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Tuesday, 26 August 2014

Tracking and genetics for the interpretation of Hermit Thrush migration and population structure. Alvarado et al; Ecology and Evolution, August 2014

Integrative tracking methods elucidate the evolutionary dynamics of a migratory divide.

Ecology and Evolution

LINK (website / open access)

Allison H. Alvarado 1,*, Trevon L. Fuller 1 and Thomas B. Smith 1,2

Author Information
1. Center for Tropical Research, Institute of the Environment and Sustainability, University of California, Los Angeles, California
2. Department of Ecology and Evolutionary Biology, University of California, Los Angeles, California
* Correspondence 
Allison H. Alvarado, Center for Tropical Research, Institute of the Environment and Sustainability, University of California, Los Angeles, La Kretz Hall, Suite 300, 619 Charles E. Young Dr. East, Los Angeles, CA 90095. Tel: 310-206-6234; Fax: 310-825-5446; 

Article first published online: 20 AUG 2014

DOI: 10.1002/ece3.1205

© 2014 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.

Migratory divides, the boundary between adjacent bird populations that migrate in different directions, are of considerable interest to evolutionary biologists because of their alleged role in speciation of migratory birds. However, the small size of many passerines has traditionally limited the tools available to track populations and as a result, restricted our ability to study how reproductive isolation might occur across a divide. Here, we integrate multiple approaches by using genetic, geolocator, and morphological data to investigate a migratory divide in hermit thrushes (Catharus guttatus). First, high genetic divergence between migratory groups indicates the divide is a region of secondary contact between historically isolated populations. Second, despite low sample sizes, geolocators reveal dramatic differences in overwintering locations and migratory distance of individuals from either side of the divide. Third, a diagnostic genetic marker that proved useful for tracking a key population suggests a likely intermediate nonbreeding location of birds from the hybrid zone. This finding, combined with lower return rates from this region, is consistent with comparatively lower fitness of hybrids, which is possibly due to this intermediate migration pattern. We discuss our results in the context of reproductive isolating mechanisms associated with migration patterns that have long been hypothesized to promote divergence across migratory divides.

Example Data

Figure 2
Geolocators and range-wide genetic data reveal a migratory divide in hermit thrushes. Geolocators indicate western British Columbia (BC) birds (n = 3) overwinter in California and Oregon (W1–W3) while eastern BC birds (n = 2) overwinter in Arkansas (E1–E2). Solid lines represent spring migration routes of eastern BC birds. Dotted lines link breeding and overwintering locations of western BC birds. Black dots connecting lines represent geolocator deployment/retrieval sites on breeding grounds and the centroid of overwintering home range on nonbreeding grounds. For our range-wide sample of birds (n = 380), we genotyped a β-fibint7 SNP within breeding (hatched circles) and nonbreeding (nonhatched circled) populations. Circle diameter represents genotype frequency (small circles = 1–3 birds; medium circles = 4–10 birds; large circles =11–20 birds; also see Table S1 for sample sizes). On the breeding grounds, genotypes AA (green) and BB (blue) occur west and east of the migratory divide in BC, respectively. During the nonbreeding season, these genotypes do not mix, indicating birds from opposing sides of the divide migrate different directions and are geographically separated while overwintering. Heterozygote genotype AB (red) is only found in central BC during the breeding season and only in New Mexico during the nonbreeding season, suggesting a likely intermediate nonbreeding location for birds from the hybrid zone.

Our study uses a combination of very different and complementary approaches to address interesting questions on the past and present evolutionary mechanisms thought to generate and maintain migratory divides. Deep divergence in mtDNA and microsatellites reveals that the hermit thrush migratory divide is the result of secondary contact following Pleistocene divergence of two lineages. A combination of fine-scale tracking with geolocators and broad-scale tracking using a diagnostic genetic marker indicate the lineages correspond to distinct eastern and western migratory forms. Evidence of genetic admixture and the intermediate morphology of individuals reveal evidence of hybridization at the secondary contact zone in central BC. Birds from this site appear to migrate to an intermediate nonbreeding location (based on genetic data) and experience lower return rates (based on geolocator data), potentially suggesting lower fitness. Therefore, postzygotic isolating mechanisms related to migratory patterns are likely involved in maintaining high levels of genetic divergence and significant morphological differences among hermit thrush populations from either side of the migratory divide. It is unclear whether and at what stage the distinct migratory forms of hermit thrushes are in the speciation process (Coyne, J. A., and H. A. Orr. 2004. Speciation. Sinauer Associates, Sunderland, MA.; Irwin, D. E., and J. H. Irwin. 2005. Siberian migratory divides: the role of seasonal migration in speciation. Pp. 27–40 in R. Greenberg and P. P. Marra, eds. Birds of Two Worlds: The Ecology and Evolution of Migration. The Johns Hopkins Univ. Press, Baltimore, MD.). However, the biogeographic histories (Weir, J. T., and D. Schluter. 2004. Ice sheets promote speciation in boreal birds. Proc. R. Soc. Lond. B 271:1881–1887.) and patterns of divergent migratory behavior (Brewer, D. 2000. Canadian Atlas of Bird Banding. Canadian Wildlife Service, Ottawa, ON.) of numerous other parapatric sister taxa, many of which have recently been designated as separate species, are similar to those of hermit thrushes. The mechanisms that historically create, currently maintain, and further promote population differences across migratory divides may also shape patterns of biodiversity and speciation in avian taxa of North America that have not traditionally been studied within this context.

