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Saturday, 25 October 2014

PubMed papers: Week 2, October 2014

1. Am Nat. 2014 Nov;184(5):E101-E114. Epub 2014 Sep 22.

Sexual Selection and Diversification: Reexamining the Correlation between Dichromatism and Speciation Rate in Birds.

Huang H1, Rabosky DL.
Author information:
1Department of Ecology and Evolutionary Biology, Museum of Zoology, University of Michigan, Ann Arbor, Michigan 48109.


Abstract Theory predicts that sexual selection can serve as an important driver of speciation, but phylogenetic comparative analyses have failed to demonstrate a consistent effect of sexual selection on species richness at macroevolutionary scales. Sexual dichromatism in birds is an example of a phenotypic trait that is hypothesized to reflect the intensity of sexual selection, yet previous studies have reached ambiguous conclusions regarding its role in promoting species diversification. Here, we revisit this problem by pairing published spectrophotometer estimates of plumage dichromatism in the bird-visible range with a newly developed method for modeling speciation rates on phylogenetic trees that explicitly accounts for diversification rate variation through time and among clades. We find little evidence linking dichromatism to speciation across birds, using several measures of dichromatism and macroevolutionary diversification. These results suggest that sexual dichromatism plays a limited role in determining speciation rates at macroevolutionary scales in birds.
PMID: 25325752 [PubMed - as supplied by publisher]

2. Am Nat. 2014 Nov;184(5):624-635. Epub 2014 Oct 1.

Reciprocal Specialization in Multihost Malaria Parasite Communities of Birds: A Temperate-Tropical Comparison.

Svensson-Coelho M1, Ellis VA, Loiselle BA, Blake JG, Ricklefs RE.
Author information:
1Department of Biology, University of Missouri, St. Louis, Missouri 63121.


Abstract How specialization of consumers with respect to resources varies with respect to latitude is poorly understood. Coexistence of many species in the tropics might be possible only if specialization also increases. Alternatively, lower average abundance of more diverse biotic resources in the tropics might force consumers to become more generalized foragers. We examine levels of reciprocal specialization in an antagonistic system-avian malaria-to determine whether the number of host species used and/or parasite lineages harbored differ between a temperate and a tropical assemblage. We evaluate the results of network analysis, which can incorporate both bird and parasite perspectives on specialization in one quantitative index, in comparison to null models. Specialization was significantly greater in both sample sites than predicted from null models. We found evidence for lower per-host species parasite diversity in temperate compared to tropical birds. However, specialization did not differ between the tropical and temperate sites from the parasite perspective. We supplemented the network analysis with estimates of specialization that incorporate phylogenetic relationships of associates and found no differences between sites. Thus, our analyses indicate that specialization within an antagonistic host-parasite (resource-consumer) system varies little between tropical and temperate localities.
PMID: 25325746 [PubMed - as supplied by publisher]

3. Am Nat. 2014 Nov;184(5):593-608. Epub 2014 Oct 1.

Unraveling the Interplay of Community Assembly Processes Acting on Multiple Niche Axes across Spatial Scales.

Trisos CH1, Petchey OL, Tobias JA.
Author information:
1Edward Grey Institute, Department of Zoology, University of Oxford, Oxford OX1 3PS, United Kingdom.


Abstract How the relative importance of community assembly processes varies with spatial scale is the focus of intensive debate, in part because inferring the scales at which specific niche-based processes act is difficult. One obstacle is that standard phylogenetic and functional diversity metrics may integrate the signals of multiple processes when combining separate niche axes into one variable (multiple-niche-axis metrics), potentially obscuring overlapping niche-based processes. We use simulations to evaluate the power of these metrics to detect competition and habitat filtering when these processes operate across multiple niche axes and vary in their relative importance. We then test for both processes at a range of spatial scales in a Neotropical bird assemblage. Simulations revealed that multiple-niche-axis metrics had low power to detect competition and habitat filtering when a mix of both processes acts across niche axes, whereas metrics focused on single-niche axes were better able to deal with this complexity. We found the same contrast in bird communities, where both competition and habitat filtering were detected at the scale of individual territories, but only by single-niche-axis metrics focused on specific niche axes (e.g., foraging traits). Our results suggest that multiple-niche-axis metrics may produce misleading evidence that niche-based processes are partitioned, particularly across scales, and highlight the importance of analyzing functional diversity patterns on individual niche axes when testing assembly models.
PMID: 25325744 [PubMed - as supplied by publisher]

4. J Exp Biol. 2014 Oct 16. pii: jeb.112946. [Epub ahead of print]

Developmental variation in sound production in water and air in the blue catfish Ictalurus furcatus.

Ghahramani ZN1, Mohajer Y2, Fine ML3.
Author information:
1Brooklyn College, City University of New York; Virginia Commonwealth University, US;
2Virginia Commonwealth University, US.
3Virginia Commonwealth University, US


Blue catfish Ictalurus furcatus Lesueur, the largest catfish in North America, produces pectoral stridulation sounds (distress calls) when attacked and held. They have both fish and bird predators, and the frequency spectrum of their sounds is better matched to hearing of birds than to that of unspecialized fish predators with low frequency hearing. It is unclear whether their sounds evolved to function in air or water. We categorized the calls and how they change with fish size in air and water and compared developmental changes in call parameters with stridulation motions captured with a high-speed camera. Stridulation sounds consist of a variable series of pulses produced during abduction of the pectoral spine. Pulses are caused by quick rapid spine rotations (jerks) of the pectoral spine that do not change with fish size although larger individuals generate longer, higher amplitude pulses with lower peak frequencies. There are longer pauses between jerks, and therefore fewer jerks and fewer pulses in larger fish that take longer to abduct their spines and therefore produce a longer series of pulses per abduction sweep. Sounds couple more effectively to water (1400 times greater pressure in Pascals at 1m), are more sharply tuned and have lower peak frequencies than in air. Blue catfish stridulation sounds appear to be specialized to produce under-water signals although most of the sound spectrum includes frequencies matched to catfish hearing but largely above the hearing range of unspecialized fishes.
PMID: 25324337 [PubMed - as supplied by publisher]

5. Glob Chang Biol. 2014 Oct 16. doi: 10.1111/gcb.12740. [Epub ahead of print]

Climate change in our backyards: the reshuffling of North America's winter bird communities.

