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Friday, 8 January 2016

Ardeola December 2015: Volume 62, Issue 2

Published by: Spanish Society of Ornithology/BirdLife

Table of Contents
Dec 2015 : Volume , 62 Issue 2 


Dispersal of the Central European Population of the Eurasian Spoonbill Platalea leucorodia
Csaba Pigniczki and Zsolt Végvári

Using the Hungarian spoonbill colour-ringing scheme database, which spans 12 years of 11 cohorts (2003–2013), we clarify dispersal patterns of spoonbills in the Carpathian Basin, a part of the Pannonian biogeographical region. We found that during the course of one year, approximately 25% of adult spoonbills disperse and are seen 100 km beyond their natal area. However, this rate is roughly 20% if we analyse only the core of the breeding season (May and June). The extent of dispersal in the Hungarian population is greater than that in the Atlantic population, where the proportion of birds showing natal site fidelity is higher. This finding could be explained by increased unpredictability in the Carpathian Basin in the temporal and spatial distribution of food resources and in the water- supply of wetlands, as well as in conditions at breeding locations there. These factors may also explain the high dispersal rate of adults in continental wetland habitats compared to coastal ones. Furthermore, the minimum distance to natal colony decreased with increasing age of age groups when age group was included as a categorical variable, indicating that immature birds in the pannonian spoonbill population tend to disperse further than adults. This also implies a higher degree of fidelity to natal areas among adult individuals. Our data show that post-fledging dispersal of juveniles starts from late May and is non-directional, and at least 12% of all ringed individuals were seen 100 km from their natal colonies before their autumn migration. The occurrence of a large number of long-distance dispersers of all age groups in the Carpathian Basin suggests the need for ongoing wetland restoration at landscape scales.

Differential Migration in the Common Chiffchaff Phylloscopus collybita: Sub-Saharan Wintering Grounds Host More Adults and Females as Well as Birds of Larger Size and Better Physical Condition
Rubén Moreno-Opo, Gorka Belamendia, Pablo Vera, Alejandro Onrubia, Alberto Monteagudo and Javier de la Puente

Avian migration strategies may include intra-specific variations, also known as differential migration. These migratory adaptations between conspecifics are particularly important given their implications for population dynamics. We aimed to examine the differential migration pattern as a function of age and sex, and whether this pattern also determines body morphology, in a passerine whose migration strategy includes movements to both pre- and sub-Saharan wintering areas. Thus, 1,100 common chiffchaffs Phylloscopus collybita were sampled during 2009–2012 at eight wintering locations within the Palearctic and Afrotropical regions. Biometric and body condition variables were studied for their relationship to geographical, climatic and productivity indexes. A higher proportion of adults and females were observed at lower latitudes. Common chiffchaffs were larger and in better body condition in sub-Saharan areas, coinciding with greater plant productivity and less annual rainfall. The selection of the southernmost areas by adults may be related to fidelity to more favourable sites. Southern and coastal locations offer better conditions for chiffchaffs, despite the challenges involved in crossing the Sahara Desert. Moreover, the greater skills of adults in finding abundant food resources may also drive greater relative abundance south of the Sahara. Greater body mass and fat deposits in birds wintering in sub-Saharan areas reflect higher resource availability and may imply that the birds are in better physical condition.

Migratory Connectivity in European Bird Populations: Feather Stable Isotope Values Correlate with Biometrics of Breeding and Wintering Bluethroats Luscinia svecica
Juan Arizaga, Daniel Alonso, José A. Cortés, Ton Eggenhuizen, Julien Foucher, Dieter Franz, Javier García, Fred Koning, Michel Leconte, Hamid Rguibi, Thijs Valkenburg, Pablo Vera and Keith A. Hobson

