Differences in vocal brain areas and astrocytes between the house wren and the rufous-tailed hummingbird.

The house wren shows complex song, and the rufous-tailed hummingbird has a simple song. The location of vocal brain areas supports the song's complexity; however, these still need to be studied. The astrocytic population in songbirds appears to be associated with change in vocal control nuclei; however, astrocytic distribution and morphology have not been described in these species. Consequently, we compared the distribution and volume of the vocal brain areas: HVC, RA, Area X, and LMAN, cell density, and the morphology of astrocytes in the house wren and the rufous-tailed hummingbird. Individuals of the two species were collected, and their brains were analyzed using serial Nissl- NeuN- and MAP2-stained tissue scanner imaging, followed by 3D reconstructions of the vocal areas; and GFAP and S100ß astrocytes were analyzed in both species. We found that vocal areas were located close to the cerebral midline in the house wren and a more lateralized position in the rufous-tailed hummingbird. The LMAN occupied a larger volume in the rufous-tailed hummingbird, while the RA and HVC were larger in the house wren. While Area X showed higher cell density in the house wren than the rufous-tailed hummingbird, the LMAN showed a higher density in the rufous-tailed hummingbird. In the house wren, GFAP astrocytes in the same bregma where the vocal areas were located were observed at the laminar edge of the pallium (LEP) and in the vascular region, as well as in vocal motor relay regions in the pallidum and mesencephalon. In contrast, GFAP astrocytes were found in LEP, but not in the pallidum and mesencephalon in hummingbirds. Finally, when comparing GFAP astrocytes in the LEP region of both species, house wren astrocytes exhibited significantly more complex morphology than those of the rufous-tailed hummingbird. These findings suggest a difference in the location and cellular density of vocal circuits, as well as morphology of GFAP astrocytes between the house wren and the rufous-tailed hummingbird.

Bird community effects on avian malaria infections.

In community assembly processes, interspecific interactions play an important role in shaping community diversity, especially at the local scale. Changes in species richness or abundance can modify local infectious disease dynamics, either reducing or increasing the risk of transmission within the community. This study evaluates the effects of bird community on avian haemosporidians infections in a Neotropical region. Bird samples were collected from areas surrounding three dams, and molecular analysis were performed to identify blood-parasitic haemosporidia infecting the birds. Generalized linear models were used to analyze the relationships between the bird community and the prevalence, number of infections, and richness of avian haemosporidian lineages. Non-significant effects of bird community dominance and richness on the prevalence of avian parasites and the number of infections of Haemoproteus were found. However, there was evidence of an amplification effect. Host dominance was associated with the total number of infections, the number Plasmodium infections and the expected richness of Plasmodium lineages, while the expected richness of Haemoproteus lineages was associated with the richness of bird species. These findings highlight the role of host community dominance and richness in the dynamics of parasite infections, potentially influenced by the availability of competent hosts. This study contributes significantly to our understanding of blood parasite diversity in tropical birds within a relatively understudied region of South America.

Beyond illness: Variation in haemosporidian load explains differences in vocal performance in a songbird.

In animal communication, signals are expected to evolve to be honest, so that receivers avoid being manipulated by signalers. One way that signals can evolve to be honest is for them to be costly, with only high-quality individuals being able to bear the costs of signal expression. It has been proposed that parasites can introduce costs that affect the expression of sexually selected traits, and there is evidence to support the role of parasitism in modulating animal behavior. If host infection status or intensity is found to relate to differences in signal expression, it may indicate a fitness cost that mediates honesty of signals. Birdsong is a good model for testing this, and physically challenging songs representing complex motor patterns provide a good example of sexually selected traits indicating individual condition. We performed a field study to evaluate the relationship between song performance and avian malaria infection in a common songbird. Previous work on this subject has almost always evaluated avian malaria in terms of binary infection status; however, parasitemia-infection intensity-is rarely assessed, even though differences in parasite load may have profound physiological consequences. We estimated parasitemia levels by using real-time PCR. We found that birds with higher parasitemia displayed lower vocal performance, providing evidence that this song trait is an honest signal of parasitic load of haemosporidian parasites. To our knowledge, this study links parasite load and the expression of a sexually selected trait in a way that has not been addressed in the past. Studies using song performance traits and parasitemia offer an important perspective for understanding evolution of characters via sexual selection.

Simulation of the song motor pathway in birds: A single neuron initiates a chain of events that produces birdsong with realistic spectra properties.

