Anthus Spinoletta Research Articles

Färgvariation hos vattenpiplärka Anthus spinoletta i vinterdräkt

This study of colour variation on Water Pipit Anthus spinoletta in winter plumage, is based on photos of 93 individuals from southern Sweden. Using moulting criteria, the birds were aged from the photographs, and the presence or absence of five specific plumage characteristics were recorded. Twelve individuals in this study confirm the hypothesis that adult Water Pipits show a distinct combination of plumage traits during winter. However, the presence of these plumage traits varied in younger birds in their first winter plumage. Among the 81 individuals classified as first winter plumage, 23 (28%) displayed all “adult characteristics”, 32 (40%) one to four of the characteristics, while 26 (32%) lacked all “adult characteristics”. The latter group thus lacked a gray nape/crown, whitish supercilium, and lighter brown colouration of the mantle/scapulars. Ever since the first Swedish records in the mid-1990s, there have been ongoing discussions regarding species-specific characters in Water Pipits. The present quantification of colour variation in different age groups complements previous criteria for a reliable species identification of Water Pipits in winter plumage.

Survey of Tick-Borne Zoonotic Agents in Ixodes Ticks Carried by Wild Passerines during Postbreeding Migration through Italy

Recently, increasing attention has been posed on the role of migrating birds in the spread of ticks and indirectly of tick-borne pathogens (TBPs). Despite, Italy is considered a bridge between continental Europe and North Africa and a necessary path to connect Mediterranean countries, few studies have been conducted on ticks collected from birds migrating through this country and associated TBPs. The aims of this research were to estimate the infestation burden and identify tick species feeding on migratory birds, and perform a molecular screening for TBPs. During autumn migration (2019–2020), birds were inspected for ticks in a ringing station located in north-east Italy. Ticks were identified and screened for tick-borne encephalitis virus (TBEV), Borrelia burgdorferi sensu latu, Rickettsia spp., Ehrlichia spp., Neoehrlichia spp., Anaplasma phagocytophilum, and Bartonella spp. Ixodes ticks (n = 209) were feeding on 2.6% of passerines (88/3411). Most of these (208/209) were Ixodes ricinus, except one Ixodes frontalis. Eight bird species were infested: common blackbird, redwing, brambling, song thrush, common chaffinch, European robin, water pipit, and coal tit. Rickettsiales showed a low prevalence, from 1.4% of Ehrlichia spp., 4.3% of A. phagocytophilum, up to 7.2% of Rickettsia spp.. Borrelia burgdorferi s.l. had the highest prevalence, 54.6%, and several zoonotic genotypes were identified: B. garinii, B. valaisiana, B. afzeli, B. burgdorferi sensu stricto, and B. miyamotoi. All specimens were negative for TBEV and Bartonella spp.. Although the tick burden was generally low, most of the vectors (>60%) were positive for at least one pathogen, highlighting the relevance of a continuous monitoring of migrating birds as potential sources of pathogen dispersal.

Molecular and acoustic evidence support the species status of Anthus rubescens rubescens and Anthus [rubescens] japonicus (Passeriformes: Motacillidae).

The Buff-bellied Pipit Anthus rubescens comprises two allopatric subspecies groups: A. r. rubescens and A. r. alticola in North America and A. [r.] japonicus in north-east Asia. Despite their great morphological resemblance in breeding plumage, most individuals can be assigned to one or the other subspecies group in non-breeding plumage. Allopatric distributions, morphological differentiation and previously reported molecular divergence suggested the need for additional taxonomic study to assess the rank of these two populations. To resolve the taxonomy of the Buff-bellied Pipit species complex we analysed i) two mitochondrial DNA (mtDNA) loci and ii) nine bioacoustic parameters across 69 sound recordings (338 flight calls) recovered from public databases using principal component analysis and Euclidean distance measures. By comparing our mtDNA and call divergence measures with similar values measured between long-recognised species pairs of the genus, we show that the level of mitochondrial and acoustic divergence between the two Buff-bellied Pipit subspecies groups is typical of species-level divergence in the genus Anthus. Therefore, we recommend splitting the Buff-bellied Pipit species complex into two species: Anthus rubescens (American Pipit) and Anthus japonicus (Siberian Pipit). Our results also suggest that the Water Pipit A. spinoletta deserves taxonomic reassessment as its lineages are highly divergent in acoustics and mtDNA, while mtDNA relationships suggest paraphyly relative to the Rock Pipit A. petrosus. Our work highlights the crucial importance of integrative approaches in taxonomy and the usefulness of bioacoustics in studying cryptic diversity.

