Oscar Gordo

... Òscar Gordo* & Xavier Ferrer, Departament de Biologia Animal (Vertebrats), Universitat de Barcelona, Av ... Ferrer & Reig (2003) re-jected this information because it was merely assumed from Companyo (1863); both Com-panyo and Vayreda were untrustworthy with re-spect to ...

ABSTRACTHost-parasite interactions play a significant role in evolution. Parasite infections impose fitness costs that can trigger trade-off responses in host reproductive strategies. Individuals can invest limited resources in parasite defense, such as stimulating the immune system, or perform terminal reproductive investment. Here, we investigated how haemosporidian co-infection and parasitemia influence different reproductive strategies in a polymorphic bird species (the white-throated sparrow, Zonotrichia albicollis). We provided an account of the impacts of co-infection and parasitemia on host reproductive success and reproductive strategies in response to parasite infection. We tested the effect of co-infection and parasitemia on reproductive success (fledgling number, extra-pair paternity, ratio social/genetic offspring) and the effect of parental infection on nestling quality (mean nestling growth rate and body condition). We found that co-infection increases reproductive ex...

espanolLa colision contra edificios es una amenaza importante para las aves, ya que causa millones de muertes en las ciudades. A pesar de la magnitud de esta mortandad, existen pocos estudios en Europa que hayan evaluado este fenomeno. Aqui se proporcionan los resultados de un estudio llevado a cabo en Tarragona durante el periodo de migracion posnupcial entre los anos 2012-2015. Durante este periodo se hicieron visitas durante 189 dias a un edificio residencial de 15 m de altura en el centro de la ciudad que tiene una fachada acristalada, caracteristica que le confiere un efecto espejo. Se encontraron 172 aves muertas o aturdidas de 15 especies, mayoritariamente migratorias. Las especies mas comunes fueron la Curruca capirotada Sylvia atricapilla, el Carricero comun Acrocephalus scirpaceus y el Papamoscas cerrojillo Ficedula hypoleuca, que representaron el 72% de la mortandad. Una vez corregido el diferente esfuerzo de muestreo realizado entre dias y anos, se estimo que el total de...

Comprehending symbiont abundance among host species is a major ecological endeavour, and the metabolic theory of ecology has been proposed to understand what constraints symbiont populations. We parameterized metabolic theory equations to predict how bird species' body size and the body size of their feather mites relate to mite abundance according to four potential energy (microbial abundance, uropygial gland size) and space constraints (wing area, number of feather barbs). Predictions were compared with the empirical scaling of feather mite abundance from 26,604 birds of 106 passerine species, using phylogenetic modelling and quantile regression. Feather mite populations were strongly constrained by host space (number of feather barbs) and not energy. Moreover, feather mite species' body size was unrelated to their abundance or to the body size of their host species. We discuss the implications of our results for our understanding of the bird-feather mite system and for sy...

Summary. Common bird monitoring schemes have become an important tool in conservation biology because they provide useful information for assessing spatial and temporal variations of bird populations. However, recorded data may suffer from several observational procedures that cause error. In recent years, a robust mathematical framework has been developed to control for potential confounding factors affecting the assessment of the actual spatial and temporal variability of bird populations. Surprisingly few attempts have been made to check the effectiveness of current methodology empirically and thus to determine to what extent monitoring scheme data can provide accurate estimates of actual bird abundances. To check the effect of intra-annual variability of bird counts, I conducted daily surveys of House Martin Delichon urbicum and Common Swift Apus apus populations along a 2-km transect line in Tres Cantos (Madrid, Spain) between March and September 2005. The data recorded perfect...

Un solo edificio de la ciudad de Tarragona se ha convertido en un auténtico sumidero para las aves, no ya urbanas, sino también en paso migratorio. La superficie reflectante de su fachada provoca abundantes colisiones y una mortandad que ha podido evaluarse gracias a un estudio iniciado en 2012.

Brood parasitized and/or colonial birds use egg features as visual identity signals, which allow parents to recognize their own eggs and avoid paying fitness costs of misdirecting their care to others’ offspring. However, the mechanisms of egg recognition and discrimination are poorly understood. Most studies have put their focus on individual abilities to carry out these behavioural tasks, while less attention has been paid to the egg and how its signals may evolve to enhance its identification. We used 92 clutches (460 eggs) of the Eurasian coot Fulica atra to test whether eggs could be correctly classified into their corresponding clutches based only on their external appearance. Using SpotEgg, we characterized the eggs in 27 variables of colour, spottiness, shape and size from calibrated digital images. Then, we used these variables in a supervised machine learning algorithm for multi-class egg classification, where each egg was classified to the best matched clutch out of 92 st...

