpolated
sheep density within a buffer of 2.5 km around transects was
validated against the number of sheep camps mapped within the
same buffers, by Pearsons correlation coefcient.
In each of the three sets of GLMs, before testing for the effects of
sheep density, we rst constructed a series of alternative plausible
models of environmental effects on houbara incidence or abun-
dance. Artemisia-dominated vegetation occurs at higher elevations
(F
3,125
¼60.42, p¼0.001, R
2
¼0.592; Tukey p<0.001) than all
other plant communities, which occur at similar elevations to each
other (p>0.05); this precluded inclusion of elevation and vege-
tation together in models. We a priori considered plant community
to be more likely to explain houbara incidence or abundance,
particularly given the low elevation range encountered in the study
area. Previous studies have found the distribution of African Hou-
bara (Carrascal et al., 2008; Le Cuziat et al., 2005a) or other bustards
(Alonso et al., 2012; Moreira, 2004; Silva et al., 2004) to be related
to topography. We therefore examined the effects of rugosity,
measured as the standard deviation (SD) of digital elevation (ASTER
GDEM V2, spatial resolution 30 m) (METI and NASA, 2011) extrac-
ted from 1 km radius buffers around observations or random
points. A 1 km radius was considered appropriate, as 50% kernel
home ranges of male African Houbara during the breeding season
vary from 0.1 to 4 km
2
(mean ¼1, SD ¼1) (Hingrat et al., 2004).
Rugosity within buffers was signicantly but only weakly related to
plant community (transect presence/absence locations:
F
3,142
¼10.79, p¼0.001, R
2
¼0.168; point counts: F
3,144
¼17.83,
p¼0.001, R
2
¼0.256), which allowed both predictors to be
included in multivariate models (Freckleton, 2002). The most
strongly supported environmental models were selected by
comparing AICc, those within 2 AICc units having similar support
(Buckland et al., 2001). For the selected environmental models, we
then included a term for mean interpolated sheep density, extrac-
ted from a 1 km buffer around the observation point, tested by
examining the change in AICc (
D
AICc) relative to the equivalent
base model.
2.3.3. Associations between sheep density, shrub composition and
vegetation structure
A total of 28 shrub species were recorded on vegetation line
intercepts; for analysis of the effects of sheep density 10 rare spe-
cies recorded on <5% of 10-km transects were omitted, allowing us
to include species identity in models of shrub height or frequency.
We categorised shrub species according to their palatability to
M.A. Koshkin et al. / Journal of Arid Environments 103 (2014) 53e6256
Author's personal copy
sheep (as: high, medium or low), following information in
Gintzburger et al. (2003). Shrub palatability was coded separately
between spring/summer and autumn/winter, because green
growth of some species is unpalatable but dried stems or seed-
heads are eaten in autumn and winter. In analysis of species
intercept frequency we considered palatability coded across all
seasons, as cumulative effects of browsing in any season may
reduce overall shrub density and cover. However, for analysis of
shrub height (a measure of that years fresh growth remaining in
June), we considered palatability in spring and summer only (see
Appendix A).
Separately for each shrub palatability class, species- and
transect-specic measures of (a) shrub frequency (total number of
shrubs on four line intercepts, treating a zero as the measure for
that transect) and (b) mean shrub height (averaged across four
intercepts, treating transects for which the species was not recor-
ded as missing data), both square-root transformed to satisfy ho-
mogeneity of variance, were related to transect-specic sheep
density (individuals km
2
, square-root transformed) by GLMs, with
normal error, controlling for species and plant community (as the
marked edaphic differences may affect productivity of those spe-
cies occurring across more than one plant community). The most
abundant shrub species within each palatability class were also
modelled separately, relating mean frequency and height per
transect to transect-specic sheep density (square-root
transformed).
All statistical models were constructed in PASW Statistics 18
(SPSS_Inc, 2009).
3. Results
On driven transects, 83 individuals or small groups of houbara
were observed, comprising 113 adults and 14 juveniles. Of the
adults, 54% were ying, 29% walking, 10% displaying, 5% crouching
and 2% standing when detected. Of the adults that could be sexed
(n¼79, 70%), 70% were male; females were considered to have
been under-recorded, as they are generally more cryptic than males
in the breeding season and many were incubating during the sur-
vey periods. For analysis of transects all observations of adult birds
were used. Houbara group size did not differ among plant com-
munities (F
3,79
¼1.029, p¼0.385; all Tukey p>0.5) and was
therefore pooled for subsequent distance analysis. To estimate
adult density we adjusted for the observed proportion of males and
multiplied by two, assuming a 50:50 sex ratio, following Combreau
et al. (2002).
At point counts, 145 individuals or groups of houbara were
recorded, comprising 153 adults and three juveniles. Of the adults,
36% were displaying, 34% standing, 20% walking, 5% ying and 5%
crouching when detected. Again, houbara group size did not differ
among plant communities (F
3,141
¼0.230, p¼0.875; all Tukey
p>0.5). Of the adults, most (86%) could be sexed; of these 93%
were males. The detectability of males was greater than that of the
highly cryptic females owing to maleslarger size, interactive
behaviour and display. Known females were therefore excluded
from further analysis of point counts. The mean distance (square-
root transformed) did not differ between males (n¼124) and
unsexed birds (n¼20) (t
136
¼1.8, p¼0.93). We therefore pooled
males and unsexed birds for subsequent analysis, adjusting for the
proportion of males and again multiplying by two to estimate adult
density.
For houbara observations both on transects (after truncating
5% of the most distant observations) and at point counts (trun-
cated at 1000 m), Half-normal and Uniform models with cosine
adjustments provided the best model t, with a mean Effective
Strip Width (ESW) of 108 m (95% CI; 84e137) and an Effective
Detection Radius (EDR) of 1000 m (95% CI; 10001000),
respectively.
On driven transects a total of 299 sheep groups were observed,
with mean group size of 158 (SD 132.4, range 1e680). Sheep group
size (square-root transformed) was similar among plant commu-
nities (after truncating 10% of the most distant observations:
F
3,263
¼1.514, p¼0.211; all Tukey >0.05) and the observed mean
was therefore used in subsequent analysis. Perpendicular distances
to observed sheep ocks did not differ among plant communities
(data truncated at 10%; F
3,263
¼1.514, p¼0.211, all Tukey p>0.05);
therefore detectability was pooled. After truncation, Half-normal,
Uniform and Hazard-rate with cosine adjustment and Uniform
with simple polynomial adjustment provided the best-tting
models, with an ESW of 422 m (95% CI; 374e476). Sheep density
extracted from interpolated density surface within 2.5 km transect
buffers was positively correlated with the density of sheep camps
mapped within the same buffers (r¼0.789, n¼142, p¼0.001).
