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# Drinking schedule of four sandgrouse species (Pterocles spp.) in relation to sunrise and season

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Sandgrouse (Pterocles spp.) are adapted to extreme desert environments. One such adaptation is that males transport water in their abdominal feathers to water the nesting female and hatchlings. Hence, understanding sandgrouse drinking regime and regularly used water holes is of great conservation importance. We studied the arrival of four sandgrouse species at a single water hole in the western Negev Desert, Israel. During our visits, the most numerous species was the Spotted Sandgrouse, and in decreasing abundance, we found Black-bellied Sandgrouse, Crowned Sandgrouse, and Pin-tailed Sandgrouse. Black-bellied Sandgrouse arrived significantly earlier than Spotted Sandgrouse and Crowned Sandgrouse. Spotted Sandgrouse arrival peaked later in the morning than Black-bellied Sandgrouse and Crowned Sandgrouse. The data suggest that this is connected to the absolute number of birds for each of the species which influences their synchronous arrival. Also, we find that the amount of time a species spends at the water hole is influenced by the number of birds present, i.e., the species that stay the longest are also the most numerous. The mean temperature when Spotted Sandgrouse peaked was marginally higher (21.2°C) than recorded for Black-bellied (19.5°C) and Crowned Sand-grouse (19.3°C).
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ORIGINAL PAPER
Drinking schedule of four sandgrouse species (Pterocles spp.)
in relation to sunrise and season
Reuven Yosef &Piotr Zduniak
Received: 24 April 2010 / Revised: 22 October 2010 /Accepted: 4 November 2010 / Published online: 23 November 2010
#Springer-Verlag and ISPA 2010
Abstract Sandgrouse (Pterocles spp.) are adapted to
extreme desert environments. One such adaptation is that
males transport water in their abdominal feathers to water
the nesting female and hatchlings. Hence, understanding
sandgrouse drinking regime and regularly used water holes
is of great conservation importance. We studied the arrival
of four sandgrouse species at a single water hole in the
western Negev Desert, Israel. During our visits, the most
numerous species was the Spotted Sandgrouse, and in
decreasing abundance, we found Black-bellied Sandgrouse,
Crowned Sandgrouse, and Pin-tailed Sandgrouse. Black-
bellied Sandgrouse arrived significantly earlier than Spotted
Sandgrouse and Crowned Sandgrouse. Spotted Sandgrouse
arrival peaked later in the morning than Black-bellied
Sandgrouse and Crowned Sandgrouse. The data suggest
that this is connected to the absolute number of birds for
each of the species which influences their synchronous
arrival. Also, we find that the amount of time a species
spends at the water hole is influenced by the number of
birds present, i.e., the species that stay the longest are also
the most numerous. The mean temperature when Spotted
Sandgrouse peaked was marginally higher (21.2°C) than
recorded for Black-bellied (19.5°C) and Crowned Sand-
grouse (19.3°C).
Keywords Drinking .Pterocles .Sandgrouse .Sunrise .
Timing
Introduction
Sandgrouse (Pterocles spp.) are a very interesting family
because of their adaptation to extreme desert environments,
gregarious behavior, phytophagus diet, secretive nesting
habits (cf. Louw and Seely 1982; Maclean 1996), and
because the males have a unique capability to transport
water in their abdominal feathers and are responsible for the
watering of the nesting female and the hatchlings (Marchant
1961,1962;vonFrisch1970;Rijke1972;Johnsgard1991).
Cade and Maclean (1976) described the importance of the
males to the survival of their precocial chicks. The males
wade into the water holes to wet their breast feathers, which
canabsorbasmuchas2040 ml. The chicks drink from the
breast feathers; as much as 3 ml of water was measured in
the crop of a sandgrouse chick, which amounts to almost
30% of the chick's total body mass (Louw and Seely 1982;
Dixon and Louw 1978).
Ward (1972) found that 12 of 16 sandgrouse species
drink in the morning 24 h after sunrise, while four species
drink mainly after sundown. De Juana (1997) reported that
drinking regime of the sandgrouse is very precise and in
accordance with the sunrise or sunset. Johnsgard (1991),
who generalized from the literature, reported that sand-
grouse leave the roost area at daybreak, typically flying in
flocks at a considerable speed, estimated to be as much as
100 km/h. He described the typical behavior upon arrival at
a water hole, as circling above the pool area before landing.
They then walk to the water's edge, drink by inserting the
bill into water to eye level, lifting the head to swallow
between draughts (for drinking behavior see Cade et al.
