Song Diversity Predicts the Viability of Fragmented Bird Populations

In the global scenario of increasing habitat fragmentation, finding appropriate indicators of population viability is a priority for conservation. We explored the potential of learned behaviours, specifically acoustic signals, to predict the persistence over time of fragmented bird populations. We found an association between male song diversity and the annual rate of population change, population productivity and population size, resulting in birds singing poor repertoires in populations more prone to extinction. This is the first demonstration that population viability can be predicted by a cultural trait (acquired via social learning). Our results emphasise that cultural attributes can reflect not only individual-level characteristics, but also the emergent population-level properties. This opens the way to the study of animal cultural diversity in the increasingly common human-altered landscapes

Climate Matching Drives Spread Rate but Not Establishment Success in Recent Unintentional Bird Introductions

Understanding factors driving successful invasions is one of the cornerstones of invasion biology. Bird invasions have been frequently used as study models, and the foundation of current knowledge largely relies on species purposefully introduced during the 19th and early 20th centuries in countries colonized by Europeans. However, the profile of exotic bird species has changed radically in the last decades, as birds are now mostly introduced into the invasion process through unplanned releases from the worldwide pet and avicultural trade. Here we assessed the role of the three main drivers of invasion success (i.e., event-, species-, and location-level factors) on the establishment and spatial spread of exotic birds using an unprecedented dataset recorded throughout the last 100 y in the Iberian Peninsula. Our multimodel inference phylogenetic approach showed that the barriers that need to be overcome by a species to successfully establish or spread are not the same. Whereas establishment is largely related to event-level factors, apparently stochastic features of the introduction (time since first introduction and propagule pressure) and to the origin of introduced species (wild-caught species show higher invasiveness than captive-bred ones), the spread across the invaded region seems to be determined by the extent to which climatic conditions in the new region resemble those of the species’ native range. Overall, these results contrast with what we learned from successful deliberate introductions and highlight that different management interventions should apply at different invasion stages, the most efficient strategies being related to event-level factors

The PHA Test Reflects Acquired T-Cell Mediated Immunocompetence in Birds

cological immunology requires techniques to reliably measure immunocompetence in wild vertebrates. The PHA-skin test, involving subcutaneous injection of a mitogen (phytohemagglutinin, PHA) and measurement of subsequent swelling as a surrogate of T-cell mediated immunocompetence, has been the test of choice due to its practicality and ease of use in the field. However, mechanisms involved in local immunological and inflammatory processes provoked by PHA are poorly known, and its use and interpretation as an acquired immune response is currently debated.) and plasma proteins circulating in the bloodstream, potentially involved in the immunological and inflammatory processes, through flow cytometry and electrophoresis.Our results showed stronger responses after a second PHA injection, independent of species, time elapsed and changes in body mass of birds between first and second injections, thus supporting the adaptive nature of this immune response. Furthermore, the concomitant changes in the plasma concentrations of T-lymphocyte subsets and globulins indicate a causal link between the activation of the T-cell mediated immune system and local tissue swelling.These findings justify the widespread use of the PHA-skin test as a reliable evaluator of acquired T-cell mediated immunocompetence in diverse biological disciplines. Further experimental research should be aimed at evaluating the relative role of innate immunocompetence in wild conditions, where the access to dietary proteins varies more than in captivity, and to ascertain how PHA responses relate to particular host-parasite interactions

Population Size, Non-Breeding Fraction, and Productivity in a Large Urban Population of Burrowing Parrots (Cyanoliseus patagonus)