Sheep density varied spatially (Fig. 2), and was low (010 in-
dividuals km
2
) or moderate (1030 individuals km
2
) across large
areas (7500 km
2
and 5500 km
2
respectively). In rangelands with
access to water, however, densities reached 3083 individuals
km
2
(on 1500 km
2
of the study area). Mean sheep density differed
among plant communities (F
3, 137
¼26.16, p¼0.001, R
2
¼0.350;
Tukey p<0.05), being more than three times higher in Astragalus,
with Artemisia,Salsola and Calligonum communities having similar
sheep densities (Tukey p>0.05). However, considerable variation
within each plant community permits the independent effects of
sheep density to be examined (Fig. 3); for example, within Arte-
misia-dominated vegetation 11 transects had mediumehigh sheep
density (535 individuals km
2
) while 13 had low density (05
individuals km
2
).
3.1. Effect of sheep density on houbara abundance and distribution
Houbara density appeared lower in the Calligonum-dominated
plant community (Fig. 4) but, owing to wide condence intervals on
density estimates, did not differ signicantly among the four plant
communities either at point counts (F
3,143
¼1.3 70, p¼0.254) or on
transects (F
3,137
¼1.3 74 , p¼0.253). Sheep density was similar be-
tween areas where houbara were observed on transects (n¼70,
mean ¼17.1 individuals km
2
,SE ¼2.1) and random locations
(n¼120, mean ¼14.5, SE ¼1.4; t¼1.054, p¼0.294).
In light of the smaller sample size in Calligonum vegetation, and
low number of houbara observations, Generalised Linear Models to
analyse the relation between houbara and sheep density were only
constructed using observations from the remaining three vegeta-
tion types. There was no strong support for an effect of desert shrub
community or landscape rugosity on either incidence or abundance
of houbara in any of the environmental models (Table 1AD).
Incorporating a term for sheep density into these base models gave
no evidence that sheep density affected houbara incidence on
transects (Table 1A and B). Surprisingly, there appeared to be some
support for a positive effect of sheep density on probability of
houbara incidence on point counts, but only for models that did not
control for plant community (Table 1C). Models of houbara abun-
dance at point locations gave no support for an effect of sheep
density when compared to environmental base models (Table 1D).
3.2. Association between sheep density, shrub frequency and height
A total of 7493 shrubs were measured along 19.2 km of walked
line intercepts, providing data for 96 of the 10-km transects across a
wide range of sheep density (mean of 78.7 shrubs, SD 35.1, range
24e190 shrubs, per 10-km transect). On transects with greater
sheep density, we recorded a greater frequency of shrubs of highly
M.A. Koshkin et al. / Journal of Arid Environments 103 (2014) 53e62 57
Author's personal copy
palatable species (controlling for plant community and individual
shrub species, n¼7; Table 2A). No relationship was found between
sheep density and the frequency of shrubs of medium (n¼6) or low
palatability (n¼5). When we examined the frequency of individual
shrub species, considering the most abundant species of high
(Alhagi pseudalhagi,A. diffusa and S. arbuscula) or medium
palatability (C. hamadae and A. villosissimus), no reductions in shrub
frequency at higher sheep density were found (Table 2A); rather, a
positive association was supported for A. diffusa. This model
controlled for plant community; however, as the abundance of
Artemisia is greatest in the Artemisia-dominated community we
repeated this test solely for the 24 transects located within this
plant community. In this test, the frequency of A. diffusa was again
greater at higher sheep density (B¼0.550, 0.09 SE;F
1,22
¼7.0 4 ,
p¼0.014).
Contrary to expectation, sheep density was not supported as
important in models of shrub height for species with high spring
palatability (n¼5) (again, controlling for plant community and
individual shrub species; Table 2B). In contrast, species of medium
spring palatability (n¼5) were lower on transects with greater
sheep density. Unsurprisingly, the height of shrub species of low
spring palatability (n¼4) was not related to sheep density.
Separate models for the height of the most abundant shrub
species within each palatability class conrmed that height was
reduced at greater sheep density for two species of medium spring
palatability: A. villosissimus (Fig. 4) and C. hamadae (Table 2B).
Predicted mean height for A. villosissimus
2
was 41.6 cm (95% CI;
23.2e65.3) at a density of 20 sheep km
2
; 37.3 cm (20.0e60.1) at 40
sheep km
2
; and 33.2 cm (16.7e55.3) at 60 sheep km
2
, a 20%
reduction in height across this range of sheep density (Fig. 5). In
contrast, no support was found for an effect of sheep density on the
Fig. 2. Sheep density surface for the study area in Bukhara District, Uzbekistan, created by interpolation of transect-specic densities (assigned to transect midpoints). Density
interpolation is limited to the area covered by driven transects and within which sheep camps were mapped.
Fig. 3. Sheep density among four plant communities, based on transect-specic
density, showing the median (horizontal line), quartiles and range (bars); means (di-
amonds) that share a superscript do not differ (Tukey test, p>0.05).
M.A. Koshkin et al. / Journal of Arid Environments 103 (2014) 53e6258
Author's personal copy
height of the abundant, highly palatable A. diffusa,S. arbuscula or A.
pseudalhagi (in models controlling for plant community). For A.
diffusa repeating this test solely for those transects located in the
Artemisia-dominated community again showed no effect of sheep
density on Artemisia height (B¼0.049, 0.09 SE;F
1,22
¼2.39,
p¼0.136).
4. Discussion
In the Bukhara study area in 2012 there appeared to be no
negative landscape-scale association between livestock density and
the abundance and/or distribution of houbara. This is consistent
with the lack of a marked effect of livestock on desert shrub
vegetation structure and composition, but may mask other poten-
tial negative and positive consequences of sheep for houbara. A
limitation of our study was the bias towards male observations in
both transects and point counts, as found previously for point
counts (Le Cuziat et al., 2005b). While females were more likely to
be encountered on driven transects than at point counts, the latter
provided a more efcient census methodology, with houbara
detected at greater distances providing greater numbers of obser-
vations and narrower condence intervals to density estimates.
Our study was designed to examine the effects of sheep grazing
on desert shrub structure, density and composition across
Fig. 4. Estimated mean density of adult houbara from (a) transects and (b) point counts in Bukhara District within four plant communities, showing 95% CI (bars). Adult density was
estimated from transect-specic and point count-specic density, then multiplied by the proportion of males among observed adults, and then by 2, assuming a 50:50 sex ratio,
following Combreau et al. (2002).
Table 1
Generalised Linear Models of houbara distribution, examining houbara incidence on transects compared to random points (binomial error), for (A) all adults (n¼64; random
n¼120), and (B) males only (n¼26, random n¼60); (C) houbara incidence at point counts (present on one or more visits, n¼64, absent n¼74; binomial error, controlling for
repeat visits); (D) houbara abundance at point counts (n¼114, negative binomial error, controlling for repeat visits). For each dependent variable (A, B, C, D), alternative
environmental models that consider one or both of topographic rugosity and plant communities (veg: 3 categories, excluding Calligonum) and the null model (intercept-only)
are compared by their relative AICc (
D
AICc); models within 2 AICc units of the best-supported model are equally plausible. For each dependent variable (AD), the effect of
sheep density is tested by its addition to the supported environmental models, with
D
AICc (relative to the corresponding environmental base model, in the same table row)
showing the effect of sheep density; reduction in AICc of more than 2 units represents strong support. Values in bold represent strong support.