R. Yosef (*)
International Birding and Research Center in Eilat,
P. O. Box 774, Eilat 88000, Israel
e-mail: ryosef@eilatcity.co.il
P. Zduniak
Department of Avian Biology and Ecology, Faculty of Biology,
Adam Mickiewicz University,
Umultowska 89,
61614, Poznań, Poland
e-mail: kudlaty@amu.edu.pl
acta ethol (2011) 14:3541
DOI 10.1007/s10211-010-0088-z
1966; de Juana 1997). Johnsgard (1991) observed that
drinking is usually finished in 15 s or less, after which the
birds run back to their original landing site, then take off in
flocks to return to foraging areas.
Hence, in order to understand the drinking regimes of
the four Sandgrouse species that breed in the Negev Desert,
we undertook to observe the species at a well-known
watering site. The importance of drinking, especially by the
males during the hot breeding season, can have consider-
able implications if drinking sites are disturbed by human
activity (eg., birdwatchers; cf. Ferns and Hinsley 1994)or
regional development. We calculated the time of arrival in
relation to sunrise of each of the species at the drinking site,
the ambient temperature, the total amount of time each
species spent on the ground, and the peak time of the
species as a function of the non-breeding seasons of late
summer, autumn, and early winter. Our study also allowed
us to understand the relative proportions of abundance of
the four species for the study area. Also, the fact that it is
difficult to find a locality at which more than a couple of
species are common at one and the same time, (de Juana
1997) makes our study of four species an important
contribution to the biology and conservation of the species
involved.
Methods and study species
On the 15th of each month, between Aug 2001 and Jan
2002, we observed the arrival times of the four sandgrouse
species at the Nizzana drinking site (30°52N, 34°27E) in
the western Negev Desert, Israel. The region has several
army camps, some of which have open fresh water or
sewage tanks. The study site was at a pair of dried out
sewage tanks with the sludge removed, at the bottom of
which a large area of water remained throughout the
summer. The area of the two ponds is ca. 60 m long by
25 m wide.
The western Negev is a vast expanse of steppe and semi-
desert habitat with transitional mixed cultivated areas, 160
180 m above sea level. The topography consists of plain or
rolling hills, with an alluvial soil of loess-sand (Lavee
1988). The rainy season is from Nov to Apr. The sparse
natural vegetation includes mainly perennials, mostly
Noaea mucronata, Artemisia monosperma, and Asphodelus
microcarpus, and a few trees of Acacia raddiana and
Tamarix sp.
All observations were made from within a parked
vehicle from a distance of ca. 80 m with the help of a
Swarovski telescope (×2060) or binoculars (15 × 56). All
sandgrouse that landed at the drinking site were counted,
time of arrival noted, and all data entered in a field
notebook. Observers were in place 15 min before sunrise to
ensure that we did not miss or disturb the sandgrouse upon
arrival. We usually left the area 60 min after the last
sandgrouse had flown away.
We decided to concentrate on these 6 months because
Shirihai (1996) showed that maximum numbers of sand-
grouse come to drink at water holes in the months of July to
Oct. Although some of the species studied are also known
to visit the water holes to drink again in the afternoon or the
evening (cf. Berry et al. 2001), our study documented only
morning visits. Also because of the large number of birds
that flew in simultaneously, and their rapid turn over at the
drinking site, no attempt was made to sex or age of the
birds, and only absolute numbers were counted.
The species studied are:
Black-bellied Sandgrouse (P. orientalis) - are found from
the Iberian Peninsula and North Africa in the west to
Xinjiang Zizhiqu, China in the east (Johnsgard 1991). The
only one of two Pterocles species occurring in Europe, and
hence is the most typical of the less xeric end of the
sandgrouse habitat range and frequently occur in semi-arid
farmland. The species occur mainly on flat plains with
grassy steppe-like or semidesert vegetation. Food consists
mainly of protein-rich seeds of legumes, grasses, and native
plants (Cramp 1985). This is an apparently monogamous
species with a 1-year period to sexual maturity. The species
is partially migratory in the northern parts of its distribu-
tion. Breeding season occurs during the spring and summer
months, generally March to Sept.
Pin-tailed Sandgrouse (P. alchata) - are distributed from
Spain and northwestern Africa in the west to western
Kazakhstan in the east (Johnsgard 1991). The second of the
two Pterocles species occurring in Europe, and hence, the
most typical of the less xeric end of the sandgrouse habitat
range and frequently occur in semi-arid farmland. Lowland
plains and stony areas on the edges of deserts, arid flats, or
sand dunes are commonly exploited by the species for
breeding. Almost exclusively vegetarians, this species takes
insects or other animal materials only incidentally. Breeding
season occurs from Apr to Aug.