Monday, 25 August 2014

Bird research this week on PubMed: August 2014 Week 4

PubMed listing for 'bird' OR 'songbird' excluding references to influenza and flu - August 2014 Week 4

1. Poult Sci. 2014 Aug 20. pii: PS3910. [Epub ahead of print]

Response to dietary supplementation of l-glutamine and l-glutamate in broiler chickens reared at different stocking densities under hot, humid tropical conditions.

Shakeri M1, Zulkifli I2, Soleimani AF1, O'Reilly EL3, Eckersall PD3, Anna AA1, Kumari S1, Abdullah FF4.Author information:
1Institute of Tropical Agriculture, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia.
2Institute of Tropical Agriculture, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia
3Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Bearsden Road, Glasgow, G61 1QH, United Kingdom.
4Faculty of Veterinary Medicine, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia.


A study was conducted to determine whether supplementing AminoGut (a commercial dietary supplement containing a mixture of l-glutamine and l-glutamic acid) to broiler chickens stocked at 2 different densities affected performance, physiological stress responses, foot pad dermatitis incidence, and intestinal morphology and microflora. A randomized design in a factorial arrangement with 4 diets [basal diet, basal diet + 0.5% AminoGut from d 1 to 21, basal diet + 0.5% AminoGut from d 1 to 42, and basal diet + virginiamycin (0.02%) for d 1 to 42] and 2 stocking densities [0.100 m2/bird (23 birds/pen; LD) or 0.067 m2/bird (35 birds/pen; HD)]. Results showed that villi length and crypt depth were not changed by different dietary treatments. However, birds in the HD group had smaller villi (P = 0.03) compared with those of the LD group. Regardless of diet, HD consistently increased the serum concentrations of ceruloplasmin, α-1 acid glycoprotein, ovotransferin, and corticosterone (P = 0.0007), and elevated heterophil to lymphocyte ratio (0.0005). Neither AminoGut supplementation nor stocking density affected cecal microflora counts. In conclusion, under the conditions of this study, dietary supplementation of AminoGut, irrespective of stocking density, had no beneficial effect on growth performance, intestinal morphology, and physiological adaptive responses of broiler chickens raised under hot and humid tropical conditions. However, AminoGut supplementation from d 1 to 42 was beneficial in reducing mortality rate. Also, the increased serum concentrations of a wide range of acute phase proteins together with elevated corticosterone and heterophil to lymphocyte ratio suggested that high stocking density induced an acute phase response either indirectly as a result of increased incidence of inflammatory diseases such as foot pad dermatitis or possibly as a direct physiological response to the stress of high stocking density.
© 2014 Poultry Science Association Inc.
PMID: 25143595 [PubMed - as supplied by publisher]

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2. Poult Sci. 2014 Aug 20. pii: PS4148. [Epub ahead of print]

Dietary calcium, phosphorus, and phytase effects on bird performance, intestinal morphology, mineral digestibility, and bone ash during a natural necrotic enteritis episode.

Paiva D1, Walk C2, McElroy A3.Author information:
1Animal and Poultry Sciences, Virginia Tech, 3140 Litton Reaves Hall, Blacksburg 24060
2 ABVista Feed Ingredients, Marlborough, Wiltshire, SN8 4AN United Kingdom.
3Animal and Poultry Sciences, Virginia Tech, 3140 Litton Reaves Hall, Blacksburg 24060.


The objective of this study was to evaluate the effects of dietary Ca, P, and phytase on performance, intestinal morphology, bone ash, and Ca and P digestibility during a necrotic enteritis (NE) outbreak. The 35-d trial was designed as a 2 × 2 × 2 factorial, which included 2 Ca levels (0.6 and 0.9%), 2 P levels (0.3 and 0.45%), and 2 levels of phytase [0 and 1,000 phytase units (FTU)/kg]. Birds were placed on litter from a previous flock that exhibited clinical signs of NE. Birds and feed were weighed on d 12, 19, and 35, and BW gain, feed intake, and feed conversion were calculated. Mortality was recorded daily, and gastrointestinal pH was measured. Tibias and ileal digesta were also collected. Birds began exhibiting clinical signs of NE on d 9, and NE-associated mortality persisted until d 26. Dietary Ca supplemented at 0.9% or inclusion of 1,000 FTU/kg of phytase significantly increased mortality compared with 0.6% Ca or 0 FTU/kg of phytase, respectively. From d 0 to 12, birds fed 0.9% Ca and 0.45% available P with phytase had greater BW gain compared with birds fed 0.6% Ca, 0.45% available P, and phytase. From d 0 to 19, birds fed diets with 0.9% Ca and 0.3% available P had decreased feed intake and improved feed conversion compared with birds fed 0.9% Ca and 0.45% available P. Calcium at 0.9% increased gizzard (d 19) and jejunum (d 12) pH. Phytase supplementation significantly increased Ca digestibility regardless of Ca and P levels of the diets. In addition, diets containing 0.6% Ca and 1,000 FTU/kg of phytase resulted in a significant increase in P digestibility. The results suggest that dietary Ca level may influence NE-associated mortality. In addition, bird performance was affected by interactions of Ca, P, and phytase during the exposure to Clostridium perfringens and the subsequent NE outbreak. Results showed improvements in bird performance when birds were fed 0.6% Ca and 0.3% P in diets supplemented with phytase, which was likely consequent to the influence of Ca in NE pathogenesis.
© 2014 Poultry Science Association Inc.
PMID: 25143591 [PubMed - as supplied by publisher]

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3. Pest Manag Sci. 2014 Aug 21. doi: 10.1002/ps.3887. [Epub ahead of print]

Bird-repellents effects on bait efficacy for control of invasive mammal pests.