Deuterium composition of feathers has been widely applied to establish provenance of birds. Surprisingly, little attention has been paid to the potential sources of unwanted hydrogen isotopic variability that may affect the comparability and replicability of deuterium measurements. Feathers may exhibit hydrogen isotopic differences between distal and proximal sections, as well as between rachis and vane. For this reason, it is recommended to always analyse ground vane from the same section of the feather. However, this protocol may be seriously limiting when working with songbird feathers, which are usually small and light. In this paper, intra-feather hydrogen isotopic variability was studied in four species of songbirds by comparing four sections of the same feather. No difference in hydrogen isotopic composition was found between distal and proximal sections of the vane. This was expected as songbird feathers grow rapidly and individuals avoid geographical movements during moult, favouring a homogeneous source of hydrogen during keratin synthesis. Conversely, as previously demonstrated for other avian species, rachis showed systematically c. 11‰ δ 2 H more negative values than vane. This is probably a result of their biochemical and ultrastructural differences, which seem strongly conserved across taxa. Such differences imply that we need to describe which feather part was used in the methods of our reports to ensure full comparability and replicability among studies. Nevertheless, vane and rachis δ 2 H were strongly correlated, demonstrating that rachis can be also used in isotope analyses because its δ 2 H can be accurately rescaled. This is useful since rachis represents an important fraction of feather mass in songbirds. Values of δ 2 H from ground and non-ground samples from the same feather were also compared. There was no effect of the processing protocol, suggesting that grinding is unnecessary when working with passerine feathers. Messungen stabiler Wasserstoffisotopen in Singvogel-Federn: Effekte der Intra-Federn-Variabilität und Probenverarbeitung Die Deuteriumzusammensetzung von Federn wird üblicherweise eingesetzt, um die Herkunft von Vögeln festzustellen. Überraschenderweise wird dabei aber nur wenig auf potenzielle Quellen einer unerwünschten Wasserstoffisotopen-Variabilität geachtet, die die Vergleichbarkeit und Wiederholbarkeit der Deuteriummessungen beeinflussen können. Federn können zwischen ihren distalen und proximalen Abschnitten sowie zwischen Wirbelsäule und Flügeln Unterschiede in den Wasserstoffisotopen aufzeigen. Deshalb empfiehlt es sich, Analysen stets von den gleichen Federabschnitten zu machen. Diese Regel führt jedoch bei Singvogelfedern zu einer ernsthaften Einschränkung, weil diese normalerweise klein und leicht sind. In dieser Studie untersuchten wir bei vier Singvogelarten die Wasserstoffisotopen-Variabilität in den gleichen Federn, indem vier Abschnitte derselben Feder verglichen wurden. Zwischen dem distalen und proximalen Abschnitt desselben Flügels wurden keine Unterschiede in der Wasserstoffisotopen-Zusammensetzung gefunden. Das war erwartet worden, weil Singvogelfedern schnell wachsen und die einzelnen Tiere Ortsveränderungen während der Mauser vermeiden und somit während der Keratin-Synthese eine homogene Wasserstoffversorgung haben. Andererseits, wie schon früher für andere Vogelarten festgestellt, zeigt der Schaft systematisch ca. 11‰ δ 2 H mehr negative Werte als die Federfahne. Vermutlich liegt das an biochemischen und ultrastrukturellen Unterschieden, die sich durch alle Taxa hindurchziehen. Diese Unterschiede machen es empfehlenswert, immer anzugeben, welche Federabschnitte verwendet wurden, um eine volle Vergleichbarkeit und Wiederholbarkeit der Untersuchungen zu gewährleisten. Nichtsdestotrotz korrelierten die δ 2 H von Schaft und Fahne hoch miteinander und zeigten, dass auch der Schaft für die Isotopenanalyse benutzt werden kann, weil seine δ 2 H-Werte entsprechend korrekt skaliert werden können. Das ist deshalb sehr hilfreich, weil bei Singvögeln der Schaft einen wichtigen Anteil der gesamten Federmasse darstellt. Die δ 2 H-Werte von zermahlenen und nicht zerkleinerten Proben der gleichen Federn wurden ebenfalls untersucht und kein Unterschied festgestellt, was nahelegt, dass bei der Arbeit mit Singvogelfedern ein Zermahlen der Federn unnötig ist.