Princé K1, Zuckerberg B.
Author information:
1Department of Forest and Wildlife Ecology, University of Wisconsin-Madison, Madison, WI, 53706, USA.


Much of the recent changes in North American climate have occurred during the winter months, and as result, overwintering birds represent important sentinels of anthropogenic climate change. While there is mounting evidence that bird populations are responding to a warming climate (e.g., poleward shifts) questions remain as to whether these species-specific responses are resulting in community-wide changes. Here, we test the hypothesis that a changing winter climate should favor the formation of winter bird communities dominated by warm-adapted species. To do this, we quantified changes in community composition using a functional index - the Community Temperature Index (CTI) - which measures the balance between low- and high-temperature dwelling species in a community. Using data from Project FeederWatch, an international citizen science program, we quantified spatiotemporal changes in winter bird communities (n = 38 bird species) across eastern North America and tested the influence of changes in winter minimum temperature over a 22-year period. We implemented a jackknife analysis to identify those species most influential in driving changes at the community level and the population dynamics (e.g., extinction or colonization) responsible for these community changes. Since 1990, we found that the winter bird community structure has changed with communities increasingly composed of warm-adapted species. This reshuffling of winter bird communities was strongest in southerly latitudes and driven primarily by local increases in abundance and regional patterns of colonization by southerly birds. CTI tracked patterns of changing winter temperature at different temporal scales ranging from 1 to 35 years. We conclude that a shifting winter climate has provided an opportunity for smaller, southerly distributed species to colonize new regions and promote the formation of unique winter bird assemblages throughout eastern North America.
© 2014 John Wiley & Sons Ltd.
PMID: 25322929 [PubMed - as supplied by publisher]

6. PeerJ. 2014 Oct 9;2:e621. doi: 10.7717/peerj.621. eCollection 2014.

A vision physiological estimation of ultraviolet window marking visibility to birds.

Håstad O1, Odeen A2.
Author information:
1Department of Anatomy, Physiology and Biochemistry, Swedish University of Agricultural Sciences , Uppsala , Sweden.
2Department of Animal Ecology, Uppsala University , Norbyvägen, Uppsala , Sweden.


Billions of birds are estimated to be killed in window collisions every year, worldwide. A popular solution to this problem may lie in marking the glass with ultraviolet reflective or absorbing patterns, which the birds, but not humans, would see. Elegant as this remedy may seem at first glance, few of its proponents have taken into consideration how stark the contrasts between ultraviolet and human visible light reflections or transmissions must be to be visible to a bird under natural conditions. Complicating matters is that diurnal birds differ strongly in how their photoreceptors absorb ultraviolet and to a lesser degree blue light. We have used a physiological model of avian colour vision to estimate the chromatic contrasts of ultraviolet markings against a natural scene reflected and transmitted by ordinary window glass. Ultraviolets markings may be clearly visible under a range of lighting conditions, but only to birds with a UVS type of ultraviolet vision, such as many passerines. To bird species with the common VS type of vision, ultraviolet markings should only be visible if they produce almost perfect ultraviolet contrasts and are viewed against a scene with low chromatic variation but high ultraviolet content.
PMID: 25320684 [PubMed]

7. J Exp Biol. 2014 Oct 15;217(Pt 20):3700-7. doi: 10.1242/jeb.106344.

Impacts of extreme climatic events on the energetics of long-lived vertebrates: the case of the greater flamingo facing cold spells in the Camargue.

Deville AS1, Labaude S2, Robin JP3, Béchet A2, Gauthier-Clerc M4, Porter W5, Fitzpatrick M5, Mathewson P5, Grémillet D6.
Author information:
1Centre de Recherche de la Tour du Valat, Le Sambuc, 13200 Arles, France Centre d'Ecologie Fonctionnelle et Evolutive (CEFE-CNRS), 1919 Route de Mende, 34090 Montpellier, France.
2Centre de Recherche de la Tour du Valat, Le Sambuc, 13200 Arles, France.
3Institut Pluridisciplinaire Hubert Curien, Département Ecologie, Physiologie et Ethologie, Unité Mixte de Recherche 7178 CNRS-ULP, 23 Rue Becquerel, 67087 Strasbourg Cedex 2, France.
4Centre de Recherche de la Tour du Valat, Le Sambuc, 13200 Arles, France Departement Chrono-Environnement, UMR UFC/CNRS 6249 USC INRA, Université de Franche-Comté, 25030 Besançon, France.
5Department of Zoology, University of Wisconsin, Madison, 250 N. Mills Street, Madison, WI 53706, USA.
6Centre d'Ecologie Fonctionnelle et Evolutive (CEFE-CNRS), 1919 Route de Mende, 34090 Montpellier, France FitzPatrick Institute, DST/NRF Centre of Excellence, University of Cape Town, Rondebosch 7701, South Africa


