Otis Tarda Research Articles

Impacts of survival and reproductive success on the long-term population viability of reintroduced great bustards Otis tarda in the UK

AbstractReintroductions aim to re-establish species within their historical ranges through the release of wild- or captive-bred individuals following extirpation (or extinction) in the wild. There is no general agreement on what constitutes a successful reintroduction but the probability of the population achieving long-term persistence should be addressed. Here we review a 10-year trial reintroduction of the great bustard Otis tarda, a globally threatened bird species, to the UK and assess the long-term population viability. Despite changes in rearing and release strategy, initial post-release survival probability remained consistently low, with only 11.3% of bustards (n = 167) surviving from release to 1 year post-release. Nineteen breeding attempts were made by eight females; however, only one chick survived > 100 days after hatching, and no wild juveniles have recruited into the population. Using demographic rates from the UK population and wild populations elsewhere, and stochastic population modelling, we investigate the viability of this reintroduced population by predicting population size over the next 10 years. Under current demographic rates the population was predicted to decline rapidly. Self-sufficiency was predicted only using the highest estimates from the UK population for first-year and adult survival, and recruitment rates from wild populations elsewhere. Although changes have been made in rearing, release strategies, habitat management and release sites used, these changes appear to have a modest effect on long-term viability. Substantial improvements in survival rates and productivity are necessary to establish a viable great bustard population in the UK, and we consider this unlikely.

Group size and disturbance effects on group vigilance in the Great Bustard Otis tarda in western China

Capsule Great Bustards Otis tarda gained vigilance benefits from increasing group size: they showed a negative correlation between group size and the percentage of individuals scanning, and a positive correlation between group size and the percentage of time with at least one individual scanning. The relationship between vigilance and group size was independent of level of disturbance but individual vigilance was higher closer to a road. Higher group size and provision of continuous areas of high-quality habitat away from disturbance allows Great Bustards to reduce individual vigilance and so potentially increase investment in feeding time and their survival.

Using dietary analysis and habitat selection to inform conservation management of reintroduced Great Bustards Otis tarda in an agricultural landscape

Capsule Reintroduced Great Bustards achieve dietary and habitat diversity despite living in an intensive agricultural setting.Aims To investigate dietary composition and habitat use of reintroduced Great Bustards Otis tarda released in southwest England and the impact of supplemental feed on autumn dietary selection.Methods Faecal samples were collected from a mixed group of free-ranging bustards without (July 2012, May, September, and November 2013) and with (October and December 2012) access to supplemental feeds. Concurrently, diurnal land use observations were recorded for all months but September and December. Composite monthly faecal samples were micro-histologically analysed to assess dietary composition. Year-round landscape-level habitat use was determined using re-sightings and satellite telemetry data for birds surviving more than 182 days post-release. Generalized linear models were used to test for differences in habitat selection across the year, by sex and within and outside release areas for each habitat type, and habitat diversity was quantified using the Shannon–Weaver Index.Results Dietary composition varied depending on plant availability and phenological stage, and invertebrates were rarely selected. Agricultural crops – primarily oil-seed rape, mustard, barley grass, lucerne, and barley seed – comprised the bulk of the diet, but grassland and weedy forbs were always important secondary foods (>25%), except when provided extruded pellets. Monthly changes in habitat use suggest sex-based habitat segregation, with females living in higher habitat diversity settings. Grasslands were used across the year. When supplemental food was provided, it came to dominate dietary intake.Conclusion Great Bustards can adapt to an intensive agricultural setting, but require unrestricted access to adjacent grasslands. They would be best served with small-scale habitat mosaics. If supplemental foods are to be provided to juvenile birds, quantities must be limited and the birds weaned off before dispersal to maximize reintroduction success.