Summary. The Iberian Chiffchaff Phylloscopus ibericus has recently been accepted as a full species, but is still very difficult to distinguish from the Common Chiffchaff P. collybita when molecular and acoustic evidence is lacking. Distinguishing these cryptospecies is essential for obtaining accurate population estimates for each, which is especially important in the case of the Iberian Chiffchaff due to its restricted distribution. We re-assessed the discriminant methods available in the literature and propose some alternative traits to distinguish both species. We used information from 24 morphological traits measured in c. 6,700 individuals of the two species trapped during the autumn migration period in Doñana National Park, Spain, between 2004 and 2015. Discriminatory methods available in the literature were unable to distinguish the two species efficiently. Despite some biometric differences, morphological measurements showed a high degree of overlap and so could not distinguish between Iberian and Common Chiffchaffs. The best discriminatory factor at our study site was the passage date, since 90% of Iberian Chiffchaffs have already departed when the first Common Chiffchaffs arrive. Those traits associated with migration, such as wing size and shape and fat deposits, were also able to discriminate the species, albeit weakly. This result fully concurs with the trans-Saharan migration of the Iberian Chiffchaff in contrast to the Common Chiffchaff, which chiefly winters in Mediterranean latitudes. In conclusion, biometric traits are useless for discriminating the two species and we do not recommend their use. A comprehensive examination of colouration and plumage seems to be the only reliable way of guaranteeing the correct identification of these species in the hand.

Biodiversity is threatened by the growth of urban areas. However, it is still poorly understood how animals can cope with and adapt to these rapid and dramatic transformations of natural environments. The COVID-19 pandemic provides us with a unique opportunity to unveil the mechanisms involved in this process. Lockdown measures imposed in most countries are causing an unprecedented reduction of human activities giving us an experimental setting to assess the effects of our lifestyle on biodiversity. We studied the birds’ response to the population lockdown by using more than 126,000 bird records collected by a citizen science project in north eastern Spain. We compared the occurrence and detectability of birds during the spring 2020 lockdown with baseline data from previous years in the same urban areas and dates. We found that birds did not increase their probability of occurrence in urban areas during the lockdown, refuting the hypothesis that nature has recovered its space in hum...

Life cycles of animals and plants worldwide are shifting in response to recent climate change. Macroecology, which deals with biological patterns and processes at a large scale, is ideally suited to address this global phenomenon, thus providing a more general and generalizable understanding of the impacts of climate change on ecosystems. To date, a macroecological approach to examining phenological changes based on historical ground observations remains mostly unexplored, as the phenological studies have been conducted at local scales, while the recent new technologies, e.g., remote sensing, can extend phenological study to global scales. Because phenology is probably the most widely used bioindicator of climate change, thus allowing for studies at the macroscale. Some meta-analyses have indeed employed broad-scale, long-term datasets to estimate overall shift rates in the timing of plant and animal phenological events. However, none has provided a convincing macroecological view of current phenological shifts, and few attempts have been made to make global-scale predictions of phenological responses under future climatic scenarios. Understanding spatial variability and clines may be essential for comprehending phenological variations stemming from future climate change. Here, we discuss how ecological mechanisms discovered in macroecology may provide new insights for understanding spatial variation of sensitivity of phenology to climate change.

Sexes cannot be distinguished with certainty by human observers in many avian species. However, some apparently monomorphic species have small but measurable sexual dimorphisms in biometry, which can be used to determine sex. Here, we develop a method based on multivariate probabilities to improve sexing in three Phylloscopus species. We captured 16 124 Common Chiffchaffs (P. collybita), Iberian Chiffchaffs (P. ibericus) and Willow Warblers (P. trochilus) during postnuptial migration in the Doñana National Park (SW Spain). We estimated the probability of them being male or female based on a combination of the density distributions of wing and tarsus lengths. Density distributions were derived as two normal components of the mixture distribution in both traits. Discriminatory ability was compared under different assumptions. 95% of Common Chiffchaffs, 92% of Iberian Chiffchaffs and 87% of Willow Warblers were sexed with 95% confidence. These percentages are greater than those reported for these species using sexing methods based only on wing length. Our method was not affected by changes between years in the degree of dimorphism or mixture of populations from different geographical origins. In the Iberian Chiffchaff and the Willow Warbler, sexing was improved when our method was applied to immatures and adults separately. Sex ratio was estimated to be two females per male in the Common Chiffchaff and the Willow Warbler. In the latter species, females migrated one week later than males. Sex ratio in the Iberian Chiffchaff was 1:1. Our sexing method could be used for other species with known and apparent dimorphism or to any data set of birds with biometric measures.

