Habitat selection by Ortolan Buntings Emberiza hortulana in post-fire succession in Catalonia: implications for the conservation of farmland populations

The Ortolan Bunting Emberiza hortulana is a long-distance migrant that has suffered major population declines across much of its European breeding range. While northern populations are bound largely to farmland, Mediterranean populations are largely confined to habitats subject to recurrent wildfires. Habitat selection of the Ortolan Bunting was assessed in a recently burnt area in Catalonia at landscape and habitat scales. A Zero-inflated Poisson procedure was used to model the abundance of birds in relation to landscape and habitat variables. The most parsimonious landscape model predicted the highest abundance on south-facing slopes, with a gradient above 10°. The most parsimonious habitat model showed a positive quadratic effect of bare ground and regenerating oak Quercus spp., with predicted optima for abundance around 20–30% and 20% cover, respectively. There was a clear relationship between predicted abundance of the Ortolan Bunting and post-fire regenerating oak shrubs. South-facing, moderately sloping areas were favoured and bare ground was a key feature of the species' habitat. A matrix combining patches of sparse oak shrubs and patches of bare ground appears to be the optimal breeding habitat in the Mediterranean. The maintenance or provision of similar habitat features, especially patches of bare ground, may prove crucial for the conservation of rapidly declining Ortolan Bunting populations on farmland across temperate Europe.     

Habitat preferences of the Ortolan Bunting (Emberiza hortulana) in its prime wintering grounds,the cereal-dominated Ethiopian Highlands

Agricultural intensification and land-use changes are major factors impacting farmland biodiversity. The Ortolan Bunting Emberiza hortulana is the long-distance trans-Saharan migratory passerine that has undergone the most dramatic decline among all European farmland birds. The factors responsible for this decline may originate from the breeding grounds, migration stopovers and/or overwintering quarters. Very little is known about conditions on the species' wintering grounds, but a recent study has highlighted the utmost importance of the traditionally managed agroecosystems in the Ethiopian Highlands as a key wintering area, apparently harbouring as much as 90% of the world's Ortolan Bunting population. Using radiotracking and line transect surveys, this study aimed to provide fine-grained information about species–habitat relationships in the Ortolan Bunting overwintering quarters. Our results showed the importance, at the landscape scale, of small-scale agriculture, notably of traditionally managed, cereal-dominated fields interspersed with semi-natural structures. At a foraging-site scale, on the other hand, patches of bare ground in combination with large areas of post-harvesting stubble represented key habitat features. Stubbles provide an essential food resource and bare ground promotes ground foraging by enhancing food accessibility. The maintenance of a traditional agricultural economy will be essential to maintain the habitat potential for the Ortolan Buntings overwintering in the Ethiopian Highlands and will be instrumental in preserving its world population from further decline.     

Habitat selection of riparian birds at restoration sites along the Trinity River,California

Riparian habitats in the western United States are imperiled, yet they support the highest bird diversity in arid regions, making them a conservation priority. Riparian restoration efforts can be enhanced by information on species response to variation in habitat features. We examined the habitat selection of four riparian birds known as management indicators at restoration and reference sites along the Trinity River, California. We compared vegetation structure and composition at nest sites, territories, and random points to quantify used versus available habitat from 2012 to 2015. Vegetation in focal species' territories differed between site types, and from available habitat, indicating nonrandom site choice. Birds selected aspects of more structurally complex habitats, such as greater canopy cover, canopy height, and tree species richness. Yellow‐breasted Chats preferred greater shrub cover, and Yellow Warblers preferred greater cover by non‐native Himalayan blackberry. Territory preferences on restoration sites were often a subset of those on reference sites. One exception was canopy height, which was taller on restoration site territories than random points for all species, suggesting that birds preferentially used patches of remnant habitat. Few variables were significant in nest site selection. Restoration plantings along the Trinity River were only 3–10 years old during this study, and have not developed many of the characteristics of mature riparian habitat preferred by birds, but may improve in habitat value over time. Understanding habitat selection is especially important in recently human‐modified environments, where indirect cues used to assess habitat quality may become disassociated from actual habitat quality, potentially creating ecological traps.     

