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Yoonseob Lim, Ryan Lagoy, Barbara G Shinn-Cunningham, Timothy J Gardner
This study examines how temporally patterned stimuli are transformed as they propagate from primary to secondary zones in the thalamo-recipient auditory pallium in zebra finches. Using a new class of synthetic click stimuli, we find a robust mapping from temporal sequences in the primary zone to distinct population vectors in secondary auditory areas. We tested whether songbirds could discriminate synthetic click sequences in an operant setup and found that a robust behavioral discrimination is present for click sequences composed of intervals ranging from 11-40ms, but breaks down for stimuli composed of longer inter-click intervals...
November 29, 2016: ELife
Karla D Rivera-Cáceres, Esmeralda Quirós-Guerrero, Marcelo Araya-Salas, William A Searcy
Although song development in songbirds has been much studied as an analogue of language development in humans, the development of vocal interaction rules has been relatively neglected in both groups. Duetting avian species provide an ideal model to address the acquisition of interaction rules as duet structure involves time and pattern-specific relationships among the vocalizations from different individuals. In this study, we address the development of the most striking properties of duets: the specific answering rules that individuals use to link their own phrase types to those of their partners (duet codes) and precise temporal coordination...
November 30, 2016: Proceedings. Biological Sciences
Daniel T C Cox, Richard Inger, Steven Hancock, Karen Anderson, Kevin J Gaston
Private gardens provide vital opportunities for people to interact with nature. The most popular form of interaction is through garden bird feeding. Understanding how landscape features and seasons determine patterns of movement of feeder-using songbirds is key to maximising the well-being benefits they provide. To determine these patterns we established three networks of automated data loggers along a gradient of greenspace fragmentation. Over a 12-month period we tracked 452 tagged blue tits Cyantistes caeruleus and great tits Parus major moving between feeder pairs 9,848 times, to address two questions: (i) Do urban features within different forms, and season, influence structural (presence-absence of connections between feeders by birds) and functional (frequency of these connections) connectivity? (ii) Are there general patterns of structural and functional connectivity across forms? Vegetation cover increased connectivity in all three networks, whereas the presence of road gaps negatively affected functional but not structural connectivity...
November 23, 2016: Scientific Reports
Dmitry Kishkinev, Dominik Heyers, Bradley K Woodworth, Greg W Mitchell, Keith A Hobson, D Ryan Norris
The ability to navigate implies that animals have the capability to compensate for geographical displacement and return to their initial goal or target. Although some species are capable of adjusting their direction after displacement, the environmental cues used to achieve this remain elusive. Two possible cues are geomagnetic parameters (magnetic map hypothesis) or atmospheric odour-forming gradients (olfactory map hypothesis). In this study, we examined both of these hypotheses by surgically deactivating either the magnetic or olfactory sensory systems in experienced white-throated sparrows (Zonotrichia albicollis) captured in southern Ontario, Canada, during spring migration...
November 23, 2016: Scientific Reports
Stefanie A Hartmann, Steffen Oppel, Gernot Segelbacher, Mery E Juiña, H Martin Schaefer
Density-dependent processes are fundamental mechanisms for the regulation of populations. Ecological theories differ in their predictions on whether increasing population density leads to individual adjustments of survival and reproductive output or to dominance and monopolization of resources. Here, we use a natural experiment to examine which factors limit population growth in the only remaining population of the endangered pale-headed brush finch (Atlapetes pallidiceps). For three distinct phases (a phase of population suppression, 2001-2002; expansion due to conservation management, 2003-2008; and equilibrium phase, 2009-2014), we estimated demographic parameters with an integrated population model using population size, the proportion of successfully breeding pairs and their productivity, territory size, and mark-recapture data of adult birds...
November 21, 2016: Oecologia
Olga Fehér, Iva Ljubičić, Kenta Suzuki, Kazuo Okanoya, Ofer Tchernichovski
At the onset of vocal development, both songbirds and humans produce variable vocal babbling with broadly distributed acoustic features. Over development, these vocalizations differentiate into the well-defined, categorical signals that characterize adult vocal behaviour. A broadly distributed signal is ideal for vocal exploration, that is, for matching vocal production to the statistics of the sensory input. The developmental transition to categorical signals is a gradual process during which the vocal output becomes differentiated and stable...
