Phylogenetic analyses of the diversity of moult strategies in Sylviidae in relation to migration

Moult in birds is highly variable both within and among bird genera. The aim of the present study was to make an extended phylogenetic analysis of the diversity of moult strategies within Sylviidae in light of the recent phylogenies based on molecular data, and with the methodology of matched-pairs analysis. In the present study we analysed 141 sylviid taxa and, to improve character reconstruction, 22 outgroup taxa. The study could corroborate the earlier results that post-breeding moult is the ancestral state in Sylviidae. Migratory habits were found to be ancestral within Sylviidae but resident habits have evolved several times with a few reverse transitions back to migratory habits. Transitions in main moult strategy were significantly related to both migratory vs. resident habits and to migratory distance, giving support to the hypothesis that moult in the non-breeding season is related to migration as such and long-distance migration, respectively. Both resident and migratory taxa used minor alternative moult strategies besides the main moult strategy and such within-taxon flexibility might be a basal trait in Sylviidae. We investigated three variables that included minor strategies and found no relationship between these and migratory habits. However, two of these variables (the potential to interrupt moult and the occurrence of moult in both the post- and non-breeding seasons) were significantly related to migration distance. We conclude that migration patterns has some influence on the choice of moult strategy, and that flexibility in timing of moult is widespread within Sylviidae and might be a basal trait. We argue that such flexibility might be a prerequisite for changes in migratory strategies.     

What are we missing with only ground‐level mist nets? Using elevated nets at a migration stopover site

ABSTRACT Mist nets deployed in a standard ground‐level fashion capture birds approximately 0.5–2.6 m above the ground. In habitats where the vegetation extends above this height, standard mist net deployment may inadequately sample the targeted avian community and age‐ and sex‐classes within species. Such sampling biases may raise questions regarding studies based on data from mist‐net captures. To determine if birds were equally likely to be captured by mist nets at different heights, we constructed a series of paired ground‐level and elevated mist nets (hereafter “net rigs”) at a research station in western New York State. Net rigs were operated during 14 migration seasons from 2000 to 2006 (spring and fall each year), and 19,735 birds of 118 species were captured. Capture rates were significantly higher in ground‐level nets, but 12 species were only captured in elevated nets. Of 44 species with at least 50 captures, 25 species were more likely to be captured in the ground‐level nets and two species in the elevated nets. For four of 18 species, more birds were captured in the elevated nets during fall migration than during spring migration. We conclude that standard ground‐level net placement was more efficient in capturing birds in the secondary growth habitats that we sampled. However, ground‐level nets may not adequately sample the entire targeted community or all age‐ or sex‐classes within species.     

鸟类和蚂蚁对桃金娘种子传播的初步研究

在中国科学院鹤山丘陵综合开放试验站观察研究了鸟类和蚂蚁对桃金娘 (Rhodomyrtustomentosa)种子的传播。据野外观察和网捕法所捕鸟的情况可知 :红耳鹎 (Pycnonotusjocosus)和白头鹎 (P .sinensis)两种鸟传播桃金娘种子 ,白头鹎比红耳鹎的数量多。在网捕到的红耳鹎和白头鹎的粪便中收集到的桃金娘种子分别为 8.0± 3.0粒/只和 10 .0± 2 .0粒 /只。在显微镜下观察经过鸟消化道的桃金娘种子都没有破损。传播桃金娘种子的蚂蚁有全异巨首蚁 (Pheidologetiondiversus)和梅花山大头蚁 (Pheidolemeihuashanensis)。它们传播的最远距离分别为 4m和 5m ,平均为 1.1± 0 .0 9m和 1.3± 0 .0 7m。全异巨首蚁占样地蚂蚁个体总数的 6 0 .0 % ;梅花山大头蚁占个体总数的8.1% ;余下的为其他种蚂蚁。每个全异巨首蚁蚁巢平均贮藏桃金娘种子 195 .0± 82 .9粒 ,其中 73.2 %是完好种子。每个梅花山大头蚁蚁巢平均贮藏 2 8.8± 11.4粒种子 ,全部是完好种子。林窗、闲置的空旷地、植物群落交错带都有桃金娘实生苗。在阳光充足的全异巨首蚁和梅花山大头蚁蚁巢边也有桃金娘实生苗的存在     

Forest Management Policy, Amenity Migration, and Community Well-Being in the American West: Reflections from the Northwest Forest Plan

This paper examines the relation between public land management policy, amenity migration, and socioeconomic well-being using the case of the Northwest Forest Plan—a forest management policy that caused 11.6 million acres of federal land in the US Pacific Northwest to be reallocated from commodity production to biodiversity services. Our analysis focuses on three propositions implicit in much of the amenity migration literature in the USA: land management policies that reduce commodity production and/or increase environmental protection (1) improve the natural amenity values of public lands; (2) increase amenity migration to communities near public lands; and (3) stimulate economic development and increase socioeconomic well-being in these communities. Our findings indicate that all three propositions are problematic and demonstrate the importance of community-scale analysis for understanding the relation between land management policies, amenity migration, and community well-being. We discuss the implications of our findings for public land management and rural community development.