An ‘ecological trap’ for yellow warbler nest microhabitat selection

Contrary to assumptions of habitat selection theory, field studies frequently detect ‘ecological traps’, where animals prefer habitats conferring lower fitness than available alternatives. Evidence for traps includes cases where birds prefer breeding habitats associated with relatively high nest predation rates despite the importance of nest survival to avian fitness. Because birds select breeding habitat at multiple spatial scales, the processes underlying traps for birds are likely scale‐dependent. We studied a potential ecological trap for a population of yellow warblers Dendroica petechia while paying specific attention to spatial scale. We quantified nest microhabitat preference by comparing nest‐ versus random‐site microhabitat structure and related preferred microhabitat features with nest survival. Over a nine‐year study period and three study sites, we found a consistently negative relationship between preferred microhabitat patches and nest survival rates. Data from experimental nests described a similar relationship, corroborating the apparent positive relationship between preferred microhabitat and nest predation. As do other songbirds, yellow warblers select breeding habitat in at least two steps at two spatial scales; (1) they select territories at a coarser spatial scale and (2) nest microhabitats at a finer scale from within individual territories. By comparing nest versus random sites within territories, we showed that maladaptive nest microhabitat preferences arose during within‐territory nest site selection (step 2). Furthermore, nest predation rates varied at a fine enough scale to provide individual yellow warblers with lower‐predation alternatives to preferred microhabitats. Given these results, tradeoffs between nest survival and other fitness components are unlikely since fitness components other than nest survival are probably more relevant to territory‐scale habitat selection. Instead, exchanges of individuals among populations facing different predation regimes, the recent proliferation of the parasitic brown‐headed cowbird Molothrus ater, and/or anthropogenic changes to riparian vegetation structure are more likely explanations.     

A quantitative analysis of habitat preferences of Woodcock Scolopax rusticola in the breeding season

In Britain, prior to breeding, Woodcock Scolopax rusticola switch from feeding on pastures by night to feeding in woodland by day. Their major food is earthworms (Lumbricidae). In April and May 1985, vegetation structure and composition and soil parameters including earthworm numbers (30 habitat variables) were recorded for quadrats containing 50 feeding locations of six radio-tagged birds, seven nests and 50 random locations in Whitwell Wood, northeast Derbyshire.
Significantly different mean values between feeding and random sites were found for 11 habitat variables. Feeding sites were in younger stands, with a higher percentage ground cover of dog's mercury Mercurialisperennis and consistently high values for pH. Earthworm biomass was on average 82% greater than in random plots. Areas of beech Fagus sylvaticus were avoided. A discriminant function based on six habitat variables correctly classified 85-5% of the feeding and random sites; 70% of the feeding locations were correctly classified by a jack-knife procedure. The important factors determining where feeding occurs are probably safety from avian predators and high availability of earthworms.
Discriminant analysis of the habitats used for feeding by solitary birds, broods and for nesting produced significant functions which correctly classified 84% of sites. Nests were in areas with a high percentage cover of brambles Rubus spp. and more open ground vegetation. Broods and solitary birds used similar areas characterized by denser ground vegetation than nest sites.
The results of this study indicate that both habitat structure and food availability influence the distribution of Woodcock in the breeding season.     

The Origin of Winter Visitors to the British Isles 7. Fieldfare (Turdus pilaris)

Capsule Large‐scale intensification of agricultural management during the past 50 years has resulted in a reduction of invertebrate abundance and higher and denser ground vegetation. Food availability for insectivorous birds foraging on the ground has been negatively affected, but the interactions between birds and their food availability are complex and often species‐specific. Populations of Wrynecks Jynx torquilla are declining all over Europe, possibly because of reduced accessibility to their main prey, ground‐dwelling ants, due to higher and denser ground vegetation. However, it is not clear which ground vegetation structures are tolerated by foraging Wrynecks and which habitats are preferred.

Aims To identify the optimal ground vegetation structure and the main habitat types in which Wrynecks search for food.