Ark or park: the need to predict relative effectiveness of ex situ and in situ conservation before attempting captive breeding

Summary When species face extinction, captive breeding may be appropriate. However, captive breeding may be unsuccessful, while reducing motivation and resources for in situ conservation and impacting wild source populations. Despite such risks, decisions are generally taken without rigorous evaluation. We develop an individual‐based, stochastic population model to evaluate the potential effectiveness of captive‐breeding and release programmes, illustrated by the critically endangered Ardeotis nigriceps Vigors great Indian bustard. The model was parameterized from a comprehensive review of captive breeding and wild demography of large bustards. To handle uncertainty in the standards of captive‐breeding performance that may be achieved, we explored four scenarios of programme quality: ‘full range’ (parameters sampled across the observed range), ‘below average’, ‘above average’ and ‘best possible’ (performance observed in exemplary breeding programmes). Results are evaluated examining: (i) the probability of captive population extirpation within 50 years and (ii) numbers of adult females subsequently established in the wild following release, compared to an alternative strategy of in situ conservation without attempting captive breeding. Successful implementation of captive breeding, involving permanent retention of 20 breeding females and release of surplus juveniles, required collection of many wild eggs and consistent ‘best possible’ performance across all aspects of the programme. Under ‘full‐range’ and ‘above‐average’ scenarios, captive population extirpation probabilities were 73–88% and 23–51% respectively, depending on egg collection rates. Although most (73–92%) ‘best possible’ programmes supported releases, re‐establishment of free‐living adults also required effective in situ conservation. Incremental implementation of effective conservation measures over the initial 10 years resulted in more free‐living adults within 35 years if eggs were left in the wild without attempting captive breeding. Synthesis and applications. For the great Indian bustard Ardeotis nigriceps, rapid implementation of in situ conservation offers a better chance to avoid extinction than captive breeding. Demographic modelling of threatened species should be used to examine whether captive breeding will bring net benefits to conservation programmes.

Climate change, human population growth, or both? Upper Paleolithic subsistence shifts in southern Greece

Abstract Changes in subsistence patterns during the Upper Paleolithic and Mesolithic at Klissoura Cave 1 in southern Greece indicate that some shifts track local climatic changes, while others do not. Specifically, increases in ungulate species diversity correlate with wetter periods, and greater abundance of certain dry-loving small game animals (e.g., great bustard) might correspond with dry periods. Other large-scale diachronic shifts, such as the increased importance of low-return hares and partridges, occur over the occupation of the site irrespective of environmental conditions. We hypothesized previously that this relates to local human population growth over the course of the Paleolithic. New data from a nearby site, Kephalari Cave, augment this hypothesis. The site complements the Aurignacian and Gravettoid occupations at Klissoura and also contains a robust late Upper Paleolithic component. Ungulate species diversity is high at Kephalari, and there is a greater reliance on low-return small animals (including fish) than at Klissoura. In this paper, we examine changes in the faunal spectra alongside preliminary charcoal data from the two sites. These data are analyzed in the context of regional environmental change in order to determine the extent to which climatic change or population growth drove subsistence shifts in southern Greece during the Late Pleistocene.

Kızılırmak Vadisinde Kuşları Etkileyen Olumsuz Faktörler

Totally, 263 bird species were observed in the Kizilirmak valley between 2010-2012 years. Among them were 93 residents, 82 summer migrants, 51 winter migrants and 37 transit migrants. When evaluated in IUCN criteria, Egyptian vulture (Neophron percnopterus), saker falcon (Falco cherrug) and velvet scoter (Melanitta fusca) are endengared (EN), marbled teal (Marmaronette angustirostris), great bustard (Otis tarda) and aquatic warbler (Acrocephalus paludicola) are vulnareble (VU) and ferruginous duck (Aythya nyroca), red kite (Milvus milvus), pallid harrier (Circus macrourus), red footed falcon (Falco vespertinus), great snipe (Gallinago media), rock partridge (Alectoris graeca), black tailed godwit (Limosa limosa), European roller (Coracias garrulus) and semi collared flycatcher (Ficedula semitorquata) are near threatened (NT). Among negatively affecting factors the birds, in Kizilirmak Valley; reed cutting, water regime changing, recreational activities in riverside, stubble burning, agricultural land expansion, chemical and noise pollution can be considered

Recent status and population decline of the Great Bustard Otis tarda in Iran

SummaryThe current distribution and recent population trends of the Great Bustard (Otis tarda) in Iran were investigated based on a literature review and unpublished data (1995–2008) followed by three years of census (2009–2011) in areas where the species is still breeding. Results suggest that Great Bustards have disappeared from a large part of their former distribution in the country, including East Azarbayjan, Hamedan and Kurdistan provinces. The surviving groups are concentrated in West Azarbayjan where numbers are rapidly declining. The present population is estimated at about 43–48 birds in 2011, confirming a marked decline compared to the 200–300 birds estimated in the early 1990s. About 80–90% of the extant birds are concentrated in the plains of Boukan. Strict conservation measures are urgently needed to prevent the extinction of this species in Iran.

