Synchrony of drinking in Double-banded Sandgrouse,Pterocles bicinctus,at Etosha National Park,Namibia

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.     

Disentangling the drivers of Black-bellied Sandgrouse Pterocles orientalis nesting habitat use in a Mediterranean arid environment

ABSTRACT

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.     

Annual climate in Mexican Spotted Owl habitat in the Sacramento Mountains,New Mexico: implications for responding to climate change

Global climate change presents a growing conservation threat, but our understanding of the effects of climate change remains limited for most species. We evaluated the annual climate cycle for threatened Mexican Spotted Owls (Strix occidentalis lucida) in high-elevation mixed-conifer forests in the Sacramento Mountains of New Mexico from 2005 to 2010. We used data from a network of weather stations in Mexican Spotted Owl habitat to describe annual temperature cycles, and precipitation data from a National Weather Service weather station to describe the annual precipitation cycle. We coupled these data with equations from the literature to estimate annual cycles in resting metabolic rate and evaporative water loss, and evaluated the potential effects of a warming climate on these parameters. Annual weather was characterized by cold, dry winters, warmer and dry springs, warm and wet summers, and cool and relatively wet falls. Ambient temperature never exceeded the upper critical temperature for Mexican Spotted Owls (35.2°C), but > 90% of 663,422 hourly temperature observations were below the lower critical temperature (18.2°C). Thus, heat stress was not predicted to occur, but owls likely expended energy on thermoregulation at low temperatures. Resting energy use peaked during winter (December–February) and was lowest when owls would be feeding young (May–August). In contrast, evaporative water loss peaked from June to August, when precipitation also peaked. Mexican Spotted Owls generally appeared well-adapted to the current climate cycle in our montane study area, but late winter (February–March) may be a critical period in terms of energy requirements, and late spring (April–May) may be critical in terms of water relationships. Predicted changes in temperature through 2099 would result in reductions in predicted energy use by Mexican Spotted Owls, but increases in predicted water use. Water relationships may become increasingly important for Mexican Spotted Owls in the face of climate change, especially in warmer and drier areas. In forested areas, retaining patches of older forest with high canopy cover in cool, mesic sites may provide continued benefits to Mexican Spotted Owls under climate change.     

Bill and hyoid apparatus of pigeons (Columbidae) and sandgrouse (Pteroclididae): a common adaptation to vegetarian feeding?

For the present study, 15 species of pigeons representing the 5 sub-families usually recognized, and 3 species of sandgrouse were examined. The skeleton and musculature of the bill and hyoid apparatus are described. Morpho-functional analyses show that from a key adaptation to the removal and deglutition (without processing) of attached plant items, pigeons would have followed two pathways, one based on the joint muscular control of the movement of the jaws (Columbinae, Treroninae, Gourinae), the other on the separate muscular control (Didunculinae, Otidiphabinae). Sandgrouse would have diverged from this latter, developing the ability to very selectively remove attached plant items as well as to peck particularly small seeds on the ground. Unexpected differences appeared between sandgrouse species which raise eco-ethological problems.     

The validity of open seasons for sandgrouse shooting: analysis of an 11‐year data set from Kenya

Variation in gonadal size of shot black‐faced sandgrouse, Pterocles decoratus , and chestnut‐bellied sandgrouse, P. exustus , considered to be indicative of their breeding condition, was studied to examine whether or not breeding seasons fall within the set shooting seasons for different parts of Kenya, and to reveal a possible relationship between rainfall patterns and the onset of breeding. Analysis of an eleven‐year data set shows large overlap between the present shooting season for sandgrouse and their main breeding period in southern Kenya, while seasons for other areas and other gamebird species seem appropriate in most years. Cumulative rainfall from four to six months earlier correlates positively with the proportion of birds breeding, while rainfall in the period shortly before breeding does not. These findings support the hypothesis that sandgrouse breed when seeds are likely to be most abundant. Results from this study further suggest that incubating females frequent waterholes more often than do males, possibly due to a higher water deficit. This hypothesis, however, needs further field testing with a genuinely random sample.     