Cowan P1, Brown S, Forrester G, Booth L, Crowell M.Author information:
1Landcare Research, PO Box 69040, Lincoln, 7640, New Zealand.



Repellents to reduce crop damage from birds and mammals have been investigated extensively but their efficacy in reducing risk to non-target birds in aerial poisoning operations for control of mammal pests is less known. We assessed the impact on bait acceptability, palatability and kill efficacy for captive wild rats (Rattus rattus L.) and possums (Trichosurus vulpecula Kerr) of adding bird repellents (anthraquinone and d-pulegone) to baits used for their control in food choice trials.


For possums, anthraquinone at 0.25% reduced acceptability and palatability but not the efficacy of poison baits, whereas d-pulegone at 0.17% had no significant effects. Rats showed little response to d-pulegone, but developed a marked aversion to prefeed baits containing anthraquinone at both 0.1 and 0.25%, such that almost no exposed rats ate poison baits and mortality was reduced significantly. The aversion induced by anthraquinone was generalised to the bait as anthraquinone-exposed rats did not eat bait with only d-pulegone.


Anthraquinone is not suitable for inclusion in bait for rat control at the concentrations tested, and also presents some risk to efficacy for possum control. D-pulegone would be suitable for inclusion in bait for possums and rats but problems related to its volatility in bait manufacture and storage would need to be overcome. Further studies should focus on an alternative secondary repellent, or establishing the maximum anthraquinone concentration that does not reduce efficacy for rats and testing whether or not that concentration is sufficient to reliably repel native birds from baits.
This article is protected by copyright. All rights reserved.
PMID: 25143303 [PubMed - as supplied by publisher]

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4. Mem Inst Oswaldo Cruz. 2014 Aug 19;0:0. [Epub ahead of print]

Is imidacloprid an effective alternative for controlling pyrethroid-resistant populations of Triatoma infestans (Hemiptera: Reduviidae) in the Gran Chaco ecoregion?

Carvajal G, Picollo MI, Toloza AC.Author information:
Consejo Nacional de Investigaciones Científicas y Técnicas, Centro de Investigaciones de Plagas e Insecticidas, Instituto de Investigaciones Científicas y Técnicas para la Defensa, Buenos Aires, Argentina.


The prevention of Chagas disease is based primarily on the chemical control of Triatoma infestans (Klug) using pyrethroid insecticides. However, high resistance levels, correlated with control failures, have been detected in Argentina and Bolivia. A previous study at our laboratory found that imidacloprid could serve as an alternative to pyrethroid insecticides. We studied the delayed toxicity of imidacloprid and the influence of the blood feeding condition of the insect on the toxicity of this insecticide; we also studied the effectiveness of various commercial imidacloprid formulations against a pyrethroid-resistant T. infestans population from the Gran Chaco ecoregion. Variations in the toxic effects of imidacloprid were not observed up to 72 h after exposure and were not found to depend on the blood feeding condition of susceptible and resistant individuals. Of the three different studied formulations of imidacloprid on glass and filter paper, only the spot-on formulation was effective. This formulation was applied to pigeons at doses of 1, 5, 20 and 40 mg/bird. The nymphs that fed on pigeons treated with 20 mg or 40 mg of the formulation showed a higher mortality rate than the control group one day and seven days post-treatment (p < 0.01). A spot-on formulation of imidacloprid was effective against pyrethroid-resistant T. infestans populations at the laboratory level.
Free Article
PMID: 25141281 [PubMed - as supplied by publisher]

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5. PLoS One. 2014 Aug 20;9(8):e105605. doi: 10.1371/journal.pone.0105605. eCollection 2014.

Tracking from the tropics reveals behaviour of juvenile songbirds on their first spring migration.

McKinnon EA, Fraser KC, Stanley CQ, Stutchbury BJ.Author information:
Dept. of Biology, York University, Toronto, Ontario, Canada.


Juvenile songbirds on spring migration travel from tropical wintering sites to temperate breeding destinations thousands of kilometres away with no prior experience to guide them. We provide a first glimpse at the migration timing, routes, and stopover behaviour of juvenile wood thrushes (Hylocichla mustelina) on their inaugural spring migration by using miniaturized archival geolocators to track them from Central America to the U.S. and Canada. We found significant differences between the timing of juvenile migration and that of more experienced adults: juveniles not only departed later from tropical wintering sites relative to adults, they also became progressively later as they moved northward. The increasing delay was driven by more frequent short stops by juveniles along their migration route, particularly in the U.S. as they got closer to breeding sites. Surprisingly, juveniles were just as likely as adults to cross the Gulf of Mexico, an open-water crossing of 800-1000 km, and migration route at the Gulf was not significantly different for juveniles relative to adults. To determine if the later departure of juveniles was related to poor body condition in winter relative to adults, we examined percent lean body mass, fat scores, and pectoral muscle scores of juvenile versus adult birds at a wintering site in Belize. We found no age-related differences in body condition. Later migration timing of juveniles relative to adults could be an adaptive strategy (as opposed to condition-dependent) to avoid the high costs of fast migration and competition for breeding territories with experienced and larger adults. We did find significant differences in wing size between adults and juveniles, which could contribute to lower flight efficiency of juveniles and thus slower overall migration speed. We provide the first step toward understanding the "black box" of juvenile songbird migration by documenting their migration timing and en route performance.
Free Article
PMID: 25141193 [PubMed - in process]