Optimising the attractiveness of winter oilseed rape fields as foraging habitat for the West Pannonian Great BustardOtis tardapopulation during winter

SummaryWinter oilseed rape represents an important food source for Great Bustards. Great Bustard surveys during four consecutive winters (2005/2006–2008/2009) were used to identify characteristics of oilseed rape fields, which increase their attractiveness for the species in its West Pannonian wintering area. The study was conducted in study areas in Eastern Austria, around the Austrian–Slovakian–Hungarian border and in the Hungarian Moson Plain. To test for effects of field size and isolation of fields from other rape fields, and the distance to the nearest paved road on occurrence and abundance of Great Bustards (maximum number of birds counted in individual rape fields per winter), we calculated generalized linear mixed models (GLMMs) including all three predictor variables as fixed effects and winter as random effect for each of the three study areas. Field size most strongly affected occurrence and abundance of Great Bustards. The availability of large (>>15 ha) winter rape fields far from paved roads is recommended as a prime conservation measure to improve the quality of rape fields as foraging habitat for Great Bustards during the winter months (November–March).

The Effect of Above-Ground Medium Voltage Power Lines on Displaying Site Selection of the Great Bustard (Otis Tarda) in Central Hungary

Abstract Our study was conducted in the Upper-Kiskunság region, Central Hungary, which hosts the largest Pannonian population of the Great Bustard (Otis tarda). The influence of the presence of aboveground medium voltage power lines on displaying site selection of Great Bustard males was investigated. The results revealed that displaying males totally reject the sites located within 350-400 m or closer to medium voltage power lines as displaying sites and show relative rejection towards potential displaying sites located at a distance between 500 and 1000 m far from power lines. Surprisingly, the overall negative effects influence much larger part of the potential displaying grounds, up to the distance to 3500 m from power lines. It can be declared that power lines reduce the extent of suitable displaying sites of the Great Bustards in the Upper-Kiskunság region. Accordingly, installation of new above-ground power lines (and other kind of wires, such as high voltage power lines, optical cables etc.) would further reduce the extent of suitable displaying sites.

Conservation of Great Bustard (Otis Tarda) Population of the Mosoni-Plain - A Success Story

Abstract At the turn of the 19-20th centuries, the Great Bustard population of the Kisalföld (Little Hungarian Plain) numbered 4000 specimens. By 1990, only about 100 individuals remained in the Hungarian and Austrian territories. Of the many possible negative factors of current times, the greatest pressure on the Great Bustard population stems from unfavorable crop structures, extensive use of intensive agricultural technologies and predation. During the past decades, we have seen a shift in nesting place locations from natural-like habitats to agrar-type habitats. This change may be explained by the more favorable structure and microclimate of this latter habitat type paralleled with greater food source availability. In order to escape this ecological trap, we have to engage in active conflict resolution that provides protection the region's Bustard population. For this very reason, the MOSON Project was founded in 1992 at the northern part of the Mosoni-Plain in the territory of Lajta-Hanság Co. Later, several Austrian regions joined the project. On these territories, out of the above mentioned 100 specimens, only 20 birds lived at the time. As the result of active habitat management of Great Bustards and coexisting small game species (mostly due to the influence of set-aside areas) as well as effective predator control (especially the Red Fox) resulted in an increase of the Great Bustard population. By the end of the 1990's, the population grew to 120-130 individuals which number was limited by the carrying capacity of this territory. Consequently, the species continued to reoccupy new regions in the Hungarian and Austrian territories. These days, the number of Great Bustards in these protected regions is estimated to be 400 individuals. In 1998, the Mosoni-plain was given IBA (HU-001) status, and in 2004, the region was protected under the Natura 2000 EU nature conservation network.