Models of environmental variables only Baseline environmental models plus test of sheep density effect
Model Predictor df B (SE) AICc
D
AICc Model Predictor df B (SE) AICc
D
AICc
A) Transects, adults, incidence 1 Rugosity 1 0.019 (0.05) 165.588 1.415 1þsheep Rugosity 1 0.010 (0.02) 163.958 1.630
Sheep D 1 0.211 (0.18)
2 Veg 2 166.250 2.077
3 Veg 2 167.024 2.851
Rugosity 1 0.003 (0.05)
4 Intercept 0.135 (0.17) 164.173 04þsheep Intercept 1 0.158 (0.21) 162.478 1.695
Sheep D 1 0.018 (0.07)
B) Transects, males, incidence 5 Rugosity 1 0.004 (0.07) 137.345 2.082
6 Veg 2 137.626 2.363
7 Veg 2 139.601 4.338
Rugosity 1 0.040 (0.08)
8 Intercept 1 0.228 (0.20) 135.263 08þsheep Intercept 1 0.105 (0.10) 136.287 þ1.124
Sheep D 1 0.574 (0.39)
C) Point counts, incidence 9 Rugosity 1 0.012 (0.06) 195.099 1.664 9þsheep Rugosity 1 0.050 (0.07) 192.553 2.546
Sheep D 1 0.025 (0.01)
10 Veg 2 192.741 010 þsheep Veg 2 194.266 þ1.525
Sheep D 1 0.015 (0.01)
11 Veg 2 193.223 0.482 11 þsheep Veg 2 194.690 þ1.467
Rugosity 1 0.106 (0.08) Rugosity 1 0.109 (0.08)
Sheep D 1
12 Intercept 1 0.251 (0.35) 193.042 0.301 12 þsheep Intercept 1 0.662 (0.41) 190.926 2.116
Sheep D 1 0.023 (0.01)
D) Point counts, abundance 13 Rugosity 1 0.107 (0.06) 291.720 013 þsheep Rugosity 1 0.124 (0.06) 292.911 þ1.191
Sheep D 1 0.074 (0.07)
14 Veg 2 296.933 5.213
15 Veg 2 294.688 2.968
Rugosity 1 0.145 (0.07)
16 Intercept 1 0.038 (0.27) 292.906 1.186 16 þsheep Intercept 1 0.144 (0.37) 294.836 þ1.930
Sheep D 1 0.031 (0.07)
M.A. Koshkin et al. / Journal of Arid Environments 103 (2014) 53e62 59
Author's personal copy
landscape rather than at local scales. Across the study landscape,
extensive areas of rangeland appeared under-utilised, probably due
to limitations of water and transport, but elsewhere sheep density
ranged from 20 to 40 individuals km
2
(on 2100 km
2
) or higher
(>40 individuals km
2
,on1000km
2
), locally reaching a maximum
of c. 80 individuals km
2
. For comparison, in a study of Houbara in
Israel, mean sheep densities also reached 80 individuals km
2
in
parts of houbara breeding area (Lavee, 1988). On transects with
greater sheep density, we recorded a greater frequency of the most
palatable shrubs (controlling for plant community and individual
shrub species), suggesting an aggregation of livestock in areas with
more food rather than a degradation of habitat from long-term
browsing. The palatable A. diffusa was more frequent in areas
subject to higher livestock pressure. Again, this may be an aggre-
gative response, with pastoralists grazing their sheep on areas that
contain more Artemisia; nevertheless, given the long-term distri-
bution of grazing determined by proximity to settlements and
water, this is evidence that livestock have not denuded these areas.
Another possibility is that the higher density is a consequence of
pastoralism, as sheep trampling can encourage Artemisia
regeneration (Gintzburger et al., 2003). No relationship was found
between sheep density and the frequency of shrubs of medium or
low palatability, indicating that low-palatability shrubs have not
increased in density across areas of higher sheep density. Although
the height of some shrub species of medium palatability was
slightly reduced in the areas supporting greatest densities of sheep,
surprisingly sheep browsing did not strongly modify the height of
the most palatable shrubs.
Although our results appear to indicate that current patterns of
sheep grazing are not degrading desert rangelands within Bukhara,
caution is needed. The lack of any difference in height of green
shrub growth between areas with low and high stocking density
may have been inuenced by the wet spring in 2012, which pro-
longed the growth of ephemeral vegetation, includingthe palatable
Carex physodes. In a drier year with less biomass and earlier
senescence of ephemeroids, there may be stronger effects of
browsing on the annual growth of shrubs. This possibility requires
longer-term study.
We found no evidence that houbaras avoided areas with greater
densities of livestock. Although our study focused on the distribu-
tion of males, and female houbaras may differ in their preference
regarding vegetation height (Hingrat et al., 2007a; Yang et al., 2002,
2003), the effects of livestock on habitat structure were found to be
subtle, suggesting that a strong response of houbara to habitat
quality mediated by livestock is unlikely in our study landscape.
This potentially contrasts with the apparent avoidance of areas
around wells observed for North African houbara (Le Cuziat et al.,
2005a). However, although suggestive, the earlier study did not
provide strong evidence that houbara avoided ocks, as incidence
and distance to wells may have been confounded with the major
effects of topography and distance to agriculture that were not
controlled for when examining distance to well (Le Cuziat et al.,
2005a). Alternatively, it may be that the intensity of sheep
browsing is less in the Kyzylkum. We are unable to compare esti-
mates of sheep density as the study in Morocco quantied this in
terms of numbers of sheep ocks while we considered the density
of individuals. Nevertheless, pastoralism may differ in other
important ways between the regions, for example in rainfall and
Table 2
Generalised Linear Models of (A) shrub frequency (number per composite 200 m line intercept, per 10-km transect, square-root transformed); (B) mean shrub height (cm,
square-root transformed); both related to sheep density (individuals km
2
, square-root transformed). Models have normal error and identity link. Palatability groups consider
annual palatability for shrub frequency but spring palatability for shrub height. Within each palatability category (high, medium and low), models control for shrub species
(species) and plant community (veg, 4 categories); separate models are also shown for the most abundant shrub species within each palatability category, again controlling
for plant community. Strength of support for the effects of sheep density is examined by the
D
AICc on variable removal from that particular model; values in bold represent
strong support (
D
AICc >2.0).