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6. Am Nat. 2014 Sep;184(3):374-83. doi: 10.1086/677397. Epub 2014 Aug 6.

Nonautosomal genetic variation in carotenoid coloration.

Evans SR1, Schielzeth H, Forstmeier W, Sheldon BC, Husby A. Author information:
1Department of Animal Ecology, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, 752 36 Uppsala, Sweden.


Abstract Carotenoid-based coloration plays an important role in signaling, is often sexually dimorphic, and is potentially subject to directional and/or sex-specific selection. To understand the evolutionary dynamics of such color traits, it is essential to quantify patterns of inheritance, yet nonautosomal sources of genetic variation are easily overlooked by classical heritability analyses. Carotenoid metabolism has recently been linked to mitochondria, highlighting the potential for color variation to be explained by cytoplasmically inherited factors. In this study, we used quantitative genetic animal models to estimate the importance of mitochondrial and sex chromosome-linked sources of genetic variation in coloration in two songbird populations in which dietary carotenoids are either unmodified (great tit plumage) or metabolized into alternative color forms (zebra finch beak). We found no significant Z-linked genetic variance in great tit plumage coloration, while zebra finch beak coloration exhibited significant W linkage and cytoplasmic inheritance. Our results support cytoplasmic inheritance of color in the zebra finch, a trait based on endogenously metabolized carotenoids, and demonstrate the potential for nonautosomal sources to account for a considerable share of genetic variation in coloration. Although often overlooked, such nonautosomal genetic variation exhibits sex-dependent patterns of inheritance and potentially influences the evolution of sexual dichromatism.
PMID: 25141146 [PubMed - in process]

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7. Am Nat. 2014 Sep;184(3):352-63. doi: 10.1086/677261. Epub 2014 Aug 6.

Asynchrony of seasons: genetic differentiation associated with geographic variation in climatic seasonality and reproductive phenology.

Quintero I1, González-Caro S, Zalamea PC, Cadena CD.Author information:
1 Laboratorio de Biología Evolutiva de Vertebrados, Departamento de Ciencias Biológicas, Universidad de los Andes, Bogotá, Colombia.


AMany organisms exhibit distinct breeding seasons tracking food availability. If conspecific populations inhabit areas that experience different temporal cycles in food availability spurred by variation in precipitation regimes, then they should display asynchronous breeding seasons. Thus, such populations might exhibit a temporal barrier to gene flow, which may potentially promote genetic differentiation. We test a central prediction of this hypothesis, namely, that individuals living in areas with more asynchronous precipitation regimes should be more genetically differentiated than individuals living in areas with more similar precipitation regimes. Using mitochondrial DNA sequences, climatic data, and geographical/ecological distances between individuals of 57 New World bird species mostly from the tropics, we examined the effect of asynchronous precipitation (a proxy for asynchronous resource availability) on genetic differentiation. We found evidence for a positive and significant cross-species effect of precipitation asynchrony on genetic distance after accounting for geographical/ecological distances, suggesting that current climatic conditions may play a role in population differentiation. Spatial asynchrony in climate may thus drive evolutionary divergence in the absence of overt geographic barriers to gene flow; this mechanism contrasts with those invoked by most models of biotic diversification emphasizing physical or ecological changes to the landscape as drivers of divergence.
PMID: 25141144 [PubMed - in process]

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8. Curr Biol. 2014 Aug 18;24(16):R751-3. doi: 10.1016/j.cub.2014.07.017.

Dinosaur evolution: feathers up for selection.

Zhou Z.Author information:
Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, 142 Xiwai Street, Beijing, 100044, China. Electronic address:


A new specimen of the early bird Archaeopteryx shows remarkable plumage preservation, including pennaceous leg feathers. But whether birds went through a four-winged stage, and in what exact functional context feathers evolved remains a matter of debate.
Copyright © 2014 Elsevier Ltd. All rights reserved.
PMID: 25137588 [PubMed - in process]

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9. Avian Pathol. 2014 Aug 18:1-24. [Epub ahead of print]

Detection and molecular characterization of infectious bronchitis-like viruses in wild bird populations.

Domanska-Blicharz K1, Jacukowicz A, Lisowska A, Wyrostek K, Minta Z.Author information:
1a Department of Poultry Diseases , National Veterinary Research Institute, , Al. Partyzantow 57, 24-100 Pulawy , Poland.