Validation of an enzyme immunoassay for measurement of excreted estrogen and testosterone metabolites in the white-crowned sparrow (Zonotrichia leucophrys oriantha)

Over the past few years there has been a growing interest in hormonal analyses, despite the cost and difficulty involved in measuring hormones using radioimmunoassays. Therefore, there is a need for alternate procedures, such as enzyme immunoassays, capable of providing similar data to that provided by radioactive methods. Enzyme immunoassays are a less expensive method of measuring estrone conjugates and testosterone. With further work, the enzyme immunoassay also provides the potential to adapt the enzyme assay for use in the field. The data in this study demonstrate that an enzyme assay can accurately detect both endogenous and exogenous hormonal changes in the droppings of white-crowned sparrows. © 1995 Wiley-Liss, Inc.     

Annual variation in numbers, age and sex ratios among migrating raptors at Falsterbo, Sweden from 1986–1995

Summary The annual variation in age and sex ratio among raptors passing the Falsterbo peninsula, Sweden was studied the ten autumns 1986–1995. The analysis encompasses thirteen species with average annual totals of between 25 and 14,000 migrants. In general, raptors occurring in low numbers showed the greatest relative annual variation. One explanation for high variation was the steep increase in the Swedish populations of Red KiteMilvus milvus and Marsh HarrierCircus aeruginosus during the period. A constant high percentage of juveniles may be due to the adults being primarily residents, like in Red Kite and GoshawkAccipiter gentilis, or to a less pronounced tendency of adults to follow leading lines, as in Marsh Harrier, MerlinFalco columbarius and HobbyF. subbuteo. In most other species the ages were represented in more balanced proportions, and the proportion of juveniles most likely reflects variations in breeding results. An average of 41% juveniles in Common BuzzardButeo buteo compared to 23% in the Rough-legged BuzzardB. lagopus indicates a considerably better production in the first species during the ten years. The extremely low average of 11% young Honey BuzzardsPernis apivorus most likely represents a very low production in the period. There was a highly significant correlation in the annual proportion of juveniles between Northern HarrierCircus cyaneus and Rough-legged Buzzard. Most likely this covariation reflects fluctuation in rodent numbers in northern Scandinavia. Most species showed a sex ratio close to 50%. In both Northern and Marsh Harrier there was however a clear dominance of females among the adults, with a ratio of 1.63 and 1.27 females/male respectively.

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Jährliche Zahlen und Alters- und Geschlechtsanteile ziehender Greifvögel in Falsterbo, Schweden, von 1986 bis 1995

Zusammenfassung Die jährliche Variation der Alters- und Geschlechterverhältnisses bei Greifvögeln, die die Halbinsel Falsterbo in Südschweden überfliegen, wurde im Herbst 1986–1995 untersucht. Die Untersuchung umfaßt dreizehn Arten mit jährlich durchschnittlich 25 bis 14.000 ziehenden Vögeln. Die weniger häufigen Arten waren in ihrem jährlichen Auftreten variabler als die häufigen Arten. Ursache dafür ist die starke Zunahme in der schwedischen Population des Rotmilans und der Rohrweihe in dieser Periode. Einen konstant hohen Anteil an Jungvögeln zeigten Arten, bei denen die Altvögel vorwiegend Standvögel sind (z. B. Rotmilan, Habicht) oder Arten, bei denen die Altvögel weniger intensiv Leitlinien folgen, wie Rohrweihe, Merlin und Baumfalke. Bei den meisten anderen Arten waren die Altersklassen mehr ausgeglichen. Bei ihnen spiegelt der jährliche Anteil an Jungvögeln wohl vornehmlich die Brutergebnisse wider. Durchschnittlich 41% Jungvögel beim Mäusebussard verdeutlichen einen besseren Bruterfolg als 23% Jungvogelanteil beim Rauhfußbussard. Mit durchschnittlich nur 11% Jungvögel war der Bruterfolg des Wespenbussards sehr niedrig, und die jährlichen Anzahlen junger Wespenbussarde variierten sehr stark. Zwischen Kornweihe und Rauhfußbussard korrelierten die jährlichen Jungvogelanteile eng. Dies deutet auf Fluktuationen der Kleinsäuger in Nordskandinavien hin, die beide Arten in gleicher Weise beeinflussen. Ähnliches gilt wohl auch für den Merlin.Die Geschlechterverhältnisse waren bei den meisten Arten ausgeglichen. Bei Kornweihe und Rohrweihe überwogen die Weibchen, mit 1,63 bzw. 1,27 Weibchen pro ziehendem Männchen. Dies dürfte die Folge der bei diesen Arten ausgeprägteren Polygynie sein. Beim Habicht überwogen junge Männchen.

