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Juan C Alonso - One of the best experts 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.

  • recent status and population decline of the great Bustard otis tarda in iran
    Bird Conservation International, 2015
    Co-Authors: Ahmad Barati, Rahim Abdulkarimi, Juan C Alonso
    Abstract:

    Summary The 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 concen-trated in West Azarbayjan where numbers are rapidly declining. The present population is esti-mated 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 cies pes in Iran. Introduction The Great Bustard Otis tarda populations have suffered marked decline during the last two cen-turies and is classified as ‘Vulnerable’ by IUCN (BirdLife International 2012 ). Factors affecting Great Bustard populations are mainly loss, degradation and fragmentation of habitat caused mainly by agricultural transformation, expansion of human infrastructure and hunting (BirdLife International 2004 , Palacin and Alonso 2008 ). The world population is currently estimated to be between 44,100 and 57,000 individuals (Alonso and Palacin 2010 ), distributed mainly in Spain and Russia. In Central Asia, small and fragmented populations persist (Del Hoyo

  • short note dna sequences from the little brown Bustard eupodotis humilis suggest its close phylogenetic relationship to the little Bustard tetrax tetrax
    Ostrich, 2014
    Co-Authors: Jose Luis Horreo, Juan C Alonso, Borja Mila
    Abstract:

    Taxonomic classification of birds based exclusively on morphology and plumage traits has often been found to be inconsistent with true evolutionary history when tested with molecular phylogenies based on neutrally evolving markers. Here we present cytochrome- b gene sequences for the poorly known Little Brown Bustard Eupodotis humilis and analyse it in a phylogenetic context together with all other Bustard species in the family Otididae. Our results suggest that this species is more closely related to the Little Bustard Tetrax tetrax than to other members of the Eupodotis genus. This finding is consistent with previous results suggesting polyphyly in the genus Eupodotis and with the fact that many of the phenotypic traits used to classify members of the family Otiidae are not phylogenetically informative. Keywords: Bustard, convergence, Eupodotis humilis , Eupodotis vigorsii , Otididae, Tetrax tetrax OSTRICH 2014, 85(1): 97–101

Carlos Palacín - One of the best experts 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.

  • a link between historical population decline in the threatened great Bustard and human expansion in iberia evidence from genetic and demographic data
    Biological Journal of The Linnean Society, 2013
    Co-Authors: Jose Luis Horreo, Carlos Palacín, Juan C Alonso, Borja Mila
    Abstract:

    Early anthropogenic impacts on the abundance and distribution of wild species are difficult to document, but can help us to understand the causes and relative importance of current declines. Genetic data can be of use in inferring historical demographic events, but the accuracy of these inferences depends on the availability and precision of demographic parameters that are difficult to obtain in the field. Here, we use demographic data on Iberian populations of the threatened great Bustard (Aves: Otis tarda), obtained from an intensive population monitoring programme over the last 20 years, to estimate critical population parameters (population size and generation time), which are then used in a Bayesian Skyline Plot (BSP) analysis of mitochondrial DNA sequence data to assess changes in population size over the last several thousand years. BSP showed a sudden and sharp great Bustard population decline coinciding with human expansion in Iberia, and the associated agricultural and urban development and increased hunting pressure. These results illustrate the importance of human population size as a possible ultimate cause of an environmental impact that occurred in the historical past, a fact that has often been neglected. Our results also suggest the role of human activities in driving historical population declines in great Bustards, and underscore the importance of precise, long-term field data to infer past demographic trends from parameters of extant populations. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 110, 518–527. ADDITIONAL KEYWORDS: BSP – conservation – control region – demography – generation time – growth rate – Middle Ages – Otis tarda – Romans.

  • 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, Juan C Alonso, Carlos A Martin, 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.

Carlos A Martin - One of the best experts 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, Juan C Alonso, Carlos A Martin, 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.