Understanding the migratory connectivity of migrant species is fundamental to their effective conservation. Analysis of individual traits that can vary geographically, such as biometrics and stable isotopic values of tissues, can help establish migratory connections. The bluethroat Luscinia svecica is a species of conservation concern in Europe (Annex I Birds Directive). Our aim was to identify the possible migratory connectivity of bluethroats Luscinia svecica breeding in central and western Europe (subspecies L. s. namnetum, L. s. azuricollis and L. s. cyanecula in part) with their wintering areas in southern Europe and Africa using biometric and stable isotopic (δ2H) analyses. Overall, the morphological and stable isotopes analyses provided two clusters of localities, one for the Atlantic French, Portuguese and Moroccan localities, corresponding to the breeding and winter quarters of L. s. namnetum, and another for the remaining localities (Spain, The Netherlands, Germany and Senegal), corresponding to the ranges of L. s. azuricollis and L. s. cyanecula. Migratory connectivity of L. s. namnetum is strong but it is much weaker for the other two subspecies. Biometric data were positively correlated to the stable isotope values, suggesting that the results derived from both methodological approaches lead to similar conclusions.

Estimating the Abundance and Habitat Selection of Conservation Priority Marsh-Dwelling Passerines with a Double-Observer Approach
José JimÉNez, Rubén Moreno-Opo, Manuel Carrasco and Jordi Feliu

Monitoring bird populations is essential for the proper management of natural areas, since birds serve as indicator species to assess the conservation status of ecosystems. Therefore, it is important to estimate population sizes using methods of the highest possible accuracy and reliability. In this study, the populations of three marsh-dwelling passerines were sampled in the Tablas de Daimiel National Park (central Spain) during the breeding season, using a double independent observer technique. Data analysis was performed using a hierarchical Bayesian model with covariates that can simultaneously determine the population size and detectability, as well as factors that significantly affect both parameters. The presence of the two most threatened species, the reed bunting Emberiza schoeniclus witherbyi and the moustached warbler Acrocephalus melanopogon, was significantly and positively related to the coverage of fen sedge Cladium mariscus, an indicator species for waters of high quality and low fluctuation in depth. The bearded parrotbill Panurus biarmicus was the most generalist species with no positive association with any of the studied variables. The moustached warbler was more readily detectable until the beginning of May and early in the morning.

Factors Affecting Red-Legged Partridge Alectoris rufa Abundance on Big-Game Hunting Estates: Implications for Management and Conservation
A. J. Carpio, J. Oteros, J. Vicente, F. S. Tortosa and J. Guerrero-Casado

The red-legged partridge Alectoris rufa is not only the most important bird game species but also an important prey species for many predators in Iberia. However, its populations have significantly declined in recent decades, principally as the result of agricultural intensification on arable land. Its abundance has also undergone a significant decline in forested areas over the last few decades, where wild ungulate management and abundance have increased. In this scenario, we aimed to test the factors that affect red-legged partridge abundance in relation to high wild ungulate (wild boar and red deer) abundance in south-central Spain. The factors included as predictors were carnivore, wild boar and red deer abundances, vegetation features, nest predation rate and invertebrate availability. Red deer abundance showed a negative relationship with partridge abundance in spring (non-significant negative trends were also evident for carnivore and wild boar), whereas variables related to food availability (grass biomass, Hemipteran abundance and total invertebrate mass) had a positive effect in the same season. Moreover, deer and carnivore abundances and spring nest predation rate were negatively associated with partridge abundance in autumn. Plant biomass and Hemipteran abundance were negatively correlated with wild boar abundance, whereas maximum pasture height was negatively related to red deer and wild boar abundance. Overall, our results show that high ungulate densities may negatively affect partridge abundance, which may be mediated by (i) a reduction in food availability (invertebrate and herbaceous plant biomass) and (ii) nest predation by wild boar. This research has shown that current intensive big-game hunting management schemes in south-central Spain are often incompatible with red-legged partridge conservation, and that these effects should be taken into account when defining big-game management and conservation policies.