Method We radiotracked seven Wrynecks in high‐intensity farmland in Switzerland to study foraging habitat use during the reproduction season. Several habitat variables were mapped at each foraging location and compared with locations selected randomly within individual home ranges.

Results Wrynecks preferentially foraged at places with ≥50% bare ground. Vegetation height was not important. Older fruit tree plantations and fallow land were the preferred foraging habitats.

Conclusion Conservation measures should concentrate on preserving semi‐open agricultural landscape matrices with loose ground vegetation cover to provide suitable foraging conditions. This can be achieved even in intensively managed farmland as illustrated in this study.     

Nightingales Luscinia megarhynchos in scrub habitats in the southern fens of East Anglia, England: associations with soil type and vegetation structure

The southeast corner of the East Anglian Fens supports a large concentration of Nightingale Luscinia megarhynchos territories. A total of 382 territories were located in extensive surveys in 1999 and 2000, probably representing over 5% of the English population. Transect counts revealed that the Fenland population is restricted in distribution and is associated with localized thickets of scrub. The highest densities are found on humus‐rich soils, suggesting that soil type, in addition to habitat availability, may have a strong influence on the Nightingale's distribution in this region. This paper provides the first assessment of habitat requirements of the Nightingale in scrub, which now forms a principal habitat for the species in England. Detailed studies of the attributes of over 100 Nightingale territories revealed subtle differences in the vegetation structure of these thickets when compared with paired, unoccupied, but apparently similar thickets. The Nightingale territories tended to have a higher proportion of bare ground or short vegetation in the field layer under the canopy, whereas paired sites were more likely to have low field layer vegetation beneath the canopy. The bare ground within the thickets is a feature of shading beneath very dense foliage cover. Within Nightingale territories, low field layer volume and shrub twig volume at the thicket edges was higher than in unoccupied thickets. The differences detected in vegetation structure suggest that a dense and continuous canopy forming a shell over bare ground but with dense low foliage at thicket edges provides the ideal vegetation structure for Nightingales in scrub habitats. Our study suggests that Nightingales occupy scrub of a very specific structure, and specific stage in vegetation succession. This structure probably provides an optimal combination of foraging habitat, microclimate and cover from predators. It is suggested that humus‐rich soils may be preferred because they may support a particularly rich source of invertebrate food, but this remains to be tested empirically.     

Birds,Cattle, and Bracken Ferns: Bird Community Responses to a Neotropical Landscape Shaped by Cattle Grazing Activities

Large areas of tropical moist forests have been converted to cattle pastures, generating complex landscapes where different habitats are represented by small patches with an uneven spatial distribution. Here, we describe how bird communities respond to the different elements present in a livestock landscape that was originally dominated by tropical moist forest. We surveyed six habitats: open pastures, pastures with shrubs, early‐ and middle‐secondary forests, mature forest, and pastures invaded by bracken ferns (Pteridium aquilinum). Bird diversity was high in secondary and mature forests, and low in fern‐invaded sites and open pastures. Fern‐dominated sites had the lowest bird species richness, and trophic guild diversity of all habitats. Habitat structure affected both bird species richness and densities in similar ways. Tree species richness was the habitat attribute that had a bigger positive effect on bird species richness. Bird community structure varied among sampled habitats, separating habitats in two major groups (forests and pastures). Our data indicate that bracken fern‐invaded pastures were the worst habitat condition for avian communities. To increase bird diversity, we recommend to eliminate or manage bracken fern and to increase shrub and tree cover in open pastures to provide food resources and shelter for birds. Finally, we encourage the maintenance of secondary and mature forest remnants as a strategy to conserve resident birds within a landscape dominated by livestock activities.     