Most studies analyzing the effects of global warming on wild populations focus on gradual temperature changes, yet it is also important to understand the impact of extreme climatic events. Here we studied the effect of two cold spells (January 1985 and February 2012) on the energetics of greater flamingos (Phoenicopterus roseus) in the Camargue (southern France). To understand the cause of observed flamingo mass mortalities, we first assessed the energy stores of flamingos found dead in February 2012, and compared them with those found in other bird species exposed to cold spells and/or fasting. Second, we evaluated the monthly energy requirements of flamingos across 1980-2012 using the mechanistic model Niche Mapper™. Our results show that the body lipids of flamingos found dead in 2012 corresponded to 2.6±0.3% of total body mass, which is close to results found in woodcocks (Scolopax rusticola) that died from starvation during a cold spell (1.7±0.1%), and much lower than in woodcocks which were fed throughout this same cold spell (13.0±2%). Further, Niche Mapper™ predicted that flamingo energy requirements were highest (+6-7%) during the 1985 and 2012 cold spells compared with 'normal' winters. This increase was primarily driven by cold air temperatures. Overall, our findings strongly suggest that flamingos starved to death during both cold spells. This study demonstrates the relevance of using mechanistic energetics modelling and body condition analyses to understand and predict the impact of extreme climatic events on animal energy balance and winter survival probabilities.
© 2014. Published by The Company of Biologists Ltd.
PMID: 25320270 [PubMed - in process]

8. J R Soc Interface. 2014 Dec 6;11(101). pii: 20140645. doi: 10.1098/rsif.2014.0645.

Wing tucks are a response to atmospheric turbulence in the soaring flight of the steppe eagle Aquila nipalensis.

Reynolds KV1, Thomas AL1, Taylor GK2.
Author information:
1Department of Zoology, University of Oxford, Oxford OX1 3PS, UK.
2Department of Zoology, University of Oxford, Oxford OX1 3PS, UK


Turbulent atmospheric conditions represent a challenge to stable flight in soaring birds, which are often seen to drop their wings in a transient motion that we call a tuck. Here, we investigate the mechanics, occurrence and causation of wing tucking in a captive steppe eagle Aquila nipalensis, using ground-based video and onboard inertial instrumentation. Statistical analysis of 2594 tucks, identified automatically from 45 flights, reveals that wing tucks occur more frequently under conditions of higher atmospheric turbulence. Furthermore, wing tucks are usually preceded by transient increases in airspeed, load factor and pitch rate, consistent with the bird encountering a headwind gust. The tuck itself immediately follows a rapid drop in angle of attack, caused by a downdraft or nose-down pitch motion, which produces a rapid drop in load factor. Positive aerodynamic loading acts to elevate the wings, and the resulting aerodynamic moment must therefore be balanced in soaring by an opposing musculoskeletal moment. Wing tucking presumably occurs when the reduction in the aerodynamic moment caused by a drop in load factor is not met by an equivalent reduction in the applied musculoskeletal moment. We conclude that wing tucks represent a gust response precipitated by a transient drop in aerodynamic loading.
Free Article
PMID: 25320064 [PubMed - in process]

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9. Biol Lett. 2014 Oct;10(10). pii: 20140665. doi: 10.1098/rsbl.2014.0665.

European starlings recognize the location of robotic conspecific attention.

Butler SR1, Fernández-Juricic E2.
Author information:
1Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
2Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA.


Looking where others are allocating attention can facilitate social interactions by providing information about objects or locations of interest. We asked whether European starlings follow the orientation behaviour of conspecifics owing to their highly gregarious behaviour. Starlings reoriented their attention to follow that of a robot around a barrier more often than when the robot's attention was directed elsewhere. This is the first empirical evidence of reorienting in response to conspecific attention in a songbird. Starlings may use this behaviour to obtain fine-tuned spatial information from conspecifics (e.g. direction of predator approach, spatial location of food patches), enhancing group cohesion.
© 2014 The Author(s) Published by the Royal Society. All rights reserved.
PMID: 25319821 [PubMed - in process]

10. Biol Lett. 2014 Oct;10(10). pii: 20140647. doi: 10.1098/rsbl.2014.0647.

Reproductive niche conservatism in the isolated New Zealand flora over 23 million years.

Conran JG1, Lee WG2, Lee DE3, Bannister JM4, Kaulfuss U3.
Author information:
1ACEBB & SGC, School of Earth and Environmental Sciences, DX 650-312, The University of Adelaide, Adelaide, South Australia 5005, Australia
2Landcare Research, Private Bag 1930, Dunedin 9054, New Zealand School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland 1010, New Zealand.
3Department of Geology, University of Otago, PO Box 56, Dunedin 9054, New Zealand.
4Department of Botany, University of Otago, PO Box 56, Dunedin 9054, New Zealand.


The temporal stability of plant reproductive features on islands has rarely been tested. Using flowers, fruits/cones and seeds from a well-dated (23 Ma) Miocene Lagerstätte in New Zealand, we show that across 23 families and 30 genera of forest angiosperms and conifers, reproductive features have remained constant for more than 20 Myr. Insect-, wind- and bird-pollinated flowers and wind- and bird-dispersed diaspores all indicate remarkable reproductive niche conservatism, despite widespread environmental and biotic change. In the past 10 Myr, declining temperatures and the absence of low-latitude refugia caused regional extinction of thermophiles, while orogenic processes steepened temperature, precipitation and nutrient gradients, limiting forest niches. Despite these changes, the palaeontological record provides empirical support for evidence from phylogeographical studies of strong niche conservatism within lineages and biomes.
© 2014 The Author(s) Published by the Royal Society. All rights reserved.
PMID: 25319820 [PubMed - in process]

PubMed articles: Week 3, October 2014

1. Cold Spring Harb Protoc. 2014 Oct 23. doi: 10.1101/pdb.prot084624. [Epub ahead of print]

In Vivo Recording of Single-Unit Activity during Singing in Zebra Finches.

