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Tuesday, 30 June 2015

Ardeola June 2015 : Volume 62 Issue 1 - Abstracts


Published by: Spanish Society of Ornithology / BirdLife

Table of Contents
June 2015 : Volume 62 Issue 1



Long-Term Changes in Mountain Passerine Bird Communities in the Sierra Nevada (Southern Spain): A 30-Year Case Study
Regino Zamora and José Miguel Barea-Azcón

Shifts in composition and abundance of bird communities were studied along an elevational gradient in the Sierra Nevada (S. Spain), comparing censuses made at the same locations in the 1980s and during 2008–2012. Censuses were made in three representative ecosystems: 1) Pyrenean oak woodland, 2) high-mountain juniper scrubland, 3) high-mountain summits. In a global change context, avian-community dynamics are related mainly to changes in two of the following drivers: climate change and land-use change occurring over the past 30 years. Our results show a continuous turnover of the bird community, with an overall 27% change in species composition, in an ecological setting that has changed little, especially in the high-mountain scrubland and summit areas. We detected an increase in species diversity relative to the 1980s, mostly in the Pyrenean oak woodland. Moreover, our results also show a sharp decrease in bird density during the 30-year study period, chiefly affecting the dominant species of the 1980s in the Pyrenean oak forest and in the high-mountain scrubland. In the high-summit ecosystems, the decline of alpine species has paralleled the uphill expansion of some mediterranean ones. The outcome of these processes is a community in continuous flux, both in composition and abundance, where interannual variability is similar to interdecadal variability. We conclude that the bird communities of Sierra Nevada are showing strong spatial and temporal dynamics that are now accelerating, perhaps because of global warming.

Moult and Morphometrics of the Pallid Swift Apus pallidus in Northwestern Italy
Giovanni Boano, Irene Pellegrino and Marco Cucco

We examined moult patterns and body morphometry of pallid swifts at two locations in NW Italy, by sampling 352 birds at their nests from July through October over a 20-year period. Birds were sexed by behaviour at the nest. We found no sexual dimorphism in 8th primary length, tail length, depth of the tail fork, rectrices T5–T4 tip delta length or body mass. We found a significant difference between the sexes in wing length (females mean: 174.7 mm, range 169–184; males: 177.0 mm, range 169–191), but because of extensive overlap it cannot be used to determine the sex of most individuals. Measurements of birds recaptured in following years did not differ with increasing age. Birds began the moult in July. Moult was estimated to last about five months, from July until November–December, and was not completed on our study sites. Females and males did not differ in the timing and progression of the moult during the season. About one-third of individuals did not replace the 9th or 10th (outermost) primary, with a complex pattern of retention and substitution in sequence year after year. The overlap of breeding season and moult in this population appears to be higher than that reported for two other Italian swifts and is similar to that found in tropical swift species.

Influence of Landscape and Field-Level Agricultural Management on a Mediterranean Farmland Winter Bird Community
Manuel B. Morales, Juan J. Oñate, Irene Guerrero and Leandro Meléndez

We studied the response to agricultural management factors of birds wintering in an unirrigated cereal farmland area of central Spain, examining the influence on species richness, abundance and community composition of different field-level and landscape-level agricultural management variables related to intensification. Our initial hypothesis was that landscape-level management factors exert a stronger effect on wintering bird species richness, total abundance and community composition than field-level ones. The particular responses of the most frequent species (skylark Alauda arvensis, corn bunting Emberiza calandra and meadow pipit Anthus pratensis) were also examined. Richer assemblages were found in more substrate-diverse plots with natural vegetation patches or in plots with higher yield crops, while the more abundant ones, dominated by the skylark, occupied more homogeneous areas dominated by cereals and arable land. As expected, landscape-level management factors explained a much greater proportion of variance in community composition compared to field-level factors (71% vs 29%, respectively). Species richness per se was favoured by substratediverse plots containing patches of natural vegetation, but also by plots where cereal crops were more productive in the previous harvest, declining in more homogeneous plots dominated by cereal crops and arable land in general. Conversely, skylark abundance and total abundance increased as landscapes became more homogeneous and dominated by cereals and arable land, although the relationship for total abundance only approached significance. Results suggest that the current landscape structure and levels of agricultural production of cereal farmland in central Spain can host relatively abundant winter populations of seed-eating and open landscape specialists like the skylark, although certain levels of habitat diversity need to be guaranteed to ensure the maintenance of rich wintering bird communities.