  • correlates of male mating success in great Bustard leks the effects of age weight and display effort
    Behavioral Ecology and Sociobiology, 2010
    Co-Authors: Juan C Alonso, Carlos Palacín, Marina Magana, Carlos A Martin
    Abstract:

    We examined how mating success varied in relation to age, weight, body size, and display behavior among great Bustard Otis tarda males. The estimated mating success was strongly skewed, with 45% of adult males being involved in copulation attempts and only 9.7% actually seen copulating successfully. Unlike most birds, body size continued increasing in great Bustards several years after reaching sexual maturity. Age, weight, and display effort were all significant and independent predictors of male mating success. The higher display effort involved performing longer full-display bouts. Older males could detach from the male flock earlier in the season as well as on each day and spend longer seasonal and daily periods displaying as solitary birds, which contributed to increase their mating success. In contrast, males weighing more did not invest more in display, which suggests that they could be recognized as dominants by other males and selected by females through assessment of their plumage sexual traits. In contrast to most other bird species, the system described for great Bustards resembles that found in some lek-mating ungulates, where social rank is a complex trait determined by both age and mass, and as in these mammals, it suggests that sexual selection continues to favor a high male weight in this extremely sexually dimorphic species.

  • differential migration by sex in the great Bustard possible consequences of an extreme sexual size dimorphism
    Ethology, 2009
    Co-Authors: Carlos Palacín, Juan C Alonso, Carlos A Martin, Marina Magana, Javier A Alonso, Beatriz Martin
    Abstract:

    We explored migration patterns in Great Bustards (Otis tarda), a species that shows strong sexual selection and the most extreme sexual size dimorphism among birds. The aim was to explain differential migration, examining whether Great Bustards fulfil the main predictions of bird migration theory hypotheses and sexual segregation theory hypotheses. We radio-tracked the seasonal movements of 65 males and 68 females in central Spain. We found four main sexual differences. First, the proportion of migratory males was higher than that of migratory females (86% vs. 51%). Second, males abandoned the leks immediately after the mating season (late May to early Jun.), whereas females remained there for another 3–7 mo. Third, 54% of the migratory males used two different post-breeding areas, the first located northwards at 82 km from the breeding sites in summer, and the second southwards at 50 km in autumn–winter. Migratory females used only one area in autumn–winter which coincided geographically with that of males. And fourth, males returned to the breeding areas earlier (between Sep. and Mar.) than females (between Jan. and Apr.). These results show that the Great Bustard is a differential migrant by sex in central Spain and support the weather sensitivity hypothesis (males were less tolerant to summer heat) and the specialization hypothesis (exclusive maternal care of the brood by females). Sexual differences in migratory behaviour are probably ultimately determined by the strong sexual selection in this species.

Francisco Moreira - One of the best experts on this subject based on the ideXlab platform.

  • male post breeding movements and stopover habitat selection of an endangered short distance migrant the little Bustard tetrax tetrax
    Ibis, 2020
    Co-Authors: Hany Rafael De Drummond Ludovice Garcia Alonso, Francisco Moreira, Jorge M Palmeirim, Ricardo Correia, Ana Teresa Marques, Joao P Silva
    Abstract:

    Migratory decisions, such as the selection of stopover sites, are critical for the success of post‐breeding migratory movements and subsequent survival. Recent advances in bio‐logging have revealed the stopover strategies of many long‐distance migrants, but far less attention has been given to short‐distance migrants. We investigated the stopover ecology of an endangered grassland bird, the Little Bustard Tetrax tetrax, a short‐distance migrant in Iberia. Using high‐resolution spatial GPS/GSM data, 27 male Little Bustards breeding in southern Portugal were tracked between 2009 and 2011. We studied post‐breeding movements using Dynamic Brownian Bridge models to identify the main stopover sites, and generalized linear mixed models to examine habitat selection in stopovers. During their post‐breeding movements, males were essentially nocturnal migrants, making frequent stopovers while maintaining a relatively fast pace to reach more productive agricultural post‐breeding areas. Stopovers occurred in most post‐breeding movements (83%) regardless of the total distance covered (average 64.3 km), and most stopovers (84%) lasted less than 24 h. Birds used mostly agricultural non‐irrigated and irrigated croplands as stopover sites and avoided other land uses and rugged terrain. There was a negative relationship between stopovers and the proximity to roads, but not to power lines. The high frequency of stopovers during post‐breeding movements, despite the short distances travelled, together with the nocturnal migratory behaviour of Bustards, may impose additional risks to a bird mainly threatened by collision with power lines in non‐breeding areas. We also conclude that even for short‐distance migrants, habitat connectivity between breeding and post‐breeding areas is likely to be a key conservation concern.