Grazing intensity drives a trophic shift in the diet of common alpine birds

Large mammalian herbivores (LMH) shape vertebrate communities and structure food webs in many terrestrial ecosystems. However, the mechanisms that underlie the effects of LMH on other vertebrates are poorly understood. In France, domestic LMH have grazed alpine and mountain grasslands for thousands of years, profoundly influencing landscapes and wildlife. As LMH modify habitat structure, favour coprophagous insects and compete with herbivorous insects, the diet of insectivorous alpine birds may be deeply influenced by LMH grazing intensity. To investigate this, we sampled common insectivorous birds faeces (water pipit Anthus spinoletta and wheatear Oenanthe oenanthe) in sites characterized by different levels of grazing intensity by domestic and wild herbivores, in the open landscapes of the southern French Alps and the western Pyrenees. We used isotopic discrimination based on nitrogen stable isotope ratios as an indicator of the trophic level of the arthropods found in bird faeces. From isotopic ratios, we found that bird diets shift from mainly herbivorous arthropods at sites of low grazing intensity, to one mainly composed of other groups, such as predatory, detritivorous or coprophagous arthropods, at sites of higher grazing intensity. This result highlights the strong trophic link between LMH and insectivorous birds in open landscapes, contributing to a better understanding of interactions between domestic grazing, an activity that has historically modelled European landscapes, and biodiversity, with particular relevance for landscape management and bird conservation.

Landscape characteristics influence regional dispersal in a high-elevation specialist migratory bird, the water pipit Anthus spinoletta.

Species living in high mountain areas are currently threatened by climate change and human land use changes. High-elevation birds frequently inhabit island-like suitable patches around mountain peaks, and in such conditions the capability to exchange individuals among patches is crucial to maintain gene flow. However, we lack information regarding the dispersal ability of most of these species and the possible influence of landscape features on dispersal. In this study, we used population genomics and landscape resistance modelling to investigate dispersal in a high-elevation specialist migratory bird, the water pipit Anthus spinoletta. We aimed to assess the levels of gene flow in this species within a wide area of the European Alps, and to assess the effects of environmental characteristics on gene flow, by testing the isolation by distance (IBD) hypothesis against the isolation by resistance (IBR) hypothesis. We found clear support for IBR, indicating that water pipits preferentially disperse across suitable breeding habitat (i.e., high-elevation grassland). IBR was stronger in the part of the study area with less extended suitable habitat. Landscape resistance was slightly better described by habitat suitability models than landscape connectivity models. Despite the observed IBR, gene flow within the study area was high, probably also because of the still wide and relatively continuous breeding range. The forecasted reduction of range of this species may lead to stronger effects of IBR on gene flow. Other high-elevation specialist birds may show similar IBR patterns, but with possibly stronger effects on gene flow because of their more reduced and patchy habitats.