Key Mortality Causes of the Great Bustard (Otis Tarda) in Central Hungary: An Analysis of Known Fatalities

Abstract In this study, we identified the key mortality causes of eggs, juveniles and adults of the Great Bustard (Otis tarda) and quantified the relative importance of those, based on systematic data collection that have been carried out during the period between 2005 and 2014 at the Upper-Kiskunság region in Central Hungary. Rate of mortality regarding juveniles and adults was 39.71% caused by anthropogenic factors. Within the anthropogenic factors leading to mortality, collision was represented by 81.48% of fatalities, whereas mowing/hay making represented by 18.52%. Hay making/mowing was the factor leading to unsuccessful breeding attempt with the strongest negative effect on the breeding success of the investigated population of the Great Bustard, as it was represented by 50.96% of all known mortality cases. Chemical treatment had the factor with the second strongest effect, as it was represented by 12.33% of all known mortality cases. The rate of unsuccessful breeding (hatching) caused by particular activities (hay making/mowing, tillage, harvesting) varied between 68.42% and 75.00%. It was the disturbance by passers-by which led to the highest portion of unsuccessful breeding with 83.33% unsuccessful nests.

Males of a strongly polygynous species consume more poisonous food than females.

We present evidence of a possible case of self-medication in a lekking bird, the great bustard Otis tarda. Great bustards consumed blister beetles (Meloidae), in spite of the fact that they contain cantharidin, a highly toxic compound that is lethal in moderate doses. In addition to anthelminthic properties, cantharidin was effective against gastrointestinal bacteria that cause sexually-transmitted diseases. Although both sexes consumed blister beetles during the mating season, only males selected them among all available insects, and ingested more and larger beetles than females. The male-biased consumption suggests that males could use cantharidin to reduce their parasite load and increase their sexual attractiveness. This plausibly explains the intense cloaca display males perform to approaching females, and the meticulous inspection females conduct of the male's cloaca, a behaviour only observed in this and another similar species of the bustard family. A white, clean cloaca with no infection symptoms (e.g., diarrhoea) is an honest signal of both, resistance to cantharidin and absence of parasites, and represents a reliable indicator of the male quality to the extremely choosy females. Our results do not definitely prove, but certainly strongly suggest that cantharidin, obtained by consumption of blister beetles, acts in great bustards as an oral anti-microbial and pathogen-limiting compound, and that males ingest these poisonous insects to increase their mating success, pointing out that self-medication might have been overlooked as a sexually-selected mechanism enhancing male fitness.

Why males and females look different

Why do males and females look different? In “Odd Couples: Extraordinary Differences Between the Sexes in the Animal Kingdom,” (2013, Princeton University Press, p. 312), Daphne J. Fairbairn provides a scrupulous catalog of possible answers, perhaps the most detailed collection of animal sex differences since Darwin’s 1874 “The Descent of Man and Selection in Relation to Sex.” Sexual dimorphism is the condition in which males and females exhibit distinct phenotypes, beyond physiological traits involved with reproduction. Fairbairn’s volume is supplied with some of the best examples of such differences now known, and the disparate sources of data are pressed into compelling shape by a talented scholar and careful experimentalist. Fairbairn’s manifesto is, “an overtly Darwinian approach to understanding sexual differences” (p. 3). She notes that when selection operates in sex-specific ways, “we expect trait distributions typical for each sex to be adaptive for that sex” (p. 4), and she launches the reader into this view of dimorphism with sweeping taxonomic and gender-modified scope. We learn of lumbering male elephant seals, who in the throes of their ardor may annihilate the offspring of their future mates; of great bustards, giant Eurasian cranes whose males shove rivals and take blows to the face like bear-pit pugilists while females watch nearby; of shellcarrying cichlid fish, whose territorial and satellite males dart and parry for opportunities to ejaculate into snail shells containing females’ unfertilized ova. As vertebrates, we humans are most familiar with mating systems in which males are larger or somehow more elaborate than females. Fairbairn answers this preexisting bias with fascinating contrasts, weaving tales of yellow garden spiders and blanket octopus, whose gigantic females either squat in the center of conspicuous webs, or float huge and enigmatic over tropical reefs, each attended by males of their species as much as 40,000 times smaller in size. We learn of giant seadevil anglerfish, whose enormous, fang-jawed females host tiny males, who cling to female undersides by their own peculiar mouths, absorbing nutrients from a shared bloodstream and dangling close enough to their mate’s genitalia to ensure successful spawning. Fairbairn details the divergent life histories of bizarre, deep-sea bone worms whose females embed their bulbous bodies within decaying skeletons of whales, and maintain hundreds of minute suitors within their translucent skins. Lastly, she describes shell-burrowing barnacles, in which embedded females may (or may not—45% of females fail to mate) host posses of minuscule males with colossal, inflatable penises that may exceed each little fellow’s corporal dimensions by as much as eight times. The density of information and much delightful prose make this a fascinating read for lay and professional readers alike. Footnotes and appendices comprise nearly one-third of the book. One diagram describes the distribution of sexual dimorphism among 73 animal classes, a synthesis across 1.4 million species that is the first I have seen of its kind. Fairbairn glides among the animals with remarkable skill, and does Darwin one better with abundant recent data. In each chapter, she recounts male and female life spans, the fractions of individuals who do and do not mate, and the numbers of offspring that individuals in each sex produce. The raw materials are here to make concise, quantitative statements about how a sex difference in the variance in relative fitness (also known as the opportunity for sexual selection; Wade 1979) can explain the magnitude and direction of sexual dimorphism. But each chapter ends without an attempt. Offspring numbers are what Fairbairn considers “the currency of Darwinian fitness,” yet the trove of such information presented is used mainly for implication. Fairbairn concludes, “the enduring message is that there is no one way of being a male or a female animal . . . there is no “normal” or “typical” pattern of sexual differentiation across the animal kingdom,” and furthermore that the lack of sex differences in externally fertilizing species “remains a mystery” (p. 165). I found such capitulation