Assessing the short‐term effects of capture,handling and tagging of sandgrouse

Capturing and marking free‐living birds permits the study of important aspects of their biology but may have undesirable effects. Bird welfare should be a primary concern, so it is necessary to evaluate and minimize any adverse effects of procedures used. We assess short‐term effects associated with the capture, handling and tagging with backpack‐mounted transmitters of Pin‐tailed Pterocles alchata and Black‐bellied Pterocles orientalis Sandgrouse, steppe birds of conservation concern. There was a significantly higher mortality (15%) during the first week after capture than during the following weeks (< 2.5%) in Pin‐tailed Sandgrouse, but no significant temporal mortality pattern in Black‐bellied Sandgrouse. In Pin‐tailed Sandgrouse, mortality rate during the first week increased with increasing relative transmitter and harness weight regardless of season, and with increasing handling time during the breeding season. There were no significant differences in mortality rate between study areas, type of tag, sex or age or an effect of restraint time. These results suggest the use of lighter transmitters (< 3% of the bird's weight) and a reduction of handling time (< 20 min), particularly during the breeding season, as essential improvements in procedure to reduce the mortality risk associated with the capture, handling and tagging of these vulnerable species.     

An improved night-lighting technique for the selective capture of sandgrouse and other steppe birds

The night-lighting technique is routinely used to catch birds. We improved this technique using a thermal infrared camera to catch steppe birds such as the sandgrouse. Target birds were located by an observer using the thermal camera, and approached and dazzled by another observer carrying a spotlight attached to a helmet and a hand-held net together with a playback noise to camouflage the footsteps of the observer. Using this improved technique, we caught on average 1.14 individuals per 3-h capture session (N = 81) and a total of 92 sandgrouse in 2007–2010 (86 pin-tailed sandgrouse Pterocles alchata and six black-bellied sandgrouse Pterocles orientalis). Capture rate and success were negatively influenced by moonlight (lowest during full moon nights). Our night-lighting technique is a highly selective and harmless method to capture sandgrouse and can be used for other small/medium-sized open-land birds or mammals.     

Population genetics of the endangered Crowned Solitary Eagle (<Emphasis Type="Italic">Buteogallus coronatus</Emphasis>) in South America

The Crowned Solitary Eagle (Buteogallus coronatus) is one of the rarest and most severely threatened birds of prey in the Neotropical region. We studied levels of neutral genetic diversity, population structure, and the demographic history of the species using 55 contemporary samples covering a large fraction of the species range, which were genotyped at 17 microsatellite loci. Our results indicated genetic homogeneity across the sampled regions, which may be explained by a high dispersal capability of Crowned Solitary Eagles resulting in high gene flow or relatively recent population expansion. Further demographic tests revealed that the species has experienced a recent demographic reduction, but inbreeding was not detected. The existing connectivity between geographically separated populations may have buffered the negative effects of the demographic bottleneck. Alternatively, the demographic reduction may be too recent to detect a genetic signature due to the long generation time of the species. Potential conservation strategies, including the possibility of translocations of individuals, are discussed.     

Embryonic development time of the freshwater mysid <Emphasis Type="Italic">Limnomysis benedeni</Emphasis> Czerniavsky as a function of water temperature

The numbers of alien species in freshwater systems and their detrimental impacts on the stability of ecosystems and global species diversity are increasing. To predict and assess such impacts, a thorough knowledge of the autecology and life cycle of the alien species is required. Limnomysis benedeni is common and one of the most invasive mysids in Europe. Here we show a clear dependency of the development time of the brood of L. benedeni on water temperature. In laboratory experiments (one in spring 2008 and two in 2009, in spring and summer) under controlled conditions, we determined embryonic development times and the probability of survival of the females and juveniles at water temperatures ranging from 4 to 25°C. At 6.5 and 25°C, the probability of survival of both the females and the larvae was lower than at 10, 15, or 20°C. Since the development time is one of the key characteristics of the life cycle and is therefore necessary to calculate, for example, birth and mortality rates, we determined an equation for the development time as a function of the water temperature. This information will be useful to understand the distribution potential of this invasive species.     

Thermotaxis and selection of a wintering site in the Ajime-loach, <Emphasis Type="Italic">Niwaella delicata</Emphasis>

The hypothesis that the Ajime-loach, Niwaella delicata, is guided to groundwater seepages by a positive thermotaxis in autumn, was tested by a field investigation and aquarium-based experiments. A total of 763 individuals of N. delicata were captured from October to November in a groundwater trap in the Yasu River, Shiga Prefecture. Niwaella delicata began to be captured as the temperature of the surface water fell to 15.8° ± 1.1°C (mean ± SD) and that of the groundwater to 15.5° ± 0.9°C. Groundwater was often warmer than surface water at night or occasionally all day, and the difference in temperature reached a maximum of 1.3°C at the night on 5 November. For the diel pattern of captures, nocturnal capture was higher than diurnal capture when the groundwater was warmer at night and colder during the daytime, whereas both diurnal and nocturnal captures were high when the groundwater was always warmer than the surface water. The aquarium-based experiments showed that N. delicata choose warmer water, ranging from 18.4° to 22.2°C, just before the capture period in the Yasu River, and are sensitive to differences in water temperature of 1.3° ± 0.1°C. Although the present results broadly support the hypothesis, a part of the results indicates that water temperature gradients may not be the only factor involved in the groundwater selection of N. delicata.     