A) Shrub frequency B) Shrub height
df B (SE) AICc
D
AICc df B (SE) AICc
D
AICc
High palatability Sheep D 1 0.125 (0.04) 1193.904 D6.100 10.006 (0.005) 734.753 0.755
Veg 3 3
Species 6 4
Alhagi pseudalhagi Sheep D 1 0.443 (0.21) 74.765 0.703 1 0.01 (0.01) 56.484 3.628
Veg 3 3
Artemisia diffusa Sheep D 1 0.336 (0.1) 274.35 D4.530 10.001 (0.003) 68.008 2.420
Veg 3 3
Salsola arbuscula Sheep D 1 0.024 (0.05) 224.600 2.182 1 0.002 (0.007) 228.602 2.287
Veg 3 3
Medium palatability Sheep D 1 0.085 (0.04) 502.438 þ1.304 1 0.014 (0.005) 342.391 D4.043
Veg 3 3
Species 5 4
Convolvulus hamadae Sheep D 1 0.210 (0.1) 156.218 þ1.215 1 0.011 (0.004) 76.242 D4.290
Veg 3 3
Astragalus villosissimus Sheep D 1 0.011 (0.06) 166.348 2.525 1 0.013 (0.005) 133.925 D2.566
Veg 3 3
Low palatability Sheep D 1 0.033 (0.03) 262.150 1.780 1 0.008 (0.004) 213.697 þ1.084
Veg 3 3
Species 4 3
Fig. 5. Mean height (cm) of Astragalus villosissimus in relation to transect-specic
sheep density (individuals km
2
).
M.A. Koshkin et al. / Journal of Arid Environments 103 (2014) 53e6260
Author's personal copy
carrying capacity, the number of camp inhabitants moving with
mobile sheep ocks, and the presence of dogs with the ock.
Although we found no strong evidence that browsing of vege-
tation by sheep modied habitat suitability for male houbara, there
may also be other trade-offs relating to livestock. In pastoral areas
there is an increased risk of nest trampling by sheep or of predation
by dogs, and frequent disturbance by ocks. Shepherds and their
dogs may keep female houbara off the nest, potentially leading to
failure through overheating of the clutch or predation by avian or
ground predators during the period of female absence (Le Cuziat
et al., 2005a). On the other hand, shepherds and their ocks may
provide protection for houbara nests and broods against predators
such as Red Fox Vulpes vulpes and Desert Monitor Varanus griseus
(eaten by shepherds). Nest despoliation by shepherds (Le Cuziat
et al., 2005a) or their dogs (Lavee, 1988) has been agged as a
problem in other parts of the houbarasrange, but we have no
recent evidence of egg collection by shepherds in our study area,
and dogs rarely follow ocks but are instead left to guard camps.
Subsistence hunting of large ground birds is evidently low in our
study area, as rearms are rare and there is some level of state
patrol to prevent illegal poaching.
The lack of avoidance by houbaras of areas grazed by livestock is
unlikely to be solely a consequence of lek inertia and the site -
delity of individual males (Hingrat et al., 2004), given that the
distribution of pastoralism has been xed for far longer than the
generation length of the Asian Houbara (6.6 years for the two
houbaras combined: BirdLife International 2012). It is also unlikely
to represent an ecological trap, whereby areas appear suitable at
the time of settlement but later prove to be suboptimal (Donovan
and Thompson, 2001), because sheep are brought into the desert
at the same time as houbara return to their breeding grounds, so
that houbara have the opportunity to settle away from grazed
areas. Our observations suggest that houbara are tolerant of sheep
and shepherds, skulking or moving away until the disturbance has
passed. This is consistent with observations in Spain of Great Bus-
tards (Otis tarda), which run away rather than y when disturbed
by sheep ocks, suggesting a lower level of disturbance (Sastre
et al., 2009). We have also observed males displaying near regu-
larly used trackways and females nesting in the vicinity of sheep
camps. Even so, it could still be argued that the houbaras need for
particular habitat structure and topographic features is so impor-
tant that it will tolerate direct and indirect disturbance from sheep
as long as the required habitat features are present.
The ndings of this study suggest that the management of
houbara stocks and the maintenance of livelihoods in semi-arid
lands are not oppositional activities or aspirations. Across the
range of the two houbara species it has generally been assumed
that livestock overgrazing degrades houbara habitat. That this
may not be true, at least in the Kyzylkum Desert, should be a spur
to further study in other parts of the speciesbreeding and
wintering range in Central Asia, Arabia and North Africa. Such
research will require well-replicated studies conducted at land-
scape scales.
Acknowledgements
This study was funded by the Ahmed bin Zayed Charitable
Foundation and generously supported by His Highness Sheikh Saif
bin Zayed. We are grateful to the State Committee for Nature
Conservation of the Republic of Uzbekistan for permissions to
conduct the study. João Guilherme, Charlotte Packman, Dave
Showler and Ellen Walford contributed to data collection, with the
collaboration and support of the Emirates Bird Breeding Center for
Conservation. We thank Prof Antonina Butnik and Dr Toshpulot
Rajabov for validation of our identication of desert shrubs. Two
referees provided signicant and valuable commentary on the
original submitted manuscript.
Appendix A. Semi-desert shrub species considered in the
analysis, showing palatability, and sample sizes (number of
individuals measured, % of 10-km transects from which
recorded).
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M.A. Koshkin et al. / Journal of Arid Environments 103 (2014) 53e6262
... The distribution of 5 shrub assemblages was previously classified and mapped, through extensive field survey (871 sampling locations; see Koshkin et al. 2016aKoshkin et al. , 2016b, as ''Salsola rigida, '' dominated by 2 saltwort species, S. rigida and S. gemmascens, on halophytic soils (2,180 km 2 ); ''Salsola arbuscula, '' characterized by high densities of this taller saltwort species, but also Artemisia diffusa and S. rigida, on gypseous and halophytic soils (3,904 km 2 ); ''Astragalus, '' categorized by the leguminous Astragalus villosissimus, with Convolvulus hamadae and Salsola spp., on semi-consolidated sands (3,778 km 2 ); ''Artemisia, '' largely dominated by A. diffusa, typical of gypseous or clay soils at slightly higher elevations (2,873 km 2 ); and ''Calligonum, '' comprising both Calligonum microcarpum and C. leucocladum and a high frequency of A. villosissimus and C. hamadae, characteristic of drifting and weakly consolidated sands (1,603 km 2 ). Pastoralism, with areas of desert used as rangeland during spring for flocks mainly of sheep (Koshkin et al. 2014), varied at the landscape scale, because it was constrained by proximity to water sources (particularly functioning wells) and roads, with most sheep camps found within 10-20 km of croplands and settlements, leaving considerable areas of desert free of grazing pressure (Koshkin et al. 2014). Although degraded areas were noted around water points and sheep camps, at the landscape scale even moderate (10-30 individuals km À2 ) to high (30-83 individuals km À2 ) sheep densities had little impact on shrub vegetation structure (Koshkin et al. 2014), nor did they affect Asian Houbara clutch size, nest success, or egg hatchability (Koshkin et al. 2016b). ...