Can Eltonian processes explain species distributions at large scale? A case study with Great Bustard (Otis tarda)

AbstractAimSpecies distribution modelling (SDM) allows identification of suitable areas where the species might occur. The Grinnellian approach relates species occurrence to abiotic limiting factors, such as topography and climate, measured at present or averaged over time at large spatial scales, whilst Eltonian approaches relate processes as reproductive rates or species abundance to factors as resource availability or functional traits described at a finer spatio‐temporal resolution. In this study, we aimed to compare the performance and reliability achieved by Eltonian and Grinnellian models developed at geographical scale when addressing two questions that may affect species distribution: breeding site selection and historical local extinctions.LocationSpain.MethodsWe used a temporal series (1988–2010) of breeding success data of Great Bustards (Otis tarda) across Spain to create: (1) a yearly series of correlative Eltonian models based on satellite data (1‐km pixel Normalized Difference Vegetation Index derived from NOAA‐AVHRR) as a proxy for resource availability and (2) a static topo‐climatic Grinnellian model. We applied two modelling algorithms (MaxEnt and Bootstrapped Generalized Mixed‐Effects Models) calibrated and validated across different distributional ranges to investigate breeding success in abiotically suitable areas and recent extinctions within the accessible range.ResultsEltonian models showed higher performance and reliability than Grinnellian models at geographical scale and allowed for comparisons of breeding habitat suitability through the study period. Then, satellite data were a more successful predictor of the species breeding success than topography and climate. Breeding was possible out of the range currently occupied by the species, but habitat suitability was significantly lower in non‐occupied areas, on where local extinctions have occurred in recent historical times.Main conclusionsThis study highlights the advisability of using remote‐sensing explanatory variables at high temporal resolution matched with population fitness data in Eltonian approaches to improve the knowledge of the relationship between realized and potential distributions of the species at geographical scale. This is a fundamental question in biogeography and a key issue for designing comprehensive conservation strategies.