OBSERVATIONS ON THE BREEDING BIOLOGY OF THE FISCAL SHRIKE

Ward, D. 1989. Behaviour associated with breeding of Crowned, Blackwinged and Lesser Blackwinged Plovers. Ostrich 60: 141–150.

The behaviour of Crowned Plovers Vanellus coronatus, Blackwinged Plovers V. melanopterus and Lesser Blackwinged Plovers V. lugubris in mate and territory acquisition and defence was documented and related to the habitats these birds occupy. The open habitat occupied by vanelline plovers makes them particularly vulnerable to predation and as a result, they have a highly-developed ability to detect potential predators and have developed a number of behavioural strategies to avoid predation. This has resulted in these birds having a higher reproductive success than that documented for other precocial birds.     

Fecundity and feeding of <Emphasis Type="Italic">Galerucella calmariensis</Emphasis> and <Emphasis Type="Italic">G. pusilla</Emphasis> on <Emphasis Type="Italic">Lythrum salicaria</Emphasis>

Fecundity and feeding of two introduced sibling biological control species, Galerucella calmariensis and G. pusilla (Coleoptera: Chrysomelidae) on purple loosestrife, Lythrum salicaria L. (Lythraceae) were compared at constant temperatures of 12.5, 15, 20, 25, and 27.5 °C. Larval feeding was also carried out at 30 °C, but at this temperature, larvae developed only to the L2 stage and none pupated. Thus, data for this temperature were not used in the analysis. There were significant species × temperature interactions in fecundity. Of the two species, Galerucella pusilla laid more eggs. Although egg production of both species was lowest at 12.5 °C and increased to 20 °C, at higher temperatures, the two species reacted differently. From 25 to 27.5 °C, egg production decreased for G. pusilla, but G. calmariensis fecundity peaked at 27.5 °C. Significant temperature × species × life-stage interactions were also observed in feeding. For each species, the amount of feeding varied with temperature and stage of development. Galerucella pusilla adults consumed more foliage at 15, 20, and 27.5 °C. However, at 12.5 °C G. calmariensis adults fed more than G. pusilla. G. pusilla larvae consumed an average of 25% less foliage than G. calmariensis. The lower larval consumption of G. pusilla suggests that when food is limited, G. pusilla larvae may have a higher survival rate because of its ability to complete larval development with less food and produce more progeny due to its greater fecundity. When food is not limited neither species would have a competitive advantage and both species could coexist temporally and spatially. However, since G. calmariensis larvae consumed more leaf material, the larval stage of this species would have a greater impact on purple loosestrife than G. pusilla.     

Temperature-dependent development of the predatory mite <Emphasis Type="Italic">Cheyletus malaccensis</Emphasis> (Acari: Cheyletidae)

The effect of temperature on the development of immature stages of the predator Cheyletus malaccensis Oudemans, produced by either fertilized or virgin females, was studied at 17.5, 20, 25, 30, 32.5, and 35°C, 80 ± 5% relative humidity, in complete darkness, and fed Tyrophagus putrescentiae (Schrank). The population maintained at 15°C failed to reproduce. The thermal data obtained were used for the estimation of the thermal requirements (developmental thresholds, thermal constant, optimum temperature) of this predator by a linear and nonlinear model (Logan type I model). Upper and lower developmental thresholds ranged between 37.4–37.8 and 11.6–12.0°C, respectively. Optimum temperature for development was estimated at between 33.1 and 33.5°C. The thermal constant ranged between 238.1 and 312.5 degree-days. Based on the data of the total pre-imaginal period, immatures’ survival peaked at 25°C. Arrhenotokous parthenogenesis (haplodiploidy) is confirmed in the species: virgin females always produce males, whereas fertilized females give rise to offspring of both sexes. Survival of the immature stages and offspring sex ratio were not significantly influenced by temperature.     