Nest‐site selection and productivity of Vesper Sparrows breeding in grazed habitats

ABSTRACT Livestock grazing in the shortgrass steppe of the Intermountain region of British Columbia may have a negative impact on ground‐nesting birds, but evidence of such an impact is lacking. We examined nest‐site selection and productivity of ground‐nesting Vesper Sparrows (Pooecetes gramineus) across sites with different grazing histories. From 2006 to 2008, we monitored Vesper Sparrow nests and measured vegetation characteristics known to be affected by grazing within nest patches. We used an information‐theoretic approach to test the relative importance of grazing‐affected vegetation variables as predictors of nest‐site selection, nest survival, and nestling condition. Vesper Sparrows selected nest sites with greater cover of late‐seral grass species that decrease in occurrence in response to grazing (i.e., “decreasers”) than was available in random patches in the same territories. Daily nest survival was also lower for nests surrounded by shorter vegetation (odds ratio = 1.12). However, “decreaser” cover was not associated with either of the two indices of productivity measured (daily nest survival probability and nestling condition). In addition, vegetation height, although an important driver of success, was not linked with nest‐site selection, and no vegetation‐cover variable was positively associated with productivity, despite nest concealment being central to our predictions. This suggests that predation risk for nests in areas with shorter vegetation was being elevated through some factor unrelated to concealment. Our results show that grazing reduced both the availability of suitable habitat for and nesting success of Vesper Sparrows, indicating that grazing could pose a threat to population persistence at a broader scale and could potentially contribute to observed declines. Additional research is needed to determine if grazing guidelines in the Intermountain region of British Columbia should be amended, better enforced, or both to prevent regional declines in populations of ground‐nesting grassland birds.     

Selection indicates preference in diverse habitats: a ground-nesting bird (Charadrius melodus) using reservoir shoreline

Animals use proximate cues to select resources that maximize individual fitness. When animals have a diverse array of available habitats, those selected could give insights into true habitat preferences. Since the construction of the Garrison Dam on the Missouri River in North Dakota, Lake Sakakawea (SAK) has become an important breeding area for federally threatened piping plovers (Charadrius melodus; hereafter plovers). We used conditional logistic regression to examine nest-site selection at fine scales (1, 3, and 10 m) during summers 2006-2009 by comparing characteristics at 351 nests to those of 668 random sites within nesting territories. Plovers selected sites (1 m(2)) that were lower than unused random sites, increasing the risk of nest inundation. Plovers selected nest sites that were flat, had little silt, and at least 1 cobble; they also selected for 3-m radius nest areas that were relatively flat and devoid of vegetation and litter. Ninety percent of nests had <38% coverage of silt and <10% slope at the site, and <15% coverage of vegetation or litter and <31% slope within the 3-m radius. Gravel was selected for at nest sites (11% median), but against in the area 10-m from the nest, suggesting plovers select for patches or strips of gravel. Although elevation is rarely evaluated in studies of ground-nesting birds, our results underscore its importance in habitat-selection studies. Relative to where plovers historically nested, habitat at SAK has more diverse topography, substrate composition, vegetation communities, and greater water-level fluctuations. Accordingly, our results provide an example of how habitat-selection results can be interpreted as habitat preferences because they are not influenced by desired habitats being scarce or absent. Further, our results will be useful for directing habitat conservation for plovers and interpreting other habitat-selection studies.     

Use of Restored Riparian Habitat by the Endangered Least Bell's Vireo (Vireo bellii pusillus)

A primary objective of riparian restoration in California is the creation of habitat for endangered species. Four restoration sites in San Diego County were monitored between 1989 and 1993 and evaluated for their suitability as nesting habitat for Vireo bellii pusillus (Least Bell's Vireo), a state and federally endangered obligate riparian breeder. Vegetation structure at each site was quantified annually and compared to a model of canopy architecture derived from Least Bell's Vireo territories in natural habitat. Vireo use of restored habitat was documented through systematic surveys and nest monitoring. By 1993, only one site in its entirety met the habitat suitability criteria of the model, but portions of each site during all years did so. Differences between sites in the time required to develop suitable habitat—well-developed layered vegetation from the ground to under 8m in height)—were attributable largely to variation in annual rainfall. Vireos visited restoration sites to forage as early as the first growing season, but they did not establish territories or nest there until at least part of the site supported suitable habitat as determined from the model. Placement of territories and nests coincided with patches of dense vegetation characteristic of natural nesting areas. Occupation of restored sites was accelerated by the presence of adjacent mature riparian habitat, which afforded birds nest sites and/or foraging habitat lacking in the planted vegetation. Vireos nesting in restored habitat achieved success comparable to that of vireos nesting in surrounding natural habitat, and there was no evidence that productivity was reduced in created areas. These findings indicate that creating nesting habitat for this target species is feasible and suggest that the critical components of vireo nesting habitat have been captured in both the design and quantitative assessment of restoration sites.     