... The distribution of 5 shrub assemblages was previously classified and mapped, through extensive field survey (871 sampling locations; see Koshkin et al. 2016aKoshkin et al. , 2016b, as ''Salsola rigida, '' dominated by 2 saltwort species, S. rigida and S. gemmascens, on halophytic soils (2,180 km 2 ); ''Salsola arbuscula, '' characterized by high densities of this taller saltwort species, but also Artemisia diffusa and S. rigida, on gypseous and halophytic soils (3,904 km 2 ); ''Astragalus, '' categorized by the leguminous Astragalus villosissimus, with Convolvulus hamadae and Salsola spp., on semi-consolidated sands (3,778 km 2 ); ''Artemisia, '' largely dominated by A. diffusa, typical of gypseous or clay soils at slightly higher elevations (2,873 km 2 ); and ''Calligonum, '' comprising both Calligonum microcarpum and C. leucocladum and a high frequency of A. villosissimus and C. hamadae, characteristic of drifting and weakly consolidated sands (1,603 km 2 ). Pastoralism, with areas of desert used as rangeland during spring for flocks mainly of sheep (Koshkin et al. 2014), varied at the landscape scale, because it was constrained by proximity to water sources (particularly functioning wells) and roads, with most sheep camps found within 10-20 km of croplands and settlements, leaving considerable areas of desert free of grazing pressure (Koshkin et al. 2014). Although degraded areas were noted around water points and sheep camps, at the landscape scale even moderate (10-30 individuals km À2 ) to high (30-83 individuals km À2 ) sheep densities had little impact on shrub vegetation structure (Koshkin et al. 2014), nor did they affect Asian Houbara clutch size, nest success, or egg hatchability (Koshkin et al. 2016b). ...
... Pastoralism, with areas of desert used as rangeland during spring for flocks mainly of sheep (Koshkin et al. 2014), varied at the landscape scale, because it was constrained by proximity to water sources (particularly functioning wells) and roads, with most sheep camps found within 10-20 km of croplands and settlements, leaving considerable areas of desert free of grazing pressure (Koshkin et al. 2014). Although degraded areas were noted around water points and sheep camps, at the landscape scale even moderate (10-30 individuals km À2 ) to high (30-83 individuals km À2 ) sheep densities had little impact on shrub vegetation structure (Koshkin et al. 2014), nor did they affect Asian Houbara clutch size, nest success, or egg hatchability (Koshkin et al. 2016b). Therefore, when modeling nest-site selection and nest survival, we did not include measures of sheep density, focusing solely on vegetation structure. ...
Article
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Nest-site choice profoundly influences reproductive success and the survival of incubating adult birds. Asian Houbara (Chlamydotis macqueenii) nest in subtly contrasting habitats where the main cause of nest failure is predation. We examined nest-site selection across 3 semiarid shrub habitats that differed in vegetation structure and hypothesized that increased concealment would reduce nest predation. We quantified vegetation structure at 210 nests and 194 random control sites at 2 scales, the “nest area” (50 m radius, considering mean “shrub height” and mean “shrub frequency”) and “nest scrape” (2 m radius, considering a “concealment index”). Variance ratio tests showed that variance in both shrub height and concealment index was lower at nests than at random sites, indicating nonrandom selection. Analysis of the probability of nest occurrence for nest area indicated consistent selection of intermediate shrub heights (shrub height + shrub height²) in the Astragalus, Salsola arbuscula, and S. rigida shrub assemblages (29.5–31.5 cm), although this was not supported statistically in S. rigida because the vegetation available was already similar to the optimal structure. Nest survival analysis, controlling for date, showed that shrub height (but not its quadratic term) in the nest area reduced nest predation rate. Females likely traded off nesting in even taller shrubs that may confer greater nest success against the ability to see approaching danger and thus to reduce the risk of being depredated themselves (head height during vigilance when incubating is ∼30 cm), given that we have no records of females being depredated on the nest. At the nest scrape, females strongly selected better-concealed locations, although the concealment index did not affect nest success. We suggest that concealing the scrape among shrubs may have other roles, such as thermoregulation.
... Livestock density may be high and increasing in parts of North Africa and the Middle East (Gamoun, Tarhouni, Belgacem, Hanchp, & Neffati, 2010;Louhaichi & Tastad, 2010). In post-Soviet Central Asia, while sedentarisation degrades habitat around wells or villages, the extent of livestock pastoralism has reduced substantially across southern Kazakhstan and Uzbekistan, but remains undiminished in Turkmenistan (Behnke, 2006;Koshkin, Collar, & Dolman, 2014). Unsurprisingly, therefore, evidence for houbara responses to livestock also varies regionally. ...
Article
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African houbara (Chlamydotis undulata) and Asian houbara (C. macqueenii), classified as Vulnerable on the IUCN Red List, have been over-exploited across their global ranges. The highest-profile conservation response has been large-scale releases of captive-bred birds, potentially threatening wild populations through introgression. Options for increasing numbers of the species are habitat management to counter overgrazing (in North Africa and the Middle East), mitigation of powerline collisions, predator control (ethically questionable and impractical), reduction of poaching and trapping, limited captive breeding, and hunting controls. Assuming hunting continues, the best model for conserving both species is a system of sustainable hunting that incorporates stakeholder observance, involvement of stakeholders and local communities in decisions and monitoring, protection of no-hunting areas, scientifically-determined quotas, small-scale use of captive-bred birds, and—if numbers still fail to respond, as a last resort—moratoria. These measures provide the only realistic guarantee for the long-term survival of Arab falconry, a part of humanity’s intangible cultural heritage.
... Nesting females might also prefer low-intensity grazing to avoid disturbance caused by livestock herds and their guard dogs; incubating MacQueen's houbara bustards Chla mydotis macqueenii have been observed to temporarily leave nests when disturbed by livestock (Koshkin et al. 2016). Although Koshkin et al. (2014Koshkin et al. ( , 2016 found that density and nesting productivity of C. macqueenii were independent of moderate levels of sheep density in Kyzylkum desert, Uzbekistan, these studies did not capture the most extreme livestock densities (> 80 km −2 ) that would resemble our study area (25 animal units or 100 sheep/goat equivalents km −2 , see Dutta 2012). Similarly, high livestock density was considered as the major reason behind poor nesting success of C. macqueenii in Israel (Lavee 1988). ...
Article
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Habitat management to accommodate ecological needs of threatened species can help abate biodiversity decline. Some species require contrasting microhabitats for different functions, and may prefer patches with ample, diverse microhabitats. We examined this problem for the Critically Endangered great Indian bustard Ardeotis nigriceps in 175 km ² breeding habitat in Kachchh, India. We developed behaviorally explicit resource selection functions (RSFs) by comparing used vs. available microhabitats using binomial generalized linear models that tested hypothesized habitat responses in an information theoretic framework. We identified suitable resource units based on fitted RSF values. We examined if availability of complementary resource units influenced density/usage at the patch level, using line transect distance sampling. Birds preferred agro-vegetation mixture, grassland, high fruit abundance and intermediate grazing density, and they avoided Prosopis thickets for foraging. They preferred moderately tall sward for day resting but shorter sward and less Prosopis for roosting. Nesting females preferred grasslands with relatively tall sward and abundant insects, while displaying males preferred grasslands with shorter sward, far from settlements. Thus, microhabitat selection differed between behaviors and differed from habitat availability. The RSF without behavioral segregation failed to capture these nuances and was non-informative for habitat management. Density/usage at the patch level was correlated with the availability of complementary microhabitats. Thus, protected area management to accommodate diverse life-history requirements may reduce species’ movements over large hostile landscapes and associated mortality. Overall, species requiring complementary microhabitats will benefit from management that promotes habitat heterogeneity. However, habitat use analysis based on behaviorally inexplicit occurrence cannot capture the habitat quality of such species.