Actual and perceived collision risk for bird strikes at Namibian airports

At Namibia’s two major airports, Hosea Kutako International and Eros (domestic), 117 bird strike collision incidents were recorded between 2006 and 2010. A risk assessment, which included a proposed risk weighting methodology, was conducted at Hosea Kutako and Eros airports, which estimated the probability of an accident/collision as well as the consequence of such a collision. The assessment included surveys of bird occurrence frequencies as well as pilot interviews. The results of the risk assessments were compared with actual bird strike incidences for each species, frequency of occurrence of birds and pilot perceptions of species risk, in order to find whether risk assessment and pilot perception are reliable measures of potential bird strike incidence. White-backed Vulture Gyps africanus and Helmeted Guineafowl Numida meleagris were the highest risk species at both airports. They were also, after Crowned Lapwing Vanellus coronatus, the species most often observed by pilots. Bird strike records showed that Crowned Lapwing and Helmeted Guineafowl were also the most frequently struck birds at both airports. The study illustrates how combining risk assessment, pilot perception and bird strike history can benefit bird strike minimisation plans at airports through the rapid identification of priority bird species.     

A matter of timing: changes in the first date of arrival and last date of departure of Australian migratory birds

Although there is substantial evidence that Northern Hemisphere species have responded to climatic change over the last few decades, there is little documented evidence that Southern Hemisphere species have responded in the same way. Here, we report that Australian migratory birds have undergone changes in the first arrival date (FAD) and last date of departure (LDD) of a similar magnitude as species from the Northern Hemisphere. We compiled data on arrival and departure of migratory birds in south‐east Australia since 1960 from the published literature, Bird Observer Reports, and personal observations from bird watchers. Data on the FAD for 24 species and the LDD for 12 species were analyzed. Sixteen species were short‐ to middle‐distance species arriving at their breeding grounds, seven were long‐distance migrants arriving at their nonbreeding grounds, and one was a middle‐distance migrant also arriving at its nonbreeding ground. For 12 species, we gathered data from more than one location, enabling us to assess the consistency of intraspecific trends at different locations. Regressions of climate variables against year show that across south‐east Australia average annual maximum and minimum temperatures have increased by 0.17°C and 0.13°C decade^?1 since 1960, respectively. Over this period there has been an average advance in arrival of 3.5 days decade^?1; 16 of the 45 time‐series (representing 12 of the 24 species studied) showed a significant trend toward earlier arrival, while only one time‐series showed a significant delay. Conversely, there has been an average delay in departure of 5.1 days decade^?1; four of the 21 departure time‐series (four species) showed a significant trend toward later departure, while one species showed a significant trend toward earlier departure. However, differences emerge between the arrival and departure of short‐ to middle‐distance species visiting south‐east Australia to breed compared with long‐distance species that spend their nonbreeding period here. On average, short‐ to middle‐distance migrants have arrived at their breeding grounds 3.1 days decade^?1 earlier and delayed departure by 8.1 days decade^?1, thus extending the time spent in their breeding grounds by ～11 days decade^?1. The average advance in arrival at the nonbreeding grounds of long‐distance migrants is 6.8 days decade^?1. These species, however, have also advanced departure by an average of 6.9 days decade^?1. Hence, the length of stay has not changed but rather, the timing of events has advanced. The patterns of change in FAD and LDD of Australian migratory birds are of a similar magnitude to changes undergone by Northern Hemisphere species, and add further evidence that the modest warming experienced over the past few decades has already had significant biological impacts on a global scale.     

Critical thermal limits and their responses to acclimation in two sub-Antarctic spiders: <Emphasis Type="Italic">Myro kerguelenensis</Emphasis> and <Emphasis Type="Italic">Prinerigone vagans</Emphasis>

Despite the relative richness of spider species across the Southern Ocean islands remarkably little information is available on their biology. Here, the critical thermal limits of an indigenous (Myro kerguelenensis, Desidae) and an introduced (Prinerigone vagans, Linyphiidae) spider species from Marion Island were studied after 7–8 days acclimation to 0, 5, 10 and 15°C. Critical thermal minima (CT_Min) were low in these species by comparison with other spiders and insects measured to date, and ranged from −6 to −7°C in M. kerguelenensis and from −7 to −8°C in P. vagans. In contrast, critical thermal maxima (CT_Max) were similar to other insects on Marion Island (M. kerguelenensis: 35.0–35.6°C; P. vagans: 35.1–36.0°C), although significantly lower than those reported for other spider species in the literature. The magnitude of acclimation responses in CT_Max was lower than those in CT_Min for both species and this suggests decoupled responses to acclimation. Whilst not conclusive, the results raise several important considerations: that oxygen limitation of thermal tolerance needs to be more widely investigated in terrestrial species, that indigenous and alien species might differ in the nature and extent of their plasticity, and that upper and lower thermal tolerance limits might be decoupled in spiders as is the case in insects.     