Effects of habitat transitions on rainforest bird communities across an anthropogenic landscape mosaic

We compared bird community responses to the habitat transitions of rainforest‐to‐pasture conversion, consequent habitat fragmentation, and post‐agricultural regeneration, across a landscape mosaic of about 600 km² in the eastern Australian subtropics. Birds were surveyed in seven habitats: continuous mature rainforest; two size classes of mature rainforest fragment (4–21 ha and 1–3 ha); regrowth forest patches dominated by a non‐native tree (2–20 ha, 30–50 years old); two types of isolated mature trees in pasture; and treeless pasture, with six sites per habitat. We compared the avifauna among habitats and among sites, at the levels of species, functional guilds, and community‐wide. Community‐wide species richness and abundance of birds in pasture sites were about one‐fifth and one‐third, respectively, of their values in mature rainforest (irrespective of patch size). Many measured attributes changed progressively across a gradient of increased habitat simplification. Rainforest specialists became less common and less diverse with decreased habitat patch size and vegetation maturity. However, even rainforest fragments of 1–3 ha supported about half of these species. Forest generalist species were largely insensitive to patch size and successional stage. Few species reached their greatest abundance in either small rainforest fragments or regrowth. All pastures were dominated by bird species whose typical native habitats were grassland, wetland, and open eucalypt forest, while pasture trees modestly enhanced local bird communities. Overall, even small scattered patches of mature and regrowth forest contributed substantial bird diversity to local landscapes. Therefore, maximizing the aggregate rainforest area is a useful regional conservation strategy.     

Habitat selection by breeding Curlews Nwnenius arquata on mosaic farmland

Territory establishment and habitat use by breeding Curlews Numenius arquata were studied during 1987 and 1988 on mosaic farmland (dominated by dry tillage) at two sites in central Sweden. Curlews preferred to breed in areas with a high proportion of grassland, close to rivers, while dry tillage was avoided. Territories at my study site were larger (mean = 4 5.2 ha) than in areas consisting entirely of grassland. Territory size seemed to depend on the spatial distribution of grasslands, which suggests that habitat fragmentation forces Curlews to establish larger territories in modern farmland than in areas of grassland. The number of territories in patches of grassland was correlated with patch area, and unoccupied patches were more isolated than occupied patches. However, patch area was a more important factor than isolation, since large patches (> 3 5 ha) were always occupied. Sown grassland was used significantly more than expected for foraging early in the season, possibly indicating the strong influence of the nutritional requirements in the pre-breeding period on territory establishment. Habitat selection when foraging seemed to be less important late in the season, since there was no significant habitat preference then. During this period distance to the nest site seemed to be more important than habitat, sinced the preferred foraging fields (including fields of all habitats used more than expected by area) were situated closer to nests than the less preferred fields, probably an adaptation to the high nest predation risk. The same fields were mostly preferred in the pre-breeding period also, suggesting that nests were built close to good foraging areas.
My results indicate that the decline of the Swedish Curlew population since 1950 is caused by changes in land use, resulting in decreased grassland area and increased habitat fragmentation, which probably have affected both breeding and foraging possibilities negatively.     

Mating success of the endemic Des Murs’ Wiretail (Sylviorthorhynchus desmursii,Furnariidae) in fragmented Chilean rainforests

Abstract: We studied the effects of fragment size, vegetation structure and presence of habitat corridors on the reproductive success of the Des Murs’ Wiretail (Sylviorthorhynchus desmursii Des Murs, Furnariidae), a small (10 g) understorey bird, endemic to South American forests. In a rural landscape of Chiloé Island, southern Chile (42°S; 70°W), we determined the mating and nesting success of wiretails in 28 territories distributed in seven small (1–20 ha) and two large (>300 ha) forest fragments during the 1997–1998 breeding season. Wiretails inhabited dense bamboo thickets in the understorey of forest patches, dense shrublands covering old fields, and dense early successional forest vegetation. Wiretails avoided open pastures. Reproductive success depended solely on the probability of finding mates, and the main factor affecting mating success was the presence of corridors. Mated individuals occupied 72% of the territories in forest patches <20 ha connected by corridors, 73% of the territories in large (>300 ha) fragments, but only 20% of territories in isolated fragments surrounded by pastures. Because of the rapid expansion of pastures in southern Chile, the conservation of wiretails and other understorey birds will depend on the maintenance of travel corridors with dense understorey vegetation between forest fragments.     