Spotted Sandgrouse (P. senegallus) - are found from the
Western Sahara, North Africa in the west to the Thar Desert
of India in the east (Johnsgard 1991). A species of semi
desert and true desert areas, it is the most common in flat
and stony habitats. George (1969) and Urban et al. (1986)
thought that Spotted Sandgrouse that forage together during
the day may also roost together at night in assemblages of
up to 50, and fly to drink together in the morning. This may
also be true for the other studied species. This monogamous
species breeds from March to July. The species has a general
tendency to locate the nest fairly near a waterholemost nests
were within 4 km of water and none more than 8 km.
Crowned Sandgrouse (P. coronatus) - are found from the
Western Sahara, North Africa in the west to India in the east
36 acta ethol (2011) 14:3541
(Johnsgard 1991). Considered to be one of the most arid-
adapted of all the sandgrouse, it inhabits the hottest and
driest parts of the desert. In India, the species was observed
arriving at waterholes from early morning until a couple of
hours after sunrise (Ali and Ripley 1983). Some returned in
the evening to drink again. The species is tolerant of saline
water, and has the largest kidneys relative to the three most
desert-adapted sandgrouse species of North Africa, which
indicates a high salt turnover rate (Thomas and Robin 1977;
Johnsgard 1991). A monogamous species, their breeding
season extends from Apr to Sept.
We analyzed the relationship between the sandgrouses'
arrival time and the ambient temperature during the
observations at the drinking site. We noted the temperature
at each full hour and translated the time into minutes after
sunrise. The data showed a strong linear increase of
temperature during the day in each month (Fig. 1). The
temperature decreased over the following months (Fig 1).
Based on obtained linear equations (see Fig. 1), we
computed the temperature for each 10-min period after
sunrise for each day of observation. The data allowed us to
compare the differences between the sandgrouse species
and the temperature at the time they arrived at the tanks,
and when their relative numbers increased.
We used standard statistical methods to describe and
analyze the data (Sokal and Rohlf 1995). All calculations
were performed using STATISTICA for Windows (Statsoft
2008). In the instances when we found a strong correlation
between the two studied variables which were not well
described by linear function, we fitted a curve to the XY
coordinate data according to the distance-weighted least
squares smoothing procedure. Because of the sample size in
all cases, the applied stiffness parameter, which determines
the function that controls the weight, was 1. This approach
allowed us to produce curves that represent the overall
pattern in the data set at the expense of individual data
points (McLain 1974). Throughout the text, mean values
are presented with standard deviation (± SD).
Results
We found great differences in numbers of the four sandgrouse
species at the waterhole. During our six visits, the most
numerous species was the Spotted Sandgrouse; mean number
of individuals observed during a visit was 1055.3± 173.1
(range 8521270, n=6). Less numerous were Black-bellied
Sandgrouse (725.3± 139.9, range 462852) and Crowned
Sandgrouse (211.5±39.3, range 178271). Pin-tailed Sand-
grouse occurred in very low numbers (9.2±2.1, range 712);
data for this species were not further analyzed. The number
of counted individuals of the three most numerous species
decreased linearly over the study period (Fig. 2). Moreover,
the mean temperature calculated for the first 4 h after sunrise
(the time during which birds arrived at the drinking site) also
significantly decreased over the study period (Fig. 2).
There were differences in arrival time of the first
birds at the watering place after sunrise between
compared species during the study period (repeated
measures ANOVA, F
2,10
=4.32, P=0.044). Black-bellied
Sandgrouse arrived at the pool significantly earlier
(x¼77:543:0 min after sunrise, n=6) than Spotted
Sandgrouse (90.8± 41.4) and Crowned Sandgrouse (90.8 ±
43.7) (Fisher's LSD test, in both cases P=0.029, Fig. 3a).
The difference in time of arrival between the first and the last
species in subsequent months was on average 18.3±7.5 min.
(range 1030 min.; Fig. 3a). Furthermore, the time elapsed
from sunrise to the first bird's arrival extended linearly
during the study period from 20 to 50 min in Aug in the
Fig. 1 Increase of ambient temperature during the days of observation
during the study period
Fig. 2 Decrease in numbers of three sandgrouse species and the mean
ambient temperature (open squares) during the first 4 h after sunrise
during the study period
acta ethol (2011) 14:3541 37
summer, 120150 min in January in winter, depending on
the species (Fig. 3a). In consequence, we did not find a
difference between the species and the ambient temperature
at the first birds' arrival (repeated measures ANOVA, F
2,10
=
3.00, P=0.095). During this time, ambient temperature
oscillated between 15ºC and 18ºC. In the case of all species,
we did not find any trends over the study period (in all cases
R
2
<0.16, P>0.45).