The Incidence of Clutch Replacements in the Pied Flycatcher Ficedula hypoleuca is Related to Nest-Box Availability: Evidence of Female-Female Competition?
Juan Moreno

Clutch destruction and replacement are sometimes observed during studies of cavitynesting birds. This could be due to abandonment by the first female to lay, with subsequent replacement by another female, or to male infanticide. Clutch replacement is accompanied in some cases by evidence of aggressive competition between females and of destruction of eggs/hatchlings immediately prior to a new clutch being laid. This may indicate that clutch replacements are in fact nest take-overs by females after eviction of incumbent females. In the course of long-term studies of pied flycatchers Ficedula hypoleuca iberiae in central Spain, I have found evidence of clutch destruction through egg burial and ejection and replacement during laying or incubation, as well as of female-female aggression. No male involvement has been detected. Clutch replacements occur with a frequency that depends on the density of available nest-boxes and is positively associated with the rate of nest-box occupation by the same or other species. Moreover, clutch replacements can be accompanied by female wounds or death and involve clutch destruction in all cases. Putative replacers within the area of highest occupation frequently display the white forehead patch that is more typical of males, which may thus be associated with social dominance in females in Iberian populations. Clutch replacements in cavity-nesters should be studied in detail to confirm whether they represent cases of nest take-overs by competing females.

Ecological Modelling of the Distribution of the Lanner Falcon Falco biarmicus feldeggii in Sicily at Two Spatial Scales
Massimiliano Di Vittorio, Andrea Ciaccio, Salvatore Grenci and Luca Luiselli

The presence of the lanner falcon Falco biarmicus feldeggi in Sicily was modelled by generalized linear models using climatic, topographic, ecological and land-use variables at both the landscape (UTM cells of 10 × 10 km) and the home range (12.56 km2) spatial scales. At the landscape scale, a significant spatial autocorrelation of the lanner population, corresponding to the longitudinal distribution of sites, was found, with the species occurring within the most xeric UTM cells. There was also a negative relationship between falcon presence and potential evapo-transpiration values, either in the coldest months or throughout the year. The same negative relationship was also seen with the surfaces of CORINE artificial areas, thus showing that the species has a low tolerance to any anthropogenic landscape. At home range scale, our predictive models revealed a preference for territories with steep slopes surrounded by natural grassland, sclerophyll vegetation, arable land and agricultural land. The lack of spatial correlation and the identification of specific preferred land use classes, suggests that the home range scale is more appropriate than the landscape scale for predicting the occurrence of lanner falcons. The maintenance of a stable lanner falcon population in Sicily should be addressed at both small and large scales.

Migration Patterns of Iberian Little Bustards Tetrax tetrax
Eladio L. García de Lamorena, Manuel B. Morales, Gerard Bota, Joao Paulo Silva, Anna Ponjoan, Francisco Suárez, Santiago Mañosa and Eduardo De Juana