Ya existen incontables evidencias que demuestran en muchos grupos taxonómicos, en muchas partes del mundo y en todo tipo de ecosistemas respuestas a los cambios experimentados por el clima durante el últmo siglo. Las aves,destacan por ser uno de los grupos en que dichas evidencias abarcan más facetas de la blologla y ecologla de las especies, desde el individuo a la población y desde la escala local a la continental.

The Common Quail is one of the most popular and economical interesting steppe-land birds. In spite of this, some aspects of its life cycle remain unfamiliar, especially those involved in wintering areas. Since 1983 a monitoring program has been conducted in a grain-producing area of NE Iberia (41º22'N, 1º15'E) at low altitude. Spring arrivals of the species were controlled by the first listened male in the study area. These individuals could be detected with high accuracy by using acoustic female calls. Firsts arrivals exhibit a strong advancement in last two decades with a rate of 0.96 days per year (r=-0.81, F(1,19)=35.5, p<0.00001). This is the first evidence about long-term changes in migratory phenology of this species and it agrees with the reported changes in most of the previous studies on trans-Saharan birds phenology during the same period. Testing the hypothesis that recent global warming may also be the cause of this advancement of spring arrival of our specie...

Sex and age classes of many seasonally reproducing organisms segregate in space and time during the non-reproductive period. Sexual segregation may arise due to differences in habitat preference, social affinity and energetic or nutritional requirements of males and females (Ruckstuhl, 2007). In bird species of the temperate zone, latitudinal sexual segregation, in which males tend to winter closer to the breeding grounds than females, appears to be a widespread phenomenon (Newton, 2008). Despite the lack of hard evidence in the form of ringing recoveries or isotopic signatures (Berthold, 2001; Newton, 2008; Coppack & Pulido, 2009), there are indications of a similar pattern for Nearctic-Neotropical (Komar et al., 2005) and Palearctic-African (Catry et al., 2005) migrants. We currently lack an in-depth understanding of the proximate mechanisms that cause sex-and age-specific differences in the timing and extent of migration (Coppack & Pulido, 2009). In one sense, research on differe...

Sex and age classes of many seasonally reproducing organisms segregate in space and time during the non-reproductive period. Sexual segregation may arise due to differences in habitat preference, social affinity and energetic or nutritional requirements of males and females (Ruckstuhl, 2007). In bird species of the temperate zone, latitudinal sexual segregation, in which males tend to winter closer to the breeding grounds than females, appears to be a widespread phenomenon (Newton, 2008). Despite the lack of hard evidence in the form of ringing recoveries or isotopic signatures (Berthold, 2001; Newton, 2008; Coppack & Pulido, 2009), there are indications of a similar pattern for Nearctic-Neotropical (Komar et al., 2005) and Palearctic-African (Catry et al., 2005) migrants. We currently lack an in-depth understanding of the proximate mechanisms that cause sex-and age-specific differences in the timing and extent of migration (Coppack & Pulido, 2009). In one sense, research on differe...

Sex and age classes of many seasonally reproducing organisms segregate in space and time during the non-reproductive period. Sexual segregation may arise due to differences in habitat preference, social affinity and energetic or nutritional requirements of males and females (Ruckstuhl, 2007). In bird species of the temperate zone, latitudinal sexual segregation, in which males tend to winter closer to the breeding grounds than females, appears to be a widespread phenomenon (Newton, 2008). Despite the lack of hard evidence in the form of ringing recoveries or isotopic signatures (Berthold, 2001; Newton, 2008; Coppack & Pulido, 2009), there are indications of a similar pattern for Nearctic-Neotropical (Komar et al., 2005) and Palearctic-African (Catry et al., 2005) migrants. We currently lack an in-depth understanding of the proximate mechanisms that cause sex-and age-specific differences in the timing and extent of migration (Coppack & Pulido, 2009). In one sense, research on differe...