  • Power line routing and configuration as major drivers of collision risk in two Bustard species
    Oryx, 2020
    Co-Authors: Ana Teresa Marques, Joao P Silva, Jorge M Palmeirim, Ricardo Martins, Francisco Moreira
    Abstract:

    Abstract Collision with power lines is a major cause of mortality for many bird species. Understanding the biotic and abiotic factors that increase collision risk is therefore important for implementing mitigation measures to minimize mortality, such as power line rerouting or wire marking. Here, we used collision events registered during 2003–2015 along 280 km of transmission power lines in southern Portugal to analyse spatio-temporal patterns and collision risk factors in two sympatric, threatened, and collision-prone species: the great Bustard Otis tarda and the little Bustard Tetrax tetrax. The occurrence of collisions was not uniform across space and time, and variations could be explained by the species' ecological requirements, distribution patterns and behaviour. Although both species fly considerable distances between areas of suitable habitat, collisions were far more likely in power line sections with > 20% (for the little Bustard) or > 50% (for the great Bustard) of open farmland habitat in the surroundings. Power line configuration was also important: taller pylons and those with a higher number of wire levels posed a higher risk for both species. Wire marking had a small but significant effect for the little Bustard, reducing collisions risk. There was, however, no similar effect for the great Bustard, possibly a result of limited data. Mitigation measures should be implemented to prevent Bustard collisions, including adequate route planning, ideally avoiding areas with > 20% of open habitat. Line configuration and wire marking are particularly important where such localities cannot be avoided and power lines cross areas with a high proportion of Bustard habitat, including outside protected areas.

  • tracking data of the little Bustard tetrax tetrax in iberia shows high anthropogenic mortality
    Bird Conservation International, 2017
    Co-Authors: Joana Marcelino, Manuel B Morales, Eladio Garcia L De La Morena, Francisco Moreira, Santi Manosa, Francesc Cusco, Gerard Bota, Jorge M Palmeirim, Joao P Silva
    Abstract:

    The Little Bustard Tetrax tetrax (Linnaeus, 1758) is a medium-sized, ‘Near Threatened’ steppe bird, whose Iberian population has been alarmingly declining over recent decades. Although this population loss has been mainly attributed to agricultural intensification, there is no information on Little Bustard adult mortality levels and their drivers. Based on a joint effort combining all the tracking data on adult Little Bustards collected over a period of 12 years by all research teams working with the species in Iberia, we found that annual anthropogenic mortality is likely to have a critical impact on the species, with values almost as high as the mortality attributed to predation. Collision with power lines was found to be the main anthropogenic threat to the adult population (3.4–3.8%/year), followed by illegal killing (2.4–3%/year), which had a higher impact than initially foreseen. Our work shows how poorly understood and previously unknown threats are affecting the survival of the most important Little Bustard population in Europe.

  • a spatially explicit approach to assess the collision risk between birds and overhead power lines a case study with the little Bustard
    Biological Conservation, 2014
    Co-Authors: Joao P Silva, Jorge M Palmeirim, Rita Alcazar, Ricardo A Correia, Ana Delgado, Francisco Moreira
    Abstract:

    Collisions between birds and overhead power lines are an important cause of human-induced mortality. Mapping collision risk is an important prerequisite to minimise the negative impact of these structures on bird populations, particularly for species of high conservation concern and that are prone to collision. We mapped and modelled power line collision risk of a threatened and collision-prone species, the little Bustard (Tetrax tetrax), based on three types of information: (i) the average daily distance flown by an individual, calculated from a satellite-telemetry study; (ii) the average percentage of flight movements at phase-conductor or shield-wire height, based on field focal observations; and (iii) a habitat suitability map for three different seasons (breeding, post-breeding and winter), modelled from an independent dataset of a nationwide population survey. An overall spatially explicit collision risk map was generated and validated with an independent mortality dataset derived from monitoring bird casualties in a sample of power lines. Collision risk of little Bustards varied significantly both spatially and temporally. Compared to post-breeding and winter, little Bustards moved smaller distances and flew at lower risk height during the breeding season, therefore minimising collision risk. The overall collision risk map contributed with relevant information to predict the likelihood of mortality events in a set of sampled power line sections. The described approach can be extended to transmission power lines, as well as to other bird species.