The term “migratory” refers to animals performing yearly round-trips between breeding grounds and post-breeding areas, whereas the term “sedentary” refers to those remaining the whole year in their breeding grounds. However, migration is a complex and varying phenomenon governed by genetic and environmental factors, particularly in species with wide distribution ranges. Here we describe and classify the seasonal movement patterns of 71 little bustards Tetrax tetrax, an endangered Palearctic steppe bird, radio- and satellite-tracked in the Iberian Peninsula. Four major movement patterns were identified, with 89% of little bustards behaving as migrants, among which 75% (summer migrants and summer-winter migrants) performed their first movement after breeding during the summer (mainly between May and July), whereas 14% (winter migrants) left their breeding sites in autumn (mainly between September and November). The remaining 11% were strictly sedentary. On average, summer migration started on June 14th, and winter migration on October 3rd, while pre-breeding migration started on March 23rd. Summer migration occurred in most Iberian regions, although it was mainly found in semiarid Mesomediterranean areas. Winter migration occurred only in the northern half of the Peninsula, being the only pattern found in Subatlantic and highland areas. All winter migrants wintered in Thermomediterranean localities of southern Iberia. The sedentary pattern was found only in the Semiarid Mesomediterranean and Thermomediterranean sectors. This is a good example of complex intraspecific variation in the migratory behaviour of a species that occupies a diverse range of environments. The variability of movement patterns of Iberian little bustards is much greater than previously thought and should be taken into account in conservation programmes for the species.

Nest-Site Selection and Reproductive Success of the Little Grebe Tachybaptus ruficollis in Northeast Algeria
Mohammed Athamnia, Farrah Samraoui, Bilal Kelailia, Ahlem Rouabah, Ahmed H. Alfarhan and Boudjéma Samraoui

We studied the phenology, habitat selection, and interannual and seasonal changes in breeding performance of the little grebe Tachybaptus ruficollis in relation to the spatial structure of a shallow lake during three breeding seasons (2010–2012). Nests were mostly located in shallow waters, close to the shore (98.3 ± 37.9 cm), in vegetation dominated by Scirpus lacustris. The egg-laying period started at the end of March and extended for four months until the end of July. Overall, the mean clutch size was 4.7 ± 1.1 (N = 154) with a modal clutch of 5. There was a seasonal decline in both egg volume and clutch size. The overall nesting success was 60% and the chief causes of nest failure were predation (52%) and adverse weather (20%). Breeding outcome was influenced by water depth, nest size and year of breeding. Predation and nest flooding markedly varied between years. Larger nests had a higher nesting success than smaller ones. Likewise, nests located at greater water depth (further from the shore) succeeded better than ones located in shallower water. As the little grebe forages preferentially in shallow waters, these results suggest that optimal nesting locations may be the result of a trade-off between conflicting selection pressures such as foraging efficiency (better in shallow waters) and nest predation risk (greater in shallow waters).

Influence of Nesting Location on Movements and Survival of Juvenile Saker Falcons Falco cherrug During the Post-Fledging Dependence Period 
Md Lutfor Rahman, Nyambayar Batbayar, Gankhuyag Purev-Ochir, Mark Etheridge and Andrew Dixon

We used patagial tags, VHF radio transmitters, and satellite-received transmitters to investigate the movements and survival of juvenile saker falcons fledged from artificial nests in open landscapes and natural nest sites in hilly areas in Mongolia. During the post-fledging dependence period (PFDP) juveniles progressively moved farther from their nest until dispersal from the natal area. Natal home ranges were larger for juveniles fledged at artificial than natural sites and the distance moved by juveniles during PFDP was positively related to fledging date and brood size. Duration of the PFDP was estimated as 40 days (range: 31–52 days). Over the PFDP, the best-fitting model to explain juvenile survival incorporated fledging date and nest site type, with juvenile survival being higher in early fledged broods from natural sites. Predation was identified as a major cause of mortality, especially in open landscapes where artificial nests were located. However, because artificial nests produced more fledglings, we found that overall productivity of juveniles to dispersal at artificial and natural nests sites did not differ significantly.