January 5, 2017: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
Courtney A Thomason, Ariel Leon, Laila T Kirkpatrick, Lisa K Belden, Dana M Hawley
Vertebrate ocular microbiomes are poorly characterized and virtually unexplored in wildlife species. Pathogen defense is considered a key function of microbiomes, but determining microbiome stability during disease is critical for understanding the role of resident microbial communities in infectious disease dynamics. Here, we characterize the ocular bacterial microbiome of house finches (Haemorhous mexicanus), prior to and during experimental infection with an inflammatory ocular disease, Mycoplasmal conjunctivitis, caused by Mycoplasma gallisepticum...
November 21, 2016: Environmental Microbiology
Felix W Moll, Andreas Nieder
Single neuron activity in the corvid nidopallium caudolaterale (NCL), the supposed avian functional analog of the prefrontal cortex, represents associations of auditory with visual stimuli. This is of high adaptive value for songbirds that need to rely on audio-visual associations to communicate, find a mate or escape predators. However, it remains unclear whether NCL neurons can represent cross-modal associations in a modality invariant, abstract fashion. To dissociate between modality-dependent and modality-invariant NCL activity, we trained two crows to match auditory sample cues with visual test stimuli, and vice versa, across a temporal memory delay...
November 15, 2016: Neurobiology of Learning and Memory
Guillermo Friis, Pau Aleixandre, Ricardo Rodríguez-Estrella, Adolfo G Navarro-Sigüenza, Borja Milá
Natural systems composed of closely-related taxa that vary in the degree of phenotypic divergence and geographic isolation, provide an opportunity to investigate the rate of phenotypic diversification and the relative roles of selection and drift in driving lineage formation. The genus Junco (Aves: Emberizidae) of North America includes parapatric northern forms that are markedly divergent in plumage pattern and color, in contrast to geographically isolated southern populations in remote areas that show moderate phenotypic divergence...
November 14, 2016: Molecular Ecology
Rindy C Anderson, William A Searcy, Susan Peters, Melissa Hughes, Adrienne L DuBois, Stephen Nowicki
Learned aspects of song have been hypothesized to signal cognitive ability in songbirds. We tested this hypothesis in hand-reared song sparrows (Melospiza melodia) that were tutored with playback of adult songs during the critical period for song learning. The songs developed by the 19 male subjects were compared to the model songs to produce two measures of song learning: the proportion of notes copied from models and the average spectrogram cross-correlation between copied notes and model notes. Song repertoire size, which reflects song complexity, was also measured...
November 14, 2016: Animal Cognition
Florian Müller, Philip D Taylor, Sissel Sjöberg, Rachel Muheim, Arseny Tsvey, Stuart A Mackenzie, Heiko Schmaljohann
Most songbird migrants travel between their breeding areas and wintering grounds by a series of nocturnal flights. The exact nocturnal departure time for these flights varies considerably between individuals even of the same species. Although the basic circannual and circadian rhythms of songbirds, their adaptation to migration, and the factors influencing the birds' day-to-day departure decision are reasonably well studied, we do not understand how birds time their departures within the night. These decisions are crucial, because the nocturnal departure time defines the potential flight duration of the migratory night...
2016: Movement Ecology
J Boiden Pedersen, Claus Nielsen, Ilia A Solov'yov
Despite decades of research the puzzle of the magnetic sense of migratory songbirds has still not been unveiled. Although the problem really needs a multiscale description, most of the individual research efforts were focused on single scale investigations. Here we seek to establish a multiscale link between some of the scales involved, and in particular construct a bridge between electron spin dynamics and migratory bird behaviour. In order to do that, we first consider a model cyclic reaction scheme that could form the basis of the avian magnetic compass...
November 10, 2016: Scientific Reports
Jonathan Chabout, Abhra Sarkar, Sheel R Patel, Taylor Radden, David B Dunson, Simon E Fisher, Erich D Jarvis
Development of proficient spoken language skills is disrupted by mutations of the FOXP2 transcription factor. A heterozygous missense mutation in the KE family causes speech apraxia, involving difficulty producing words with complex learned sequences of syllables. Manipulations in songbirds have helped to elucidate the role of this gene in vocal learning, but findings in non-human mammals have been limited or inconclusive. Here, we performed a systematic study of ultrasonic vocalizations (USVs) of adult male mice carrying the KE family mutation...