Psittaciformes are one of the bird orders with the highest number of threatened species and the most marked declining population trends. At present, the lack of information on the population size, reproductive fraction, and productivity of most parrot populations makes it difficult to design effective conservation actions. In this study, we monitored a population of Burrowing Parrots (Cyanoliseus patagonus) breeding in urbanized habitats in the southwest of Buenos Aires province, Argentina. Every December and February from 2018 to 2023, we counted the individuals arriving at a single communal roost, located in the main park of Bahía Blanca city, which gathers all the parrots breeding in 18–22 colonies within a radius of 20 km. Censuses were conducted before (December) and immediately after the incorporation of juveniles into the flocks (February). Breeding pairs were also counted annually in the colonies, and the average annual productivity and the proportion of juveniles were estimated from surveys in pre-roosting and feeding areas in February. The non-breeding fraction approached half of the population with no statistically significant differences among years (range: 37–53%), and the breeding population showed little annual variation, with a minimum of 1363 and a maximum of 1612 breeding pairs. The proportion of juveniles in the flocks and the estimated productivity showed larger variations among breeding seasons. Our results add insight to the scarce information available on the breeding-to-non-breeding-population ratios in parrots, and birds in general, and show key breeding parameters for a species that is thriving well in urban habitats.Fil: Lera, Daiana Noelia. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia. Grupo de Estudios en Conservación y Manejo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; ArgentinaFil: Cozzani, Natalia Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; Argentina. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia. Grupo de Estudios en Conservación y Manejo; ArgentinaFil: Tella, José L.. Consejo Superior de Investigaciones Científicas; EspañaFil: Zalba, Sergio Martín. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia. Grupo de Estudios en Conservación y Manejo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; Argentin

Social and individual features affecting natal dispersal in the colonial lesser kestrel.

Abstract. Causes of natal dispersal were studied in an isolated population of the migratory, facultatively colonial Lesser Kestrel (Falco naumanni) in northeastern Spain. During a seven-year study, we gathered information on natal dispersal of 751 individuals and on 24 explanatory variables that evaluated individual traits, conspecific cues in terms of colony size, and different ecological and populational features. We examined separately whether or not individuals changed colonies and how far they moved. Dispersal from the natal colony was high (83%), and dispersers covered a median distance of 7225 m (range 112-136 500 m). The probability of natal dispersal decreased with the size of the natal colony and with the distance to the nearest colony, but not with the distance to unoccupied buildings, in the year of recruitment. Moreover, the shorter the distance to the nearest colony, the shorter the distances that individuals dispersed, particularly to large colonies (Ͼ10 pairs). These results support the conspecific attraction hypothesis. Accordingly, the probability of recruiting in the natal colony increased with the proportion of philopatric adults, although beyond a threshold individuals were prevented from recruiting by the more dominant adults in a despotic way. The timing of arrival from the wintering grounds was positively related to the probability of colony change, especially in males. To the extent that this variable is related to the phenotypic quality of individuals, it reinforces the idea that natal dispersal is shaped by intraspecific competition in crowded colonies. Males showed lower frequencies of colony change and dispersed shorter distances than did females, as explained by the different role of the sexes in nest acquisition and defense. Our results indicate that natal dispersal is an evolutionarily labile trait simultaneously influenced by ecological, social, and individual features both within and between populations

Physiological dormancy broken by endozoochory: Austral parakeets (Enicognathus ferrugineus) as legitimate dispersers of calafate (Berberis microphylla) in the Patagonian Andes