  • long term trends in great Bustard otis tarda populations in portugal suggest concentration in single high quality area
    Biological Conservation, 2005
    Co-Authors: Marcia Nascimento Pinto, Pedro Rocha, Francisco Moreira
    Abstract:

    Abstract Areas of occurrence, population trends and extinction patterns for great Bustard Otis tarda populations in Portugal are described for a 22-year period (1980–2002). The major population trends were a large decline in the 1984–1995 period, followed by a fast post-1995 increase. Most of this variation was explained by the trend observed in a single site, Castro Verde, where population has been increasing, in contrast with all other areas where populations have been declining. Eight local extinctions were documented, and probability of extinction increased fast below a threshold of 30 individuals in the initial (1980) population. Agricultural intensification, illegal hunting, road and power line building, and afforestations were the main causes of population decline and extinctions. The exceptional character of the Castro Verde population is explained by the maintenance of good habitat quality, the existence of a Bustard conservation project and of an agri-environmental scheme promoting farm management compatible with Bustard conservation. Stochastic computer simulations, using VORTEX, suggested that migration of individuals from other sites into Castro Verde was likely, as local productivity alone could not explain the observed population increase. The Portuguese population was estimated at 1150 birds in 2002, of which 912 were concentrated in Castro Verde. The present trend for the increasing concentration of the Portuguese population of great Bustards in a single site might lead to increased probability of extinction, particularly due to environmental stochasticity.

Joao P Silva - One of the best experts on this subject based on the ideXlab platform.

  • male post breeding movements and stopover habitat selection of an endangered short distance migrant the little Bustard tetrax tetrax
    Ibis, 2020
    Co-Authors: Hany Rafael De Drummond Ludovice Garcia Alonso, Francisco Moreira, Jorge M Palmeirim, Ricardo Correia, Ana Teresa Marques, Joao P Silva
    Abstract:

    Migratory decisions, such as the selection of stopover sites, are critical for the success of post‐breeding migratory movements and subsequent survival. Recent advances in bio‐logging have revealed the stopover strategies of many long‐distance migrants, but far less attention has been given to short‐distance migrants. We investigated the stopover ecology of an endangered grassland bird, the Little Bustard Tetrax tetrax, a short‐distance migrant in Iberia. Using high‐resolution spatial GPS/GSM data, 27 male Little Bustards breeding in southern Portugal were tracked between 2009 and 2011. We studied post‐breeding movements using Dynamic Brownian Bridge models to identify the main stopover sites, and generalized linear mixed models to examine habitat selection in stopovers. During their post‐breeding movements, males were essentially nocturnal migrants, making frequent stopovers while maintaining a relatively fast pace to reach more productive agricultural post‐breeding areas. Stopovers occurred in most post‐breeding movements (83%) regardless of the total distance covered (average 64.3 km), and most stopovers (84%) lasted less than 24 h. Birds used mostly agricultural non‐irrigated and irrigated croplands as stopover sites and avoided other land uses and rugged terrain. There was a negative relationship between stopovers and the proximity to roads, but not to power lines. The high frequency of stopovers during post‐breeding movements, despite the short distances travelled, together with the nocturnal migratory behaviour of Bustards, may impose additional risks to a bird mainly threatened by collision with power lines in non‐breeding areas. We also conclude that even for short‐distance migrants, habitat connectivity between breeding and post‐breeding areas is likely to be a key conservation concern.

  • Power line routing and configuration as major drivers of collision risk in two Bustard species
    Oryx, 2020
    Co-Authors: Ana Teresa Marques, Joao P Silva, Jorge M Palmeirim, Ricardo Martins, Francisco Moreira
    Abstract:

    Abstract Collision with power lines is a major cause of mortality for many bird species. Understanding the biotic and abiotic factors that increase collision risk is therefore important for implementing mitigation measures to minimize mortality, such as power line rerouting or wire marking. Here, we used collision events registered during 2003–2015 along 280 km of transmission power lines in southern Portugal to analyse spatio-temporal patterns and collision risk factors in two sympatric, threatened, and collision-prone species: the great Bustard Otis tarda and the little Bustard Tetrax tetrax. The occurrence of collisions was not uniform across space and time, and variations could be explained by the species' ecological requirements, distribution patterns and behaviour. Although both species fly considerable distances between areas of suitable habitat, collisions were far more likely in power line sections with > 20% (for the little Bustard) or > 50% (for the great Bustard) of open farmland habitat in the surroundings. Power line configuration was also important: taller pylons and those with a higher number of wire levels posed a higher risk for both species. Wire marking had a small but significant effect for the little Bustard, reducing collisions risk. There was, however, no similar effect for the great Bustard, possibly a result of limited data. Mitigation measures should be implemented to prevent Bustard collisions, including adequate route planning, ideally avoiding areas with > 20% of open habitat. Line configuration and wire marking are particularly important where such localities cannot be avoided and power lines cross areas with a high proportion of Bustard habitat, including outside protected areas.