Heterothermy in an Australian passerine, the Dusky Woodswallow (Artamus cyanopterus)

Information regarding passerine heterothermy and torpor is scant, although many species are small and must cope with a fluctuating food supply and presumably would benefit from energy savings afforded by torpor. We studied whether insectivorous Dusky Woodswallows (Artamus cyanopterus; ∼35 g) enter spontaneous torpor (food ad libitum) when held outdoors as a pair in autumn/winter. Woodswallows displayed pronounced and regular daily fluctuations in body temperature (T _b) over the entire study period. The mean T _b ranged from ∼39°C to 40°C (photophase, day time) and ∼33°C to 36°C (scotophase, night time). However, on 88% of bird nights, nocturnal T _b minima fell to < 35°C. The lowest T _b observed in air was 29.2°C. However, when a bird fell into water its T _b dropped further to ∼22°C; this T _b was regulated for several hours and the bird survived. Our observations suggest that heterothermy is a normal part of the daily thermal regime for woodswallows to minimise energy expenditure. Spontaneous nocturnal torpor in captive woodswallows suggests that torpor in the wild may be more pronounced than recorded here because free-living birds are likely challenged by both low food availability and adverse weather.     

Screening of Grassland Plants for Restoration after Spotted Knapweed Invasion

Invasions of North American grasslands by Spotted knapweed (Centaurea maculosa Lam.) are mediated in part by Spotted knapweed root exudation of (±)‐catechin, a potent phytotoxin. Residual soil (±)‐catechin may interfere with reestablishment of native grassland species even after Spotted knapweed populations are controlled. Grassland species that are resistant to (±)‐catechin may be more successful for restoration of areas infested by Spotted knapweed. We evaluated the (±)‐catechin resistance of 23 grassland species by measuring the effects of seven (±)‐catechin concentrations (0–4.0 mg/mL) on seed germination, seedling root and shoot elongation, and seedling mortality. (±)‐Catechin treatments were chosen to reflect the range of observed Spotted knapweed field soil (±)‐catechin concentrations. Inhibition of root elongation was the strongest and most common effect of (±)‐catechin treatment. High (±)‐catechin concentrations reduced mean root lengths of 5 of the species by more than 75% and another 10 species by more than 55%. Experimentally derived concentrations needed to reduce root length by 50% (EC50), an indicator of (±)‐catechin resistance, ranged from 0.43 mg/mL ± 0.30 SE to greater than 4.0 mg/mL among species. Eight species with EC50s greater than 3.0 mg/mL were identified as resistant to (±)‐catechin and are likely suitable for revegetation of Spotted knapweed–infested areas. (±)‐Catechin resistance was positively correlated with mean seed mass, suggesting that seed carbohydrate reserves may allow seedlings to detoxify (±)‐catechin, develop barriers to (±)‐catechin exposure, or sustain a positive growth rate, despite (±)‐catechin‐induced cell death. Future efforts to identify allelochemical‐resistant grassland species should focus on large‐seeded species.     

Multi‐decadal trends in spring arrival of avian migrants to the central Arctic coast of Alaska: effects of environmental and ecological factors

Warming in the Arctic has caused the transition from winter to summer to occur weeks earlier over the last half century, yet little is known about whether avian migrants have altered their timing of arrival on breeding areas to match this earlier seasonal transition. Over a 50‐yr period, we examined trends in the timing of the first arrival for 16 avian migrant species at the terminus of their northward migration along the central Arctic coast of Alaska and compared these trends to factors potentially influencing migration phenology. Date of first arrival occurred an average of 0.12 d yr^?1 or 6 d (range = 3–10 d) earlier across all species and did not differ significantly among species between 1964 and 2013. Local climatic variables, particularly temperature, had a greater effect on a species first arrival date than did large‐scale climatic predictors. First arrival date was 1.03 d earlier for every 1°C annual change in temperature, but there was nearly a 2‐fold difference in the range of responses across species (0.69–1.33 d °C^?1), implying that some species did better than others at timing their arrival with changing temperature. There was weak support for an influence of foraging strategy, migration distance, and flight path on timing of first arrival. Our findings, like others from temperate latitudes, indicate that avian migrants are responsive to changing environmental conditions, though some species appear to be more adaptive than others.