Brood parasitized and/or colonial birds use egg features as visual identity signals, which allow parents to recognize their own eggs and avoid paying fitness costs of misdirecting their care to others' offspring. However, the mechanisms of egg recognition and discrimination are poorly understood. Most studies have put their focus on individual abilities to carry out these behavioural tasks, while less attention has been paid to the egg and how its signals may evolve to enhance its identification. We used 92 clutches (460 eggs) of the Eurasian coot Fulica atra to test whether eggs could be correctly classified into their corresponding clutches based only on their external appearance. Using SpotEgg, we characterized the eggs in 27 variables of colour, spottiness, shape and size from calibrated digital images. Then, we used these variables in a supervised machine learning algorithm for multi-class egg classification, where each egg was classified to the best matched clutch out of 92 studied clutches. The best model with all 27 explanatory variables assigned correctly 53.3% (CI = 42.6-63.7%) of eggs of the test-set, greatly exceeding the probability to classify the eggs by chance (1/92, 1.1%). This finding supports the hypothesis that eggs have visual identity signals in their phenotypes. Simplified models with fewer explanatory variables (10 or 15) showed lesser classification ability than full models, suggesting that birds may use multiple traits for egg recognition. Therefore, egg phenotypes should be assessed in their full complexity, including colour, patterning, shape and size. Most important variables for classification were those with the highest intraclutch correlation, demonstrating that individual recognition traits are repeatable. Algorithm classification performance improved by each extra training egg added to the model. Thus, repetition of egg design within a clutch would reinforce signals and would help females to create an internal template for true recognition of their own eggs. In conclusion, our novel approach based on machine learning provided important insights on how signallers broadcast their specific signature cues to enhance their recognisability.

En muchas especies es imposible distinguir visualmente los sexos, si bien en algunas de
ellas, machos y hembras muestran pequeñas, pero cuantificables, diferencias  biométricas que pueden usarse para discriminarlos. Este es el caso del grupo de los mosquiteros Phylloscopus, en los que se usa la longitud alar para distinguir los sexos. Hemos desarrollado un método en el que además del ala se tiene en cuenta el tarso y en el que mediante probabilidades multivariantes hemos aumentado la proporción de individuos que se pueden discriminar en tres especies: mosquitero común P. collybita, mosquitero musical P. trochilus y mosquitero ibérico P. ibericus. Además, nuestro método de sexado no tiene sesgos hacia uno de los dos sexos. El objetivo de este artículo es ofrecer una guía práctica para la implementación de nuestro método usando el software libre R.

Deuterium composition of feathers has been widely applied to establish provenance of birds. Surprisingly, little attention has been paid to the potential sources of unwanted hydrogen isotopic variability that may affect the comparability and replicabil-ity of deuterium measurements. Feathers may exhibit hydrogen isotopic differences between distal and proximal sections, as well as between rachis and vane. For this reason, it is recommended to always analyse ground vane from the same section of the feather. However, this protocol may be seriously limiting when working with songbird feathers, which are usually small and light. In this paper, intra-feather hydrogen isotopic variability was studied in four species of songbirds by comparing four sections of the same feather. No difference in hydrogen isotopic composition was found between distal and proximal sections of the vane. This was expected as songbird feathers grow rapidly and individuals avoid geographical movements during moult, favouring a homogeneous source of hydrogen during keratin synthesis. Conversely, as previously demonstrated for other avian species, rachis showed systematically c. 11‰ δ 2 H more negative values than vane. This is probably a result of their biochemical and ultrastructural differences, which seem strongly conserved across taxa. Such differences imply that we need to describe which feather part was used in the methods of our reports to ensure full comparability and replicability among studies. Nevertheless, vane and rachis δ 2 H were strongly correlated, demonstrating that rachis can be also used in isotope analyses because its δ 2 H can be accurately rescaled. This is useful since rachis represents an important fraction of feather mass in songbirds. Values of δ 2 H from ground and non-ground samples from the same feather were also compared. There was no effect of the processing protocol, suggesting that grinding is unnecessary when working with passerine feathers.