2016: Frontiers in Behavioral Neuroscience
J W G Slade, M J Watson, T R Kelly, G B Gloor, M A Bernards, E A MacDougall-Shackleton
In jawed vertebrates, genes of the major histocompatibility complex (MHC) play a key role in immunity by encoding cell-surface proteins that recognize and bind non-self antigens. High variability at MHC suggests that these loci may also function in social signalling such as mate choice and kin recognition. This requires that MHC genotype covaries with some perceptible phenotypic trait. In mammals and fish, MHC is signalled chemically through volatile and non-volatile peptide odour cues, facilitating MHC-dependent mate choice and other behaviours...
November 16, 2016: Proceedings. Biological Sciences
Cameron J Nordell, Samuel Haché, Erin M Bayne, Péter Sólymos, Kenneth R Foster, Christine M Godwin, Richard Krikun, Peter Pyle, Keith A Hobson
Understanding bird migration and dispersal is important to inform full life-cycle conservation planning. Stable hydrogen isotope ratios from feathers (δ2Hf) can be linked to amount-weighted long-term, growing season precipitation δ2H (δ2Hp) surfaces to create δ2Hf isoscapes for assignment to molt origin. However, transfer functions linking δ2Hp with δ2Hf are influenced by physiological and environmental processes. A better understanding of the causes and consequences of variation in δ2Hf values among individuals and species will improve the predictive ability of geographic assignment tests...
2016: PloS One
Douglas W Wacker, Sahar Khalaj, Lindsey J Jones, Tara L Champion, Jason E Davis, Simone L Meddle, John C Wingfield
Dehydroepiandrosterone, DHEA, is a testosterone/estrogen precursor and known modulator of vertebrate aggression. Male song sparrows (Melospiza melodia morphna) show high aggression during breeding and non-breeding life history stages when circulating DHEA levels are high, and low aggression during molt when DHEA levels are low. We previously showed that androgen receptor and aromatase mRNA expression are higher during breeding and/or non-breeding in brain regions associated with reproductive and aggressive behavior, but DHEA's potential role in mediating these seasonal changes remained unclear...
November 2, 2016: Journal of Neuroendocrinology
Khemraj Budachetri, Jaclyn Williams, Nabanita Mukherjee, Michael Sellers, Frank Moore, Shahid Karim
Seasonal migration of passerine birds between temperate North America and tropical Central and South America is an ecological phenomenon. Migration of birds has been associated with the introduction of ectoparasites like ticks or tick-borne pathogens across the avian migration routes. In this study, the microbial diversity was determined in the ticks and bird DNA samples using 454 pyrosequencing of bacterial 16S rRNA gene. Tick DNA samples showed the dominance of genera Lactococcus, Francisella, Raoultella, Wolbachia and Rickettsia across all the ticks, but birds DNA did not share common microbial diversity with ticks...
October 28, 2016: Ticks and Tick-borne Diseases
Kristal E Cain, Sarah R Pryke
Testosterone (T) is an important mediator of reproductive behaviours and potential target for selection. However, there are few data relating natural variation in T to fitness estimates. Here, we use the GnRH challenge (an injection of gonadotropin-releasing hormone which stimulates maximal T release), to examine how individual differences in T relate to reproductive success and how T changes across date and breeding stage. We measured pre and post-challenge T, in captive male Gouldian finch (Erythrura gouldiae), before and after introducing females, and across breeding stage...
October 31, 2016: Journal of Evolutionary Biology
Heinz Richner
Darwin was fascinated by melodic performances of insects, fish, birds, mammals, and men. He considered the ability to produce musical notes without direct use the most mysterious endowment of mankind. Bird song is attributed to sexual selection, but it remains unknown how the expected relationship between melodic performance and phenotypic quality arises. Melodies consist of sequences of notes, and both Pythagoras and music theorists in the Middle Ages found that their tonal frequencies form simple ratios that correspond to small-integer proportions derived from the harmonic series...
October 25, 2016: Proceedings of the National Academy of Sciences of the United States of America
Ila Mishra, Sanjay K Bhardwaj, Shalie Malik, Vinod Kumar
Hypothalamic expression of the thyroid hormone (TH) responsive gonadostimulatory (eya3, cga, tshβ, dio2, dio3, gnrh, gnih) and neurosteroid pathway genes (androgen receptor [ar], aromatase [cyp19], estrogen receptor [er] α and β) was examined in photosensitive redheaded buntings exposed to 2 (acute, experiment 1) or 12 (chronic, experiment 2) long days (16L:8D). Experiment 2 also included a photorefractory group. Acute long days caused a significant increase in eya3, cga, tshβ, dio2 and gnrh and decrease in dio3 mRNA levels...
October 24, 2016: Molecular and Cellular Endocrinology
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