The arrival time after sunrise, when the highest
numbers of drinking birds were observed, differed
between species (repeated measures ANOVA, F
2,10
=
11.36, P=0.003; Fig. 3b). Spotted Sandgrouse peaked later
(x¼164:237:3minaftersunrise, n=6) than Black-
bellied Sandgrouse (139.2±53.0; Fisher's LSD test,
P=0.006) and Crowned Sandgrouse (130.8 ± 33.6; Fisher's
LSD test, P=0.001), between which there was no significant
difference (Fisher's LSD test, P>0.27; Fig. 3b). The mean
difference in the time of the peak numbers between the first
and the last bird of a species in subsequent months of the
study period was 38.3±14.7 and varied between 20 and
60 min. Moreover, in the case of each species, the time
elapsed from sunrise to peak numbers extended throughout
the study period (Fig. 3b). The ambient temperature at peak
numbers differed between species (repeated measures
ANOVA, F
2,10
=4.51, P=0.040). The mean temperature
when Spotted Sandgrouse peaked was marginally higher
(21.2± 1.7°C) than recorded for Black-bellied (19.5± 1.6°C)
and Crowned Sandgrouse (19.3±1.4°C) (Fisher's LSD test,
P=0.033 and P=0.022,respectively).Furthermore,inthe
case of each species, the time elapsed from sunrise to peak
numbers was related to the time elapsed from sunrise to the
first bird's arrival at the water hole (Fig. 4).
Themeantimethebirdswerepresentatthewater
hole differed between species (repeated measures
ANOVA, F
2,10
=47.88, P<0.001). Spotted Sandgrouse
were observed on average for 175.0± 26.6 min, Black-
bellied Sandgrouse for 138.8± 19.4 min and Crowned
Sandgrouse for 73.3±20.6 min. Differences between all
species were significant (Fisher's LSD test, P<0.005).
Discussion
We found that Spotted Sandgrouse was the most abundant
species, followed by Black-bellied, Crowned, and Pin-
tailed Sandgrouse, respectively. This is in contrast to
Hinsley (1994), who studied Sandgrouse at Sede Boqer,
in the central Negev Highlands, and found that the most
numerous species in her study area were Black-bellied
Sandgrouse with smaller numbers of Spotted Sandgrouse,
and very few Crowned and Pin-tailed Sandgrouse. The
disparity in numbers is most probably the result of differ-
ences in precipitation between the two study sites and the
Fig. 3 Differences in arrival time of the first birds (a) and of peak
numbers at the watering hole (b) after sunrise between compared
sandgrouse species during the study period; curves were fitted using
the distance-weighted least squares smoothing technique, stiffness=1
Fig. 4 Correlation between the time since sunrise to the first arrival of
the sandgrouse at the water hole, and the time elapsed from sunrise to
peak numbers; curves were fitted using the distance-weighted least
squares smoothing technique, stiffness=1
38 acta ethol (2011) 14:3541
resulting groundcover and vegetation. The Sede Boqer area
has an average annual precipitation of 105 mm (Hinsley
1994) as compared to 87 mm at our study site in the
Western Negev (Wasserberg et al. 2002).
The number of counted individuals of the three most
numerous species decreased over the study period and
appears to be an effect of our sampling regime. The fact
that we counted birds beginning in Aug coincided with
peak fledging period for the Sandgrouse in the Negev
Desert, so we probably documented the seasonal effect
representing survival and dispersal within the local popu-
lation using the studied water hole. During the fledging
period, numbers are inflated with the new cohorts of the
season, and dispersal to other suitable breeding areas or
drinking sources probably had an effect on the numbers
counted (cf. Maclean 1976; Malan et al. 1994). Further-
more, the mean monthly temperatures calculated for the
period from sunrise to the time when all Sandgrouse
finished arriving at the drinking site, decreased over the
study period. The results support the assumption that
decreasing numbers of birds coming to drink are also
influenced by decreasing temperature. It is possible that
birds in the later part of the study period do not need to
drink every day (for experimental water deprivation experi-
ments see Cade et al. 1966), especially during the rainy
seasons when small puddles of rainwater can meet the daily
requirements of the sandgrouse. This is consistent with the
findings of Cade et al. (1966) who also found that in Africa,
the largest flocks occurred during the summer, and numbers
declined greatly in the autumn and winter.