Birdsong is a complex learned behavior regulated by Neuromuscular coordination of different muscle sets necessary for producing relevant sounds. We developed a heterogeneous and stochastically connected neural network representing the pathway from the high vocal center (HVC) to the robust nucleus of the arcopallium (RA) neurons that drive the muscles to generate sounds. We show that a single active neuron is sufficient to initiate a chain of spiking events that results to excite the entire network system. The network could synthesize realistic bird sounds spectra, with spontaneous generation of intermittent sound bursts typical of birdsong (song syllables). This study confirms experiments on animals and on humans, where results have shown that single neurons are responsible for the activation of complex behavior or are associated with high-level perception events.

A morphological database for 606 Colombian bird species.

Colombia is the country with the highest bird diversity in the world. Despite active research in ornithology, compelling morphological information of most bird species is still sparse. However, morphological information is the baseline to understand how species respond to environmental variation and how ecosystems respond to species loss. As part of a national initiative, the Instituto Alexander von Humboldt in collaboration with 12 Colombian institutions and seven biological collections, measured up to 15 morphological traits of 9,892 individuals corresponding to 606 species: 3,492 from individuals captured in field and 6,400 from museum specimens. Species measured are mainly distributed in high Andean forest, páramo, and wetland ecosystems. Seven ornithological collections in Colombia and 18 páramo complexes throughout Colombia were visited from 2013 to 2015. The morphological traits involved measurements from bill (total and exposed culmen, bill width and depth), wing (length, area, wingspan, and the distance between longest primary and longest secondary), tail (length and shape), tarsus (length), hallux (length and claw hallux), and mass. The number of measured specimens per species was variable, ranging from 1 to 321 individuals with a median of four individuals per species. Overall, this database gathered morphological information for >30% of Colombian bird diversity. No copyright, proprietary, or cost restrictions apply; the data should be cited appropriately when used.

Learning speed is affected by personality and reproductive investment in a songbird.

Individuals from different taxa, including songbirds, differ consistently in behaviour and personality when facing different situations. Although our understanding of animal behaviour has increased, knowledge about between-individual differences in cognitive abilities is still limited. By using an experimental approach and a free-living songbird (Parus major) as a model, we attempted to understand between-individual differences in habituation to playbacks (as a proxy of learning speed), by investigating the role of personality, age and reproductive investment (clutch size). Pre-breeding males were tested for exploration (a proxy of personality) in standardized conditions. In addition, the same individuals were exposed to three playbacks in the field during incubation. Birds significantly moved less, stayed further away and overlapped less the playback with successive playback stimulation. While a decrease in the locomotor behaviour can be explained by personality, differences in habituation of overlapping were predicted by both reproductive investment and personality. Fast explorers habituated less. Moreover, males paired to females with larger clutches did not vary the intensity of overlapping. Since habituation requires information for recognition of non-threatening signals, personality may bias information gathering. While fast explorers may collect less information from the environment, slow explorers (reactive birds) seem to pay attention to environmental clues and collect detailed information. We provided evidence that the rate of habituation of behavioural responses, a proxy of cognitive abilities, may be affected by different factors and in a complex way.

The Female Perspective of Personality in a Wild Songbird: Repeatable Aggressiveness Relates to Exploration Behaviour.

Males often express traits that improve competitive ability, such as aggressiveness. Females also express such traits but our understanding about why is limited. Intraspecific aggression between females might be used to gain access to reproductive resources but simultaneously incurs costs in terms of energy and time available for reproductive activities, resulting in a trade-off. Although consistent individual differences in female behaviour (i.e. personality) like aggressiveness are likely to influence these reproductive trade-offs, little is known about the consistency of aggressiveness in females. To quantify aggression we presented a female decoy to free-living female great tits (Parus major) during the egg-laying period, and assessed whether they were consistent in their response towards this decoy. Moreover, we assessed whether female aggression related to consistent individual differences in exploration behaviour in a novel environment. We found that females consistently differed in aggressiveness, although first-year females were on average more aggressive than older females. Moreover, conform life history theory predictions, 'fast' exploring females were more aggressive towards the decoy than 'slow' exploring females. Given that personality traits are often heritable, and correlations between behaviours can constrain short term adaptive evolution, our findings highlight the importance of studying female aggression within a multivariate behavioural framework.

Análisis de coliformes y bacterias reductoras de sulfato en reservorios acuíferos de corrales de San Luis Beltrán, Atlántico, Colombia / Analysis of coliforms and sulfate-reducing bacteria in reservoirs aquifer of corrales de San Luis Beltran, Atlantico, Colombia