Effect of Age, Colony of Origin and Year on Survival of Yellow-Legged Gulls Larus michahellis in the Bay of Biscay
Leire Juez, Asier Aldalur, Alfredo Herrero, Aitor Galarza and Juan Arizaga

We studied sources of variation in apparent local survival of yellow-legged gulls ringed as chicks in a number of colonies with different size trends. Specifically, our aim was to test whether individuals hatched in colonies with decreasing population trends had lower survival rates than those from stable or increasing colonies. From 2006 to 2013, 3,024 chicks were colour-ringed in four colonies along the coast of the Basque Country (from east to west): Ulia, Santa Clara, Guetaria and Izaro. Sighting data of these gulls were compiled from August 2006 to June 2013. Cormack-Jolly-Seber models with mixtures were used to estimate apparent survival (hereafter, survival). Overall, survival differed between two age classes (first-year birds < older birds), colony of origin and in relation to year. The Izaro colony, one of the decreasing colonies, showed the lowest survival rate. However, survival was observed to be reasonably high in another declining colony. Hence we did not find a general link between survival and colony trends. Survival did not seem to be affected by colony size and we did not find evidence supporting a decrease in survival across the study period. More research is needed to disentangle factors explaining variation in local survival in yellow-legged gulls.


Sparrow Plagues in Extremadura (Western Spain) Over Four Centuries (1501–1900): A Spatio-Temporal Analysis of Records From Historical Archives
Luis M. Torres-Vila, Juan J. Ferrero-García, Daniel Martín-Vertedor, Francisco J. Moral-García, Pedro P. Bueno, Juan Morillo-Barragán, Álvaro Sánchez-González and F. Javier Mendiola

Some bird species can cause crop damage but the historical variation in the incidence of such events is poorly documented. We analyse the spatio-temporal variation of damage attributed to sparrows (Passer domesticus, P. hispaniolensis and/or P. montanus) at a regional scale in Extremadura (western Spain) over four centuries (1501–1900). Textual data were extracted from historical documentary sources using over 12,000 Books of Accords (Libros de Acuerdos) belonging to 203 municipal archives. Sparrow agricultural damages were estimated from reported actions to control sparrow populations and two simple indices were constructed to analyse the spatial (PIM) and temporal (PIY) variation in sparrow plagues. We used these indices to fit geostatistical models and analyse time curves. We found 251 accords reporting sparrow plagues, distributed across 236 years and involving 47 municipalities. Most of these reports (97.2%) were mandatory impositions (repartimientos) on residents to deliver a certain number of dead sparrows within a fixed period, under penalty of a fine or imprisonment. Results show a significant spatio-temporal variation in sparrow plagues, which we tentatively relate to dynamic environmental and agroecological factors. The spatial index showed high values (PIM > 4) in certain cereal-producing areas, among which La Raya zone located in western Badajoz province was the best example. The temporal index reached maximum values (PIY = 7.3) in the mid 18th century (1741–1770), probably because this was a milder period (within the so-called Little Ice Age) coinciding with increased food availability for birds. In addition, we also examine some sociopolitical, economic and historical features that could have shaped the plague indices. We particularly discuss the normative and legislative developments (e.g. mandatory impositions), the municipal activity itself (affected by wars and other historical events) and the bird conservation interest (which flourished during the final quarter of the 19th century). We conclude that textual data-based indices provide a suitable historical perspective of the agricultural impact of sparrows in Extremadura and of human perceptions of them.


Key Factors Controlling the Metapopulation Dynamics of the Little Grebe Tachybaptus ruficollis in an Artificial Habitat Network of Irrigation Ponds
Esther Sebastián-González, Karen Luisa Alexander, José Antonio Sánchez-Zapata and Francisco Botella

Most applied metapopulation studies have focused on habitat structures that are the result of landscape fragmentation but few have studied the dynamics in newly created patches. In artificial habitats, factors determining habitat quality can become especially relevant. Here, we studied the dynamics of linked populations of the little grebe Tachybaptus ruficollis inhabiting a group of irrigation ponds, sited and designed purely for agricultural purposes. We used five years of detection/nondetection data to parametrise incidence function models, in order to analyse the metapopulation dynamics of the species. We aimed to detect the role of pond size, isolation and intrinsic pond characteristics related to the habitat quality (i.e. pond construction design) in determining pond colonisation, extinction and turnover rates. We also used repeated surveys during one year to calculate detection probability of the species in the system. The incidence function model used accurately predicted the proportion of irrigation ponds occupied and detection probability was high (0.88). Little grebes inhabiting the irrigation ponds performed as a metapopulation with extinction events related to pond size and colonisation events related to pond construction design but unaffected by isolation factors. Our simulations highlight the importance of pond construction design in the persistence of the metapopulation and show a simple method for studying the dynamics of a population using detection/non-detection data.

