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Tuesday, 23 June 2015

Oecologia - July 2015 Abstracts

Oecologia

Volume 178, Issue 3, July 2015

LINK














Selected Avian Research Articles

Survival and local recruitment are driven by environmental carry-over effects from the wintering area in a migratory seabird
K. Lesley Szostek 1   and Peter H. Becker 1
(1)Institute of Avian Research, Vogelwarte Helgoland, An der Vogelwarte 21, 26386 Wilhelmshaven, Germany

Abstract

We estimated annual apparent survival rates, as well as local recruitment rates in different age groups and for different breeding status in the common tern Sterna hirundo using mark–recapture analysis on a long-term individual-based dataset from a breeding colony in Germany. Strong inter-annual variability in survival rates became apparent, especially in prospectors. Local recruitment also varied strongly between years and age groups. To explain these fluctuations, we linked survival and recruitment estimates to several environmental covariates expected to be limiting during the wintering period and migration, including the global climate indices of North Atlantic Oscillation and Southern Oscillation, fish abundance indices, and marine primary productivity in the West African wintering area. Contrary to expectations, global indices did not seem to be linked strongly to vital rates. Results showed that primary productivity had the strongest effect on annual survival, especially in young and inexperienced individuals. Primary productivity in the wintering area was also strongly associated with the probability of recruitment in the following breeding season, indicating that conditions during winter can have carry-over effects on the life cycle of individuals.


Changes in the apparent survival of a tropical bird in response to the El Niño Southern Oscillation in mature and young forest in Costa Rica
Jared D. Wolfe 1, 2   , C. John Ralph 1, 2  and Pablo Elizondo 3
(1)USDA Forest Service, Pacific Southwest Research Station, Arcata, USA
(2)Klamath Bird Observatory, Ashland, OR, USA
(3)Costa Rica Bird Observatories, Instituto Nacional de Biodiversidad (INBio), Santo Domingo de Heredia, Costa Rica

Abstract
The effects of habitat alteration and climatic instability have resulted in the loss of bird populations throughout the globe. Tropical birds in particular may be sensitive to climate and habitat change because of their niche specialization, often sedentary nature, and unique life-cycle phenologies. Despite the potential influence of habitat and climatic interactions on tropical birds, we lack comparisons of avian demographics from variably aged forests subject to different climatic phenomena. Here, we measured relationships between forest type and climatic perturbations on White-collared Manakin (Manacus candei), a frugivorous tropical bird, by using 12 years of capture data in young and mature forests in northeastern Costa Rica. We used Cormack–Jolly–Seber models and an analysis of deviance to contrast the influence of the El Niño Southern Oscillation (ENSO) on manakin survival. We found that ENSO had little effect on manakin survival in mature forests. Conversely, in young forests, ENSO explained 79 % of the variation where dry El Niño events negatively influenced manikin survival. We believe mature forest mitigated negative effects of dry El Niño periods and can serve as refugia for some species by buffering birds from climatic instability. Our results represent the first published documentation that ENSO influences the survival of a resident Neotropic landbird.


Experimental evidence that ptarmigan regulate willow bud production to their own advantage
Katie S. Christie 1   and R. W. Ruess 1
(1)The Institute of Arctic Biology, University of Alaska Fairbanks, 902 N. Koyukuk Dr., Fairbanks, AK, USA

Abstract

In some ecosystems, vertebrate herbivores increase the nutritional quality and biomass of their food source through repeated grazing, thereby manipulating their environment to support higher densities of animals. We tested whether ptarmigan (Lagopus lagopus and L. muta) are capable of regulating the nutritional quality, abundance, and availability of feltleaf willow (Salix alaxensis) buds using a simulated browsing experiment and a feeding preference study with wild birds. Simulated ptarmigan browsing resulted in smaller buds, but greater numbers of buds per shoot. Furthermore, browsing altered the morphology of willow branches such that buds were at higher densities and closer to snow level compared to unbrowsed controls. Browsing increased the number of willows with accessible buds (buds within 50 cm of snow level) from 55 to 89 %, and increased total accessible bud biomass from 113 ± 30 to 129 ± 50 mg/ramet. Browsing did not affect bud nitrogen or carbon concentration and slightly reduced protein precipitation capacity (tannins) in buds the following winter, indicating that ptarmigan browsing does not induce a defensive response in this species. When branches of broomed (previously browsed) and unbroomed willows were placed in the snow at equal heights, ptarmigan showed no preference for either type; however, they obtained more buds from broomed willows. Increased accessibility and density of willow buds caused by browsing has the potential to increase habitat carrying capacity, thereby supporting higher densities of ptarmigan.
  