Relationships between seed banks and spatial heterogeneity of North American alvar vegetation

Abstract. This is the first quantitative study of seed bank characteristics in North American alvar habitats. We assessed seed bank density, species richness, and species composition in 75 plots distributed among five alvar sites in Bruce Peninsula National Park, Ontario, Canada, each of which displayed areas of high and low vegetation cover within the alvar and a fully forested perimeter area. Forested habitats immediately adjacent to alvar patches contained minimal seed banks for species restricted to the alvar patches. Open alvars contained less than 1% seeds from woody forest species. This suggests that forest is not invading adjacent alvar habitat via seeds and that adjacent forest does not contain a reservoir of alvar seeds. When compared to areas on the alvar with high vascular plant cover, areas with low cover contained a slightly smaller viable seed bank, but seed banks from high and low vegetation cover plots had similar species composition and species richness. High vegetation cover plots had slightly higher mean and maximum soil depths compared with low cover plots, but no differences in other physical and chemical parameters. Thus, spatial heterogeneity in plant cover is associated only weakly with heterogeneity in below‐ground factors. Despite the availability of seed and soil resources, vegetation dynamics are constrained in areas with low plant cover, and thus alvar community development seems to respond non‐linearly to resource availability.     

Plasticity of nest-site selection in the trumpeter finch: A comparison between two different habitats

In habitats with more predators, a species is expected to breed in safer sites and be less successful than in predator-impoverished habitats. We tested this hypothesis by studying nest-habitat selection and nest predation in two populations of Trumpeter finch (Bucanetes githagineus). One breeds in a predator-rich habitat (Tabernas, Iberian Peninsula), and the other is found on an island with fewer predators (La Oliva, Canary Islands). In both localities, we studied the features of nests in two different substrates, on the ground and in cliffs, including visibility and position in the cliff. We measured the habitat characteristics in a series of plots around the ground nests and compared them to random points. We also studied the influence of nest features and habitat selection on predation of both nest types. Trumpeter finches built more nests in cliffs in Tabernas, probably because there are more cliffs available there. In this locality, the patches selected for ground nesting had below-average vegetation cover, lower vegetation height, and were on steeper slopes. In La Oliva, they selected above-average vegetation height and steeper slopes. Cliff nests were less predated than ground nests in La Oliva, but not in Tabernas. The only variable that affected survival rates in Tabernas was the height of vegetation around ground nests, with nests in lower vegetation having higher survival rates. These results suggest that locality-related differences in habitat selection by vegetation height could be related to the different predator assemblages present in any given area, though we cannot rule out confounding influences of other differences between the two sites.     

Habitat preferences of tree pipit ( Anthus trivialis) and meadow pipit ( A. pratensis) at sympatric and allopatric localities

Habitat preferences of the tree pipit (Anthus trivialis) and the meadow pipit (A. pratensis; Passeriformes: Motacillidae) were observed during the years 1998–1999 at three localities in the Czech Republic; two with one pipit species only, and a third with both species present. We investigated one of the possible mechanisms allowing syntopic coexistence—different habitat selection. We characterised territories of each pipit pair by the habitats present in the territory (defined by dominant plant composition) and by quantitative parameters (territory size, height and density of the vegetation, number of look-outs of different height categories, and proportion of wet ground). Tree pipits preferred significantly higher vegetation of lower density than meadow pipits, and there was generally a higher number of high look-outs in their territories. However, in some of the preferred territories at the allopatric locality of the tree pipit, steep hill slopes could well substitute for higher look-outs, which were almost absent. The two pipit species at the sympatric locality occupied very different habitats, which was also reflected in quantitative parameters of their territories. The available data of pipit habitat at different European localities show that the two species can occupy a much wider range of habitats. The habitat separation in sympatry might therefore be one of the mechanisms allowing syntopic coexistence of both species.Communicated by F. Bairlein     

