“…Females with juveniles seem to prefer short or medium swards, which to some extent differs from the findings of Silva et al (2014), who did not find any relationship with vegetation height. The occurrence in short swards may in some cases be related to livestock management under high stocking rates (large herds using small pastures for short periods), which are tricky to model since their effect seems to depend on the interaction with other grazing management and weather variables.…”
Section: Discussioncontrasting
confidence: 99%
“…Little Bustard occurs here at densities (0.4 males/100 ha; Silva and Pinto 2006) lower than in other areas of southern Portugal (e.g. São Vicente and Vila Fernando plains; Silva et al 2014), although locally the species can be found at moderate to high densities (up to three males/100 ha; unpubl. data).Figure 1.Location of the study area and sampling fields.…”
Section: Methodsmentioning
confidence: 60%
“…The Little Bustard is a sexually dimorphic species in which males do not participate in brood rearing (Cramp and Simmons 1980). Although males and females tend to use different vegetation structures (short vegetation in the case of males and medium height – up to 30–40 cm – in females; Morales et al 2008; Silva et al 2014), recent studies demonstrated a considerable overlap in habitat requirements between males and females during the breeding season (e.g. grazing intensity and landscape features; Faria et al 2012; Tarjuelo et al 2013).…”
SummaryWe investigated population productivity and habitat selection of the Little Bustard Tetrax tetrax in the late breeding period, in grassland-dominated landscapes of south-west Iberia. Specifically, our goals were to investigate how these parameters are influenced by the management of (1) grazing and (2) hay production. We conducted bird counts from 22 June to 4 July (2012 to 2016) using low speed 4x4 car surveys. The relationship between the density of the species, population productivity and farm management (grazing and haying) was evaluated using Generalized Linear Mixed Models and Kruskal-Wallis tests. Male and female densities were significantly higher in short vegetation compared to all other types of vegetation considered, but population productivity was similar in short and medium vegetation. Hay stubbles were found to be unattractive for the species. The availability of suitable habitats depends on the timing of grazing, notably of seasonal (spring) grazing. Species density was higher in fields ungrazed during winter and with moderate to high stocking rates in spring (around 0.8 LU/ha or higher), depending, at least for males and females, on each year’s weather characteristics. We conclude that low to moderate stocking rates during winter and spring are essential to ensure successful breeding and thus population persistence. Current levels of haying in our study area are detrimental for the species’ conservation.
“…Females with juveniles seem to prefer short or medium swards, which to some extent differs from the findings of Silva et al (2014), who did not find any relationship with vegetation height. The occurrence in short swards may in some cases be related to livestock management under high stocking rates (large herds using small pastures for short periods), which are tricky to model since their effect seems to depend on the interaction with other grazing management and weather variables.…”
Section: Discussioncontrasting
confidence: 99%
“…Little Bustard occurs here at densities (0.4 males/100 ha; Silva and Pinto 2006) lower than in other areas of southern Portugal (e.g. São Vicente and Vila Fernando plains; Silva et al 2014), although locally the species can be found at moderate to high densities (up to three males/100 ha; unpubl. data).Figure 1.Location of the study area and sampling fields.…”
Section: Methodsmentioning
confidence: 60%
“…The Little Bustard is a sexually dimorphic species in which males do not participate in brood rearing (Cramp and Simmons 1980). Although males and females tend to use different vegetation structures (short vegetation in the case of males and medium height – up to 30–40 cm – in females; Morales et al 2008; Silva et al 2014), recent studies demonstrated a considerable overlap in habitat requirements between males and females during the breeding season (e.g. grazing intensity and landscape features; Faria et al 2012; Tarjuelo et al 2013).…”
SummaryWe investigated population productivity and habitat selection of the Little Bustard Tetrax tetrax in the late breeding period, in grassland-dominated landscapes of south-west Iberia. Specifically, our goals were to investigate how these parameters are influenced by the management of (1) grazing and (2) hay production. We conducted bird counts from 22 June to 4 July (2012 to 2016) using low speed 4x4 car surveys. The relationship between the density of the species, population productivity and farm management (grazing and haying) was evaluated using Generalized Linear Mixed Models and Kruskal-Wallis tests. Male and female densities were significantly higher in short vegetation compared to all other types of vegetation considered, but population productivity was similar in short and medium vegetation. Hay stubbles were found to be unattractive for the species. The availability of suitable habitats depends on the timing of grazing, notably of seasonal (spring) grazing. Species density was higher in fields ungrazed during winter and with moderate to high stocking rates in spring (around 0.8 LU/ha or higher), depending, at least for males and females, on each year’s weather characteristics. We conclude that low to moderate stocking rates during winter and spring are essential to ensure successful breeding and thus population persistence. Current levels of haying in our study area are detrimental for the species’ conservation.