... obs.). Koshkin et al. (2014Koshkin et al. ( , 2016a and Guilherme et al. (2018) give further details of shrub habitat structure and composition. ...
Article
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The Turkestan Ground-jay Podoces panderi, a corvid endemic to the deserts of Central Asia, is both understudied and underprotected. Using standardised nest-monitoring protocols and nest cameras, we estimated its breeding productivity for the first time as 0.586 fledglings per nesting attempt (inter-quartile range, IQR 0.413‒0.734), strongly constrained by a diverse set of predator species (accounting for 88% of failures), supporting the broad pattern that a wide spectrum of nest predators operate in arid environments. The probability of nest success for the 35 days from the start of incubation to fledging was low, 0.186 ± 0.06 se (N = 37), with no influence of season date, nest height or nest shrub species. However, pervasive shrub harvest severely limited availability of taller shrubs for nest-site selection, and thus our ability to detect any effect of height on nest survival. Mean clutch size was 4.8 ± 0.8 sd while hatching probability of an egg from a clutch surviving incubation was 0.800 ± 0.050 se and fledging probability was 0.824 ± 0.093 se for individual chicks in successful nests (i.e. that fledged one or more chicks). Two shrub genera, saxaul Haloxylon spp. and Calligonum spp., were used for nesting more frequently than expected ( F2 15 = 784.02, P < 0.001), highlighting their importance to breeding habitat suitability. This near-sole reliance on these taller shrub genera, both targeted for illegal cutting, indicates that habitat degradation may lead to increased predation and declines in productivity. Habitat conservation is, therefore, likely to be the most important management strategy for the species and other components of desert systems, as management of so diverse a set of nest predators would be both impractical and inappropriate.
... Several aspects of this population (e.g. breeding productivity, habitat selection, migration and survival) have already been investigated (Koshkin et al. 2014;Burnside et al. 2016;Koshkin et al. 2016a;Koshkin et al. 2016b;Burnside et al. 2017Burnside et al. , 2018Guilherme et al. 2018). Fieldwork was conducted annually during the entire breeding season (March-July) from 2012 to 2018 inclusive, with a satellite-tagging and brood-monitoring programme from 2013. ...
Article
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Backpack-mounted satellite transmitters (PTTs) are used extensively in the study of avian habitat use and of the movements and demography of medium- to large-bodied species, but can affect individuals’ performance and fitness. Transparent assessment of potential transmitter effects is important for both ethical accountability and confidence in, or adjustment to, life history parameter estimates. We assessed the influence of transmitters on seven reproductive parameters in Asian houbara Chlamydotis macqueenii, comparing 114 nests of 38 females carrying PTTs to 184 nests of untagged birds (non-PTT) over seven breeding seasons (2012–2018) in Uzbekistan. There was no evidence of any influence of PTTs on: lay date (non-PTT x̅ = 91.7 Julian day ± 12.3 SD; PTT x̅ = 95.1 Julian day ± 15.7 SD); clutch size (non-PTT x̅ = 3.30 ± 0.68 SD; PTT x̅ = 3.25 ± 0.65 SD); mean egg weight at laying (non-PTT x̅ = 66.1 g ± 5.4 SD; PTT x̅ = 66.4 g ± 5.4 SD); nest success (non-PTT x̅ = 57.08% ± 4.3 SE; PTT x̅ = 58.24% ± 4.5 SE for nests started 2 April); egg hatchability (non-PTT x̅ = 88.3% ± 2.2 SE; PTT x̅ = 88.3% ± 2.6 SE); or chick survival to fledging from broods that had at least one surviving chick (non-PTT x̅ = 63.4% ± 4.2 SE; PTT x̅ = 64.4% ± 4.7 SE). High nesting propensity (97.3% year⁻¹ ± 1.9% SE) of tagged birds indicated minimal PTT effect on breeding probability. These findings show that harness-mounted transmitters can give unbiased measures of demographic parameters of this species, and are relevant to other large-bodied, cursorial, ground-nesting birds of open habitats, particularly other bustards.
... Despite extensive ecological study (Koshkin et al., 2016a;Koshkin et al., 2016b;Koshkin et al., 2014), no opportunity exists to enhance in situ breeding productivity to offset mortality. We reject predator control across breeding landscapes because: (1) the key predator, Varanus griseus, is vulnerable and protected (Anon, 2009); (2) poison-bait is indiscriminate; (3) disrupting predator/prey dynamics risks unforeseen consequences; (4) predator reduction may affect selection on wild houbara traits (e.g. ...
Article
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To evaluate the potential contribution of captive breeding to the conservation of exploited migratory Asian houbara Chlamydotis macqueenii, we estimated release numbers required to stabilise a population in a hunting concession (14,300 km 2), under scenarios of local licensed hunting and flyway-scale protection. We developed a population model, initially 2350 adult females, re-sampling parameters measured through fieldwork and satellite telemetry, over 1000 iterations. With current flyway-scale unregulated harvest, and without any licensed hunting in the concession, populations declined at 9.4% year −1 (95% CI: −18.9 to 0% year −1); in this scenario a precautionary approach (85% probability λ ≥ 1.0) to population stabilisation required releasing 3100 captive-bred females year −1 (131% of initial wild numbers). A precautionary approach to sustainable hunting of 100 females year −1 required releasing 3600 females year −1 (153% of initial wild numbers); but if interventions reduced flyway-scale hunting/trapping mortality by 60% or 80%, sustaining this quota required releasing 900 or 400 females year −1 , 38% and 17% of initial wild numbers, respectively. Parameter uncertainty increased precautionary numbers for release, but even with reduced precaution (50% probability λ ≥ 1.0), sustainable hunting of 100 females year −1 required annual releases of 2200 females (94% wild) without other measures, but 300 (13%) or no (0%) females under scenarios of a 60% or 80% reduction in flyway-scale hunting/trapping. Captive breeding cannot alone sustain migrant populations of wild C. macqueenii because it risks replacement and domestication. Trade and exploitation must be restricted to avoid either extinction or domestication. For exploited populations, supplementation by captive breeding should be used with caution.
... Both Great and Little Bustard, recent beneficiaries of post-Soviet farmland abandonment, are predicted to suffer as their habitat reverts to agriculture (Kamp et al. 2011, Goroshko in press); in particular, the much commoner Little Bustard can be predicted to decline sharply, as seen in France since 1980 and Iberia since 2000 (Jolivet & Bretagnolle 2002. Even Asian Houbara, whose distribution and productivity are unaffected by present livestock levels in the Kyzylkum Desert, Uzbekistan (Koshkin et al. 2014(Koshkin et al. , 2016a, has disappeared as a winter migrant to the Arabian Peninsula due to habitat degradation in combination with hunting . In South Asia, habitats of Great Indian Bustard, Bengal Florican and Lesser Florican continue to be turned over to intensive cultivation, whilst invasions of exotic plant species such as Prosopis juliflora alongside ill-planned plantations in grasslands represent another major, albeit more recent, cause of habitat loss for Great Indian Bustard and Lesser Florican (SD, YVJ pers. ...