Introducción: La verificación y seguimiento de la presencia de microrganismos indicadores de la calidaddel agua es imprescindible debido al riesgo que representan para la población que la utiliza para consumo, recreación o deporte. Los reservorios acuíferos de Corrales de San Luis Beltrán, Atlántico, Colombia, son fuente de sustento de las comunidades campesinas aledañas, animales y plantas de la reserva; sin embargo, su calidad microbiológica no ha sido estudiada. Objetivo: Evaluar la calidad sanitaria del agua de reservorios acuíferos de Corrales de San Luis Beltrán. Materiales y métodos: Se realizaron muestreos de aguas superficiales y sedimento de reservorios acuíferos de Corrales de San Luis Beltrán, y se midieron in situ algunos parámetros fisicoquímicos (temperatura, pH, y oxígeno disuelto), y la calidad microbiológica (coliformes totales, coliformes fecales y bacterias reductoras de sulfato). Resultados: Se presentaron concentraciones bajas de oxígeno disuelto (2,71 mg/L), temperatura promedio de 26 °C y pH ligeramente básico (8,1). Los coliformes totales oscilaron entre 1,0x104 y 1,3x107 UFC/100 mL y los fecales entre 0 y 1,3x105 UFC/100 mL. Se encontró una correlación negativa entre el pH y los coliformes totales, y entre el oxígeno disuelto y los coliformes fecales; y una correlación positiva entre los coliformes fecales y la temperatura. Los recuentos de bacterias reductoras de sulfato fueron superiores a 103 UFC/100 g...

Introduction: The verification and monitoring of indicator microorganisms of water quality is essential.A low water quality may represent a risk for human health, because human populations frequently use it for consumption, recreation, or sport. Water reservoirs situated in Corrales de San Luis Beltran, Atlantico, Colombia, are source of sustenance to local peasant communities, animals, and plants around the village. However, the microbiological quality has not been established. Objective: To assess the sanitary water quality from Corrales de San Luis Beltran. Materials and methods: Surface water and sediment were sampled and some physicochemical parameters (temperature, pH, and dissolved oxygen), and the microbiological quality (total coliforms, fecal coliforms, and sulfate-reducing bacteria) were measured in situ. Results: The analysis showed low dissolved oxygen levels (2,71 mg/L), an average temperature of 26 °C and a slightly basic pH (8,1). Total coliform counts ranged from 1,0x104 and 1,3 x 107 CFU/100 mL and fecal coliform between 0 and 1,3 x 105 CFU/100 g. A negative correlation occurred between pH and total coliform as well as between dissolved oxygen and fecal coliforms. In addition, a positive correlation occurred between fecal coliform and temperature. The number of sulfate-reducing bacteria was more than 103 CFU/100 mL...

Difficulties when assessing birdsong learning programmes under field conditions: a re-evaluation of song repertoire flexibility in the great tit.

There is a remarkable diversity of song-learning strategies in songbirds. Establishing whether a species is closed- or open-ended is important to be able to interpret functional and evolutionary consequences of variation in repertoire size. Most of our knowledge regarding the timing of vocal learning is based on laboratory studies, despite the fact that these may not always replicate the complex ecological and social interactions experienced by birds in the wild. Given that field studies cannot provide the experimental control of laboratory studies, it may not be surprising that species such as the great tit that were initially assumed to be closed-ended learners have later been suggested to be open-ended learners. By using an established colour-ringed population, by following a standardized recording protocol, and by taking into account the species' song ecology (using only recordings obtained during peak of singing at dawn), we replicated two previous studies to assess song repertoire learning and flexibility in adult wild great tits elicited by social interactions. First, we performed a playback experiment to test repertoire plasticity elicited by novel versus own songs. Additionally, in a longitudinal study, we followed 30 males in two consecutive years and analysed whether new neighbours influenced any change in the repertoire. Contrary to the previous studies, song repertoire size and composition were found to be highly repeatable both between years and after confrontation with a novel song. Our results suggest that great tits are closed-ended learners and that their song repertoire probably does not change during adulthood. Methodological differences that may have led to an underestimation of the repertoires or population differences may explain the discrepancy in results with previous studies. We argue that a rigorous and standardized assessment of the repertoire is essential when studying age- or playback-induced changes in repertoire size and composition under field conditions.

Songs differing in consistency elicit differential aggressive response in territorial birds.

Acoustic signals during intrasexual interactions may help receivers to establish the cost and benefits of engaging in a confrontation versus avoiding the cost of escalation. Although birdsong repertoires have been previously suggested as providing information during agonistic encounters, the cost (time/neural resources) of assessing large repertoires may decrease the efficiency of the signal for mutual assessment. Acoustic-structural features may, therefore, be used to enable a fast and accurate assessment during this kind of encounters. Recently, it has been suggested that the consistency of songs may play a key role during intrasexual interactions in bird species. Using a playback experiment in a colour-ringed great tit population, we tested the hypothesis that songs differing in consistency may elicit a differential response, indicating that the signal is salient for the receivers. Great tit males clearly responded more aggressively towards highly consistent songs. Our findings, together with previous evidence of increased song consistency with age in the great tit, suggest that song consistency provides information on experience or dominance in this species, and this phenomenon may be more widespread than currently acknowledged.