Okubo TS, Mackevicius EL, Fee MS.
Author information:
Department of Brain and Cognitive Sciences, McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139.


The zebra finch is an important model for investigating the neural mechanisms that underlie vocal production and learning. Previous anatomical and gene expression studies have identified an interconnected set of brain areas in this organism that are important for singing. To advance our understanding of how these various brain areas act together to learn and produce a highly stereotyped song, it is necessary to record the activity of individual neurons during singing. Here, we present a protocol for recording single-unit activity in freely moving zebra finches during singing using a miniature, motorized microdrive. It includes procedures for both the microdrive implant surgery and the electrophysiological recordings. There are several advantages of this technique: (1) high-impedance electrodes can be used in the microdrive to obtain well-isolated single units; (2) a motorized microdrive is used to remotely control the electrode position, allowing neurons to be isolated without handling the bird, and (3) a lateral positioner is used to move electrodes into fresh tissue before each penetration, allowing recordings from well-isolated neurons over the course of several weeks. We also describe the application of the antidromic stimulation and the spike collision test to identify neurons based on the axonal projection patterns.
© 2014 Cold Spring Harbor Laboratory Press.
PMID: 25342072 [PubMed - as supplied by publisher]

2. Cold Spring Harb Protoc. 2014 Oct 23. doi: 10.1101/pdb.prot084582. [Epub ahead of print]

An Optimized Protocol for High-Throughput In Situ Hybridization of Zebra Finch Brain.

Carleton JB, Lovell PV, McHugh A, Marzulla T, Horback KL, Mello CV.
Author information:
Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, Oregon 97239.


In situ hybridization (ISH) is a sensitive technique for documenting the tissue distribution of mRNAs. Advanced nonradioactive ISH methods that are based on the use of digoxigenin (DIG)-labeled probes and chromogenic detection have better spatial resolution than emulsion autoradiography techniques and, when paired with high-resolution digital imaging, allow for large-scale profiling of gene expression at cellular resolution within a histological context. However, technical challenges restrict the number of genes that can be investigated in a small laboratory setting. This protocol describes an optimized, low-cost, small-footprint, high-throughput ISH procedure to detect gene expression patterns in 10-µm brain sections from zebra finches. It uses DIG-labeled riboprobes synthesized from cDNA templates available through the Songbird Neurogenomics Consortium. The method is compatible with high-resolution digital imaging; it produces images with low background and a resolution approaching that of immunohistochemical methods. Approximately 180 slides can be processed each week using this protocol, but it can be scaled to accommodate a broad range of tissues from which cryosections can be obtained.
© 2014 Cold Spring Harbor Laboratory Press.
PMID: 25342071 [PubMed - as supplied by publisher]

3. Cold Spring Harb Protoc. 2014 Oct 23. doi: 10.1101/pdb.emo084574. [Epub ahead of print]

The Zebra Finch, Taeniopygia guttata: An Avian Model for Investigating the Neurobiological Basis of Vocal Learning.

Mello CV.
Author information:
Department of Behavioral Neuroscience, Oregon Health and Science University, Portland, Oregon 97239.


Songbirds are capable of learning their vocalizations by copying a singing adult. This vocal learning ability requires juveniles to hear and memorize the sound of the adult song, and later to imitate it through a process involving sensorimotor integration. Vocal learning is a trait that songbirds share with humans, where it forms the basis of spoken language acquisition, with other avian groups (parrots and hummingbirds), and with a few other mammals (cetaceans, bats). It is however absent in traditional model organisms such as rodents and nonhuman primates. Zebra finches, a songbird species from Australia, are popular pets and are easy to breed. They also sing a relatively simple and stereotyped song that is amenable to quantitative analysis. Zebra finches have thus emerged as a choice model organism for investigating the neurobiological basis of vocal learning. A number of tools and methodologies have been developed to characterize the bioacoustics properties of their song, analyze the degree of accurate copying during vocal learning, map the brain circuits that control singing and song learning, and investigate the physiology of these circuits. Such studies have led to a large base of knowledge on song production and learning, and their underlying neural substrate. Several molecular resources have recently become available, including brain cDNA/EST databases, microarrays, BAC libraries, a molecular brain atlas, a complete genome assembly, and the ability to perform transgenesis. The recent availability of many other avian genomes provides unique opportunities for comparative analysis in the search for features unique to vocal learning organisms.
© 2014 Cold Spring Harbor Laboratory Press.
PMID: 25342070 [PubMed - as supplied by publisher]

4. Cold Spring Harb Protoc. 2014 Oct 23. doi: 10.1101/pdb.prot084590. [Epub ahead of print]

A Method for Exploring Adult Neurogenesis in the Songbird Brain.

Asik K, Rao JL, Kirn JR.
Author information:
Department of Biology, Neuroscience & Behavior Program, Wesleyan University, Middletown, Connecticut 06459.


The avian brain is a valuable model for exploring adult neurogenesis. Here we use immunohistochemical methods to detect cell division and the incorporation of new neurons in the adult zebra finch brain. The nonradioactive, relatively inexpensive thymidine analog bromodeoxyuridine (BrdU) is used to label replicating DNA in dividing cells. The brain is harvested, fixed, and dehydrated before being embedded in polyethylene glycol (PEG), which results in superior histology compared to frozen specimens. After the PEG-embedded brain tissue is sectioned and mounted on slides, standard immunohistochemical procedures are used to detect both BrdU and the neuron-specific marker Hu.
© 2014 Cold Spring Harbor Laboratory Press.
PMID: 25342069 [PubMed - as supplied by publisher]

5. Cold Spring Harb Protoc. 2014 Oct 23. doi: 10.1101/pdb.prot084608. [Epub ahead of print]

Generation of Transgenic Zebra Finches with Replication-Deficient Lentiviruses.