Variation in wing morphology is related to breeding environment in a high‐elevation specialist bird

The morphology of bird wings is subject to a variety of selective pressures, including migration, predation, habitat structure and sexual selection. Variation in wing morphology also occurs at the intraspecific and intrapopulation level, and can be related to sex, age, migration strategy and environmental factors. The relationship between environment and intraspecific variation in wing morphology is still poorly understood. In this work, we studied the relationship between wing morphology and breeding environment in a high‐elevation specialist bird, the water pipit Anthus spinoletta. We calculated wing isometric size, pointedness and convexity of 84 birds mist‐netted at breeding sites in year 2021 in the European Alps. We then searched for associations between these traits and potentially relevant breeding site characteristics (vegetation structure, elevation, latitude). For all wing traits, sex and one or more environmental factors best explained the variation, with environmental factors explaining between 3 and 8% of the variation. Wing size was negatively related to tree cover and wing convexity was negatively related to bush cover. Elevation contributed to explain variation in wing pointedness, but the direction of its effect was unclear. The negative relationship between wing size and tree cover could be due to intraspecific competition, i.e. to the relegation of smaller winged low‐quality individuals in marginal grassland areas. Higher wing convexity could improve predator escape ability in areas with scarce protecting vegetation, with possible effects on habitat choice. These findings represent one of the few demonstrated cases of wing morphology–environment relationships at the intraspecific level.

Identifying climate refugia for high-elevation Alpine birds under current climate warming predictions.

Identifying climate refugia is key to effective biodiversity conservation under a changing climate, especially for mountain‐specialist species adapted to cold conditions and highly threatened by climate warming. We combined species distribution models (SDMs) with climate forecasts to identify climate refugia for high‐elevation bird species (Lagopus muta, Anthus spinoletta, Prunella collaris, Montifringilla nivalis) in the European Alps, where the ecological effects of climate changes are particularly evident and predicted to intensify. We considered future (2041–2070) conditions (SSP585 scenario, four climate models) and identified three types of refugia: (1) in‐situ refugia potentially suitable under both current and future climate conditions, ex‐situ refugia suitable (2) only in the future according to all future conditions, or (3) under at least three out of four future conditions. SDMs were based on a very large, high‐resolution occurrence dataset (2901–12,601 independent records for each species) collected by citizen scientists. SDMs were fitted using different algorithms, balancing statistical accuracy, ecological realism and predictive/extrapolation ability. We selected the most reliable ones based on consistency between training and testing data and extrapolation over distant areas. Future predictions revealed that all species (with the partial exception of A. spinoletta) will undergo a range contraction towards higher elevations, losing 17%–59% of their current range (larger losses in L. muta). We identified ~15,000 km2 of the Alpine region as in‐situ refugia for at least three species, of which 44% are currently designated as protected areas (PAs; 18%–66% among countries). Our findings highlight the usefulness of spatially accurate data collected by citizen scientists, and the importance of model testing by extrapolating over independent areas. Climate refugia, which are only partly included within the current PAs system, should be priority sites for the conservation of Alpine high‐elevation species and habitats, where habitat degradation/alteration by human activities should be prevented to ensure future suitability for alpine species.

Grassland bird species in mountain pastures Zaprikraj and Zapleč in the southern Julian Alps, Slovenia

AbstractGrassland birds were surveyed in two mountain pastures (Zaprikraj and Zapleč) in the southern part of the Julian Alps, Slovenia. The survey was carried out during the mornings between 26 and 30 June 2005. Due to the incomplete survey (only one visit, no nocturnal or targeted surveys and late season survey), the surveyed birds’ breeding density is only a rough estimate. 167 pairs belonging to 12 species were counted, with Tree (average density of 1.64 p/10 ha) and Water Pipit (average density of 1.60 p / 10 ha) being the most abundant. Both were observed in all altitudinal belts. The highest density in individual altitudinal belt was calculated for Red-backed ShrikeLanius collurio(3.78 p/10 ha) and Water Pipit (3.61 p/10 ha). In well preserved grasslands in the study area, most species reached high breeding densities compared to other parts of Slovenia and all were recorded higher than during the 1992 survey, although still mostly within limits of the elevations elsewhere in Slovenia. Breeding density of SkylarkAlauda arvensisdecreased with the elevation. WhinchatSaxicola rubetra, Skylark and Red-backed Shrike used significantly gentler slopes, while Pipits showed no preference for particular slopes.

