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Bustard

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Juan C Alonso – 1st expert on this subject based on the ideXlab platform

  • food availability but not sex determines morning foraging area size in the great Bustard otis tarda the most sexually size dimorphic bird species
    Ardeola, 2017
    Co-Authors: Luis M Bautista, Carolina Bravo, Carlos Ponce, Dacil Unzuebelmonte, Juan C Alonso

    Abstract:

    Summary. Sexual size dimorphism (SSD) may favour physiological peculiarities in diet, behaviour and home-range size both across species and within species. Sex-specific differences in diet and behaviour have been reported in several bird species but there are fewer studies of foraging area size in sexually dimorphic bird species. Foraging area size should be greater in the bigger sex according to home-range size predictions based on body mass. We tested this prediction in a winter study of foraging area size in the Great Bustard Otis tarda, the most sexually size-dimorphic bird species, which forages in unisexual flocks. In this species the temporal pattern of a flock’s feeding intensity; the proportion of birds actively feeding (FI) and the size of the morning foraging area (MFA) of each sex are unknown. We recorded the behaviour and movements of unisexual flocks of Great Bustards during winter mornings and sampled food availability to take into account its effect on FI and MFA. FI increased and then dec…

  • alarming decline and range reduction of the highly threatened great Bustard otis tarda in morocco
    Ostrich, 2016
    Co-Authors: Juan C Alonso, Carlos Palacín, Alejandro Onrubia, Rachid Aboulouafae, Mohamed Amezian, Abdelaziz El Idrissi Essougrati, Rachid El Khamlichi, Mohamed Noaman

    Abstract:

    A Great Bustard Otis tarda survey carried out in spring 2015 in Morocco confirmed the decline of this highly endangered population. Bustards were only seen at two of the seven leks occupied ten years ago. The total number of birds counted was 40-44, which represents a 40% decline over the last decade. The sex-ratio was still strongly female-biased (1 male: 3 females), but less than in previous surveys, which suggests that trophy hunting has not been the major mortality cause in recent times. The productivity was 0.29-0.33 juveniles per female, the highest ever recorded in this population, suggesting that breeding success doesn’t represent the main problem for the survival of this population. Based on the recent development of the power line network at some areas, the main threat today is probably collision with power lines. Reducing this mortality cause should be considered a high conservation priority.

  • assessing the extinction risk of the great Bustard otis tarda in africa
    Endangered Species Research, 2016
    Co-Authors: Carlos Palacín, Beatriz Martin, Alejandro Onrubia, Juan C Alonso

    Abstract:

    We studied the dynamics and trend of the last extant population of great Bustards Otis tarda in Africa. Moroccan great Bustards are the southernmost population of this species, and thus show the characteristics of a peripheral population: small size, isolation and low gene flow. Available counts indicate a severe population decline (62% in the last 15 yr), as well as a contrac- tion of the species’ distribution. We used a population viability analysis (PVA) to evaluate the quasi-extinction risk and to identify the most important threats. The estimated geometric growth rate of the more realistic of a set of possible scenarios was 0.87 (95% CI: 0.85, 0.89). This implies a 13% annual decline over 50 yr. However, projections derived from these results should be inter- preted with caution, because models have a great deal of uncertainty and vital rates from Iberian populations may be different from those of the Moroccan population. PVA showed the negative consequence of human-induced mortality. According to the model that best fits our census data and if present threats remain in the coming years, this peripheral population could go extinct in ca. 20 yr. Agricultural intensification, infrastructure developments and new power lines in rural areas where the species occurs are causing habitat destruction and fragmentation and increasing artifi- cial mortality. Urgent conservation measures, especially to reduce human-induced mortality, are needed to save African great Bustards from extinction. We suggest that these findings can be gen- eralized to other peripheral great Bustard populations living in highly humanized landscapes.