Article
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The inherent defencelessness against natural predators of bustards, which have relatively small bills and can neither perch in trees nor take refuge in water at night, renders them warier than other large-bodied birds. They are therefore dependent on large areas of little-disturbed, little-developed open country within which they can see and keep danger at a good distance. In Asia (here including Central Asia and Asian Russia), six species—Little Bustard Tetrax tetrax (IUCN global category Near Threatened), Great Bustard Otis tarda (Vulnerable), Asian Houbara Chlamydotis macqueenii (Vulnerable), Great Indian Bustard Ardeotis nigriceps (Critically Endangered), Bengal Florican Houbaropsis bengalensis (Critically Endangered) and Lesser Florican Sypheotides indicus (Endangered)—are already at serious risk of extinction. Great Bustard (of the nominate race) is struggling to survive in Asian Russia (<200 individuals), Kazakhstan (100–1,000) and China (maximum 52 seen in extensive surveys, 2014–2016), while in Asian Russia the eastern race dybowskii numbers just 380–430 (with only 5% in protected areas), fewer than 1,000 in Mongolia and 600 in China. Little Bustard is now largely restricted to Kazakhstan and westernmost Asian Russia and, although its status evidently improved in the 1990s with the post-Soviet abandonment of agriculture in Central Asia, re-intensification of farming is poised to cause new declines. Asian Houbara has a population claimed to be between 50,000–100,000 individuals, but is certainly declining despite largescale captive breeding programmes, with one study suggesting an offtake of 27.1% in the years 1994–2008 when the maximum sustainable level was 7.2%, and another indicating a current annual population decline in Uzbekistan of 9.4%. Great Indian Bustard (<200 birds in the most recent assessments, some in unviable habitat fragments), Bengal Florican (225–249 males estimated for South Asia; several hundred in Cambodia) and Lesser Florican (270 males estimated in 2017 compared with 1,103–1,765 in 1994–1999) are all in extreme trouble. Habitat change, chiefly in the form of rapid and widespread agricultural intensification (mechanisation, chemical applications, overgrazing, increased fencing and new choices of crop), but also involving infrastructure developments and disturbance, is probably the single biggest threat; only the semi-desert-dwelling Asian Houbara remains relatively unaffected. Hunting and poaching is a particularly serious threat to Great and Little Bustards and Asian Houbara, as well as Great Indian Bustard. Powerlines are known to have killed and injured birds of five of the six species and currently are the most serious cause of mortality to Great Indian Bustards, and problems caused by powerlines are anticipated to intensify for all species. Predation, most seriously by uncontrolled dogs, has been registered as a strong negative influence on Great Bustard and seems likely also to affect Little Bustard, Great Indian Bustard and both floricans. The long-term prospects of all six species are extremely bleak unless their conservation is prioritised and significantly strengthened. Adult survival and productivity are key to the health and recovery of bustard populations and both need to be improved through well-managed nature reserves (organised along flyways for long-distance migrants), plus: special protection of areas where males display and around which females are known or expected to breed; continuous unfragmented landscapes subsidised for low-impact farming with reduced grazing pressure within which the birds’ social dynamics are unconstrained; the strategic planting of crops favoured by all species; strict and strong regulation of both powerlines and fencing within and beyond those landscapes; equally strict and strong control of hunting, poaching, dog predation and inappropriate grass-fires; and sustained campaigns of public awareness and engagement. The model of Castro Verde Special Protection Area in Portugal, where Great and Little Bustard numbers have multiplied and the livelihoods of communities have been supported through subsidy, provides evidence that practical solutions are possible. Detailed cataloguing of records and intensive biological research programmes are also needed for all species, together with support for local conservation groups and scrupulous review of all landscape-related plans to prevent adverse developments. Hunting of Asian Houbara must come under national systems of control based on an internationally agreed strategy. Governments must now prioritise the conservation of bustards as the burden of responsibilities is too great for NGOs to bear alone. International coordination and collaboration will, with high levels of communication, be crucial to success. The setting of time-bound targets is required to spur key staff into rapid action.
... The Asian Houbara (Chlamydotis macqueenii) is one of the three species of the Otididae family in the Gruiformes subclass, classified as a vulnerable species by the world conservation union (Koshkin et al. 2014). A bustard of desert and semiarid landscapes, Asian Houbara have suffered near extirpation of resident populations in the Iran and major declines across Central Asia and Arabian Peninsula, primarily as a consequence of unregulated hunting and trapping during migration and winter (Koshkin et al. 2016). ...
Article
The Asian Houbara is vulnerable species, the population of which is dwindling. Its protection must be prioritized in conservation programs. In this study, maximum entropy models were developed in four seasons to evaluate habitat suitability and factors affecting Asian Houbara in the Center and East Iran. Environmental variables used in modeling and evaluating the niche consisted of 24 environmental and climate variables for Gharetapeh hunting prohibited region and 36 environmental and climate variables for Petregan protected area. Also, seasonal overlap area was obtained using the ENM TOOLS software. The results showed that the most important factors affecting habitat suitability of the Asian Houbara in all seasons included the ratio of distance to the type of Artemisia sieberi–Zygophyllum eurypterum, distance to the slope 2–5%, distance to the type of Seidlitzia rosmarinus in the Gharetapeh hunting prohibited region, distance to the type of Artemisia aucheri, distance to the land passion, and distance to the dry land farming in the Petregan region. In summer and fall–winter, the most suitable habitat is Gharetapeh but is Petergan during fall–winter. There is maximum overlap in fall and winter, and the least overlap in the spring in these areas.
Technical Report
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Como consecuencia del estatus de conservación de la avutarda hubara canaria (Chlamydotis undulata fuertaventurae), resulta necesario disponer de información fiable y actualizada que permita realizar un diagnóstico de la situación actual de la especie, así como de la tendencia de sus poblaciones. El trabajo de censo realizado a lo largo de noviembre-diciembre del año 2016 pretende aportar información que se sume a la ya obtenida en censos anteriores. Lo hace aplicando una metodología que se repite respecto a esos censos previos, tanto en relación a la fecha en la que se efectúa, como a las localidades donde se muestrea, de tal manera que los resultados obtenidos en los diferentes periodos puedan conducir a un análisis comparativo. El objetivo final del trabajo, que por tanto no se circunscribe a un único censo sino a un conjunto de ellos, es obtener evidencias robustas acerca de la evolución temporal de los efectivos poblacionales en los últimos años para esta especie tan emblemática de la avifauna canaria.