Habitat, climate, topography and management differently affect occurrence in declining avian species: Implications for conservation in changing environments

Climate and land-use change are the most severe threats to biodiversity; their effects are often intermingled, also with those of landscape/habitat management. Birds of mountain grassland are declining throughout Europe. Disentangling climate effects from those of land-cover and management on their occurrence is essential to identify distribution drivers, potential impacts of climate/land-use changes, and effective conservation strategies. We investigated the occurrence of water pipit (elevation specialist), skylark and red-backed shrike (elevation generalists) in Central Apennines, Italy (750–2130 m asl), using point counts. Topographic/climatic, land-cover and management fine-scale variables were considered as potential occurrence predictors in Generalized Linear Models. For all species, combining different types of predictors led to the most accurate models, but the relative importance of single-groups varied: land cover was the most important for skylark, climate/topography for water pipit, all three groups had similar support for red-backed shrike. Skylark was positively affected by solar radiation and grassland cover, and negatively by bare ground, hedgerows, rocks, shrubland, ski-pistes and buildings, confirming sensitivity to anthropic alteration of semi-natural grassland. Water pipit was favoured by grazing and negatively impacted by shrubland and average temperature (most important predictor). Red-backed shrike was affected negatively by broadleaved forest and grazing occurrence, quadratically by isolated shrubs and positively by grassland cover. Climate was a fundamental determinant of water pipit occurrence, but not for the other species. Land-cover was important for all species and also management factors were invariably included in models. Climate, habitat and management factors differently contributed to occurrence patterns in these declining species. Conservation strategies need to embrace landscape planning to preserve grassland extents/mosaics, identify climate refugia for water pipit and implement dedicated management (preventing new ski-pistes over areas suitable for birds and carefully planning grazing). It should be feasible to combine local, sustainable economies with biodiversity conservation into landscape planning for Central Apennines.

Living in a time of change: Late Pleistocene/Holocene transitional vertebrate fauna of Grot Skeliastyi (Crimea, Ukraine)

ABSTRACT The paper presents the results of the study of vertebrate fossil assemblages recovered from the Grot Skeliastyi rock shelter in south-western Crimea (Ukraine). The deposition of its fossil-bearing layers covers the time span from the Late Glacial to the early Holocene. The studied sample consists of 2,736 bones belonging to 52 species of vertebrates (including 3 fishes, 1 amphibian, 12 reptiles, 10 birds, 26 small and large mammals). Among them, the past presence of the Aesculapian snake, four-lined ratsnake, squacco heron, tree pipit, and water pipit in the region is here documented for the first time. Extinct taxa in the faunal assemblage of Grot Skeliastyi were represented by wild horse, European ass, steppe bison, and woolly mammoth. Remains of small animals were accumulated due to the feeding activity of the eagle owl, while bones of large mammals could have been a part of the prey of carnivores but mostly are associated with the hunting activity of ancient people who inhabited the rock shelter. Most of the species persisted from the Pleistocene to the Holocene without losses. Our results indicate that the Pleistocene/Holocene transition in Crimea was not characterised by drastic faunal changes unlike those in other parts of Eastern Europe.Not StartedCompletedRejected

Microclimate affects the distribution of grassland birds, but not forest birds, in an Alpine environment