Individual and Geographical Variation in the Territorial Calls of Tawny Owls Strix aluco in Eastern Europe
Sergey Mikhailovich Shekhovtsov and Alexander Viktorovich Sharikov

Territorial calls (hooting) of two tawny owl subspecies, Strix aluco aluco (the eastern European subspecies) and Strix aluco willkonskii (the Caucasian subspecies), were recorded from October 2007 to February 2013, to study variation between individuals and subspecies. Calls of the eastern European subspecies were recorded in Moscow region (Russia) and “Gomolshanskie Lesa” National Park (Ukraine). Males of the Caucasian subspecies were recorded in “Bolshoi Utrish” Reserve and “Sochinskii” National Park (Russia). The territorial calls of the eastern European and Caucasian subspecies are compared for the first time. The discriminatory accuracy of individual calls reached 98% for S. a. aluco and 77% for S. a. willkonskii when accounting for six frequency and temporal parameters of their call. We found the call of the two subspecies to differ in half of the acoustic parameters considered, suggesting that macrogeographic variation between the Eastern European and Caucasian subspecies may have taken place.

Long-Term Variation in Laying Date and Clutch Size of the Great Tit Parus major in Central Poland: A Comparison between Urban Parkland and Deciduous Forest
Jarosław Wawrzyniak, Adam Kaliński, Michał Glądalski, Mirosława Bańbura, Marcin Markowski, Joanna Skwarska, Piotr ZielińSki, Iwona Cyżewska and Jerzy Bańbura

Numerous studies from different locations in Europe show that nest-box populations of tits in urban areas lay earlier and produce fewer eggs than do tits in rural areas. We collected data on laying dates and clutch size in two great tit Parus major populations nesting in oak deciduous forest and urban parkland areas, only about 10 km apart, in central Poland over 11 years. The abundance of caterpillars, the optimal food of breeding tits, at both breeding areas was also quantified. We analysed long-term trends in the timing of egg laying and clutch size. We focused on the effects of year, habitat type, insect availability and weather conditions shortly before egg laying on the patterns of variation in laying date and clutch size. In general, our study supports earlier generalisations on urban and rural tit populations. In particular, our finding that great tits initiated breeding consistently earlier in the urban site than in the forest area supports earlier studies on urbanised birds. The mean laying date was strongly and negatively associated with air temperature between 15 March and 15 April in both habitats. Mean clutch size was lower in the parkland than in the forest population, at least partly in response to the greater abundance of caterpillars in the forest. A novel result of this study is that clutch size differed between habitats to a varying degree in different years, in association with a stronger response to caterpillar abundance in the forest than in the park. Clutch size tended to decline with the progress of the breeding season within years in the parkland site, especially in “early years”, but not in the forest habitat.

Nest Building by Monk Parakeets Myiopsitta monachus in Urban Parks in Buenos Aires, Argentina: Are Tree Species Used Randomly?
Ivana P. Romero, Mariano Codesido and David N. Bilenca

The monk parakeet Myiopsitta monachus is a very successful invasive species and a worldwide agricultural pest. Knowledge of its nest tree selection could be a valuable pest control tool, given that its population expansion could be more effectively controlled by reducing potential nest tree availability. In this study we describe monk parakeet use and selection patterns of nest trees in five parks in Buenos Aires, Argentina. The species and structural characteristics of each nest tree was recorded. A census of potential nest trees was also performed to calculate Savage's selectivity index for each tree species. We found 128 parakeet nests in 60 trees. The tree species selected by monk parakeets were cedars Cedrus atlantica, araucaria pines Araucaria sp. and palms (Butia capitata,Washingtonia robusta, Syagrus romanzoffiana, Phoenix sp.). Cedars were particularly selected as nest trees: they supported 40% of all nests and held more nests per tree than any other species. This is the first study to reveal that cedars and araucarias are selected by monk parakeets. Nest tree selection is a context-dependent process and it is guided by tree species and their structural characteristics and phenology. According to our findings, it would be advantageous to implement a careful selection of the tree species to be planted in Buenos Aires City parks and in urban areas elsewhere, in order to properly manage potential human-bird conflicts.


