Proximate and ultimate factors that promote aggregated breeding in the Western Sandpiper

We report that Western Sandpipers （Calidris mauri） on Alaska’s Yukon-Kuskokwim River Delta exhibited aggregated breeding behavior at a relatively small spatial scale. Prior to clutch initiation, males performing song flight displays on a 36 ha plot were aggregated as were subsequent initial nesting attempts on the plot. We tested three hypotheses commonly invoked to explain aggregated breeding in territorial species （social mate choice, predation, and material resources hypotheses）, and found support for the material resources hypothesis, as dispersed individuals were more often associated with tundra habitat patches, and aggregated individuals nested more often in undulating-tundra habitat patches compared to patch availability. The pattern of habitat occupancy conformed to an ideal despotic distribution with aggregated nesting birds in undulating-tundra patches experiencing lower reproductive success. On our study plot, older, more aggressive males solicited females more often, and defended larger, more dispersed sites in tundra habitat patches, compared to younger, less aggressive males that were aggregated in undulating-tundra habitat patches. Breeding aggregations are often concentrated on or near a critical resource. In contrast, Western Sandpiper breeding aggregations occur when dominant and/or older individuals exclude younger, subordinate individuals from preferred habitat. Although many taxa of non-colonial birds have been reported to aggregate breeding territories, this is the first quantitative report of aggregated breeding behavior in a non-colonial monogamous shorebird species prior to hatch.

The Influence of Avian Biodiversity and a Weedy Understorey on Canopy Arthropod Assembly

Identifying the factor causing species decline from a multitude of potential disturbances is essential for successful management. Invasive species are often drivers of decline, either through direct effects such as recruitment limitation, or through indirect effects such as habitat modification that facilitate biota changes in other taxa. In this study, we tested the importance of bird predation on arthropods in eucalypt canopies in wet sclerophyll forest that had been invaded by the understorey weed Lantana camara. A strong top-down effect is in agreement with studies that show elevated numbers of insectivorous birds, such as the despotic bell miner, Manorina melanophrys, reduce damaging herbivorous insect numbers and their effect on tree health. Abundance, order and family composition were compared among sites, feeding guilds, among the presence and absence of a despotic bird, and among presence and absence within sites, using a three-way nested Multivariate Analysis of Variance (MANOVA), and tested our representation of insect feeding guilds with rarefaction curves. In total, we found arthropods from 20 families on eucalypt trees, 16 where bell miners were present and 18 where they were absent (a sampling efficiency of 78% and 92% of families based on the Chao-I index). Overall, there was a difference in the abundance of insects in areas where bell miners were present (n = 181), and where they were absent (n = 67). There was also a difference in the families present in areas with bell miners and without them. Under some conditions, despotic birds may not change the insect canopy community. Further studies should examine the effects of a despotic bird on the insect canopy community in a variety of conditions and throughout their range.

Constructing a New Political Category： Robespierre and the Theory of Revolutionary Government

By two major speeches in the name of the Committee of Public Safety on 25 December 1793 （5 niv6se an lI） and 5 February 1794 （17 pluvi6se an II）, Robespierre reconsidered the definition of the revolutionary government and proposed a genuine ＂theory＂ of it. Strangely, these interventions were prononced after the organization of this government by Saint-Just and Billaud-Varenne. The aim oft his article is not to propose a new overview of Robespierre＇s theory of revolutionary government, but to research why Robespierre considered the development of this theory necessary and how this theory was to be elaborated. To ask these questions is to retrace the birth of a genuine political category of ＂＇revolutionary government＂ which can be added to the classical categories： the democracy, the aristocracy, the monarchy and the despotism.