Predictions derived from species distribution models (SDMs) are strongly influenced by the spatial scale at which species and environmental data (e.g. climate) are gathered. SDMs of mountain birds usually build on large-scale temperature estimates. However, the topographic complexity of mountain areas could create microclimatic refuges which may alter species distributions at small spatial scales. To assess whether fine-scale data (temperature and/or topography) improve model performance when predicting species occurrence, we collected data on presence–absence of bird species, habitat and fine-scale temperature at survey points along an elevational gradient in the Alps (NW Italy). Large-scale temperature data, and both large- and fine-scale topography data, were extracted from online databases for each point. We compared species models (fine-scale vs large-scale) using an information-theoretic approach. Models including fine-scale temperature estimates performed better than corresponding large-scale models for all open habitat species, whereas most forest/ecotone species showed no difference between the two scales. Grassland birds such as Northern Wheatear Oenanthe oenanthe and Water Pipit Anthus spinoletta were positively associated with warmer microclimates. These results suggest that alpine grassland species are potentially more resistant to the impact of climate change than previously predicted, but that indirect effects of climate change such as habitat shifts (forest- and shrub encroachment at high elevations) pose a major threat. Therefore, active management of alpine grassland is needed to maintain open areas and to prevent potential habitat loss and fragmentation. SDMs based solely on large-scale temperatures for open habitat species in the Alps should be re-assessed.

Autumn migration of birds over Polonyna Borzhava (Ukrainian Carpathians)

Migration processes of birds occurring on the Polonyna Borzhava ridge were studied. Material was collected during 52-days period since September till November 2018 and total duration of observations was equal to 307 hours. It was found that despite difficult terrain and variable weather conditions at least 48 species of birds migrate over Polonyna Borzhava. Among them the following species dominate: Chaffinch Fringilla coelebs, Common Crane Grus grus, Eurasian Siskin Spinus spinus, Common Wood Pigeon Columba palumbus, Great Tit Parus major, Goldfinch Carduelis carduelis, Water Pipit Anthus spinoletta, Blue Tit Cyanistes caeruleus, and also raptors: Sparrowhawk Accipiter nisus, Common Buzzard Buteo buteo, Goshawk Accipiter gentilis, Hen Harrier Circus cyaneus, Marsh Harrier Circus aeruginosus and other species. Among detected species six are under protection of the Red Data Book of Ukraine: Common Crane, Hen Harrier, Stock Dove Columba oenas, Alpine Accentor  Prunella collaris, Osprey Pandion haliaetus, and Peregrine Falcon Falco peregrinus. Median date of the overall bird passage falls on 9 October. Passage dynamics differs among species. Most of species prefer flight heights not higher than 55 m above the ridge, but some numerous species choose higher altitudes, for instance Wood Pigeon (85.6±62.7 m), and Common Crane (227.5±62.5 m).

A spatially explicit definition of conservation priorities according to population resistance and resilience, species importance and level of threat in a changing climate

AbstractAimHuman‐induced climate change requires conservation strategies incorporating its potential effects on species and communities. Key components of population persistence can be attributed to resistance (the capacity to remain unaffected) or resilience (capacity to absorb and recover) to climate change. In situ climatic refugia can act as resistant distribution units, and ex situ climatic refugia and the corridors to reach them may enhance resilience. We develop a novel approach selecting conservation priorities, resistant units and resilient areas according to structural connectivity and future distribution, to identify strategies that maximize the chances of species persistence in a changing climate.LocationItalian Alps.MethodsConservation priorities were defined across species according to the regional conservation status and the level of threat from climate change, and across sites according to their suitability for target species and their related potential for population persistence (in situ climatic refugia, i.e., resistant units) or redistribution (ex situ climatic refugia and main corridors according to current and future connectivity, i.e., resilient units).ResultsModels suggested a marked loss of suitable area for all species by 2050 (ranging from ~50% for pygmy owl and water pipit, to 84% for snowfinch in the worst scenario), and a general loss of connectivity, which was particularly marked for pygmy owl and snowfinch. The approach applied to Alpine birds of different habitats led to a spatially explicit definition of conservation priorities.Main conclusionsThe spatial definition of conservation priorities according to species (regional importance and level of threat), resistance and resilience refines the definition of management/conservation priorities (including protected area definition), complementing the existing approaches to address climate change‐induced threats in planning conservation and ecological networks.

Surviving at high elevations: an inter- and intra-specific analysis in a mountain bird community.