Aims: Seed dispersal by endozoochory is an important process in plant regeneration and the establishment of new populations. Seeds with dormancy may especially benefit after disperser gut passage. However, the ways in which gut passage affect the germination of plant species with physiological dormancy remain unclear. Here, we experimentally assessed the mutualistic interaction between the Austral parakeet (Enicognathus ferrugineus) as a disperser of calafate (Berberis microphylla), a thorny bush inhabiting the understory of the Austral temperate forests of South America with seeds that are characterized by deep physiological dormancy. Methods: Germination success and viability of calafate seeds obtained from faeces and from intact fruits were tested under four treatments: (i) digested seeds, (ii) digested seeds with faecal extract, (iii) intact seeds from fruit and (iv) intact seeds from fruit with pulp. Important Findings: About 65% of the Austral parakeet droppings contained calafate seeds. Viability of seeds did not differ between treatments. However, germination was significantly higher in digested seeds than in intact seeds from fruits, while no difference was found between faecal and pulp extracts. Neither faecal matter nor fruit pulp provided seeds with any ecological advantages derived from enhancing germinability, but did confer some disadvantage in germination time. Faecal matter is expected to be completely lacking around seeds after several months under snow before germinating in the following spring, given intense washing due to persistent rain and the spring thaw in the Patagonian Andes. The higher germinability along with faster germination of digested seeds supports the hypothesis of a legitimate mutualistic interaction between Austral parakeets and calafate. We hypothesized that the passage through the disperser digestive tract might break physiological dormancy as differences in germinability between ingested and non-ingested seeds. Our results highlight the relevant role of endozoochory in plant species with physiological dormancy living in highly seasonal environments.种子由动物内携传播是植物再生和新种群建立的重要过程。具有休眠的种子经过传播者肠道传代作用后可能特别受益。然而，肠道 传代作用如何影响具有生理休眠植物的萌发尚不清楚。在本研究中，我们实验性地评估了南鹦哥(Enicognathus ferrugineus)作为小檗属植 物(Berberis microphylla)传播者的互惠共生。Berberis microphylla是一种多刺的灌木，栖息在南美洲温带森林的下层，其种子具有深度生 理休眠的特性。本研究通过四种处理：(1)种子消化处理，(2)粪便提取物消化处理，(3)果实种子完整处理和(4)包含果肉果实种子完整 处理，测定了从粪便和完整果实中提取的B. microphylla种子的发芽成功率和活力。研究结果表明，大约65%的南鹦哥的粪便中含有B. microphylla种子。不同处理的种子存活率无显著差异。然而，消化后的种子萌发率显著高于完整果实种子，而粪便和果肉提取物处理之间没有差异。粪便和果肉都没有为种子提供任何提高发芽能力的生态优势，但在萌发时间上确实造成了一些劣势。由于持续降雨和巴塔哥尼亚安第斯山脉春季融雪带来的严重冲刷，种子附近的粪便在雪下几个月后就会完全缺失。消化种子较高的发芽能力和较快的发芽速度验证了南鹦哥和B. microphylla之间具有合理互惠共生的假设。因为消化和非消化种子发芽能力的差异，我们假设通过传播者的肠道传代作用可能打破种子的生理休眠。我们的研究结果强调了在具有高度季节性的环境下，具有生理休眠的植物物种中与动物内携传播的相关作用。Fil: Bravo, Carolina. Consejo Superior de Investigaciones Científicas; España. Museo Nacional de Ciencias Naturales; EspañaFil: Chamorro, Daniel. Consejo Superior de Investigaciones Científicas; España. Universidad de Castilla-La Mancha; EspañaFil: Hiraldo, Fernando. Consejo Superior de Investigaciones Científicas; España. Estación Biológica de Doñana; EspañaFil: Speziale, Karina Lilian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Lambertucci, Sergio Agustin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Tella, José L.. Estación Biológica de Doñana; España. Consejo Superior de Investigaciones Científicas; EspañaFil: Blanco, Guillermo. Consejo Superior de Investigaciones Científicas; España. Museo Nacional de Ciencias Naturales; Españ

Overlooked Parrot Seed Dispersal in Australia and South America: Insights on the Evolution of Dispersal Syndromes and Seed Size in Araucaria Trees

While Psittaciformes (parrots and allies) are well-recognized as highly-mobile seed predators, their role as seed dispersers has been overlooked until very recently. It remains to be determined whether this role is anecdotic or is a key mutualism for some plant species. We recently found that the large nut-like seeds of the two South American Araucaria tree species (Araucaria araucana in Andean forests and Araucaria angustifolia in Atlantic forests, weighing c. 3.5 and 7 g, respectively) are frequently dispersed, and to long distances, by parrots. Moreover, both observational and experimental work demonstrated that dispersed seeds can germinate faster after partial predation by parrots. Here, we hypothesized that a third, even larger-seeded (17.5 g) congeneric Australian species (A. bidwillii) is also dispersed by parrots. We surveyed 52 A. bidwillii and 42 A. cunninghamii (a sympatric species with small winged seeds, c. 0.2 g) during the seeding period. We found that sulfur-crested cockatoos (Cacatua galerita) consumed large amounts of seeds from all of the A. bidwillii trees surveyed. Cockatoos dispersed ca. 30% of the seeds they removed from the mother tree, carrying the seeds to distant perches for handling or dropped them while flying. Dispersal distances ranged between 10 and 153 m (mean = 61 m). Most seeds handled for consumption (93%) were fully eaten but others were dropped intact (3%) or only partially eaten (4%), and germination was confirmed for both intact and partially-eaten dispersed seeds. Moreover, seeds dropped by cockatoos facilitated secondary seed dispersal by conspecifics and another three bird species. We found no evidence of other primary dispersal species for A. bidwillii, while the small, winged seeds of Araucaria cunninghamii were only dispersed through barochory and anemochory. The seed weight of the three Araucaria species dispersed by zoochory is strongly related to the body mass of their main seed-disperser parrot species. These results support a role for parrots as key dispersers of the three large-seeded Araucaria species around the world, and suggest that large seeds may have evolved–at least partially–as an adaptation that allows trees to attract parrots, satiate them, and benefit from their long-distance seed dispersal services