Throughout our study, Black-bellied Sandgrouse arrived
first at the water hole, and were significantly earlier than the
first Spotted and Crowned Sandgrouse. This has not been
reported to date, but then, there are very few studies of
several Sandgrouse species simultaneously (eg., Hinsley
1994; Berry et al. 2001). Our finding suggests that Black-
bellied Sandgrouse probably breed and forage in proximity
to the water hole, resulting in their being the first to arrive
every morning. This is probably a prerequisite for the
survival of the species because it is known to be a less able
thermoregulator under hot conditionsthan other species
(Hinsley et al. 1993). Black-bellied Sandgrouse is one of
only two Pterocles species occurring in Europe, and is most
typical of the less arid-adapted of the Sandgrouse. Con-
versely, Spotted and Crowned Sandgrouse are considered to
be some of the most arid-adapted of all Sandgrouse,
inhabiting the hottest and driest parts of the desert (Ali
and Ripley 1983). This fact may allow these species to
remain in more inhospitable areas of the Negev desert at a
greater distance from the water hole, resulting in their
arriving to drink later in the morning. This, to a certain
extent, confirms that Black-bellied Sandgrouse occur closer
to the drinking site than Spotted and Crowned Sandgrouse,
which is indicative of their inability to adapt to extreme arid
environments.
In addition, time elapsed from sunrise to the first bird's
arrival extended linearly during the study period from 20
050 min in the summer in Aug to 120150 min in winter in
Jan, depending on the species (also see Cade et al 1966;
Berry et al. 2001). de Juana (1997) reported that in the
Kalahari, the Namaqua Sandgrouse (P. namaqua) drinks
12 h after dawn and Burchell's (P. burchelli)22.5 h after
dawn. In Spain, Pin-tailed Sandgrouse arrive on average
2.53 h after dawn, but Black-bellied Sandgrouse arrive 3 h
after dawn.
The latter two species also fly to water in the evening
during the summer, the Pin-tailed approximately an hour
and 20 min before sunset, but the Black-bellied arrives
about an hour earlier. The study shows that delay in the
drinking schedule is the result of environmental conditions
connected to the decrease in ambient temperatures, as well
as demand and access to water during the subsequent
months of the study. In the summer, the number of water
sources is limited; temperatures are high and rise quickly
following sunrise, requiring the Sandgrouse to reach a
water source as early as possible. In contrast, in autumn and
winter, when temperatures are lower and increase gradually
after sunrise, humidity is higher and occasional rains create
temporary pools. Therefore, the urgent need to fly to the
central water hole is reduced. The disparity in conditions
most probably allows the Sandgrouse to drink later in the
morning. This assumption confirms the lack of significant
changes in ambient temperature during the study period of
when the first birds arrived at the drinking site. This also
suggests that the timing of arrival is to some extent related
to ambient temperature.
Peak numbers after sunrise of Spotted Sandgrouse were
later than Black-bellied and Crowned Sandgrouse. We think
this is apparently connected to the absolute number of birds
for each of the species, and most probably influenced their
synchronous arrival (cf. Berry et al. 2001). Therefore, the
most numerous Spotted Sandgrouse peaked later than the
less numerous Black-bellied and Crowned Sandgrouse,
which arrived in smaller numbers and therefore, more
synchronously. This was also correlated with the differ-
ences in the ambient temperature at the drinking site, and
was marginally higher for the Spotted Sandgrouse than all
the other species.
In each of the three analyzed species, the time elapsed
from sunrise to peak numbers was related to the elapsed
time from sunrise to the first bird's arrival at the waterhole.
This relationship between the two parameters indicates that
the environmental cues to which the species react are
uniform and that a different parameter, such as distance to
water hole, influences the difference in time between arrival
of the vanguard and the major body of visiting birds.
acta ethol (2011) 14:3541 39
Also, we find that the amount of time which a species
spends at the water hole is influenced by the number of
birds, i.e., the species that stay the longest are also the most
numerous. This is most probably the result of the difference
in time between the vanguard and the last of the sandgrouse
arriving for the morning. The last birds to arrive usually
come from a greater distribution than those with smaller or
closer numbers (cf. Maclean 1983). It is also possible that
the numbers reflect breeding populations. As Maclean
(1983) observed, the female parent flies to the watering
place to drink an hour or so after sunrise and takes over,
brooding the chicks on her return. The male then flies to
drink and to soak his belly feathers at the waterhole.
However, because we did not evaluate the relative numbers
of the sexes in the flocks, this remains to be tested in future
studies.
