Are white-crowned sparrow badges reliable signals?

Status badges, such as crown plumage, mediate intraspecific interactions. The reliability of crown morphology as a status badge in male mountain white-crowned sparrows (Zonotrichia leucophrys oriantha) is uncertain. We examined morphological and physiological correlates of the proportion of crown that was white (“crown-white”) in 178 male mountain white-crowned sparrows during the 2008–2009 breeding seasons. Using a paired experimental design, we presented territory-holding males with white-enhanced and white-reduced decoys and recorded aggressive behaviors. To assess physiological constraints on signal bluffing, a subsample of birds was captured and released after manipulating natural crowns to simulate bluffed white-enhanced or white-reduced crowns; corticosterone concentrations were assayed from blood drawn upon recapture and after a restraint-induced stressor. We found a significant positive association between crown-white and a measure of body size—tarsus length—which is an established indicator of resource-holding potential. In the decoy challenge, males responded more aggressively toward white-enhanced than white-reduced decoys. In the hormone experiment, white-enhanced birds had higher baseline corticosterone levels, whereas white-reduced birds had similar concentrations to controls. Furthermore, white-enhanced birds had an attenuated restraint-induced corticosterone response, while white-reduced birds mounted a significantly larger increase in corticosterone than controls. Taken together, these findings indicate that crown-white is a reliable status badge of resource-holding potential in male mountain white-crowned sparrows during the breeding season.     

Renewable energies for climate benign fuel production. Powering fuel-cell vehicles

Transportation contributes to energy consumption and greenhouse gas emissions, while sustainable mobility requires reductions in both areas. Alternative fuels from natural gas and from renewable resources can contribute in the mid and long-term to the fuel market for mobile as well as stationary applications. The lack of reliable data on emissions, energy chain efficiencies, and costs demonstrates the need for field tests and demonstration projects. Fuel cells offer the technology to use ‘new fuels’ in a highly efficient way.     

Strike-induced chemosensory searching is absent in the cordylid lizard,Cordylus cordylus,a scleroglossan ambush forager

Summary Strike-induced chemosensory searching (SICS) was not detected experimentally in the cordylid lizard,Cordylus cordylus. Both components of SICS, a post-strike elevation in tongue-flick rate (PETF) and searching movements for attacked and released prey, were absent. The findings are consistent with previous data showing that PETF and/or SICS are lacking in all lizard families yet studied that forage primarily by ambush, but are present in actively foraging scleroglossan families and the herbivorous iguanian family Iguanidae. It is suggested that foraging behavior is a primary determinant of the presence or absence of SICS in lizards. Nevertheless, in most families in the two major clades, Iguania and Scleroglossa, the plesiomorphic foraging mode is retained. The findings agree with the prediction that SICS is absent in families lacking lingually mediated prey chemical discrimination (PCD), presumably due to selection against movement by ambush foragers that avoid being detected by either prey or predators because they remain motionless. Although PETF and SICS were absent, labial-licking and lingual movements similar to those observed after swallowing increased after biting prey, suggesting that the functions of these lingual movements may have been related to grooming. Locomotory movements did not increase following biting and appeared to represent avoidance of the experimenter.     

Exploratory Analysis and a Stochastic Model for Humusdisintegration

Ulrich (1981) supposes in the hypothesis of humusdisintegrationthat the balance between polymerisation and breakdown of organicmaterial may be disturbed in chemically well buffered Europeanforest soils. This new aspect of aluminium toxicity may causenitrogen exceedance in forest ecosystems and subsequent seasonalnitrate output (Eichhorn and Hütterman, 1999).In a research program the substances in the seepage water aremonitored in a small woodland in central Germany. We explorethese multivariate data for examining possible influences on theprocess of humusdisintegration and its temporal evolution. As aresult, a regression model for carbon is developed, whichincludes covariables, i.e., other substances, as well as spatialand temporal terms describing systematic variability. Especiallyiron and aluminium turn out to be very influential in the model.So far our work is a basic step for monitoring the seepage waterdata by means of stochastic modelling.