Animal Behavior

Numerous attempts have been made in the mass media and in the sciences to describe the gender differences between human males and females. While we joke that men are from Mars and women are from Venus, human gender differences don’t come close to those of our other relatives in the Animal Kingdom. Odd Couples: Extraordinary Differences between the Sexes in the Animal Kingdom, introduces readers to important and interesting new discoveries in animal behavior and evolution. I discovered this myself a few years ago while visiting the Natural History Museum of Los Angeles. Housed within the Spider Pavilion was a yellow “orb-weaving” female garden spider (Argiope aurantia). Lying motionless next to this large spider was a much smaller spider. I later learned that the smaller male spider was preparing to mate with the much larger female; a very dangerous task indeed, since the male garden spider spontaneously dies after mating with a female more than 50 times his size! I understand much more about these arachnids now that I’ve read this engaging new book by Daphne Fairbairn, a professor of biology at the University of California, Riverside. She knows the yellow garden spider well, along with the seven other examples from the Animal Kingdom she highlights in the book.Odd Couples: Extraordinary Differences between the Sexes in the Animal Kingdom begins with an intimate foray through the roots of extreme sexual differences and reproductive behaviors of several species. Fairbairn starts with examples from male northern elephant seals, which I learned can weigh in at almost 3 tons, about 4 times the weight of females. This major difference, as with so many biological oddities described in the book, appears to emanate in the selective advantage that size affords male seals in the race to sire offspring. A successful “harem master” has the build of a professional sumo wrestler, for it is his job to eject an opponent male that challenges his authority and attempts to mate with a female in his harem.There are a number of other sexual oddities in the Animal Kingdom that Fairbairn describes. For instance, “great” bustards – which, by the way, get their name not because of the impressiveness of their amazingly gorgeous plumage but, rather, the huge size of the adult males (historical records credit males with weights of up to 24 kg, or 53 lb), which qualifies them as the heaviest flying birds. Not so for females, however. Female great bustards are much smaller than males. This vast discrepancy in size “makes great bustards the unchallenged bird champions in terms of sexual size dimorphism. Other examples of extraordinary differences between the sexes in animals highlighted in the book include the female cichlids, which guard their eggs and larvae – even from the hungry appetites of their own partners. The key to this particular sexual dimorphism lies in the reproductive behavior of males and females. One of the oddest animals I encountered in the book is the male blanket octopus, which employs a copulatory arm longer than its own body to mate with a female that outweighs it by 4 orders of magnitude! Fairbairn further goes on to reveal to the reader why dwarf male giant seadevils parasitically fuse to their giant female partners for life. The book concludes with remarks on our experiences as humans, which tend to bias our perception (or misperception) of what is “typical” of animals in general.This very engaging and well-organized book tackles some of the fundamental questions in animal evolution and behavior by addressing questions such as “What does it mean to be a male or female in the animal kingdom and why do these gender gulfs exist?” In doing so, evolutionary biologist Daphne Fairbairn reveals the unique and strange characteristics – in size, reproductive behavior, ecology, and life history – that exist in the animals described in this book and the special techniques and strategies they use to maximize reproductive success.

Effects of great bustard (Otis tarda) gut passage on black nightshade (Solanumnigrum) seed germination

AbstractBirds are important seed dispersers for fleshy fruits through their transportation of ingested seeds. The seeds of many species germinate faster and in greater proportions after passing through a digestive tract, although the effects of this passage vary amongst bird and plant species. Many factors determine the germination success of ingested seeds, such as seed scarification during the digestion process, the fertilizing effect of droppings and the removal of pulp surrounding the seeds. In central Spain, the great bustard (Otis tarda) may act as a disperser of European black nightshade (Solanum nigrum). We analysed the germination success of ingested and non-ingestedS. nigrumseeds. The fertilizing effect of bustard droppings and the disinhibition effect of the removal ofSolanumpulp on final germination percentage, germination speed and viability were also assessed. Although ingested seeds germinated faster than non-ingested seeds, the former showed a lower germination percentage than the latter: 80–87% versus 99%. Droppings and fruit pulp showed no effect on germination enhancement, except in one aspect: the germination speed of non-ingested seeds decreased when they were sprayed with a fruit extract. We confirm that seeds ingested by great bustards had lower germination success than non-ingested seeds. Although seed ingestion by great bustards reduced seedling emergence, the number of emerged seedlings was still quite large. Thus, great bustards may play a role as aS. nigrumseed dispersal vector.

Obtaining the best possible predictions of habitat selection for wintering Great Bustards in Cangzhou, Hebei Province with rapid machine learning analysis