It is possible that the numbers of interactions occurring
before and after drinking water are more prolonged by the
larger number of individuals interacting with one another
(Berry et al. 2001). Or perhaps, concentrations require the
birds to increase individual awareness and to stand around
longer before approaching the water to drink (cf. Ferns and
Hinsley 1995). Another factor that could affect time spent
at the water hole is the foraging constraint. The amount of
food required to sustain the individual, the amount of
foraging time available, and the amount of food available
could affect the amount of time the bird will spend
interacting with conspecifics at the water hole. Hinsley
(1994) found that sandgrouse spent ca. 75% of their
daylight hours either foraging or inactive during the hottest
hours. It has also been suggested that en mass drinking
(Cade et al. 1966; Berry et al. 2001) and the topography of
the water holes reduces predation pressure on the flocks
(Cade 1965; Thomas and Maclean 1981; Ferns and Hinsley
1994,1995). However, we are unable to state an opinion on
the subject because the barbed wire enclosure at the ponds
excluded mammalian predators, and we did not observe any
avian predators attack the sandgrouse during our study.
Although this is the first study of the drinking regimes of
the four Sandgrouse species in the Negev Desert of Israel,
our study allows us to understand the requirements of the
species but not to reach any firm conclusions. All four of
the Sandgrouse species studied have decreased drastically
in numbers in recent years (RY pers. obs.). The reasons for
the declines remain uncertain.
Besides knowledge of the timing and drinking regimes,
we need to understand topographic requirements. These
include the amount of bare ground surrounding the cistern,
which ensures that the water hole can be utilized with
confidence by the Sandgrouse. The bare ground helps them
to avoid avian or terrestrial predators (cf. Ferns and Hinsley
1995). This knowledge, together with ensuring a constant
number of potable water holes throughout the year, should
help to ensure the continued survival of these four species
in the western Negev desert and throughout their global
range.
Acknowledgments We thank Susan Craig, two anonymous
reviewers, and the editor for improving an earlier version of the
manuscript.
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... Our results also suggest the absence of nests on elevations above 295 m. Above this height, the topographic conditions (presence of cliffs) are not really appropriate (see Znari et al. 2008, Yosef & Zduniak 2011and Traba et al. 2013 to accommodate the nests of this species. The choice of the altitude range between 245 and 295 m for nesting would be a strategy trade-off between topographic (shallow slope and flat areas), anthropogenic factors (low human presence), and landscape factors (habitat cover). ...
... Furthermore, at this scale, the probability of Black-bellied Sandgrouse nest presence is also associated with the cover of natural water. This is in agreement with Yosef & Zduniak (2011) who, in studying the drinking schedule of four sandgrouse species, have suggested that Black-bellied Sandgrouse breed and forage in proximity to water holes. According to Hinsley et al. (1993), this choice is probably a prerequisite for survival because the species is known to be a 'less able thermoregulator under hot conditions' than other species. ...
Article
Capsule: Nest site selection of Black-bellied Sandgrouse Pterocles orientalis in an Algerian arid environment is dictated by a combination of topography, human presence, landscape and space. Aims: To disentangle the drivers affecting Black-bellied Sandgrouse nest habitat use in an Algerian arid environment. Methods: We used data on a series of topographic, anthropogenic, landscape and space variables, to identify the predictors of the occurrence probability of Black-bellied Sandgrouse nests. These variables were measured at nests (n = 33) and random points (n = 33) within landscape plots of 250 m radius. Results: The probability of a site being selected for nesting by Black-bellied Sandgrouse was negatively related to distance to the nearest cereal crops, but positively associated with the cover of natural water, cover of rocks, and distance to the nearest road. This probability was also high at elevations between 251 and 289 m. Conclusion: From a practical perspective, it would be interesting to reproduce the same investigation in other Mediterranean arid environments to find out if this species follows a similar pattern of nesting habitat use. This would provide guidance for future conservation actions and inform appropriate habitat management for this species.
... This characteristic can be used to estimate the average annual recruitment by regular waterhole counts of juveniles, after the last belly-soaking males were recorded or two months following hatching. In this regard, Namaqua Sandgrouse juveniles appeared at the waterhole for the first time once they were almost fully grown and were moulting into an adult-type plumage (Lloyd 1998;Yosef and Zduniak 2011). After their first summer, one-year-old adults could not be distinguished from older birds (two-and three-yearold) by plumage characteristics. ...
Article
Full-text available
The sandgrouse, family Pteroclididae, are a group of birds adapted to open, arid habitats and powerful fliers but information on their plumage development and moult is scarce. In this study, the annual cycle of body plumage development, sequence and duration of primary flight feathers moult were investigated in Black-bellied Sandgrouse Pterocles orientalis, from hatching to the adult stage. Body plumage differed among juvenile, immature and subadult birds before their first breeding season. Yearling Black-bellied Sandgrouse showed three annual moults with only the pre-breeding one being complete. Juvenal body plumage was acquired shortly before the first attempts to fly at 5–6 weeks of age. The acquisition of definitive adult body plumage took place after the breeding season in late August, when birds were about 10–12 months old. The species typically replaced all primaries annually with a gradual descendent moult at a slow rate, taking 10–11 months for their completion, from December to September, including the breeding period. This study provides the first detailed analysis of flight feather development and moulting in the Black-bellied Sandgrouse, which provides useful ageing criteria based on the patterns of both primary growth and moult.