Carlos Palacín – 2nd expert on this subject based on the ideXlab platform

  • Are trellis vineyards avoided? Examining how vineyard types affect the distribution of great Bustards
    Agriculture Ecosystems & Environment, 2020
    Co-Authors: Fabian Casas, Israel Hervas, William F Fagan, Eliezer Gurarie, Kumar P. Mainali, Raúl Santiago, Carlos Palacín, Eulalia Moreno, Javier Vinuela

    Abstract:

    Abstract A significant restructuring of vineyards is currently taking place in the European Union (EU) as a result of the implementation of a restructuring and conversion of vineyards regulation (CE 1493/1999) in southwest Europe, so that trellis vineyards are rapidly replacing traditional vineyards (e.g., surface area from 18.1 % in 2010 to 34 % in 2015 in Castilla-La Mancha, Central Spain). These changes may influence patterns of space use in birds, which may avoid modified habitats. We assess how the location of traditional and trellis vineyards might influence the distribution of great Bustard (Otis tarda), a globally threatened species. We estimate Resource Selection Functions (RSFs) to quantify the relative probability of use of different areas by the great Bustards, and use the RSF’s to simulated scenarios of conversion from traditional to trellis vineyards (low – 10 %, medium – 30 %, and high rate – 60 %) to quantify the potential impact of such modifications on the availability of suitable great Bustard habitat. Our results revealed that great Bustards significantly avoid trellis vineyards, especially at closer distances. Transition scenarios show how an increase in the proportion of traditional vineyards converted to trellis vineyards greatly decrease the proportion of suitable habitat for great Bustard. Compared to current conditions, the percentage loss of suitable habitat increased steadily with higher rates of converted vineyards, up to 60 % loss of suitable habitat at the highest rate of conversion. Because the effect of transforming traditional vineyards to trellis vineyards depends both on the amount of habitat available for Bustards before the transformation occurs and on the overall area covered by vineyards, a correct estimation of transformable vineyard area will require a case-by-case assessment to assure a low impact on Bustard populations. We identified alternative vineyard management options that would mitigate impacts on the great Bustard populations.

  • alarming decline and range reduction of the highly threatened great Bustard otis tarda in morocco
    Ostrich, 2016
    Co-Authors: Juan C Alonso, Carlos Palacín, Alejandro Onrubia, Rachid Aboulouafae, Mohamed Amezian, Abdelaziz El Idrissi Essougrati, Rachid El Khamlichi, Mohamed Noaman

    Abstract:

    A Great Bustard Otis tarda survey carried out in spring 2015 in Morocco confirmed the decline of this highly endangered population. Bustards were only seen at two of the seven leks occupied ten years ago. The total number of birds counted was 40-44, which represents a 40% decline over the last decade. The sex-ratio was still strongly female-biased (1 male: 3 females), but less than in previous surveys, which suggests that trophy hunting has not been the major mortality cause in recent times. The productivity was 0.29-0.33 juveniles per female, the highest ever recorded in this population, suggesting that breeding success doesn’t represent the main problem for the survival of this population. Based on the recent development of the power line network at some areas, the main threat today is probably collision with power lines. Reducing this mortality cause should be considered a high conservation priority.

  • assessing the extinction risk of the great Bustard otis tarda in africa
    Endangered Species Research, 2016
    Co-Authors: Carlos Palacín, Beatriz Martin, Alejandro Onrubia, Juan C Alonso

    Abstract:

    We studied the dynamics and trend of the last extant population of great Bustards Otis tarda in Africa. Moroccan great Bustards are the southernmost population of this species, and thus show the characteristics of a peripheral population: small size, isolation and low gene flow. Available counts indicate a severe population decline (62% in the last 15 yr), as well as a contrac- tion of the species’ distribution. We used a population viability analysis (PVA) to evaluate the quasi-extinction risk and to identify the most important threats. The estimated geometric growth rate of the more realistic of a set of possible scenarios was 0.87 (95% CI: 0.85, 0.89). This implies a 13% annual decline over 50 yr. However, projections derived from these results should be inter- preted with caution, because models have a great deal of uncertainty and vital rates from Iberian populations may be different from those of the Moroccan population. PVA showed the negative consequence of human-induced mortality. According to the model that best fits our census data and if present threats remain in the coming years, this peripheral population could go extinct in ca. 20 yr. Agricultural intensification, infrastructure developments and new power lines in rural areas where the species occurs are causing habitat destruction and fragmentation and increasing artifi- cial mortality. Urgent conservation measures, especially to reduce human-induced mortality, are needed to save African great Bustards from extinction. We suggest that these findings can be gen- eralized to other peripheral great Bustard populations living in highly humanized landscapes.