Male-Biased Sex-Ratio of Dunlins Calidris alpina in the Gulf Of Gdańsk (Southern Baltic) During Autumn Migration
Włodzimierz Meissner

This long-term study (10 years) aimed to check if the sex-ratio of dunlins Calidris alpina at a stopover site in the southern Baltic region was biased. Two age classes among non-juvenile dunlins were recognised: immatures (2nd calendar year) and adults (> 2nd calendar year). There was a significant male bias in the sample of 4,406 non-juvenile dunlins captured during their southward migration. Overall, 60.3% of immatures and 59.4% of adults were males. Particularly among adults, the proportion of males increased significantly after the start of autumn migration. The annual sex-ratios were consistently male biased, but varied somewhat and fluctuated in parallel for adults and immatures. One plausible explanation for the male bias is that males and females differ in migration strategy. Females may make longer flights and avoid stopover sites with unpredictable feeding conditions, such as the southern Baltic coasts, which provide low quality habitat. Assuming a balanced non-juvenile population sex ratio, the ‘missing’ females could stopover elsewhere in the Baltic or fly directly to the tidal areas of the Wadden Sea. The sex ratio in the study area may depend on wind conditions during the early phase of autumn migration. In some years, adverse weather may force more females than usual to stopover in the study area.

Spatio-Temporal Overlap between Local and Non-Local Reed Warblers Acrocephalus scirpaceus During the Autumn Migration Period
Nerea Pagaldai and Juan Arizaga

During the autumn migration period, northern populations commonly reach southern stopover sites where they meet conspecifics that may still be breeding or at least still at their breeding sites. Establishing whether local breeding birds overlap temporally with migrants is essential to studying the strategies adopted by the former when they have to suddenly cope with conspecific influxes. Our objectives here were (1) to establish the phenology of local and transient birds within the study area and (2) to test whether biometrics can differentiate between these two groups. Local reed warblers were observed nesting until the end of July; these birds were recaptured up to late August (although very few later than mid-August), suggesting that at least some individuals depart from the area before most nonlocals arrive. Local breeding birds were found to have longer wings than non-locals. A discriminant function classified 73.4% of the non-local and local reed warblers correctly, indicating considerable morphological overlap between the two groups.

Dispersal and Survival of Juvenile Black Vultures Aegypius monachus in Central Spain
Juan P. Castaño, Juan F. Sánchez, Miguel A. Díaz-Portero and Mónica Robles

We studied initial dispersal of juvenile black vultures Aegypius monachus from 2010 to 2012 in Castilla-La Mancha (central Spain) by using GPS satellite transmitters. Our aim was to get information about dispersal areas and home ranges and to study possible differences in dispersal behaviour according to sex and marking circumstances (as nestlings or released from care). We found large differences between individuals, especially with respect to dispersal distances and the areas most used during dispersal. However, we found no differences between the areas mostly used and those used by other satellite-tracked individuals from other Iberian populations. Furthermore, we did not find significant differences for home ranges or dispersal distances related to sex or marking circumstances (nestling / released). Birds marked as nestlings used different areas from those used by released birds. Juveniles usually remained close to the main breeding areas. Finally, survival rates were very high both during the first year (0.92) and second year (0.70). Five birds were found dead up to July 2014, three of which had been poisoned.

Parasitism by Botflies Philornis Sp. on European Starlings Sturnus vulgaris, an Exotic Bird in Argentina
Lucía M. Ibañez, Vanina D. Fiorini, Diego Montalti, Osvaldo Di Iorio and Paola Turienzo

We studied the parasitism of the exotic European starling Sturnus vulgaris by native botflies Philornis spp. in Argentina. We installed thirty nest boxes in the northeastern Buenos Aires province in the 2010–2011 breeding season. In the first brood, subcutaneous larvae of Philornis (Muscidae) parasitised 34 nestlings (89.4%) of 11 clutches (91.6%) and only three nestlings fledged. In the second brood, Philornis parasitised 15 (48.3%) nestlings of seven clutches (70%) and all the nestlings died. Compared to the mortality of other Neotropical birds parasitised by Philornis, the mortality in European starling nests is the highest found in the region. Our results show that the studied population of European starling suffers a high level of parasitism by Philornis, although this factor was not directly associated with the high mortality of starling nestlings. The fact that most non-parasitised nestlings also died indicates that other factors are also affecting nestling survival. Experiments that allow us to isolate the effect of Philornis from other variables would be needed to evaluate the impact of botfly larvae on starling nestlings.

