Opposing population trajectories in two Bustard species: A long-term study in a protected area in Central Spain

Casas, Fabián; Mougeot, François; Arroyo, Beatriz; Morales, Manuel B.; Hervás, Israel; Morena, Eladio L. García de la; Fagan, William F.; Viñuela, Javier

doi:10.1017/s0959270918000254

Cited by 10 publications

(6 citation statements)

References 52 publications

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“…The loss of agro-steppe habitat is one of the factors behind little bustard's population declines observed in recent decades. In Portugal little bustards declined by 49% between 2003-2006(Silva et al, 2018, with similar trends found in some protected areas in Spain (Casas et al, 2019).…”

Section: Impacts Of Agro-steppe Area Loss On Great Bustard Populationssupporting

confidence: 75%

Effectiveness of the European Natura 2000 network at protecting Western Europe's agro-steppes

Gameiro

Silva

Franco

et al. 2020

Biological Conservation

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Agro-steppes, a key bird habitat, are declining inside and outside Natura 2000 sites.• Agro-steppes are being converted mostly to permanent and irrigated crops.• Declines of agro-steppe area were 45% slower within Special Protected Areas.• The area lost in the studied SPAs could hold more than 500 great bustards.• Effective protection of Network sites is needed to achieve CBD conservation targets.

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Section: Impacts Of Agro-steppe Area Loss On Great Bustard Populationssupporting

confidence: 75%

Effectiveness of the European Natura 2000 network at protecting Western Europe's agro-steppes

Gameiro

Silva

Franco

et al. 2020

Biological Conservation

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“…The trend of the TRIM population index can be used as an estimate of annual variations in the abundance of bird species ( Gordo, 2018 ; Stjernman et al, 2013 ) (see ( Traba & Morales, 2019 ) for a similar procedure). Indeed, the SACRE program provides the best information of population trends for common breeding bird species in Spain ( SEO/BirdLife, 2016 ; Casas et al, 2019 ). The indices of a group of species can be summarized into a single estimate to analyze trends of related bird species ( Bowler et al, 2019 ).…”

Section: Methodsmentioning

confidence: 99%

Extensive sheep grazing is associated with trends in steppe birds in Spain: recommendations for the Common Agricultural Policy

Traba

Pérez‐Granados

2022

PeerJ

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Iberian natural steppes have traditionally been used for extensive sheep grazing, which has been noted to be positively associated with steppe bird abundance and diversity. Sheep numbers in Spain, which harbors the largest European populations of many steppe bird species, decreased by 9.2 million (37.3%) between 1992 and 2020. Steppe birds in Spain have faced dramatic declines during the same period, but there is a lack of knowledge about the potential association between sheep and open-habitat bird declines. We used sheep data from the Spanish Ministry of Agriculture and bird data (1998–2018) from the Spanish Common Bird Monitoring Program to assess the association at the Spanish scale between sheep decline and the Farmland Bird Index (FBI) and the Natural Shrub-steppe Bird Index (SBI). We also used an independent dataset on population trends of the Dupont’s Lark (Chersophilus duponti) to assess the relationship between sheep numbers and the decline of this threatened steppe specialist passerine in Spain, whose European population is restricted to Iberian natural steppes. To test for a spurious relationship between temporal series, variables were tested for cointegration. After confirming cointegration, we found a strong positive relationship between sheep abundance and the trends of the FBI and SBI indices during the period 1998–2018. The association between sheep abundance and trends of the Dupont’s Lark (2004–2015) was positive although it was not statistically significant. Although the main causes of decline of farmland and steppe birds are mainly related to agricultural intensification and land use changes, the correlation found, using two independent cointegrated datasets, between the reduction in farmland and shrub-steppe birds and sheep numbers at the country scale suggests that the decline of steppe birds in Spain may be also associated with the decline in sheep numbers. This agrees with previous studies that found a positive relationship between intermediate levels of sheep grazing and steppe bird abundance in Iberian steppes. Further research (e.g. experimental studies) is needed to corroborate our study and identify the most appropriate level of grazing intensity for protecting the most farmland and shrub-steppe birds. Our results suggest that the promotion of extensive grazing should be considered as a key factor in future Common Agricultural Policy reforms and conservation programmes to protect steppe birds.