Collision with buildings is a major threat to birds that provokes the death of millions of birds every year in built-up areas. Despite its magnitude, this phenomenon remains poorly studied in Europe. We studied bird-window collisions during postnuptial migration in the city of Tarragona (NE Spain). We surveyed a 15-m-high residential building in the city centre with a reflective façade for 189 days during postnuptial periods in 2012– 2015. We found 172 dead birds belonging to 15 species, most of them migratory. Blackcaps Sylvia atricapilla, Reed Warblers Acrocephalus scirpaceus and Pied Flycatchers Ficedula hypoleuca were the commonest casualties, representing 72% of all recovered bird corpses. Once the uneven sampling effort between days and years was corrected for, we estimated that the total number of fatalities during the study period was 350 birds (SE = 22.2). However, this figure is probably an underestimate due to certain biases in sampling carcasses in a city including collection by pedestrians or removal by cleaning services and owners. Overall, there was a patent seasonal pattern to the collisions, with a peak around 1 October, probably reflecting the timing of migration in the species present at the site. There were no differences in either age, sex or biometrics between the birds found in Tarragona and those trapped on the same days at a ringing station in the Ebro Delta, 60 km to the south-west. This suggests that the probability of collision affected all migrants in a uniform fashion. Our study demonstrates for the first time that bird collisions with buildings are a serious threat to migrants in the Mediterranean, a key area for bird migration in Europe.

Key words: bird collision, glasses, reflectivity, migration, mortality, Tarragona, NE Spain.

Sexes cannot be distinguished with certainty by human observers in many avian species. However, some apparently monomorphic species have small but measurable sexual dimorphisms in biometry, which can be used to determine sex. Here, we develop a method based on multivariate probabilities to improve sexing in three Phylloscopus species. We captured 16 124 Common Chiffchaffs (P. collybita), Iberian Chiffchaffs (P. ibericus) and Willow Warblers (P. trochilus) during postnuptial migration in the Doñana National Park (SW Spain). We estimated the probability of them being male or female based on a combination of the density distributions of wing and tarsus lengths. Density distributions were derived as two normal components of the mixture distribution in both traits. Discriminatory ability was compared under different assumptions. 95% of Common Chiffchaffs, 92% of Iberian Chiffchaffs and 87% of Willow Warblers were sexed with 95% confidence. These percentages are greater than those reported for these species using sexing methods based only on wing length. Our method was not affected by changes between years in the degree of dimorphism or mixture of populations from different geographical origins. In the Iberian Chiffchaff and the Willow Warbler, sexing was improved when our method was applied to immatures and adults separately. Sex ratio was estimated to be two females per male in the Common Chiffchaff and the Willow Warbler. In the latter species, females migrated one week later than males. Sex ratio in the Iberian Chiffchaff was 1:1. Our sexing method could be used for other species with known and apparent dimorphism or to any data set of birds with biometric measures.

We analyze environmental determinants of roost site selection by tree gleaning passerines wintering in a Mediterranean montane oakwood at a craggy area of high variation in altitude and hill-shading pattern. We hypothesize that in temperate latitudes of cold winter climate, birds should spend the night in areas of low altitudes, higher temperatures, and higher solar radiation in order to minimize thermoregulation costs during resting time and to improve foraging conditions just before and after roosting. We study night occupation of woodland locations by the presence of feces in 159 wooden nest boxes (i.e., under identical controlled roosting situations). We employ GIS methods to quantify solar radiation at each location surrounding the nest boxes and data loggers to measure air temperature in the field. Birds prefer to roost in forest patches with higher solar radiation, where the period of light available for foraging is extended and thermoregulation costs during daytime are minimized. They also selected woodland patches with taller trees, a pattern consistent with their foraging preferences for trunks and branches. Other environmental variables played a negligible role in determining the selection of roost sites. Here, we show, for the first time, the importance of sun radiation determining where to spend the night in wintering birds and call attention on considering the thermal space in forest management. Forest management should preserve woodland patches with taller trees more exposed to solar radiation to enhance winter habitat suitability for birds in these Mediterranean oakwoods.