We examined 884 wild birds mainly from the Anseriformes, Charadriiformes, Galliforme orders for infectious bronchits (IBV)-like coronavirus in Poland between 2008 and 2011. Coronavirus (CoV) was detected in 31 (3.5%) of the tested birds with detection rates of 3.5% in Anseriformes and 2.3% in Charadriiformes and as high as 17.6% in Galliformes. From the 31 positive samples only ten gave positive results in molecular tests aimed at various IBV genome fragments: five samples were positive for the RdRp gene, four for gene 3, eight for gene N and eight for the 3'UTR fragment. All analyzed genome fragments of the CoV strains shared different evolutionary branches, resulting in a different phylogenetic tree topology. Most detected fragment genes seem to be IBV-like genes of the most frequently detected lineages of IBV in this geographical region, i.e. Massachusettes, 793B and QX. Two waves of CoV infections were identified: one in spring (April-May) and another in late autumn (October-December). To our knowledge this is the first report of the detection of different fragment IBV-like genes in wild bird populations.
PMID: 25133705 [PubMed - as supplied by publisher]

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10. ScientificWorldJournal. 2014;2014:157824. doi: 10.1155/2014/157824. Epub 2014 Jul 15.

Bird Diversity and Distribution in relation to Urban Landscape Types in Northern Rwanda.

Gatesire T1, Nsabimana D2, Nyiramana A2, Seburanga JL2, Mirville MO3.Author information:
1University of Rwanda, P.O. Box 117, Butare, Rwanda ; Karisoke Research Center, Dian Fossey Gorilla Fund International, 800 Cherokee Avenue Southeast, Atlanta, GA 30315-1440, USA.
2University of Rwanda, P.O. Box 117, Butare, Rwanda.
3Karisoke Research Center, Dian Fossey Gorilla Fund International, 800 Cherokee Avenue Southeast, Atlanta, GA 30315-1440, USA.


Using the point count method, linear mixed models, Shannon's diversity index, and Bray-Curtis cluster analysis, we conducted a study of the effect of urban fabric layout on bird diversity and distribution in northern Rwanda. The results showed a significant effect of city landscapes on bird richness and relative abundance; residential neighborhoods, institutional grounds, and informal settlements had the highest species diversity in comparison to other microlandscape types. Riversides were characterized by specialized bird species, commonly known to be restricted to wetland environments. Built-up areas and open field landscapes had comparable results. One Albertine Rift endemic bird species, the Ruwenzori Double-collared Sunbird (Cinnyris stuhlmanni), was recorded. Three migratory birds were found in Musanze city for the first time: the Common Sandpiper (Actitis hypoleucos), the Spotted Flycatcher (Muscicapa striata), and the Willow Warbler (Phylloscopus trochilus). Two bird species have not been previously reported in Rwanda: the Garden Warbler (Sylvia borin) and the Lesser Spotted Eagle (Aquila pomarina). The implications of this study are particularly relevant to urban decision makers who should consider the existence of a great diversity of avian fauna when developing and implementing master plans, especially when villages and cities are in proximity of protected areas or natural reserves.
PMCID: PMC4123549 Free PMC Article
PMID: 25133203 [PubMed - in process]

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Tuesday, 19 August 2014

Journal of Raptor Research September 2014, Volume 48, Issue 3: Contents and Abstracts

Journal of Raptor Research

Table of Contents : SEPTEMBER 2014 : Volume 48 Issue 3 


Population Density, Home Range, and Habitat Use of Crested Serpent-Eagles (Spilornis cheela hoya) in Southern Taiwan: Using Distance-Based Analysis and Compositional Analysis at Different Spatial Scales Full Access

Bruno A. Walther, Ta-Ching Chou, Pei-Fen Lee
pg(s) 195–209

For many tropical raptors, studies of population density and habitat use are still lacking. We used radio-tracking to study population density, home-range size, and habitat use of the Formosan Crested Serpent-Eagle (Spilornis cheela hoya) in Kenting National Park, southern Taiwan, during 1995–1997 and 1998–2007. Over two years, we documented a minimum population density of 2.69 individuals/km2, which is one of the highest ever reported. Home ranges calculated using minimum convex polygons and 95% fixed kernel areas averaged 12.34 km2 and 2.86 km2 (n  =  18), respectively. Core areas represented by the 50% fixed kernel areas averaged 0.41 km2. We used distance-based analysis and compositional analysis to compare habitat use within the entire study area and the home ranges. Both methods indicated the overwhelming use (>90%) of somewhat degraded and semi-open mixed forests, followed by the use of Acacia confusaforests and grasslands to a much lesser degree. Habitat use was nonrandom both within the study area and the home range, as mixed forests covered only 24.4% of the study area. Many perch sites were near the primary monsoon forest, which was, however, almost never used for hunting. As many other species of serpent-eagles are threatened by habitat loss and human persecution, our study provides valuable information for their future monitoring and management.
Abstract & References : Full Text : PDF (2496 KB)


Use of Protected Activity Centers by Mexican Spotted Owls in the Sacramento Mountains, New Mexico Full Access

Joseph L. Ganey, James P. Ward, Jr, Jeffrey S. Jenness, William M. Block, Shaula Hedwall, Ryan S. Jonnes and Darrell L. Apprill, Todd A. Rawlinson, Sean C. Kyle, Steven L. Spangle
pg(s) 210–218