An inter-regional approach to intraspecific variation in habitat association: Rock Buntings Emberiza cia as a case study

The habitat association approach has been increasingly used in ecology to resolve problems in wildlife conservation and management. One problem related to habitat association studies is that they are restricted to small geographical areas within a species' range, and thus they are applicable to only a limited set of environmental conditions utilized by the species. In addition, very few studies address why the preference for specific habitat components may be adaptive for the species in question. The objective of this study was to examine how consideration of populations of a species from two dramatically different environments affects the results of habitat association modelling for a ground-nesting passerine, the Rock Bunting Emberiza cia . At a regional scale, a trend to defending breeding habitat patches with relatively higher stone cover was confined to birds from a temperate region in Slovakia. In contrast, in a semi-arid region in southeastern Spain, Rock Buntings preferred to use breeding habitat patches that had relatively higher grass cover. Combining data from both regions, breeding Rock Buntings showed a general pattern of using habitat patches close to hedges, with low bush cover, high ditch density and a steep slope. Whereas regional habitat association models appear to be sensitive to the particularities of the breeding environment, our study suggests that Rock Bunting breeding habitat association is constrained by the adults' tactics to protect themselves against predators. Although the birds prefer to nest in patches of low vegetation, the better to see nearby predators, these patches are ideally close to taller vegetation that can be used to provide cover when evading predators, and they are also of a rugged profile that helps the birds to approach and leave the nest stealthily.     

Modelling the nesting-habitat of the Cinereous Vulture Aegypius monachus on a fine scale for conservation purposes

Capsule Nests of Cinereous Vultures were found to be located farther from roads, villages and the edge of large vegetation patches. They preferred large vegetation patches containing extensive Cork Oak cover on steeper slopes and with lower solar radiation. Less than 8% of the study area was predicted to be suitable for nesting.

Aims To generate a predictive habitat suitability map for the Cinereous Vulture's nesting-habitat on a fine scale for conservation applications within its breeding range.

Methods Habitat features of 43 nest-locations and random points were compared in order to identify nest-habitat selected in the region of the Hornachuelos Natural Park (Spain). A logistic regression approach was used to create habitat models.

Results Compared with random points, nests were found to be located farther from roads, villages and patch edges, and in large vegetation patches containing extensive Cork Oak cover on steeper slopes with lower solar radiation. The predictive map revealed that less than 8% of the study area had a greater probability of occupancy than 0.8.

Conclusions Most habitats in the study area are unsuitable for nesting suggesting that conservation of the best suitable areas is important. The fine-scale predictive map approach may be valuable in designating conservation priority areas.     

Nest-predation at the edge: an experimental study contrasting two types of edges in the dry Chaco, Paraguay

Forest fragmentation leads to the creation of isolated forest patches with subsequent impact on forest-interior flora and fauna. Forested corridors have been suggested to alleviate some of the impact by increasing the connectivity between remnant forest patches. However, both fragmentation and corridors increase the ratio of edge to core habitat. We studied nest predation of artificial nests at edges between I) contiguous forests and pastures and 2) forested corridors and pastures, in a forest-dominated landscape in the dry Chaco, Paraguay, The aim was lo determine if nest predation was higher near habitat edges compared to within forests and pastures, with special emphasis on edges at forested corridors. We found that predation rates were similar at edges and in interior habitats. Nest predation was higher for both ground and shrub nests in forested areas than in pastures, Predation rates were also higher for both ground and shrub nests at edges along forested corridors compared to edges neighbouring contiguous forests. Forested corridors connecting contiguous forests may thus act as an ecological sink for some species breeding here. Analysis of predator categories revealed that ground nests in pastures were relatively more depredated by mammals and less by birds, compared to both shrub nests in pastures and ground nests in forests.