Keywords Nest boxes . Night roosting . Sun radiation . Temperature .Winter .Woodland birds

We evaluated damage to commercial crops caused by the monk parakeet, Myiopsitta monachus, in the Baix Llobregat agricultural area (1,024 ha) bordering the city of Barcelona, Spain. Average crop loss was 0.4% for tomatoes, 28% for corn, 9% for red plums, 36% for round plums, 37% for pears, 17% for persimmons, and 7% for quinces. Our data show that the potential damage to crops by monk parakeets in this invaded area is now a reality. As a wait–and–see approach is likely to be a more costly strategy in the long–term, policy makers should assess issues such as the extent of damage, feasibility/cost benefit analysis, and public opinion so as to avoid greater damage and loss in the future

Key words: Monk parakeet, Myiopsitta monachus, Damage to crops, Invasive species

The Iberian Chiffchaff Phylloscopus ibericus has recently been accepted as a full
species, but is still very difficult to distinguish from the Common Chiffchaff P. collybita when molecular
and acoustic evidence is lacking. Distinguishing these cryptospecies is essential for obtaining accurate
population estimates for each, which is especially important in the case of the Iberian Chiffchaff due
to its restricted distribution. We re-assessed the discriminant methods available in the literature and
propose some alternative traits to distinguish both species. We used information from 24 morphological
traits measured in c. 6,700 individuals of the two species trapped during the autumn migration period
in Doñana National Park, Spain, between 2004 and 2015. Discriminatory methods available in the
literature were unable to distinguish the two species efficiently. Despite some biometric differences,
morphological measurements showed a high degree of overlap and so could not distinguish between
Iberian and Common Chiffchaffs. The best discriminatory factor at our study site was the passage date,
since 90% of Iberian Chiffchaffs have already departed when the first Common Chiffchaffs arrive. Those
traits associated with migration, such as wing size and shape and fat deposits, were also able to
discriminate the species, albeit weakly. This result fully concurs with the trans-Saharan migration of
the Iberian Chiffchaff in contrast to the Common Chiffchaff, which chiefly winters in Mediterranean
latitudes. In conclusion, biometric traits are useless for discriminating the two species and we do not
recommend their use. A comprehensive examination of colouration and plumage seems to be the only
reliable way of guaranteeing the correct identification of these species in the hand.

Key words: autumn migration, cryptic species, discriminant analysis, identification, morphology,
Phylloscopus.

Life cycles of animals and plants worldwide are shifting in response to recent climate change. Macroecology, which deals with biological patterns and processes at a large scale, is ideally suited to address this global phenomenon, thus providing a more general and generalizable understanding of the impacts of climate change on ecosystems. To date, a macroecological approach to examining phenological changes based on historical ground observations remains mostly unexplored, as the phenological studies have been conducted at local scales, while the recent new technologies, e.g., remote sensing, can extend phenological study to global scales. Because phenology is probably the most widely used bioindicator of climate change, thus allowing for studies at the macroscale. Some meta-analyses have indeed employed broad-scale, long-term datasets to estimate overall shift rates in the timing of plant and animal phenological events. However, none has provided a convincing macroecological view of current phenological shifts, and few attempts have been made to make global-scale predictions of phenological responses under future climatic scenarios. Understanding spatial variability and clines may be essential for comprehending phenological variations stemming from future climate change. Here, we discuss how ecological mechanisms discovered in macroecology may provide new insights for understanding spatial variation of sensitivity of phenology to climate change.

Common bird monitoring schemes have become an important tool in conservation biology because they provide useful information for assessing spatial and temporal variations of bird populations. However, recorded data may suffer from several observational procedures that cause error. In recent years, a robust mathematical framework has been developed to control for potential confounding factors affecting the assessment of the actual spatial and temporal variability of bird populations. Surprisingly few attempts have been made to check the effectiveness of current methodology empirically and thus to determine to what extent monitoring scheme data can provide accurate estimates of actual bird abundances. To check the effect of intra-annual variability of bird counts, I conducted daily surveys of House Martin Delichon urbicum and Common Swift Apus apus populations along a 2-km transect line in Tres Cantos (Madrid, Spain) between March and September 2005. The data recorded perfectly mimicked the information collected every spring by observers participating in the common bird monitoring schemes of Spain. Computer simulations with my data showed that the probability of recording the actual annual maximum of individual numbers was less than 9% by the available protocols. Simulations of protocols with increased survey frequency demonstrated that three or four surveys per year would be enough to increase the accuracy of recorded House Martin abundance significantly. However, at least weekly surveys in spring would be required to produce acceptable annual estimates of the abundance of the Common Swift. My results suggest that two surveys per spring are not enough in the studied species, due to the huge between-day variability of records. Such variability is primarily caused by the nature of the count data and the seasonal patterns of occurrence/ detectability of individuals. Abundance data for swifts and house martins recorded in common bird monitoring schemes should thus be used cautiously due to its potential inaccurary.