Velho TA, Lois C.
Author information:
Department of Neurobiology, University of Massachusetts Medical School, Worcester, Massachusetts 01655.


Zebra finches have been a rich experimental system for studying neurobiological questions of relevance to human health for decades. In particular, finches are the leading nonhuman model organisms for investigating the biological basis of vocal learning, a critical behavioral substrate for speech acquisition. In addition, zebra finches are an ideal system for the study of brain asymmetry, hormonal control of brain development, physiological function of sleep, sex differences in the brain, behavioral-induced gene expression, and adult neurogenesis, among other questions. Despite their importance for neurobiology, the usefulness of finches as an experimental system has been restricted by a lack of genetic manipulation methods. To overcome this barrier, our laboratory has developed methods for generating transgenic birds, including zebra finches. The successful implementation of this transgenic technology by multiple research laboratories has the potential to dramatically accelerate the progress of our understanding of the genetic basis of complex biological processes such as vocal learning. Moreover, the ability to genetically manipulate zebra finches could also be used to generate novel genetic models for human disorders that cannot be studied elsewhere or that can be more easily studied in this small bird. Here, we describe a protocol to generate transgenic zebra finches using recombinant lentiviruses.
© 2014 Cold Spring Harbor Laboratory Press.
PMID: 25342068 [PubMed - as supplied by publisher]

6. Cold Spring Harb Protoc. 2014 Oct 23. doi: 10.1101/pdb.prot084780. [Epub ahead of print]

Proper Care, Husbandry, and Breeding Guidelines for the Zebra Finch, Taeniopygia guttata.

Olson CR, Wirthlin M, Lovell PV, Mello CV.
Author information:
Department of Behavioral Neuroscience, Oregon Health and Science University, Portland, Oregon 97239.


The zebra finch Taeniopygia guttata castanotis is a songbird commonly used in the laboratory, particularly for studies of vocal learning, neurobiology, and physiology. Within the laboratory, it is important to adopt careful husbandry practices that allow for normal development of the birds. For example, their song is a learned trait, passed culturally from adult males to juveniles, and thus its learning can be influenced by the health and social conditions of the birds present in the laboratory. Here we present guidelines for the successful maintenance and breeding of captive zebra finches.
© 2014 Cold Spring Harbor Laboratory Press.
PMID: 25342067 [PubMed - as supplied by publisher]

7. J R Soc Interface. 2014 Dec 6;11(101). pii: 20140961. doi: 10.1098/rsif.2014.0961.

Nanomechanical properties of bird feather rachises: exploring naturally occurring fibre reinforced laminar composites.

Laurent CM1, Palmer C2, Boardman RP3, Dyke G4, Cook RB5.
Author information:
1Ocean and Earth Science, National Oceanography Centre, University of Southampton, Southampton, UK
2Earth Sciences, University of Bristol, Bristol, UK.
3µ-Vis X-ray Imaging Centre, Faculty of Engineering and the Environment, University of Southampton, Southampton, UK.
4Ocean and Earth Science, National Oceanography Centre, University of Southampton, Southampton, UK Department of Evolutionary Zoology and Human Biology, University of Debrecen, Debrecen, Hungary.
5National Centre for Advanced Tribology at Southampton (nCATS), Faculty of Engineering and the Environment, University of Southampton, Southampton, UK.


Flight feathers have evolved under selective pressures to be sufficiently light and strong enough to cope with the stresses of flight. The feather shaft (rachis) must resist these stresses and is fundamental to this mode of locomotion. Relatively little work has been done on rachis morphology, especially from a mechanical perspective and never at the nanoscale. Nano-indentation is a cornerstone technique in materials testing. Here we use this technique to make use of differentially oriented fibres and their resulting mechanical anisotropy. The rachis is established as a multi-layered fibrous composite material with varying laminar properties in three feathers of birds with markedly different flight styles; the Mute Swan (Cygnus olor), the Bald Eagle (Haliaeetus leucocephalus) and the partridge (Perdix perdix). These birds were chosen not just because they are from different clades and have different flight styles, but because they have feathers large enough to gain meaningful results from nano-indentation. Results from our initial datasets indicate that the proportions and orientation of the laminae are not fixed and may vary either in order to cope with the stresses of flight particular to the bird or with phylogenetic lineage.
© 2014 The Author(s) Published by the Royal Society. All rights reserved.
PMID: 25339689 [PubMed - in process]
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8. Parasitol Res. 2014 Oct 24. [Epub ahead of print]

Culex pipiens s.l. and Culex torrentium (Culicidae) in Wrocław area (Poland): occurrence and breeding site preferences of mosquito vectors.

Weitzel T1, Jawień P, Rydzanicz K, Lonc E, Becker N.
Author information:
1German Mosquito Control Association (GMCA/KABS), Georg-Peter-Süß-Str. 3, 67346, Speyer, Germany,