... This characteristic can be used to estimate the average annual recruitment by regular waterhole counts of juveniles, after the last belly-soaking males were recorded or two months following hatching. In this regard, Namaqua Sandgrouse juveniles appeared at the waterhole for the first time once they were almost fully grown and were moulting into an adult-type plumage (Lloyd 1998;Yosef and Zduniak 2011). After their first summer, one-year-old adults could not be distinguished from older birds (two-and three-yearold) by plumage characteristics. ...
Article
Full-text available
The sandgrouse, family Pteroclididae, are a group of birds adapted to open, arid habitats and powerful fliers but information on their plumage development and moult is scarce. In this study, the annual cycle of body plumage development, sequence and duration of primary flight feathers moult were investigated in Black-bellied Sandgrouse Pterocles orientalis, from hatching to the adult stage. Body plumage differed among juvenile, immature and subadult birds before their first breeding season. Yearling Black-bellied Sandgrouse showed three annual moults with only the pre-breeding one being complete. Juvenal body plumage was acquired shortly before the first attempts to fly at 5–6 weeks of age. The acquisition of definitive adult body plumage took place after the breeding season in late August, when birds were about 10–12 months old. The species typically replaced all primaries annually with a gradual descendent moult at a slow rate, taking 10–11 months for their completion, from December to September, including the breeding period. This study provides the first detailed analysis of flight feather development and moulting in the Black-bellied Sandgrouse, which provides useful ageing criteria based on the patterns of both primary growth and moult.
... Sandgrouse are characterized by highly synchronized early morning and late afternoon arrivals to drinking points during breeding season, a behaviour that has been mainly interpreted as a strategy to reduce predation risk or to reduce evaporative water loss and save energy (Ward, 1972;Yosef and Zduniak, 2011). Our data indicate that the timing of incubation reliefs, and therefore for travelling to drinking points is constrained by thermal conditions (in order to maximize eggs and small chick survival). ...
Article
Full-text available
Most Pterocles namaqua concentrate in Bushmanland, NW Cape Province, from December-March. From April-July the sandgrouse move N and E of Bushmanland and apparently return to Bushmanland from August-November. This west-east movement occurs at a relatively constant rate of 30-50km per month. Only 15% of the sandgrouse ringed at an estate within the eastern part of this species range returned the following winter. Belly-soaking was more prevalent in early summer in Bushmanland than in any season in the east. South African populations of Namaqua sandgrouse are partial migrants which breed primarily in early summer (October-November) in Bushmanland. -from Authors
Article
Double-banded Sandgrouse, Pterocles bicinctus, at Etosha National Park in Namibia exhibit a predictable and remarkably synchronized activity pattern when flying to drink at water-holes. The primary environmental cue that activates this pattern appears to be decreasing light intensity. The species is highly synchronized in this regard, with an average interval of 16 minutes after time of sunset and the time when sandgrouse arrive at water. Birds stay at water for 28 minutes on average. P. bicinctus numbers decrease significantly at artificially supplied water when rain falls. Floodlights have no significant effect on times of arrival or times of departure of these birds at drinking places. The predominantly crepuscular nature of Double-banded Sandgrouse may have evolved as part of their survival strategy by placing them less at risk to diurnal raptors, and may also save energy and reduce evaporative water loss.
Article
1. Undulating ground resembles cover in offering opportunities for vertebrate predators to remain hidden from prey and vice versa. Some species prefer to forage in the open so as to avoid being surprised by predators while others remain close to cover and use it as a refuge when attacked. 2. To determine if topography was important in influencing the sites chosen by sandgrouse for drinking, we measured a range of variables at water-holes used by black-bellied, pin-tailed and crowned sandgrouse (Pterocles orientalis, P. alchata and P. coronatus) in Spain and Israel. All species drank at sites reasonably close to their feeding and nesting areas. 3. In Spain, water-hole selection was quantified using stepwise logistic and linear regression analysis. The amount of dead ground surrounding each water-hole (i.e. ground not visible to drinking sandgrouse) was the most important factor influencing the birds' choice. 4. These regression relationships were used to predict the pattern of use of water-holes at two localities in Israel. The agreement between observed and expected levels of exploitation was good, confirming the strong aversive influence of dead ground. 5. Predatory birds were the biggest source of disturbance at drinking sites. By choosing sites with the least dead ground, sandgrouse probably reduced their risk of being surprised by predators while drinking.