The Iberian Peninsula is an Area of Infection by Haemoproteus payevskyi and Haemoproteus nucleocondensus for the White-Throated Dipper Cinclus cinclus
M. Ángeles Rojo, M. Ángeles Hernández, Francisco Campos, Tomás Santamaría, Susana Dias and Patricia Casanueva

Investigating the spatial distribution of avian blood parasites can shed light on the occurrence of host switching and expansion in new territories, two key factors for which to account when addressing future parasite impacts on vertebrates. We examined the mitochondrial cytochrome b lineages of haemosporidians infecting the white-throated dipper Cinclus cinclus in order to assess their distribution across five mountains in the Central Iberian Peninsula and the possible implications of lineage transmission in that geographical context. Of 71 host individuals, 79.6% were infected with Haemoproteus spp., 0.9% with Plasmodium spp. and 19.5% with Leucocytozoon spp. We identified seven lineages from genus Haemoproteus spp. (four were novel), one lineage of Plasmodium spp. and nine of Leucocytozoon spp. (five previously undescribed). Only two of the Haemoproteus lineages (RW1 and MW1) showed widespread distribution across the study sites whereas the novel lineages each corresponded to a single area. Given the non-migratory behaviour of the host species in the region, our results provide the first proof of LeucocytozoonWW6 lineage transmission within Europe. Furthermore, this study is the first to reveal the transmission in Europe of Haemoproteus payevskyi and Haemoproteus nucleocondensus, corresponding to the identified RW1 and GRW01 lineages respectively. Both findings support the idea that these lineages could be transmitted year-round transcontinentally.

Daily Survival Rates of Eggs in Artificial Ground and Shrub Bird Nests on Small Adriatic Islands
Jenő J. Purger, Eduard Kletečki, Balázs Trócsányi, Jasmina Mužinić, Gabriella L. Széles and József Lanszki

Predation may cause important losses to the biodiversity of small islands. In this study we analysed the predation pressure on clutches of nesting birds in two islands of the Zadar Archipelago, Olib and Silba, which belong to an Important Bird Area (IBA) in Croatia. We paid special attention to introduced mammals: black rats Rattus rattus and feral domestic cats Felis silvestris catus. In May 2009, we carried out a study with artificial ground and bush nests. One quail egg and a plasticine egg of similar size were placed in each nest. On Olib, the daily survival rate of quail eggs in ground nests (0.92) was similar to that of nests located in shrubs (0.93), whereas on Silba the daily survival rates of quail eggs in ground (0.94) and shrub nests (0.86) were significantly different. We used the marks left on the plasticine eggs to identify nest predators. Many eggs in shrub nests (40% on Olib and 70% on Silba) were predated by hooded crows Corvus cornix. In ground nests on Olib, 43% of eggs were predated by hooded crows and small mammals, mainly black rats. On Silba Island, eggs in 33% of the ground nests were damaged by the above predators and also by the Montpellier snake Malpolon monspessulanus. Contrary to our expectations, feral cats were not found to be egg predators on either of the islands.


The Apparent Contradictions in the Ratification by Spain of the 1950 International Convention for the Protection of Birds
Juan José Ferrero-García

This paper studies the ratification by Spain, in 1955, of the 1950 Convention for the Protection of Birds. This international agreement established a general protocol for the protection of all wild birds, although it included some exceptions for the capture of certain species that could be harmful to agriculture or hunting, through requesting individual authorisations. I have analysed the possible reasons why the Spanish Government accepted the 1950 Convention at the same time as it passed a law that supported the indiscriminate elimination of different animals that were considered harmful. This latter law, which included most diurnal raptors, had severe consequences for the avifauna. Bibliographic research allows me to suggest that perhaps these seemingly contradictory actions were not casually made. Both originated from the same people and official government departments, whose new utilitarian orientation lacked scientific expertise and usually depended on forestry and hunting management, and the sociopolitical circumstances of the time. Furthermore, the 1950 Convention's own limitations could have had a negative influence, mainly due to the difficulties of implementation and the absence of institutional infrastructure to lobby States into greater involvement.

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