Both ornithophilic mosquito species, Culex pipiens s.l. (L.) and Culex torrentium (Martini, 1925), occur sympatric in temperate Europe. They are presumed to be primary vectors of West Nile and Sindbis viruses. Differentiation of these morphologically similar Culex species is essential for evaluation of different vector roles, for mosquito surveillance and integrated control strategies. Cx. torrentium has been neglected or erroneously determined as Cx. pipiens s.l. in some previous studies, because only males of both species can be diagnosed reliably by morphology. Thus, knowledge about species abundance, geographical distribution, breeding site preferences and the zoonotic risk assessment is incomplete also in Poland. In Wrocław area (Silesian Lowland), besides typical urban breeding sites, huge sewage irrigation fields provide suitable breeding conditions for Culex species. They are also inhabited by 180 resident and migratory bird species serving as potential virus reservoirs. In this study, morphology of larvae and males as well as species diagnostic enzyme markers, namely adenylate kinase (AK) and 2-hydroxybutyrate dehydrogenase (HBDH), were used to discriminate Cx. pipiens s.l. and Cx. torrentium. In a total of 650 Culex larvae from 24 natural and artificial breeding sites, Cx. pipiens s.l. had a proportion of 94.0 % and Cx. torrentium only 6.0 %. It could be shown that both species are well adapted to various breeding site types like ditches, catch basins, flower pots and buckets with diverse water quality. Cx. torrentium preferred more artificial water containers in urban surrounding (12 % species proportion), whereas in semi-natural breeding sites, Cx. torrentium was rare (3 %). In 12 of 24 breeding sites, larvae of both species have been found associated.
PMID: 25339516 [PubMed - as supplied by publisher]

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9. Mem Inst Oswaldo Cruz. 2014 Oct 14;0:0. [Epub ahead of print]

Phlebotomine fauna, natural infection rate and feeding habits of Lutzomyia cruzi in Jaciara, state of Mato Grosso, Brazil.

Brito VN1, Almeida AD2, Nakazato L2, Duarte R3, Souza CD2, Sousa VR2.
Author information:
1Secretaria Estadual de Saúde de Mato Grosso, Cuiabá, MT, Brasil.
2Departamento de Clínica Médica Veterinária, Faculdade de Agronomia, Medicina Veterinária e Zootecnia, Universidade Federal de Mato Grosso, Cuiabá, MT, Brasil.
3Escola Nacional de Saúde Pública Sérgio Arouca-Fiocruz, Rio de Janeiro, RJ, Brasil.


Visceral leishmaniasis (VL) in Brazil is transmitted by the phlebotomine Lutzomyia longipalpis and in some midwestern regions by Lutzomyia cruzi. Studies of the phlebotomine fauna, feeding habits and natural infection rate by Leishmania contribute to increased understanding of the epidemiological chain of leishmaniases and their vectorial capacity. Collections were performed in Jaciara, state of Mato Grosso from 2010-2013, during which time 2,011 phlebotomines (23 species) were captured (68.70% Lu. cruzi and 20.52% Lutzomyia whitmani). Lu. cruzi females were identified by observing the shapes of the cibarium (a portion of the mouthpart) and spermatheca, from which samples were obtained for polymerase chain reaction to determine the rates of natural infection. Engorged phlebotomines were assessed to identify the blood-meal host by ELISA. A moderate correlation was discovered between the number of Lu. cruzi and the temperature and the minimum rate of infection was 6.10%. Twenty-two females were reactive to the antisera of bird (28%), dog (3.30%) and skunk (1.60%). We conclude that Lu. cruzi and Lu. whitmani have adapted to the urban environment in this region and that Lu. cruzi is the most likely vector of VL in Jaciara. Moreover, maintenance of Leishmania in the environment is likely aided by the presence of birds and domestic and synanthropic animals.
Free Article
PMID: 25338156 [PubMed - as supplied by publisher]
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10. PLoS One. 2014 Oct 22;9(10):e109397. doi: 10.1371/journal.pone.0109397. eCollection 2014.

Relative roles of grey squirrels, supplementary feeding, and habitat in shaping urban bird assemblages.

Bonnington C1, Gaston KJ2, Evans KL1.
Author information:
1Department of Animal and Plant Sciences, University of Sheffield, Sheffield, United Kingdom.
2Environment and Sustainability Institute, University of Exeter, Penryn, Cornwall, United Kingdom.


Non-native species are frequently considered to influence urban assemblages. The grey squirrel Sciurus carolinensis is one such species that is widespread in the UK and is starting to spread across Europe; it predates birds' nests and can compete with birds for supplementary food. Using distance sampling across the urbanisation intensity gradient in Sheffield (UK) we test whether urban grey squirrels influence avian species richness and density through nest predation and competition for supplementary food sources. We also assess how urban bird assemblages respond to supplementary feeding. We find that grey squirrels slightly reduced the abundance of breeding bird species most sensitive to squirrel nest predation by reducing the beneficial impact of woodland cover. There was no evidence that grey squirrel presence altered relationships between supplementary feeding and avian assemblage structure. This may be because, somewhat surprisingly, supplementary feeding was not associated with the richness or density of wintering bird assemblages. These associations were positive during the summer, supporting advocacy to feed birds during the breeding season and not just winter, but explanatory capacity was limited. The amount of green space and its quality, assessed as canopy cover, had a stronger influence on avian species richness and population size than the presence of grey squirrels and supplementary feeding stations. Urban bird populations are thus more likely to benefit from investment in improving the availability of high quality habitats than controlling squirrel populations or increased investment in supplementary feeding.
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PMID: 25338062 [PubMed - in process]

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Tuesday, 14 October 2014

Speciation in Tropical Bird Populations: Large-scale geographical transformation barriers or dispersal and differentiation? Smith et al, Nature September 2014.

The drivers of tropical speciation.

Nature. 2014 Sep 10. doi: 10.1038/nature13687. [Epub ahead of print]
PMID: 25209666 [PubMed - as supplied by publisher]



Smith BT, McCormack JE, Cuervo AM, Hickerson MJ, Aleixo A, Cadena CD, Pérez-Emán J, Burney CW, Xie X, Harvey MG, Faircloth BC, Glenn TC, Derryberry EP, Prejean J, Fields S, Brumfield RT.