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“…Grape vines are grown either in a traditional way-free standing without any attachment (goblet-shaped)-or as trellised vines with partial irrigation. The area has been highlighted as a hot spot for steppe birds (Traba et al 2007) and supports a significant population of breeding Little Bustards, which has declined steeply in recent years (Casas et al 2019).…”

Section: Study Area and Speciesmentioning

confidence: 99%

“…Each year, 110 ± 8 (mean ± SD) of those points were surveyed (range 91-116). Little Bustards observed from each point were plotted on a map, and double counting among consecutive points was avoided (if a bird was spotted in the same place, it was considered to be the same individual as in the nearby point and was not counted again [see Casas et al 2019 for more details]). We detected both males and females, but most observations were of males; females accounted for about 13% of the total 1489 Little Bustard observations over the years.…”

Section: Little Bustard Abundance and Habitat Datamentioning

confidence: 99%

“…Using 10 years of field data on this species in a study area in central Spain (Casas et al 2019), we evaluated whether spatial or temporal variability in Little Bustard abundance was explained by functional habitat suitability (i.e., variations in nesting or foraging habitat suitability), and whether urban encroachment modified the relationships between habitat suitability and the species' abundance.…”

Section: Introductionmentioning

confidence: 99%

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Functional habitat suitability and urban encroachment explain temporal and spatial variations in abundance of a declining farmland bird, the Little Bustard Tetrax tetrax

Arroyo¹,

Estrada²,

Casas³

et al. 2022

ACE

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Species response to land use can be examined under a functional perspective, where habitats are described according to species´ resource dependencies. Distribution or abundance models based on resource availability rather than land use types can be more informative about the ultimate processes behind observed population or distribution trends. Habitat use may depend on resources available, as well as disturbances that affect accessibility to such resources. Increasing human presence and urban encroachment may thus alter the relationships between habitat suitability and species abundance. Using 10 years of field data, we investigated whether variability in Little Bustard (Tetrax tetrax) abundance was explained by functional habitat suitability (assessed through resource-based models) and urban encroachment. We found that spatial and temporal variations in Little Bustard abundance were explained by functional habitat suitability and avoidance of urban areas, but that the significance of each variable varied with spatial scale. Little Bustard abundance at each observation point significantly increased with local nesting but not foraging habitat suitability, and decreased with increasing proportion of urban areas. At larger spatial scales, temporal changes in Little Bustard abundance were highly significantly related to changes in foraging habitat suitability. Moreover, the positive relationship between foraging habitat suitability and Little Bustard abundance weakened as the proportion of urban areas increased, and almost disappeared when the proportion of urban areas was more than 5%. Our results underline the benefits of using resource-based models to better understand processes that relate animal abundance and habitat suitability, while simultaneously considering avoided elements of the landscape.L'adéquation fonctionnelle de l'habitat et l'empiètement urbain expliquent les variations temporelles et spatiales de l'abondance d'un oiseau champêtre en déclin, l'Outarde canepetière, Tetrax tetrax RÉSUMÉ. Le comportement des espèces en fonction de l'affectation des terres peut être examiné dans une perspective fonctionnelle, selon laquelle les habitats sont décrits suivant la dépendance des espèces envers les ressources. Les modèles de répartition ou d'abondance fondés sur la disponibilité des ressources, plutôt que sur le type d'affectation des sols, peuvent être plus informatifs sur les processus ultimes qui sous-tendent les tendances observées en matière de population ou de répartition. L'utilisation de l'habitat peut dépendre des ressources disponibles et des perturbations qui affectent l'accessibilité à ces ressources. La présence humaine croissante et l'empiètement urbain accru peuvent donc modifier les relations entre l'adéquation de l'habitat et l'abondance des espèces. En utilisant 10 ans de données prises sur le terrain, nous avons cherché à savoir si la variabilité de l'abondance de l'Outarde canepetière (Tetrax tetrax) s'expliquait par l'adéquation fonctionnelle de l'habitat (évaluée par des modèles basés ...

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Opposing population trajectories in two Bustard species: A long-term study in a protected area in Central Spain

Cited by 10 publications

References 52 publications

Effectiveness of the European Natura 2000 network at protecting Western Europe's agro-steppes

Effectiveness of the European Natura 2000 network at protecting Western Europe's agro-steppes

Extensive sheep grazing is associated with trends in steppe birds in Spain: recommendations for the Common Agricultural Policy

Functional habitat suitability and urban encroachment explain temporal and spatial variations in abundance of a declining farmland bird, the Little Bustard Tetrax tetrax

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