Fledgling Productivity in Relation to Diet Composition of Tengmalm's Owl Aegolius funereus in Central Europe
Markéta Zárybnická, Bohuslav Kloubec, Ján Obuch and Jan Riegert

Based on 52 nesting attempts of Tengmalm's owl Aegolius funereus in the Šumava Mountains (South Bohemia, Czech Republic), in habitats comprised mainly of Norway spruce forests, we investigated the relationships between diet composition and fledgling productivity of this owl. We found that (i) owls feed mainly on Sorex shrews (39%), Microtus voles (19%), Apodemus mice (15%), bank voles Myodes glareolus (14%) and birds (6%), (ii) the percentage of Apodemus mice, as well as the percentage of Myodes glareolus, negatively correlated to the percentage of Sorex shrews and birds in the owls' diet, and (iii) the fledgling productivity of the owls positively correlated to the percentage of Apodemus mice in the diet. Finally, (iv) the percentage of Microtus voles, the second most common prey, exhibited no close relationships with other prey groups or fledgling productivity of the owls. These results suggest that Apodemus mice were an important prey in the diet of the Tengmalm's owl in our study area, and support the theory that, compared to their northern counterparts, nocturnal raptors in Central Europe may be less dependent on Microtus voles due to the increased diversity of available prey species.

Phenological Parameters of a Bluethroat Luscinia svecica azuricollis Population Breeding at High Altitude in Spain
Juan Arizaga and Daniel Alonso

Bluethroats Luscinia svecica azuricollis breeding in Spain belong to a poorly known endemic subspecies that is restricted to a relatively small distribution range. We aimed to present information on some basic life-history parameters from a population breeding at high altitude in central Spain. In particular, we wanted to answer the following questions: (1) When do these birds reach their breeding area, and when do they depart? (2) When do chicks appear in the population? (3) Do adult birds reach their breeding area with extra fuel? Do they depart from their breeding areas with fuel? (4) Do they moult within their breeding area? To answer these questions we used ringing data of birds captured during 2011 at La Covatilla, Salamanca province. Adults were caught mostly from May to July (no captures in August, 2.4% of adults in September). First-year bluethroats, however, appeared in June and remained in the zone up to September. Moulting adults (66% of 12 birds in total) were caught only in July. Moulting first-year birds were caught from July to September. The percentage of moulting firstyear birds in relation to all captures in August and September was comparatively low (10% in both months) relative to July (40%), indicating that most birds underwent their post-juvenile moult shortly after fledging. Body condition (residual body mass) did not differ between age classes and months. We detected no evidence suggesting fuel accumulation before the autumn migration. Thus, if the population needs to gain fuel for this migration, this must happen elsewhere.

Isolation and Characterisation of Eight Microsatellite Markers of the Thorn-Tailed Rayadito Aphrastura spinicauda
Diego I. Yáñez, Verónica Quirici, Gabriel J. Castaño-Villa, Elie Poulin and Rodrigo A. Vásquez

Eight novel microsatellites were isolated and characterised in the thorn-tailed rayadito Aphrastura spinicauda in order to evaluate genetic diversity in three contrasting populations, two of them at the boundaries of the geographic range of the species. All loci were found to be polymorphic and 3–15 alleles were found per locus. Expected and observed heterozygosity ranged from 0.26 to 0.89 and from 0.27 to 0.87, respectively. Global and pairwise Weir and Cockerham's Fst showed that genetic differentiation was greater between the northern population and the ones in central and southern Chile. The eight markers developed will be useful to study the genetic diversity of the thorn-tailed rayadito across its distribution.

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