Elevation represents an important selection agent on self-maintenance traits and correlated life histories in birds, but no study has analysed whether life-history variation along this environmental cline is consistent among and within species. In a sympatric community of passerines, we analysed how the average adult survival of 25 open-habitat species varied with their elevational distribution and how adult survival varied with elevation at the intra-specific level. For such purpose, we estimated intra-specific variation in adult survival in two mountainous species, the Water pipit (Anthus spinoletta) and the Northern wheatear (Oenanthe oenanthe) in NW Spain, by means of capture-recapture analyses. At the inter-specific level, high-elevation species showed higher survival values than low elevation ones, likely because a greater allocation to self-maintenance permits species to persist in alpine environments. At the intra-specific level, the magnitude of survival variation was lower by far. Nevertheless, Water pipit survival slightly decreased at high elevations, while the proportion of transient birds increased. In contrast, no such relationships were found in the Northern wheatear. Intra-specific analyses suggest that living at high elevation may be costly, such as for the Water pipit in our case study. Therefore, it seems that a species can persist with viable populations in uplands, where extrinsic mortality is high, by increasing the investment in self-maintenance and prospecting behaviours.

Population Trends of Central European Montane Birds Provide Evidence for Adverse Impacts of Climate Change on High-Altitude Species.

Climate change is among the most important global threats to biodiversity and mountain areas are supposed to be under especially high pressure. Although recent modelling studies suggest considerable future range contractions of montane species accompanied with increased extinction risk, data allowing to test actual population consequences of the observed climate changes and identifying traits associated to their adverse impacts are very scarce. To fill this knowledge gap, we estimated long-term population trends of montane birds from 1984 to 2011 in a central European mountain range, the Giant Mountains (Krkonoše), where significant warming occurred over this period. We then related the population trends to several species' traits related to the climate change effects. We found that the species breeding in various habitats at higher altitudes had more negative trends than species breeding at lower altitudes. We also found that the species moved upwards as a response to warming climate, and these altitudinal range shifts were associated with more positive population trends at lower altitudes than at higher altitudes. Moreover, long-distance migrants declined more than residents or species migrating for shorter distances. Taken together, these results indicate that the climate change, besides other possible environmental changes, already influences populations of montane birds with particularly adverse impacts on high-altitude species such as water pipit (Anthus spinoletta). It is evident that the alpine species, predicted to undergo serious climatically induced range contractions due to warming climate in the future, already started moving along this trajectory.

Response of bird assemblages to windstorm and salvage logging — Insights from analyses of functional guild and indicator species

Natural disturbances, such as fire, windstorms and insect outbreaks, are important drivers of biodiversity in forest ecosystems, but at the same time cause large economic losses. Among the natural disturbances in Europe, windstorms cause the highest economic loss. After such storms, damaged forest stands are commonly salvage logged to restore economic value. However, such interventions could affect species assemblages of various taxonomic groups, including breeding birds. Despite these potential effects, investigations of the impacts of post-storm logging are largely lacking. We thus investigated assemblages of breeding birds in 21 logged and 21 unlogged windstorm-disturbed forest plots and 18 undisturbed, control forest plots using fixed-radius point-stop counts three, five and seven years after a windstorm within the Bavarian Forest National Park as part of the European Long-Term Ecosystem Research Network. We recorded 2100 bird individuals of 55 bird species. Bird assemblages were predominantly altered by the consequences of the windstorm and affected only to a minor degree by subsequent logging of storm-felled trees. Nevertheless, bird species richness was significantly reduced by post-storm logging within the first season. In general, the windstorm led to a shift in bird assemblage composition from typical forest species towards open- and shrub-land species. Assemblages of logged and unlogged disturbed plots consisted mainly of long-distance migrants and ground-foraging bird species, whereas assemblages of undisturbed control plots consisted of resident species that forage within vegetation. Both unlogged and logged storm-felled coniferous forest stands were inhabited by endangered or declining bird species, such as Water Pipit (Anthus spinoletta) on logged plots and Eurasian Redstart (Phoenicurus phoenicurus) on unlogged plots. Indicator species analyses suggested that species of unlogged storm disturbed plots depended on storm-created legacies, such as pits and snags, for foraging and nesting. Hence, we recommend reducing post-storm logging of these legacies to support species restricted to unlogged disturbed forest. To increase the diversity of breeding birds on the landscape scale, diverse logged and unlogged post-disturbance stands should be provided, which could be gained by a partial benign neglect strategy of storm disturbed forest stands.

