., et al. 2012. Positive relationships between association strength and phenotypic similarity characterize the assembly of mixed-species bird flocks worldwide. American Naturalist 180: 777-90. AuthorsHari Sridhar, Umesh Srinivasan, Robert A. Askins, Julio Cesar Canales-Delgadillo, Chao-Chieh Chen Submitted February 10, 2012; Accepted August 1, 2012; Electronically published MONTH? xx, 2012 Online enhancement: appendix. Dryad data: http://dx.doi.org/10.5061/dryad.th198.abstract: Competition theory predicts that local communities should consist of species that are more dissimilar than expected by chance. We find a strikingly different pattern in a multicontinent data set (55 presence-absence matrixes from 24 locations) on the composition of mixed-species bird flocks, which are important subunits of local bird communities the world over. By using null models and randomization tests followed by meta-analysis, we find the association strengths of species in flocks to be strongly related to similarity in body size and foraging behavior and higher for congeneric compared with noncongeneric species pairs. Given the local spatial scales of our individual analyses, differences in the habitat preferences of species are unlikely to have caused these association patterns; the patterns observed are most likely the outcome of species interactions. Extending group-living and social-information-use theory to a heterospecific context, we discuss potential behavioral mechanisms that lead to positive interactions among similar species in flocks, as well as ways in which competition costs are reduced. Our findings highlight the need to consider positive interactions along with competition when seeking to explain community assembly.

Shape-selective hydrocarbon catalysis, such as the conversion capability of zealite catalysts of the ZSM-5 type to produce high-grade gasoline from methanol, can be extended to produce a similar gasoline or aromatics from plant extracts. Examples are rubber latex, corn oil, and peanut oil. Novel mechanisms for shape-selective reaction sequences are demonstrated.

During annual migrations between breeding and nonbreeding grounds, billions of land birds encounter migratory barriers en route. Although birds are thought to be more selective (i.e., cross under favorable wind conditions) and spend more time refueling at stopover sites when confronted with these barriers, there is no direct evidence to support these hypotheses. Using 2 automated radio-telemetry arrays at stopover sites situated before (south of) and after (north of) a large ecological barrier (Lake Erie), we tracked departure decisions of American redstarts Setophaga ruticilla and yellow-rumped (myrtle) warblers Setophaga coronata coronata during spring migration. We found evidence that condition, age, and tailwind assistance were all positively correlated with the likelihood of departure. Interestingly, these patterns did not differ between species, with presumably differing migratory tactics, nor across sites, suggesting that during spring migration, migratory songbirds may follow general rules for departure from stopover sites, despite varying ecological and life-history contexts.

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â€" We evaluated the effects of plant succession on habitat use and fruit resource availability for autumn migratory and resident songbirds in 43 ha of abandoned farm fields in central New Jersey. Using fixed net sites, standardized effort, and simultaneous sampling across habitat types, we mist-netted birds to compare habitat use and found that (1) use of three shrub-tree invasion interfaces declined as fruit-bearing shrubs were overgrown by trees, while use of three open shrublands changed little over the same period; (2) use of two pairs of contrasting successional habitats, shrubland and young woodland, was higher in the shrubland with abundant, highly nutritional fruits than in young woodland with sparse fruit; and (3) use of three shrublands at similar successional stages but with different fruit availability differed by bird taxonomic family and migratory strategy. Data on species composition and relative abundance of fruit-bearing shrubs and fruit consumption by birds (assessed by regurgitated and defecated matter) were used to elucidate avian patterns of habitat use. The relative abundance of truit-bearing species may be more important than habitat structure in determining habitat use by birds. Shrubland dominated by panicled dogwood (Corn us racemosa) was favored over shrubland dominated by red cedar (Juniperus virginianum ) or multiflora rose ( Rosa multiflora). Favored vines were Japanese honeysuckle (Lonicera japonica), Virginia creeper (Parthenocissus quinquefolia), poison ivy ( Toxicodendron radicans ), and grape ( Vitis spp.).

This paper describes a novel one-step synthesis of y-lactones by the reaction of manganic and other higher valenc metal carboxylates with readily available olefins and carboxylic acids. A free radical mechanism involving the selective generation and oxidation of organic free radicals is presented.As part of our studies on the oxidation mechanisms of metal carboxylates, we have observed' a novel reaction of manganic and ceric carboxylates with olefins leading to ybutyrolactones in excellent yields. This paper is intended to summarize our work on the development of this simple onestep synthesis of y-lactones from olefins and to establish the free radical mechanism for formation of these lactones.

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