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Little is known about the ecology of the Sand Cat Felis margarita throughout its range in the deserts of northern Africa to central Asia. We present observations of the Sand Cat in the southern Kyzylkum Desert, Uzbekistan, potentially preying upon a large bird and returning to the kill on subsequent nights. This record contributes to the knowledge about the feeding ecology and varied diet of the Sand Cat and its opportunistic hunting strategy.
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This chapter presents an analysis of contemporary status of rangelands, vegetation, and land use in Uzbekistan. Constraints to development include the climate and other physical conditions, but the socioeconomic and the policy environment are also barriers to adoption of better land management. The large rural population in remote areas is in subsistence mode, and there is little opportunity to improve household income in the face of the lack of access to grazing lands, lack of secure land tenure, and limited rural financial services. Measures to introduce and implement sustainable land management concepts and practices are outlined.
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This article examines the traditional relationship between the houbara bustard (Chlamydotis undulata macqueenii) and desert falconry in the Middle East and reviews the factors causing the decline of houbara populations. Hunting with falcons, industrial development, changes to traditional agriculture, political instability, subsistence hunting, and wars are important factors combining to threaten this species throughout its range. Many initiatives to conserve the houbara bustard in the Middle East are supported by Arab falconers. The role of national wildlife conservation agencies in the Middle East in establishing captive breeding and restoration programs, habitat protection, ecological studies, biomedical research, local hunting organizations, falcon research groups, sustainable use in range countries, public awareness programs, rehabilitation projects, and international agreements to conserve the houbara bustard are described.
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Aims: Human activities have been reported to impinge on the distribution of the endangered Houbara Bustard Chlamydotis undulata undulata. The present study intends to investigate spatial relationships between Bustard and pastoral distribution in order to identify avoidance patterns and potential exclusions of the species from still-suitable grounds. Location: The study was conducted on a 600 km2 area within the semi-arid steppe-lands of Eastern Morocco. Methods: Spatial relationships between sheep flocks and Houbara flocks were explored and tested using the spatial point pattern analytical framework. Results: Significant mutually-exclusive distribution patterns between sheep and goat flocks and bustards were detected throughout the whole year. Bustards' avoidance of sheep flocks appeared to be a spatially variant and temporally scaled process. Conclusions: Exclusion patterns are identified and discussed. Subsequent conservation implications are briefly presented.
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We studied the effects of female distribution, topography, and human infrastructures on lek-site selection in a ground-displaying bird, the great bustard Otis tarda. Our aim was to investigate the relative importance of maximizing visibility to females (hotspot hypothesis) versus minimizing predation risk (predation avoidance hypothesis). Using a geographic information system, a very high-resolution digital elevation model, and an extensive survey database, we compared the 350 lek centers known in Spain with randomly generated sites. Males preferred lek sites that increase their visibility to surrounding females, reduce the distance to them, enhance the probability of detecting predators, and increase the distance to human disturbance sources. Logistic regression analyses confirmed these patterns. A final model identified five relevant variables indicative of higher short-range visibility, more centered location with respect to females, and farther distance to human disturbance sources in lek centers comp
Book
This book contains a selection of papers presented at the Advanced Research Workshop on ‘The Socio-economic causes and consequences of desertification in Central Asia’ held in Bishkek, Kyrgyzstan, in June 2006. The meeting provided a forum for twenty-six scientists from Central Asia and NATO countries to discuss the human dimensions of the desertifi- tion process. Papers presented to the meeting examined recent scientific evidence on the impact of desertification on livestock production, public health, and biodiversity, and contributed to the formulation of coh- ent national and regional policies for the management of watersheds, rangelands, and irrigated agriculture. The meeting was co-directed by Roy Behnke of the Macaulay Institute, UK, and by Lapas Alibekov of the Samarkand State University, Uzbekistan. Both the workshop and this subsequent publication have been financed by the NATO Scientific Affairs Division and we gratefully acknowledge this support. The Bishkek meeting was ably hosted by the Kyrgyz Sheep Breeders Association under the dir- tion of Akylbek Rakaev who contributed substantially to the successful running of the workshop. Deliberations at the workshop emphasized that policy failures at national level had promoted desertification within the region.
Article
More than half of the world's population of the little bastard Tetrax tetrax lives in the Iberian Peninsula, where it is mostly dependent for survival on extensive agricultural areas. The species has declined dramatically, chiefly due to changes in agricultural practices, and is now globally 'Near Threatened'. Knowledge of its habitat requirements is crucial to reverse the trend of habitat deterioration. Winter habitat preferences were studied in a region dominated by extensive cereal farming in Southern Portugal, comparing the characteristics of sites used by 54 flocks with those of randomly selected sites within the study area. The birds preferred recent fallows and grassy vegetation of mid-size (about 11–20 cm) and mid-density (about 11–50% cover). They tended to concentrate on the tops of hills and to avoid disturbed areas near roads and houses. Overall, the observed preferences suggest that predator avoidance is a significant factor in habitat selection. To improve habitat suitability for little bustard, managers of key wintering areas should minimize permanent sources of human disturbance, encourage rotations with frequent fallows, and favour moderate levels of grazing to manipulate vegetation height and cover. Particular attention should be given to the upper parts of the hills.
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Display-site selection by houbara bustards was studied in Mori, Xinjiang, China during the breeding seasons from April to June 2000. Most of the habitats chosen for displaying were short sub-shrubby and open areas close to high shrub patches. The displaying males clearly prefer low covered areas and avoid densely covered and high vegetation sites. The vegetation density and number of plant species at display sites were significantly lower from that at randomly selected sites. The average distance to the closest shrub patch was significantly shorter at display sites than at random sites. Plant species richness, vegetative density, vegetative cover and distance to the shrub patches are possibly the most important factors that determined the display-sites selection of houbara bustard.
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Activity rhythms of captive-bred reintroduced houbara bustards (Chlamydotis undulata macqueenii) were studied in the Mahazat as-Sayd reserve in Saudi Arabia. Birds were radio tagged with solar powered transmitters and activity was recorded with an automatic recording station over several weeks in the summer of 1993. Peaks of diurnal activity were observed at dawn and dusk. Daytime activity was negatively related to solar radiation and soil surface temperature. Nocturnal activity was triggered by moonlight. Food consumption, the duration of night-time activity and the minimum distance moved at night by houbara were positively correlated to the duration of moonlight.
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Houbara bustards Chlamydotis undulata are uncommon winter visitors to Abu Dhabi. People attempting to increase numbers are considering establishing reserves and restoring habitats but they are hampered by poor knowledge of the bird's requirements. We studied winter habitat use by recording the locations of three satellite-tagged houbara, verified by the presence of tracks, and detailed habitat assessments at the landscape scale. Our initial results show that houbara used habitat in patches averaging about 40 km2 and spaced 14–34 km apart. Patches were used for up to three weeks before the birds moved on. Habitats were characterised by flat or gently undulating terrain, and a higher than average incidence of vegetation. These results indicate a conflict between rural development and houbara, both of which favour flat, vegetated plains over sand dunes. We suggest that Managed Resource Protected Areas should be established for the houbara and that relatively small changes to forestry practice could provide the birds with suitable wintering habitat within developed areas.