Carlos A Martin – 3rd expert on this subject based on the ideXlab platform

  • population increase of the great Bustard otis tarda in its main distribution area in relation to changes in farming practices
    Ardeola, 2012
    Co-Authors: Carlos A Martin, Carmen Martinez, Luis M Bautista, Beatriz Martin

    Abstract:

    Summary.—We update and present relevant information regarding the abundance and distribution of the great Bustard Otis tarda in Castilla y Leon (Spain) in 2008, compare it with previous census results, and analyse the effects of agricultural changes on the provincial abundance and distribution of the species. The study area was surveyed from four-wheel drive vehicles driven at low speed (20–30 km/h) along predetermined transects, stopping frequently at prominent spots. The intention was to detect all the great Bustards present in the study area. The great Bustard population in Castilla y Leon during the breeding season of 2008 was 14,025 birds: 5,637 males, 7,760 females and 628 individuals whose sex could not be determined. The population was 34% greater in 2008 than in 1998 when the area surveyed in both censuses is compared. Population increases were recorded in all provinces except for Soria, where no birds were observed. Not all local populations within provinces increased: we detected population dec…

  • influence of spatial heterogeneity and temporal variability in habitat selection a case study on a great Bustard metapopulation
    Ecological Modelling, 2012
    Co-Authors: Beatriz Martin, Carlos Palacín, Carlos A Martin, Juan C Alonso, Marina Magana, Javier A Alonso

    Abstract:

    We modelled great Bustard abundance patterns and their spatial structure in relation to habitat and landscape variables. We developed Generalized Linear Models (GLM) using long term data series – years 1997–2006 – during the breeding season in Madrid region, central Spain. Our main goal was to assess spatial and temporal variability effects on habitat selection in this species evaluating the impact of interannual variability on habitat selection, the consistency of model predictions among years and the effect of data accumulation in the model performance. We examined the predictive ability of our models using internal and external validation techniques. We built separate models for each year and different models using the addition of several year data. The model perfomance increased as more census data were included in the calibration. One-off temporal data was insufficient to predict great Bustard abundance properly. The final model (calibrated with all period data) showed a reasonable accuracy, attending to the validation tests. The variability in habitat suitability predictions between annual models does not seem to be caused by changes in habitat selection between years because the global model had a better explanatory ability than annual models. As far as interannual variability in spring greenness is concerned, the most variable sites are preferred, suggesting a selection for sites with smaller land use units and with a traditional rotation system. The great Bustard abundance in Madrid was affected by the presence of other conspecifics but this pattern was conditioned to the existence of a suitable habitat denoted by the other variables in the final model. Future persistence of great Bustards in Madrid region depends on a sustainable economic development that maintains traditional land uses, at least in areas with high ecological value for great Bustards, whether they are occupied or not.

  • positive interactions between vulnerable species in agrarian pseudo steppes habitat use by pin tailed sandgrouse depends on its association with the little Bustard
    Animal Conservation, 2010
    Co-Authors: Carlos A Martin, Fabian Casas, Francois Mougeot, Jesus T Garcia, Javier Vinuela

    Abstract:

    Positive interactions between species can have important conservation implications, especially when the species associating are both vulnerable. We studied the habitat use of pin-tailed sandgrouses Pterocles alchata and their association with another vulnerable species, the little Bustard Tetrax tetrax in agrarian pseudosteppes of central Spain using radio-tracking. The occurrence of mixed-species flocks varied seasonally, being more frequent in winter (65% of pin-tailed sandgrouse flocks). In this season, pin-tailed sandgrouses preferred stubble fields and fallows. Moreover, we found that habitat selection of pin-tailed sandgrouse depended on the association with little Bustards in mixed-species flocks. When in mixed-species groups, sandgrouses changed their agrarian substrate preferences, and used stubble fields significantly more often than when in sandgrouse-only flocks. We also provide evidence that pin-tailed sandgrouse benefited from the anti-predator vigilance of little Bustards, allowing sandgrouse to exploit new feeding grounds (stubble fields) that would otherwise be too risky to exploit. Our results indicate a close positive association between these two species, which are both declining in Europe, and we discuss implications for their management and conservation. We also recommend taking into account inter-specific positive interactions when designing conservation strategies for threatened species.