Drivers of the Ectoparasite Community and Co-Infection Patterns in Rural and Urban Burrowing Owls

We analyzed the ectoparasite community of a monomorphic and non-social bird, the burrowing owl, Athene cunicularia, breeding in rural and urban habitats. Such community was composed by two lice, one mite and one flea species. Rural individuals had more fleas and less mites than urban ones. Adult birds harbored less ectoparasites than young ones and females harbored more lice than males. The presence of lice was positively related to the presence of fleas. On the contrary, the presence of mites was negatively related to the presence of fleas and lice. The study of parasite communities in urban and rural populations of the same species can shed light on how urban stressor factors impact the physiology of wildlife inhabiting cities and, therefore, the host-parasite relationships. Urbanization creates new ecological conditions that can affect biodiversity at all levels, including the diversity and prevalence of parasites of species that may occupy these environments. However, few studies have compared bird-ectoparasite interactions between urban and rural individuals. Here, we analyze the ectoparasite community and co-infection patterns of urban and rural burrowing owls, Athene cunicularia, to assess the influence of host traits (i.e., sex, age, and weight), and environmental factors (i.e., number of conspecifics per nest, habitat type and aridity) on its composition. Ectoparasites of burrowing owls included two lice, one flea, and one mite. The overall prevalence for mites, lice and fleas was 1.75%, 8.76% and 3.50%, respectively. A clear pattern of co-infection was detected between mites and fleas and, to less extent, between mites and lice. Adult owls harbored fewer ectoparasites than nestlings, and adult females harbored more lice than males. Our results also show that mite and flea numbers were higher when more conspecifics cohabited the same burrow, while lice showed the opposite pattern. Rural individuals showed higher flea parasitism and lower mite parasitism than urban birds. Moreover, mite numbers were negatively correlated with aridity and host weight. Although the ectoparasitic load of burrowing owls appears to be influenced by individual age, sex, number of conspecifics per nest, and habitat characteristics, the pattern of co-infection found among ectoparasites could also be mediated by unexplored factors such as host immune response, which deserves further research

Epizoochory in Parrots as an Overlooked Yet Widespread Plant–Animal Mutualism

Plant–animal interactions are key to sustaining whole communities and ecosystem function. However, their complexity may limit our understanding of the underlying mechanisms and the species involved. The ecological effects of epizoochory remain little known compared to other seed dispersal mechanisms given the few vectors identified. In addition, epizoochory is mostly considered non-mutualistic since dispersers do not obtain nutritional rewards. Here, we show a widespread but unknown mutualistic interaction between parrots and plants through epizoochory. Combining our observations with photos from web-sources, we recorded nearly 2000 epizoochory events in 48 countries across five continents, involving 116 parrot species and nearly 100 plant species from 35 families, including both native and non-native species. The viscid pulp of fleshy fruits and anemochorous structures facilitate the adherence of tiny seeds (mean 3.7 × 2.56 mm) on the surface of parrots while feeding, allowing the dispersion of these seeds over long distances (mean = 118.5 m). This parrot–plant mutualism could be important in ecosystem functioning across a wide diversity of environments, also facilitating the spread of exotic plants. Future studies should include parrots for a better understanding of plant dispersal processes and for developing effective conservation actions against habitat loss and biological invasions.This research was funded by Severo Ochoa Program (SVP-2014-068732), Action COST “ParrotNet” (ES1304), and Loro Parque Fundación (PP-146-2018-1). E.S.-G. is funded by a Ramón y Cajal contract (RYC-2019-027216I) from the Spanish Ministry of Science and Innovation