“…Transmitters have been deployed on a number of bustard species (see Introduction) because biologging is the only way to study many aspects of their biology, given their generally longlived, cryptic nature ) and the legal restrictions on disturbing nesting birds for monitoring (Magaña et al 2010;Morales et al 2013;Silva et al 2014) due to their threatened status . Nevertheless, this is the first quantitative assessment of the impact of transmitters on the reproductive performance of a bustard species.…”
Backpack-mounted satellite transmitters (PTTs) are used extensively in the study of avian habitat use and of the movements and demography of medium-to large-bodied species, but can affect individuals' performance and fitness. Transparent assessment of potential transmitter effects is important for both ethical accountability and confidence in, or adjustment to, life history parameter estimates. We assessed the influence of transmitters on seven reproductive parameters in Asian houbara Chlamydotis macqueenii, comparing 114 nests of 38 females carrying PTTs to 184 nests of untagged birds (non-PTT) over seven breeding seasons (2012)(2013)(2014)(2015)(2016)(2017)(2018) in Uzbekistan. There was no evidence of any influence of PTTs on: lay date (non-PTT x ̅ = 91.7 Julian day ± 12.3 SD; PTT x ̅ = 95.1 Julian day ± 15.7 SD); clutch size (non-PTT x ̅ = 3.30 ± 0.68 SD; PTT x ̅ = 3.25 ± 0.65 SD); mean egg weight at laying (non-PTT x ̅ = 66.1 g ± 5.4 SD; PTT x ̅ = 66.4 g ± 5.4 SD); nest success (non-PTT x ̅ = 57.08% ± 4.3 SE; PTT x ̅ = 58.24% ± 4.5 SE for nests started 2 April); egg hatchability (non-PTT x ̅ = 88.3% ± 2.2 SE; PTT x ̅ = 88.3% ± 2.6 SE); or chick survival to fledging from broods that had at least one surviving chick (non-PTT x ̅ = 63.4% ± 4.2 SE; PTT x ̅ = 64.4% ± 4.7 SE). High nesting propensity (97.3% year −1 ± 1.9% SE) of tagged birds indicated minimal PTT effect on breeding probability. These findings show that harness-mounted transmitters can give unbiased measures of demographic parameters of this species, and are relevant to other large-bodied, cursorial, ground-nesting birds of open habitats, particularly other bustards.
“…The Little Bustard Tetrax tetrax is a bird that lives in natural steppes and in extensive agricultural landscapes and it has been decreasing and disappearing from several countries (Iñigo and Borov 2010, Silva et al 2014a). The species has a fragmented range encompassing south-western and south-eastern Europe and Central Asia (Iñigo and Borov 2010, Silva et al 2014a). It is considered Near Threatened (IUCN 2008) and a conservation priority species under the European Bird Directive (2009/147/CE).…”
SummaryWith the combination of worldwide landscape changes and the uncertainty about the impact on species abundance and distribution, the value of spatio-temporal modelling tools is increasingly obvious. The Little Bustard Tetrax tetrax breeds on low-intensity arable cultivation and pastoral land and is currently threatened by diverse landscape modifications. The aim of this research was to predict Little Bustard population trends in the face of realistic scenarios of land use and infrastructure changes, applying a recently developed spatially explicit framework, based on the stochastic dynamic methodology (StDM). The application of this approach provided some basis to analyse the responses of breeding populations’ spatial distribution and abundance to the scenarios implemented. Since some of these scenarios represent local and/or regional risks to the viability of Little Bustard breeding populations, the results obtained demonstrate the potential of the proposed framework for landscape planning in the scope of the conservation of this threatened species. This approach also provides a promising baseline to support ecological risk assessments for other species, derived from ecological models with increased predictive power and intuitiveness to decision makers and environmental managers.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