Nectar robbery by a hermit hummingbird: association to floral phenotype and its influence on flowers and network structure
Pietro Kiyoshi Maruyama 1, 2  , Jeferson Vizentin-Bugoni 1, 2, Bo Dalsgaard 2, Ivan Sazima 3, 4 and Marlies Sazima 5
(1)Programa de Pós-Graduação em Ecologia, Universidade Estadual de Campinas (Unicamp), Cx. Postal 6109, Campinas, SP, 13083-970, Brazil
(2)Center for Macroecology, Evolution and Climate, Natural History Museum of Denmark, University of Copenhagen, Universitetsparken 15, 2100 Copenhagen Ø, Denmark
(3)Museu de Zoologia, Universidade Estadual de Campinas (Unicamp), Campinas, SP, 13083-970, Brazil
(4)Projeto Dacnis, Estrada do Rio Escuro 4754, Sertão das Cotias, Ubatuba, SP, 11680-000, Brazil
(5)Departamento de Biologia Vegetal, Instituto de Biologia, Universidade Estadual de Campinas (Unicamp), Cx. Postal 6109, Campinas, SP, 13083-970, Brazil

Abstract

Interactions between flowers and their visitors span the spectrum from mutualism to antagonism. The literature is rich in studies focusing on mutualism, but nectar robbery has mostly been investigated using phytocentric approaches focused on only a few plant species. To fill this gap, we studied the interactions between a nectar-robbing hermit hummingbird, Phaethornis ruber, and the array of flowers it visits. First, based on a literature review of the interactions involving  P. ruber, we characterized the association of floral larceny to floral phenotype. We then experimentally examined the effects of nectar robbing on nectar standing crop and number of visits of the pollinators to the flowers of Canna paniculata. Finally, we asked whether the incorporation of illegitimate interactions into the analysis affects plant–hummingbird network structure. We identified 97 plant species visited by P. ruber and found that P. ruber engaged in floral larceny in almost 30 % of these species. Nectar robbery was especially common in flowers with longer corolla. In terms of the effect on C. paniculata, the depletion of nectar due to robbery by P. ruber was associated with decreased visitation rates of legitimate pollinators. At the community level, the inclusion of the illegitimate visits of P. ruber resulted in modifications of how modules within the network were organized, notably giving rise to a new module consisting of P. ruber and mostly robbed flowers. However, although illegitimate visits constituted approximately 9 % of all interactions in the network, changes in nestedness, modularity, and network-level specialization were minor. Our results indicate that although a flower robber may have a strong effect on the pollination of a particular plant species, the inclusion of its illegitimate interactions has limited capacity to change overall network structure.


Urbanized birds have superior establishment success in novel environments
Anders Pape Møller 1  , Mario Díaz 2, Einar Flensted-Jensen 3, Tomas Grim 4, Juan Diego Ibáñez-Álamo 5, Jukka Jokimäki 6, Raivo Mänd 7, Gábor Markó 8, 9, 10 and Piotr Tryjanowski 11
(1)Laboratoire d’Ecologie, Systématique et Evolution, CNRS UMR 8079, Université Paris-Sud, Bâtiment 362, 91405 Orsay Cedex, France
(2)Department of Biogeography and Global Change, Museo Nacional de Ciencias Naturales (BGC-MNCN-CSIC), 28006 Madrid, Spain
(3)Cypresvej 1, 9700 Brønderslev, Denmark
(4)Laboratory of Ornithology and Department of Zoology, Palacky University, 77146 Olomouc, Czech Republic
(5)Departamento de Zoología, Facultad de Ciencias, Campus Universitario de Fuentenueva s/n, Universidad de Granada, 18071 Granada, Spain
(6)Nature Inventory and EIA-services, Arctic Centre, University of Lapland, P. O. Box 122, 96101 Rovaniemi, Finland
(7)Department of Zoology, Institute of Ecology and Earth Sciences, University of Tartu, 51014 Tartu, Estonia
(8)Ecology Research Group, MTA-ELTE-MTM, Pázmány Péter sétány 1/c, 1117 Budapest, Hungary
(9)Department of Plant Pathology, Corvinus University of Budapest, Ménesi Út 44, 1118 Budapest, Hungary
(10)Behavioral Ecology Group, Department of Systematics, Zoology and Ecology, Eötvös Loránd University, Pázmány Péter sétány 1/c, 1117 Budapest, Hungary
(11)Institute of Zoology, Poznan University of Life Sciences, Wojska Polskiego 71C, 60-625 Poznan, Poland

Abstract

Many animals have adapted to the proximity of humans and thereby gained an advantage in a world increasingly affected by human activity. Numerous organisms have invaded novel areas and thereby increased their range. Here, we hypothesize that an ability to thrive in urban habitats is a key innovation that facilitates successful establishment and invasion. We test this hypothesis by relating the probability of establishment by birds on oceanic islands to the difference in breeding population density between urban and nearby rural habitats as a measure of urbanization in the ancestral range. This measure was the single-most important predictor of establishment success and the only statistically significant one, with additional effects of sexual dichromatism, number of releases and release effort, showing that the ability to cope with human proximity is a central component of successful establishment. Because most invasions occur as a consequence of human-assisted establishment, the ability to cope with human proximity will often be of central importance for successful establishment.

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