Great Bustards (Otis tarda dybowskii) are one of the world’s heaviest flying birds, occupying grassland habitats in Eastern Asia. Our study is located at the most eastern Chinese wintering site in Cangzhou, Hebei Province, where approximately 100 individuals are concentrated in a small area (17.53 km2). Solid information is still lacking about the wintering areas for this subspecies in its eastern range and specifically for China. The study area consists of intensely used farmland in proximity to humans and is lacking conservation areas and wild, open fields. Here, we present our results from two years of field data collection on habitat selection. We choose a machine learning model approach based on a rapid assessment methodology for the winter habitat of the Great Bustard. It is based on a spatial analysis of the best available environmental data, which were collected relatively quickly. These relatively new methods in ecology are based on an ensemble of decision trees and include algorithms such as TreeNet, Random Forest and CART used in parallel. In this study, we collected bustard droppings (presence only) from 48 locations between December 2011 and January 2012 and used the sites as training data. Droppings from 23 locations were collected in November 2012, and those sites were used as test data. We used eight environmental variables as predictor layers for the response variable of bustard presence/availability. We employed a Geographic Information System (ArcGIS 10.1 and Geospatial Modelling Environment) and Google Earth. Compared with the other three models, we found that predictions from Random Forest obtained a significant difference between presence and absence. According to this model, the three most important factors for wintering Great Bustards are distance to residential area, distance to water pools, and farmland area. Our model shows that wintering Great Bustards prefer locations that are over 400 m away from residential areas, within 900 m of water pools and on areas of farmland smaller than 0.5 km2. We think we can apply our analysis to Great Bustard management in our study area and the adjacent region and that this work sets a baseline for future research.

Genetic structure in Iberian and Moroccan populations of the globally threatened great bustardOtis tarda: a microsatellite perspective

Patterns of genetic structure and gene flow among populations help us understand population dynamics and properly manage species of concern. Matrilineal mtDNA sequence data have been instrumental in revealing genetic structure at the intraspecific level, but bi‐parentally inherited markers are needed to confirm patterns at the genome level and to assess the potential role of sex‐biased dispersal on gene flow, particularly in species where males are known to be the main dispersing sex. Here we use microsatellite loci to examine patterns of genetic structure across the range of the great bustard in Iberia and Morocco, an area representing 70% of the world population of this globally threatened species. We used population differentiation statistics and Bayesian analysis of population structure to analyse data from 14 microsatellite loci. These data provide greater resolution than mtDNA sequences, and results reveal the existence of three main genetic units corresponding to Morocco, the northeastern part of Spain, and the rest of the Iberian Peninsula. Our results, together with previous mtDNA data, confirm the genetic differentiation of the northern Africa population and the importance of the Strait of Gibraltar as a barrier to gene flow for both males and females, rendering the Moroccan population a separate management unit of high conservation concern.

Are Species Coexistence Areas a Good Option for Conservation Management? Applications from Fine Scale Modelling in Two Steppe Birds

Biotic interactions and land uses have been proposed as factors that determine the distribution of the species at local scale. The presence of heterospecifics may modify the habitat selection pattern of the individuals and this may have important implications for the design of effective conservation strategies. However, conservation proposals are often focused on a single flagship or umbrella species taken as representative of an entire assemblage requirements. Our aim is to identify and evaluate the role of coexistence areas at local scale as conservation tools, by using distribution data of two endangered birds, the Little Bustard and the Great Bustard. Presence-only based suitability models for each species were built with MaxEnt using variables of substrate type and topography. Probability maps of habitat suitability for each species were combined to generate a map in which coexistence and exclusive use areas were delimitated. Probabilities of suitable habitat for each species inside coexistence and exclusive areas were compared. As expected, habitat requirements of Little and Great Bustards differed. Coexistence areas presented lower probabilities of habitat suitability than exclusive use ones. We conclude that differences in species' habitat preferences can hinder the efficiency of protected areas with multi-species conservation purposes. Our results highlight the importance of taking into account the role of biotic interactions when designing conservation measurements.

Subulura halli (Ascaridida: Subuluridae) from the endangered great bustard Otis tarda Linnaeus (Aves: Gruiformes) in China

Subulurid nematodes identified as Subulura halli Barreto, 1918 were collected from the endangered bird Otis tarda Linnaeus (Gruiformes: Otididae) in China. A detailed redescription of the hitherto poorly known species is presented using both light and, for the first time, scanning electron microscopy. Previously unreported and erroneous morphological features of taxonomic significance are revealed. This species can be readily distinguished from its congeners by the relatively long oesophagus (1.47-1.92 mm long, representing 10.6-16.9% of body length), the number and arrangement of male caudal papillae (11 pairs in total, arranged as five pairs of precloacal and six pairs of postcloacal papillae), the equal length of spicules (1.35-1.52 mm long, representing 10.7-13.7% of body length) and the presence of a small medioventral, precloacal papilla in the male.