Timing and duration of moult in relation to weather conditions in four montane passerine species at the Gran Sasso, Central Italy

Summer primary and secondary moult were investigated in four species of passerines, Northern Wheatear Oenanthe oenanthe, Black Redstart Phoenicurus ochruros, Linnet Linaria cannabina and Water Pipit Anthus spinoletta, in a mountain environment in central Italy. For each species we determined mean starting date and duration of both primary and secondary moults, and whether factors such as spring precipitation or temperature affected the timing or the duration of each moult. Northern Wheatear, the only long-distance migrant among the study species, was the first to start and to complete its moult. Furthermore, this species was the only one to moult earlier in years with warmer springs and with less snow, as predicted. Black Redstarts, on the other hand, started to moult later in warmer years, possibly because a greater proportion of pairs produced a second brood. In each of the species with distinguishable sexes, moult began later in females than in males. In Linnets, females finished primary moult on average two days earlier than males, due to a shorter moult duration. Similarly, Black Redstart females finished their secondary moult exactly at the same time as males, despite a later start.

The intensity of male-male interactions declines in highland songbird populations

Elevation gradients are associated with sharp environmental clines that play a crucial role in the phenotypic diversification of animal populations. In a variety of organisms, the reproductive output of females declines with elevation in parallel to the drop in environmental productivity and shortening of the breeding season. Little evidence is available on male traits associated with reproductive activities, such as territorial defence and signalling, which may decline because of the low economic defendability of resources and the selective advantage of investing in parental rather than mating (e.g. signalling, chasing intruders) effort in such conditions. Along a broad elevational gradient, we investigated variation in the intensity of territorial defence and sexual signalling in males of the water pipit Anthus spinoletta exposed to song playbacks simulating the territorial intrusion of a conspecific. We found that birds from the lower limits of the species distribution approached song stimuli more closely than those from the upper limits. Moreover, physically challenging songs (broad frequency bandwidths and fast trills) elicited a closer approach, and low elevation birds uttered songs ending with the broadest bandwidths. Other responses to the intrusion, such as the number of songs uttered or the latency to approach, exhibited seasonal or spatial variation irrespective of elevation. This study illustrates the decline of some trait associated with aggressive territorial behaviours during male-male conflicts along elevation, and points to the allocation in sexual signalling and motor constraints to signal production, as potential mechanisms underlying it.

The effects of a settling-down period on estimates of bird species richness and occurrence from point counts in the Alps

Capsule The effect of a settling-down period (SDP) on estimates of species richness, and on the presence of 12 species, was considered on point counts along altitudinal transects in the Alps. For the individual species, Water Pipit was the only species which showed evidence that a SDP increased detectability. Species richness was higher when a point count was preceded by a settling period. A SDP may therefore confer some slight advantage in surveying birds in alpine habitats.

Dräktvariation hos skärpiplärka Anthus petrosus littoralis och vattenpiplärka Anthus spinoletta i vinterdräkt

Plumage variation in nine neutral (i. e. not concerning colour hues) characters was studied from October through February in 77 Rock Pipit Anthus petrosus littoralis and 47 Water Pipit Anthus spinoletta in southern Sweden. The Rock Pipit generally showed more variation than the Water Pipit. Several characters were overlapping between the species, while especially streaking on the underparts significantly distinguished between them. The most reliable differences concerned the width and sharpness of the streaks on the lower breast, and on the anterior and, especially, rear flanks, the Water Pipit having considerably thinner and more clearcut streaks than Rock Pipit.