     

A comparative analysis of some life-history traits between cooperatively and non-cooperatively breeding Australian passerines

Summary Comparative analyses were carried out for some life-history traits of cooperatively and non-cooperatively breeding Australian Corvida (i.e. old-endemic passerines). Multivariate statistical analyses at the family and genus levels revealed no significant differences between cooperative and non-cooperative breeders. A matched-pairs analysis between congeneric species showed that cooperatively breeding species lay smaller clutches than non-cooperatively breeding congenerics. Preliminary results also suggest that cooperative breeders have higher probabilities of rearing a second brood in the season and lower probabilities of survival than do non-cooperative breeders. However, the result for survival was significant in only one out of three tests. We conclude that cooperatively and non-cooperatively breeding Australian Corvida cannot be separated into distinct groups showingK- andr-selected life-history traits, respectively. Some life-history traits follow the prediction of ther-K selection model, others show evidence of co-adaptation instead, whereas still others show evidence of trade-offs.     

Breeding birds from reedbeds to alpine meadows

The main processes that determine the behaviour ofheavy metals in the Scheldt estuary are tidalhydrodynamics, sediment transport, and sorption ofheavy metals on suspended matter. The water qualitymodel WASP is applied to simulate the spatialdistribution of five heavy metals in the estuary,under average hydrodynamic and suspended sedimenttransport regimes. First, the hydrodynamical part ofthe model is constructed and the results are verifiedby comparison with measured water levels and flowvelocities. Secondly, a salt transport model is set upin order to evaluate the hydrodynamical dispersivemixing characteristics. Thirdly, a suspended sedimenttransport model is constructed and finally a transportmodel for heavy metals. The simulated distributions of the sorbedamounts of heavy metals, suspended sediment andsalinity in the estuary agree well with observations.The calculated profiles of dissolved and sorbedconcentrations of heavy metals in the water columnindicate an accumulation of heavy metals in the zoneof the turbidity maximum, while closer to the sea theconcentrations diminish due to mixing of the pollutedfluvial sediments with unpolluted marine sediments andbecause of sediment deposition in the estuary. It canbe concluded that only a small part of the heavymetals reaches the sea. This revised version was published online in July 2006 with corrections to the Cover Date.     

Does migration promote or restrict circumpolar breeding ranges of arctic birds?

Aim Migration has been suggested to promote large breeding ranges among birds because of the greater mobility of migratory compared with non‐migratory species, but migration has also been suggested to restrict breeding ranges because of evolutionary constraints imposed by the genetically based migration control programme. We aim to investigate the association between migration and the breeding ranges of both land birds and pelagic birds breeding in the Arctic region. Location The Arctic region. Methods Information on breeding and wintering ranges and migratory status of bird species breeding in the arctic tundra biome was compiled from the literature. The association between breeding range, migration distance and primary winter habitat was tested using multivariate generalized linear models and pair‐wise Mann–Whitney U‐tests. Phylogenetic effects were tested for using Mantel’s permutation tests. Results We found different relationships depending on the species’ major winter habitat. Among birds that are pelagic during winter, long‐distance migrants have the largest breeding ranges, while among terrestrial birds, residents and short‐distance migrants have the largest breeding ranges. Breeding ranges of coastal birds of all migratory distance classes are comparatively restricted. Main conclusions As a new explanation for this pattern we suggest that the possibility of colonizing large winter ranges is a key factor for the subsequent expansion of breeding ranges in arctic bird communities and possibly also in bird communities of other regions of the world. Because of the reversal in the relative extent of continents and oceans between the hemispheres, longitudinally wide winter ranges are more likely for long‐distance than short‐distance migrants among pelagic birds, while the reverse holds true for birds that use terrestrial winter habitats. For coastal birds both continents and oceans form barriers restricting colonization of extensive winter quarters and consequently also of extensive breeding ranges, regardless of the distance to the winter quarters.     

An extraordinary new family of spiders from caves in the Pacific Northwest (Araneae, Trogloraptoridae, new family)

The new spider genus and species Trogloraptor marchingtoni Griswold, Audisio & Ledford is described as the type of the new family Trogloraptoridae. The oblique membranous division of the basal segment of the anterior lateral spinnerets of Trogloraptor suggests that this haplogyne family is the sister group of the other Dysderoidea (Dysderidae, Oonopidae, Orsolobidae and Segestriidae). Trogloraptor is known only from caves and old growth forest understory in the Klamath-Siskiyou region of Oregon and California.