Key words: abundance, Apus apus, citizen science, Delichon urbicum, line-transect, population, Spain.

Long-term studies are those studies with a longer duration than usual in its topic. They have been essential in ecology to understand the ecological processes that happen in long temporal scales, to determine how general is a pattern emerging from a punctual finding, and to connect cause and effect in biological processes happening with some time lag. Most of ecologists agree about the scientific relevance of long-term studies, but they seldom carry out them (0.3% of published studies). The main handicap is to keep continuous funding during a long time because funding and evaluation system of science is based on short periods. However, there are opportunities to develop long-term studies with available data yet, such as monitoring programs of protected areas or threatened species, museum collections, hunting bags, fisheries or citizen sciences projects; although we will need to keep in mind that those data were not gathered with a long-term aim and this fact may constrain soundness of our conclusions. In spite of the fact that behavioral ecology is a young discipline in Spain, there are already some notable examples of long-term studies. For instance, it has been demonstrated that birds and insects are changing their life cycles in response to climate change and these changes can be leading to phenological mismatchings with the trophic levels in which they rely on. Marking and monitoring of the same individuals along years in the host-parasite system of magpies and cuckoos demonstrated that magpies learn to protect themselves against parasites, while have an inflexible reproductive phenology unable to adapt to environmental variation. Individual-based monitoring of black kites showed the effect of senescence and learning in migratory behavior, breeding territory acquisition, and fitness changes along the life of these birds. Similar results were found for other long-lived birds such as white storks, gulls or storm petrels. Individual marking has allowed building complete pedigrees in bird populations using nest boxes for breeding. Such pedigrees have been essential to understand heritability of several coloration traits of plumage directly linked to the phenotypic individual quality.

Keywords: animal models; individual-based monitoring; microevolution; phenotypic plasticity; replication; temporal trends.

• La llegada primaveral de las aves migratorias se ha adelantado desde mediados de los 70 en torno a una semana, si bien las fechas actuales son similares a las que ya se registraban en los años 40.
• La fecha en que las aves abandonan nuestro país en otoño ha fluctuado a lo largo de las últimas seis décadas, pareciendo existir una cierta tendencia a irse antes en los últimos años.
• La fenología migratoria depende de las temperaturas en España en los periodos migratorios y, en el caso de la migración primaveral, además de las condiciones acaecidas durante todo el invierno en sus cuarteles de invierno.
• Los años calurosos favorecen una llegada más temprana, pero la sequía en África la retrasa.

The European Turtle Dove is a common breeder in Catalonia. It occurs usually from April to October in a wide variety of habitats, but there are also some exceptional winter records from near Barcelona (2.I.96; 4.XII.04). During the sampling period of this study, 1 immature bird was regularly recorded between November 2008 and February 2009 in the Ebro delta. Its behaviour suggests that this individual was probably ill or injured and was unable to continue migration. It was finally killed by a hunter and it was found in active moult.

There were 33 winter records of Barn Swallows during the study period. In almost all cases, swallows were found near the coast, especially in marshlands and builtup areas. The number of records varied markedly from year to year. Most records (60%) were from the end of November or the beginning of February and thus could be consistent, respectively, of exceptionally late or early migrants. In the remaining cases, it is impossible to know whether observed birds were overwintering or not, and probably only a few aberrant individuals remain during the winter in Catalonia.

Pallid Swifts were recorded during the study period from 3 sites in L’Alt Empordà – El Port de la Selva (18.XI.06), Montperdut (26.XI.06) and Els Aiguamolls de l’Empordà (29.XI.08) – and from the Llobregat (3.XII.08) and Ebro (22.XI.06) deltas. These observations concur with previous records of this species from Catalonia, since it is frequently sighted in the Empordà region (its main breeding area in Catalonia) and the Llobregat and Ebro deltas between mid-November and the beginning of December, records that probably correspond to the final postnuptial migrants.

The Common Swift is one of the commonest trans-Saharan bird species in Catalonia. Winter records for this species are not unusual, although numbers vary notably from year to year. All records are from near the coast. During the study period, 1 dead individual was found in the city of Reus (21.XII.06). Winter records could correspond to vagrant birds performing large-scale movements in response to adverse weather conditions in the tropics, although birds reported in December could also be individuals that did not migrate.