These authors contributed equally to this work.
Brian Tilston Smith & Robb T. Brumfield


Museum of Natural Science, Louisiana State University, Baton Rouge, Louisiana 70803, USA

Since the recognition that allopatric speciation can be induced by large-scale reconfigurations of the landscape that isolate formerly continuous populations, such as the separation of continents by plate tectonics, the uplift of mountains or the formation of large rivers, landscape change has been viewed as a primary driver of biological diversification. This process is referred to in biogeography as vicariance. In the most species-rich region of the world, the Neotropics, the sundering of populations associated with the Andean uplift is ascribed this principal role in speciation. An alternative model posits that rather than being directly linked to landscape change, allopatric speciation is initiated to a greater extent by dispersal events, with the principal drivers of speciation being organism-specific abilities to persist and disperse in the landscape. Landscape change is not a necessity for speciation in this model. Here we show that spatial and temporal patterns of genetic differentiation in Neotropical birds are highly discordant across lineages and are not reconcilable with a model linking speciation solely to landscape change. Instead, the strongest predictors of speciation are the amount of time a lineage has persisted in the landscape and the ability of birds to move through the landscape matrix. These results, augmented by the observation that most species-level diversity originated after episodes of major Andean uplift in the Neogene period, suggest that dispersal and differentiation on a matrix previously shaped by large-scale landscape events was a major driver of avian speciation in lowland Neotropical rainforests.

Figure 1
Sampling points of the 27 bird lineages (circles) and prominent dispersal barriers within the landscape matrix, including the Andes (and associated arid habitats in the Caribbean lowlands of South America), the Isthmus of Panama and three major rivers in the Amazon Basin (Amazon, Negro and Madeira Rivers).

Figure 2
An exemplar taxon for each lineage is illustrated. Yellow bars correspond to the 95% highest posterior density for divergence times of each species. The Quaternary (2.6 Myr ago–present) and the Neogene (23–2.6 Myr ago) periods are shaded in grey and light blue, respectively. Mean stem ages for 25 of the lineages occurred within the Neogene and for two lineages within the Quaternary. Outgroups for each lineage are not included in the depicted phylogeny.

Figure 3
a, The variation in divergence times across barriers cannot be attributed to ecologically mediated vicariance. There was no significant association between dispersal ability and divergence times across the Andes and the Isthmus of Panama. Only part of the variance in divergence times across rivers was attributable to dispersal ability. Divergence levels across Amazonian rivers were generally shallower in canopy birds, but understorey birds diverged multiple times across each river. Circles represent mean estimates and bars represent the 95% highest posterior density. Colour coding of the points corresponds to the foraging stratum of each lineage: understorey, orange; canopy, green. Vertical hashed lines at 2.58 million years represent the transition between the Neogene (to the right of line) and Quaternary (to the left of line). b, Within-lineage species diversity increases with lineage (stem) age. Solid lines represent the fit of the data to a model using phylogenetic generalized least-squares analyses. Black points and line correspond to mean stem ages, and the purple points and lines correspond to the high and low values of the stem age 95% highest posterior density. c, Box plot illustrating that species diversity is significantly higher in the understorey lineages than in forest canopy lineages. The box plot shows the first, second and third quartiles, the lines are the 95% confidence intervals and the circles represent outliers. Significant associations in panels a, b and c are supported by phylogenetic generalized least-squares analyses shown in Table 1 and Supplementary Tables 9–15. Statistical tests were performed independently on each data set except for divergences across rivers; all rivers were combined into a single analysis.

The accumulation of bird species in the Neotropical landscape occurred through a repeated process of geographical isolation, speciation, and expansion, with the amount of species diversity within lineages influenced by how long the lineage has persisted in the landscape and its ability to disperse through the landscape matrix. A growing body of phylogenetic evidence indicates that average rates of avian diversification have been relatively constant in the Neotropics and, consistent with this, our results show that tumultuous changes to the South American landscape may not have led to marked pulses in speciation. Correlations between lineage ages and the Andean uplift or Quaternary climatic events reported elsewhere are suggestive of landscape and environmental change being a component of the diversification process, but the details of how, when and to what extent these changes drove the origin of standing species-level diversity remain unclear. Our phylogeographic-scale analysis indicated most species-level variation postdates the Andean uplift, and our results contribute to a growing number of studies reporting dispersal events as the primary initiators of geographical isolation and speciation. Our results also have an important conservation implication. Anthropogenic alterations of the landscape matrix by deforestation and climate change affect not only the evolutionary persistence of rainforest lineages, but also the occurrence of cross-barrier dispersal events within lineages that lead to new biological diversity.

Monday, 13 October 2014

Sexual selection in the Yellow-browed Warbler (Phylloscopus inornatus) Animal Behaviour, 1998:55

The evolution of multiple male traits in the yellow-browed leaf warbler


Animal Behaviour, 1998, 55, 361–376 (Received 6 March 1996; initial acceptance 10 August 1996;final acceptance 28 March 1997; MS. number: A7544)

Karen Marchetti
Section of Evolution and Ecology, University of California at Davis


I examined how male competition and female choice influence the evolution of multiple male traits in the yellow-browed leaf warbler, Phylloscopus inornatus, by investigating the roles of colour patches, territory size, body weight and song rate in sexual selection. Comparison of 3 years of observational studies and 3 years of experimental studies, in which the colour patches on the wings of males were experimentally altered, suggest several mechanisms that may explain the evolution of multiple characters in males. First, females based their choice of mates on several male characters, not a single character. Second, the male characters preferred by females were different in observational and experimental studies. Females apparently preferred high-quality males as mates, and were able to vary the characters used in mate choice to distinguish these individuals under both experimental and
observational conditions. Third, the characters important in male competition differed from those that formed the basis of female choice: the manipulation of colour patch size directly affected male territory size but was not associated with female choice. These results may provide an explanation for the diversity of sexual ornaments shown by males of many species.