A Recovery Plan developed for the threatened Mexican Spotted Owl (Strix occidentalis lucida) recommended designating Protected Activity Centers (PACs) with a minimum size of 243 ha to conserve core use areas of territorial owls. The plan assumed that areas of this size would protect “… the nest site, several roost sites, and the most proximal and highly-used foraging areas.” The PAC concept remains an important component of the recovery strategy nineteen years later, although use of designated PACs by territorial owls has never been evaluated. We assessed use of PACs for nesting and roosting by Mexican Spotted Owls in the Sacramento Mountains, New Mexico, using location data obtained during a study of owl demography from 2004–2011. High proportions of both nest and roost locations were located within the PAC boundary for most, but not all, PACs. Many locations outside of PAC boundaries were adjacent to those boundaries, but some occurred >1 km from PAC boundaries. Proportions of roost locations within the PAC also were high for most, but not all, individual owls of both sexes, and in all years of the study. Proportions of locations within PACs remained relatively high for periods of up to 24 yr following PAC establishment, suggesting that owls continued to use these areas over relatively long periods. A number of vacant PACs were recolonized by owls during the study, and these owls also used PAC areas at high levels in most, but not all, cases. It would be desirable to assess PAC use over longer time periods, in other geographic areas, and to incorporate foraging use in such evaluations. In the meantime, however, our results suggest that most resident owls concentrated nesting and roosting activity within designated PAC areas in our study area, that some vacant PACs were recolonized, and that use levels in PACs remained high as long as 24 yr after PAC establishment, suggesting that PACs in this area are providing important habitat for owls.


Age-Related Differential Migration Strategies in Northern Saw-Whet Owls (Aegolius acadicusFull Access

Ross A. Brittain and B. Casey Jones
pg(s) 219–227


We analyzed differences in wing loading and body condition indices (BCI) between hatch-year (HY) and after-hatch-year (AHY) Northern Saw-whet Owls (Aegolius acadicus) captured during autumn migration in south-central Indiana. From 2002 to 2012, banders captured 1469 owls at two sites, including 826 HY owls and 641 AHY owls. The mean BCI (mass to wing chord ratio) was 0.665 g/mm and did not vary between HY and AHY owls. BCI was lowest in 2005 (0.658 g/mm) and highest in 2008 (0.679 g/mm). During autumn 2007, the banders photographed 267 owls at the two banding sites to enable comparisons of wing loading (mass to wing surface area ratio) and BCI for different age categories. Mean wing loading was 0.242 g/cm2 and also did not vary between HY and AHY owls, confirming the BCI results and suggesting that the age classes were not gaining or losing mass differentially. The median arrival date was 3 d earlier and the nightly median capture time was 10 min later for HY owls. In addition, the mass of HY owls correlated positively with the nightly capture time, whereas this was not true for adults. Together these results suggest that HY Northern Saw-whet Owls in south-central Indiana make up for any limitations in migratory/hunting abilities by migrating earlier each night and foraging more frequently while migrating. Migrating earlier, whether by choice or as a result of density-dependent adult competition, likely affords the younger birds greater access to prey in commonly exploited foraging areas. Available data indicate the potential for regional variation in the mass to wing chord correlation for this species, which needs further research. We also suggest that future studies obtain full wingspan measurements and compare the wingtip shape (amount of point and convexity) between juvenile and adult birds.
Abstract & References : Full Text : PDF (1037 KB)


Factors Related to Northern Goshawk Landscape Use in the Western Great Lakes Region Full Access

Jason E. Bruggeman, David E. Andersen, James E. Woodford
pg(s) 228–239


Northern Goshawks (Accipiter gentilis) are a species of special conservation concern in the western Great Lakes bioregion and elsewhere in North America, and exhibit landscape-scale spatial use patterns. However, little information exists about Northern Goshawk habitat relations at broad spatial extents, as most existing published information comes from a few locations of relatively small spatial extent and, in some cases, short durations. We used an information-theoretic approach to evaluate competing hypotheses regarding factors (forest canopy cover, successional stage, and heights of the canopy top and base) related to odds of Northern Goshawk landscape use throughout the western Great Lakes bioregion based on an occupancy survey completed in 2008 (Bruggeman et al. 2011). We also combined these data with historical data of Northern Goshawk nest locations in the bioregion from 1979–2006 to evaluate the same competing hypotheses to elucidate long-term trends in use. The odds of Northern Goshawk use in 2008, and from 1979–2008, were positively correlated with average percent canopy cover. In the best-approximating models developed using 1979–2008 data, the odds of landscape use were positively correlated with the percentages of the landscape having canopy heights between 10 m and 25 m, and 25 m and 50 m, and the amount of variability in canopy base height. Also, the odds of landscape use were negatively correlated with the average height at the canopy base. Our results suggest multiple habitat factors were related to Northern Goshawk landscape-scale habitat use, similar to habitat use described at smaller spatial scales in the western Great Lakes bioregion and in western North America and Europe.