Article
D OVES, pigeons, and sandgrouse are notably wary in approaching the isolated and usually exposed, open water holes where they congregate in large numbers to drink in desert regions, as, for instance, in parts of Australia (Cameron, 193s) and Africa (Bowen, 1927). What are the haz-ards which make such obvious behavior of adaptive significance in the lives of these birds? During fieldwork carried out between 18 and 23 January and between 5 July and 11 August 1964 in the Namib Desert, I had frequent . . opportumtles to observe flocks of columbiform birds drinking at a water hole in the dry bed of the Kuiseb River and to gain some insight into the role which diurnal raptors play in determining their approach to water. bed of the Kuiseb River provides one of the six or eight sources of surface water for thousands of square miles in this region. The diameter of the pit at the level of the river bed was about 40 feet, the depth to the water, about 10 feet, while the diameter of the water surface itself was about 6 feet. The well is located approximately in the center of the riverbed, where its width is some 250 feet. On either side there are stands of rather dense riparian woods consisting mainly of Acacia giraff ae and Acacia albida growing to a height of 40 to 50 feet. Vegetationless sand dunes stretch southward from the left limit of the river for hundreds of miles. Northward lies an equally vast expanse of sparsely vegetated gravel plains. Most of the birds in this region are necessarily associated with the river valley or with the better vegetated portions of the gravel plains. OBSERVATIONS Five species of columbiform birds were regular users of this water hole during my periods of observation. These were: Namaqua Sandgrouse (Pterocles namaqua) , Speckled Rock Pigeon (Colzzmba guinea), Cape Tur-tle Dove (Streptopelia capicola) , Laughing Dove (Stigmatopeh senegahsis) , and Namaqua Dove (Oena capensis). Mackworth-Praed and Grant (1962) can be consulted for a description of these species.
Article
Sandgrouse of the genus Pterocles are good models for studying adaptations to deserts, with 14 species living in different parts of a habitat spectrum ranging from semiarid to extreme desert. To evaluate possible differences in bioenergetic and thermoregulatory ability within the group, we studied two species, black-bellied sandgrouse (Pterocles orientalis) and pin-tailed sandgrouse (Pterocles alchata). These two species are partly sympatric, but the latter also occurs in hotter and more arid regions than the former. Black-bellied sandgrouse had a mean resting metabolic rate (RMR) similar to the allometric prediction (5.53 m W g⁻¹ by day, 5.04 mWg⁻¹ at night; 97% and 110% of allometric prediction, respectively), whereas mean RMR in pin-tailed sandgrouse was lower than predicted (4.04 mW g⁻¹ by day; 62% of allometric prediction). Similarly, the pin-tailed sandgrouse was the better thermoregulator of the two species, especially at high temperatures, with a well-developed evaporative cooling ability. At 40°C, evaporative heat loss ( $\dot{H}_{e}$ ) dissipated 89% of metabolic heat production ( $\dot{H}_{m}$ ), and at 25°C, $\dot{H}_{e}$ was 152% of the allometric prediction. This compares to 53% at 40°C and 101% at 25°C for black-bellied sandgrouse. However, both species had high lower and upper critical temperatures, and metabolism at high ambient temperatures ( $T_{a}'s$ ) was relatively insensitive to increasing temperature. Black-bellied sandgrouse showed greatly increased thermal conductance ( $C_{d}$ ) at high temperatures facilitating nonevaporative heat loss. This species also demonstrated labile body temperature ( $T_{b}$ ), especially at low $T_{a}$ ), allowing energy savings under cooler conditions. It was not possible to measure $T_{b}$ for pin-tailed sandgrouse because of the birds' behavior.
Article
Time budgets and activity patterns of sandgrouse were studied in semi-arid agricultural land in Spain (Black-bellied and Pin-tailed Sandgrouse) and in more desertic conditions in Israel (Black-bellied and Spotted Sandgrouse). During c. 75% of daylight hours, all four species were either foraging or inactive. The birds in Israel spent more time foraging than those in Spain, despite having lower thermoregulatory costs, reflecting a likely difference in the productivity of the sites. Partitioning of foraging habitat was evident at both sites and, contrary to expectation, it was the larger Black-bellied Sandgrouse which spent the most time foraging. In Israel, Spotted Sandgrouse became inactive at high temperatures whereas the Black-bellied continued to forage, utilizing the shade available in its dwarf shrub foraging habitat. The range of Black-bellied Sandgrouse may be limited by its thermoregulatory ability in hot conditions and its need to forage for long periods.