(C) 1998 The Association for the Study of Animal Behaviour

Assessing barriers to breeding wild animals in captivity: European Starling study 2014.

Stress, captivity, and reproduction in a wild bird species.


Dickens MJ-1, Bentley GE-2.

Author information
1-Department of Integrative Biology, University of California, Berkeley, USA. Electronic address:
2-Department of Integrative Biology, University of California, Berkeley, USA; Helen Wills Neuroscience Institute, University of California, Berkeley, USA.

Horm Behav. 2014 Sep 23;66(4):685-693. doi: 10.1016/j.yhbeh.2014.09.011. [Epub ahead of print]

In seasonal species, glucocorticoid concentrations are often highest during the breeding season. However, the role of increased hypothalamic-pituitary-adrenal (HPA) activity in the regulation of reproduction remains poorly understood. Our study is the first, to our knowledge, to document reproductive consequences of a non-pharmacological hindrance to seasonal HPA fluctuations. Using wild-caught male and female European starlings (Sturnus vulgaris) housed in an outdoor, semi-natural environment, we divided birds into two mixed-sex groups. One group remained in the outdoor aviary, where starlings breed at the appropriate time of year. The other group was transferred into an indoor flight aviary, where we predicted reproductive suppression to occur. We measured changes in corticosterone (CORT) at baseline and stress-induced concentrations prior to group separation and at the experiment's conclusion. After ten days, the birds showed remarkable differences in breeding behavior and HPA activity. Outdoor birds exhibited increases in baseline and stress-induced CORT and progressed into active breeding (pairing, nest building, egg laying, etc.). In contrast, indoor birds displayed no change in baseline or stress-induced CORT and few signs of active breeding. We found significant sex and treatment effects on expression of HPA and hypothalamic-pituitary-gonadal (HPG) axis elements, suggesting sex-specific regulatory mechanisms. Our data suggest a novel, facilitating role for the HPA axis in the transition between early breeding and active breeding in a wild, seasonal avian species. In addition, understanding how changes in housing condition affect seasonal HPA fluctuations may help alleviate barriers to breeding wild animals in captivity.
Copyright © 2014. Published by Elsevier Inc.

Captivity; Corticosterone; Hypothalamic–pituitary–adrenal axis; Hypothalamic–pituitary–gonadal axis; Seasonality

PMID: 25257808 [PubMed - as supplied by publisher]

Saturday, 11 October 2014

Timing of feather moot and spring migration in white-throated Sparrows. J Exp Zool Oct, 2014

Timing of feather molt related to date of spring migration in male white-throated sparrows, Zonotrichia albicollis.


Cristobalite DA(1), Johnson KM, Jenkins KD, Hawley DM.

Author information:
1Institute for Integrative Bird Behavior Studies, Department of Biology, The College of William and Mary, Williamsburg, Virginia.

J Exp Zool A Ecol Genet Physiol. 2014 Oct 6. doi: 10.1002/jez.1899. [Epub ahead of print]


In migratory birds, the ability to depart wintering grounds at the appropriate time is an important determinant of fitness. Understanding the regulation of this timing will be essential for predicting whether timing of bird migration keeps up with global climate change. We examined whether the timing of the late-winter molt, in which white-throated sparrows (Zonotrichia albicollis) replace head and body feathers in advance of mating, may constrain the timing of northward migratory departure. In an observational study, we found a significant correlation between timing of molt and the date on which free-living male white-throated sparrows disappeared from our study site during migration. The following year, we tested whether experimentally manipulating molt date by advancing photoperiod during temporary captivity would subsequently advance disappearance date once the birds were released. Sparrows that were experimentally induced to molt early disappeared from the wintering site before controls. However, the captive control birds also molted and disappeared from the site earlier than free-living controls, suggesting that the diet during captivity had played a role. In the third winter we completed the study by advancing or delaying molt using only dietary manipulation. Together, these results show that the ability to molt early in spring is related to early disappearance from the wintering site. Early molt likely has carry-over effects on reproduction and the requirements of molt may prevent populations from adjusting migration timing in response to global climate change.

© 2014 Wiley Periodicals, Inc.

PMID: 25287905 [PubMed - as supplied by publisher]

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Evolution of Rallidae species. PLoS One, 2014; 9(10)

Eocene diversification of crown group rails (aves: gruiformes: rallidae)

García-R JC, Gibb GC, Trewick SA

Author information:
Phoenix Lab, Ecology Group, Institute of Agriculture and Environment, Massey University, Palmerston North, New Zealand.

PLoS One. 2014 Oct 7;9(10):e109635. doi: 10.1371/journal.pone.0109635. eCollection 2014.


Central to our understanding of the timing of bird evolution is debate about an apparent conflict between fossil and molecular data. A deep age for higher level taxa within Neoaves is evident from molecular analyses but much remains to be learned about the age of diversification in modern bird families and their evolutionary ecology. In order to better understand the timing and pattern of diversification within the family Rallidae we used a relaxed molecular clock, fossil calibrations, and complete mitochondrial genomes from a range of rallid species analysed in a Bayesian framework. The estimated time of origin of Rallidae is Eocene, about 40.5 Mya, with evidence of intrafamiliar diversification from the Late Eocene to the Miocene. This timing is older than previously suggested for crown group Rallidae, but fossil calibrations, extent of taxon sampling and substantial sequence data give it credence. We note that fossils of Eocene age tentatively assigned to Rallidae are consistent with our findings. Compared to available studies of other bird lineages, the rail clade is old and supports an inference of deep ancestry of ground-dwelling habits among Neoaves.

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PMID: 25291147 [PubMed - in process]

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