Correlation of Cere Color with Intra- and Interspecific Agonistic Interactions of Crested Caracaras Full Access

James F. Dwyer
pg(s) 240–247


Bright coloration in birds is an important indicator of individual quality often used in social displays. Structural, carotenoid-, and melanin-based colors are long-lasting, widespread, and widely studied. Hemoglobin-based colors are ephemeral, rare, and less studied. Hemoglobin-based displays occur when an individual facultatively enhances or restricts blood flow through caruncles, combs, wattles, or other highly vascularized un-feathered skin patches. In Crested Caracaras (Caracara cheriway; hereafter “caracara”) highly vascularized ceres facultatively undergo immediately reversible hemoglobin-based color changes, hypothesized to correlate with status during contests. I predicted aggressors in contests would consistently display hemoglobin-deprived ceres (hereafter “light”), and receivers would display hemoglobin-enhanced ceres (hereafter “dark”), or vice versa. To test this hypothesis, I conducted 149 30-min group observations during which I recorded outcomes of all observed intra- and interspecific agonistic interactions involving caracaras in groups including up to 46 caracaras (x¯  =  13.4, SD  =  6.9). I recorded 2586 agonistic interactions in which I could identify cere colors and ages of both caracaras involved in an intraspecific interaction (n  =  1160), or of one caracara involved in an interspecific interaction (n  =  1426). Cere colors of caracaras were consistently light when acting as aggressors in intra- and interspecific agonistic interactions, and dark when acting as receivers. Within age classes, caracaras displaying light-colored ceres were consistently aggressors toward caracaras displaying dark ceres, and between age classes, adults with light-colored ceres were aggressors toward younger birds with dark ceres. Caracaras displaying light-colored ceres were aggressors toward Black Vultures (Coragyps atratus) and Turkey Vultures (Cathartes aura) and caracaras with dark ceres were receivers of aggression from these species. Regardless of the cere color, caracaras were subordinate to much larger Bald Eagles (Haliaeetus leucocephalus) and dominant over much smaller American Crows (Corvus brachyrhynchos). My observations support the hypothesis that cere color is correlated with agonistic behaviors and support the signaling hypothesis by correlating specific cere colors displayed with individual roles in intra- and interspecific interactions.
Abstract & References : Full Text : PDF (1895 KB) 


Post-fledging Dependence Period in the Eurasian Kestrel (Falco tinnunculus) in Western France Full Access

Nicolas Boileau, Vincent Bretagnolle
pg(s) 248–256


The post-fledging dependence period (PDP) of 25 Eurasian Kestrel (Falco tinnunculus) fledglings was studied in a coastal marsh in western France in 2002 and 2003. Body condition at fledging was the only parameter that had a positive effect on the length of the PDP, which averaged 18 d (range 3–31 d). Mean daily distance from the nest increased 15 m per day until independence, and mean area used during the PDP was 7.3 ha. Male kestrels provided food for fledglings during the PDP (though decreasing their delivery rate with time). Females stopped feeding their young 3 d after they fledged. First fledglings received more food than others and food per fledgling decreased with brood size.
Abstract & References : Full Text : PDF (354 KB) 


Raptor Presence Along an Urban–Wildland Gradient: Influences of Prey Abundance and Land Cover Full Access

Stan Rullman and John M. Marzluff
pg(s) 257–272


Native animals are affected differently by urbanization. Some species respond favorably and thrive in human-dominated landscapes, but others are extirpated. Raptors are often sensitive to changes in land cover and prey abundance. We therefore used a combination of broadcast surveys and incidental observations while spot-mapping to evaluate the influences of these two variables on the presence of raptors at 21 sites from 2004–2008 along an urban-to-wildland gradient in western Washington, U.S.A. We detected three species of hawks: Sharp-shinned Hawk (Accipiter striatus), Cooper's Hawk (Accipiter cooperii), and Red-tailed Hawk (Buteo jamaicensis); and five species of owls: Northern Pygmy-Owl (Glaucidium gnoma), Western Screech-Owl (Megascops kennicottii), Barred Owl (Strix varia), Great Horned Owl (Bubo virginianus) and Barn Owl (Tyto alba). Models that included specific land-cover elements as independent variables explained presence for all species better than models including only prey abundance. Cooper's Hawks and Barred Owls showed a positive response to human-altered landscapes, specifically the edges between deciduous-mixed forest and light intensity urban land cover. Raptor species richness was consistent across the gradient of urbanization (  =  3.67 species/site) and not correlated with land-cover diversity, songbird species richness, or total forest cover.
Abstract & References : Full Text : PDF (1848 KB)


Abundance and Distribution of Overwintering Red-tailed Hawks and American Kestrels in an Agricultural Landscape in Northeastern Arkansas Full Access

Melissa M. Bobowski, Virginie Rolland and Thomas S. Risch
pg(s) 273–279


Although Red-tailed Hawks (Buteo jamaicensis) and American Kestrels (Falco sparverius) are common raptors in the U.S.A., their wintering population abundance and distribution has not been studied recently in Arkansas. We assessed the temporal and spatial variation in population abundance of Red-tailed Hawks and American Kestrels over the winter in northeastern Arkansas. We conducted weekly surveys from an automobile in Craighead and Poinsett counties, Arkansas, October 2012–March 2013. Abundance of Red-tailed Hawks (n  =  854 total observations) and American Kestrels (n  =  165 total observations) along the transect increased during winter months. The overall abundance indices were 7.05 Red-tailed Hawks per 10 km (highest ever recorded) and 1.36 American Kestrels per 10 km. We found no significant differences in the utilization of the various cover types (i.e., short rice stubble, soybean stubble, and fallow areas/roadsides) for either species. However, both species differed in their use of perch types (i.e., utility poles, utility crossbeams, utility wires, trees, and other [such as ground, signs, or farming equipment]). Red-tailed Hawks perched on trees and crossbeams significantly more than on other perches. American Kestrels used utility wires as perches significantly more than any of the other perch types. We concluded that northeastern Arkansas is an important wintering area for migrating Red-tailed Hawks and American Kestrels, despite the large-scale agricultural fields present year-round in the landscape.
Abstract & References : Full Text : PDF (276 KB) 