  • tracking data of the little Bustard tetrax tetrax in iberia shows high anthropogenic mortality
    Bird Conservation International, 2017
    Co-Authors: Joana Marcelino, Manuel B Morales, Eladio Garcia L De La Morena, Francisco Moreira, Santi Manosa, Francesc Cusco, Gerard Bota, Jorge M Palmeirim, Joao P Silva
    Abstract:

    The Little Bustard Tetrax tetrax (Linnaeus, 1758) is a medium-sized, ‘Near Threatened’ steppe bird, whose Iberian population has been alarmingly declining over recent decades. Although this population loss has been mainly attributed to agricultural intensification, there is no information on Little Bustard adult mortality levels and their drivers. Based on a joint effort combining all the tracking data on adult Little Bustards collected over a period of 12 years by all research teams working with the species in Iberia, we found that annual anthropogenic mortality is likely to have a critical impact on the species, with values almost as high as the mortality attributed to predation. Collision with power lines was found to be the main anthropogenic threat to the adult population (3.4–3.8%/year), followed by illegal killing (2.4–3%/year), which had a higher impact than initially foreseen. Our work shows how poorly understood and previously unknown threats are affecting the survival of the most important Little Bustard population in Europe.

  • a spatially explicit approach to assess the collision risk between birds and overhead power lines a case study with the little Bustard
    Biological Conservation, 2014
    Co-Authors: Joao P Silva, Jorge M Palmeirim, Rita Alcazar, Ricardo A Correia, Ana Delgado, Francisco Moreira
    Abstract:

    Collisions between birds and overhead power lines are an important cause of human-induced mortality. Mapping collision risk is an important prerequisite to minimise the negative impact of these structures on bird populations, particularly for species of high conservation concern and that are prone to collision. We mapped and modelled power line collision risk of a threatened and collision-prone species, the little Bustard (Tetrax tetrax), based on three types of information: (i) the average daily distance flown by an individual, calculated from a satellite-telemetry study; (ii) the average percentage of flight movements at phase-conductor or shield-wire height, based on field focal observations; and (iii) a habitat suitability map for three different seasons (breeding, post-breeding and winter), modelled from an independent dataset of a nationwide population survey. An overall spatially explicit collision risk map was generated and validated with an independent mortality dataset derived from monitoring bird casualties in a sample of power lines. Collision risk of little Bustards varied significantly both spatially and temporally. Compared to post-breeding and winter, little Bustards moved smaller distances and flew at lower risk height during the breeding season, therefore minimising collision risk. The overall collision risk map contributed with relevant information to predict the likelihood of mortality events in a set of sampled power line sections. The described approach can be extended to transmission power lines, as well as to other bird species.

  • managing landscapes for the little Bustard tetrax tetrax lessons from the study of winter habitat selection
    Biological Conservation, 2004
    Co-Authors: Joao P Silva, Marcia Nascimento Pinto, Jorge M Palmeirim
    Abstract:

    More than half of the world’s population of the little bastard Tetrax tetrax lives in the Iberian Peninsula, where it is mostly dependent for survival on extensive agricultural areas. The species has declined dramatically, chiefly due to changes in agricultural practices, and is now globally ‘Near Threatened’. Knowledge of its habitat requirements is crucial to reverse the trend of habitat deterioration. Winter habitat preferences were studied in a region dominated by extensive cereal farming in Southern Portugal, comparing the characteristics of sites used by 54 flocks with those of randomly selected sites within the study area. The birds preferred recent fallows and grassy vegetation of mid-size (about 11–20 cm) and mid-density (about 11–50% cover). They tended to concentrate on the tops of hills and to avoid disturbed areas near roads and houses. Overall, the observed preferences suggest that predator avoidance is a significant factor in habitat selection. To improve habitat suitability for little Bustard, managers of key wintering areas should minimize permanent sources of human disturbance, encourage rotations with frequent fallows, and favour moderate levels of grazing to manipulate vegetation height and cover. Particular attention should be given to the upper parts of the hills. # 2003 Elsevier Ltd. All rights reserved.