Hatching Rank Influences Nutritional Condition in the Common Buzzard: Evidence from Ptilochronology Full Access

Péter Fehérvári, Szabolcs Solt, Károly Erdélyi, Reuven Yosef
pg(s) 280–284


It is believed that the chicks that hatch first in a clutch have a better condition than their siblings. To test this hypothesis, we monitored six clutches of Buteo buteo in Jászság area, Hungary. Note the order of hatching chicks ( n  = 21) and prior to fledging measure the length of the central tail feather pen, tarsus length and body mass of all chicks. To assess the nutritional status on, cut the central tail feather for a blind ptilochronological analysis. The average length of the central tail feathers was 69.5 mm, tarsus length was 77.0 mm, body mass was 824.9 g and the average growth bar width was 4.05 mm / day. The first chicks hatched bars had wider growth compared with chicks hatched second or third and assume that this represented a better nutritional status. The data corroborate existing information for other species of Buteo and suggest that sibling competition on nutrition affects younger chicks a clutch.
Abstract & References : Full Text : PDF (229 KB) 


Focal Activity of Nesting Golden Eagles near Unused Nests Full Access

James W. Watson, Robert Marheine and Thad Fitzhenry
pg(s) 284–288


Protection of nests used by individuals Aquila chrysaetos and implementation of buffer zones to minimize the effects of human activities associated conservation practices are accepted. The need to protect and create buffer zones unused nesting eagles is less clear. Analyzing the intensity of the functional behavior, or focal activity of 14 adults of A. chrysaetos tracked by telemetry used and unused nests in relation to their home ranges full in eastern Washington and Oregon between 2005 and 2013 The focal activity of eagles nesting in unused areas was variable and typically lower than that occurred near the nests used, but almost all unused nests were located within the core areas of the areas of action of the eagles. Nests were located in unused areas of high use of home ranges, even when they were separated by> 1 km of nests used and pretended to have been unused for several years. The Eagles may have been attracted to areas near nests unused due to the preference of hangers or flight conditions, or focal activity near nests without use may have played a territorial function. Because eagles moved to nests located up to 2.5 km of nests and used, could not identify nests that would not benefit from the protective buffer zone and concluded that all nests without using merit protective buffer zones.
Abstract & References : Full Text : PDF (318 KB) 


Improved Satellite Transmitter Harness Attachment Technique Full Access

John S. Humphrey and Michael L. Avery
pg(s) 289–291


Satellite telemetry often requires the attachment of a transmitter on the bird using a backpack harness configuration. The proper fit of the harness on the bird is essential for effective deployment and for the welfare of the birds. Introducing an improved harness attachment technique that uses inexpensive and available immediately rivet. This method reduces handling time and allows researchers to adjust the guides harness then secure them quickly and efficiently without sewing, gluing or screwing hot plastic.
Abstract & References : Full Text : PDF (935 KB) 


Cannibalism in Bonelli's Eagle (Aquila fasciataFull Access

Jesús Caro, Diego Ontiveros and Juan M. Pleguezuelos
pg(s) 292–294
Citation : Full Text : PDF (55 KB)  

Proning Behavior in Cooper's Hawks (Accipiter cooperiiFull Access

Robert N. Rosenfield, Larry E. Sobolik
pg(s) 294–297
Citation : Full Text : PDF (4926 KB) 

Observations of Predatory Behavior by White-headed Vultures Full Access

Campbell Murn
pg(s) 297–299
Citation : Full Text : PDF (49 KB) 

Monday, 18 August 2014

‘The thieving magpie’? No evidence for attraction to shiny objects. Animal Cognition, August 2014, Shepherd et al, University of Exeter

‘The thieving magpie’? No evidence for attraction to shiny objects

T.V. Shephard, S.E.G. Lea, N. Hempel de Ibarra

First Author Details
Centre for Research in Animal Behaviour, University of Exeter, Perry Road, Exeter, EX4 4QG, UK,

It is widely accepted in European culture that magpies (Pica pica) are unconditionally attracted to shiny objects and routinely steal small trinkets such as jewellery, almost as a compulsion. Despite the long history of this folklore, published accounts of magpies collecting shiny objects are rare and empirical evidence for the behaviour is lacking. The latter is surprising considering that an attraction to bright objects is well documented in some bird species. The present study aims to clarify whether magpies show greater attraction to shiny objects than non-shiny objects when presented at the same time. We did not find evidence of an unconditional attraction to shiny objects in either captive or free-living birds. Instead, all objects elicited responses indicating neophobia in free-living birds. We suggest that humans notice when magpies occasionally pick up shiny objects because they believe the birds find them attractive, while it goes unnoticed when magpies interact with less eye-catching items. The folklore may therefore result from observation bias and cultural inflation of orally transmitted episodic events.

Link to pdf