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Nest Structures (nest + structure)
Selected AbstractsUNIQUE MANIRAPTORAN EGG CLUTCH FROM THE UPPER CRETACEOUS TWO MEDICINE FORMATION OF MONTANA REVEALS THEROPOD NESTING BEHAVIOURPALAEONTOLOGY, Issue 6 2008DARLA K. ZELENITSKY Abstract:, Egg clutches of non-avian maniraptoran theropods (Dinosauria) are rare, particularly in North America where those of Troodon formosus are the only maniraptoran clutches known. Here we describe a new partial maniraptoran clutch and nesting trace referred to Montanoolithus strongorum oogen. et oosp. nov. (Montanoolithidae oofam. nov.), from the Upper Cretaceous Two Medicine Formation of Montana. Based on a cladistic analysis of reproductive traits, we infer that this clutch belonged either to a caenagnathid or to a dromaeosaurid, which makes it the first clutch known of either taxon. This specimen preserves impressions and eggshell fragments of at least five eggs on a nest structure. The eggs are asymmetrical, paired, and lay radially in a ring configuration on the sloped sides of a bioturbated, flat-topped sandstone mound. Geology of the locality indicates the female nested in a poorly-vegetated area of freshly deposited sand, possibly near an active river channel. This clutch reveals that the egg-layer of Montanoolithus strongorum had a unique suite of reproductive characteristics and nesting behaviours among maniraptorans. [source] Gut content analysis and a new feeding group classification of termitesECOLOGICAL ENTOMOLOGY, Issue 4 2001S. E. Donovan Summary 1. Gut content analysis of termites was undertaken using microscopical techniques. The 46 study species covered the entire range of taxonomic and feeding forms within the Order. 2. Inter-specific gut contents data were analysed using principal components analysis, placing species along a clear humification gradient based on variations in the amount of silica and plant tissue fragments in the gut. 3. Redundancy analysis was used to find morphological correlates of the observed variation in gut contents. A total of 22 morphological characters (out of 45 candidate characters) were correlated significantly with the gut contents. 4. Three of the 22 significantly correlated characters unambiguously defined feeding groups, which were designated groups I to IV in increasing order of humification of the feeding substrate. Group I contains lower termite dead wood and grass-feeders; group II contains Termitidae with a range of feeding habits including dead wood, grass, leaf litter, and micro-epiphytes; group III contains Termitidae feeding in the organic rich upper layers of the soil; group IV contains the true soil-feeders (again all Termitidae), ingesting apparently mineral soil. These groupings were generally supported statistically in a canonical covariance analysis, although group II apparently represents termite species with a rather wide range of feeding habits. 5. Using existing hypotheses of termite phylogenetic relationships, it seems probable that group I feeders are phylogenetically basal, and that the other groupings have arisen independently on a number of occasions. Soil-feeding (i.e. group III and group IV feeding) may have evolved due to the co-option of faecal material as a fungal substrate by Macrotermitinae-like ancestral forms. As a consequence, these forms would have been constrained to build nest structures from soil and would therefore have passed at least some soil through their guts. [source] Descriptions and biological notes of Ctenoplectra bees from Southeast Asia and Taiwan (Hymenoptera: Apidae: Ctenoplectrini) with a new species from North BorneoENTOMOLOGICAL SCIENCE, Issue 3 2009I-Hsin SUNG Abstract Six Ctenoplectra species are recorded from Southeast Asia and Taiwan. They are C. chalybea Smith, C. cornuta Gribodo, C. davidi Vachal, C. elsei Engel, C. sandakana sp. nov. and C. vagans Cockerell. Females of C. sandakana sp. nov. from North Borneo are similar to the mainland species C. chalybea, but differ mainly in the clypeal keel and the length of the antennal segments. The small blackish species, C. cornuta, is distributed in Myanmar, China and Taiwan and C. davidi is distributed in China, Russia and Taiwan; both species are seen at the flowers of Thladiantha. Ctenoplectra chalybea was collected from the Malay Peninsula, Myanmar, Taiwan and Vietnam. Ctenoplectra apicalis Smith and C. kelloggi Cockerell are allied to C. chalybea; however, C. kelloggi is excluded from this study due to insufficient material. A key to the six known Ctenoplectra species is given. The large metallic species, C. chalybea and C. elsei, visit flowers of Momordica cochinchinensis (Lour.) Spreng. For the first time observations on the nest structures of C. chalybea and C. cornuta are presented. They choose remarkable places, such as artificial structures and buildings, for nest sites. The nest architecture prevents rain and direct sunlight from entering the nest. Bees used pre-existing holes or crevices in wood for nesting shelters and collected soil and appeared to mix it with some other substance to build nests. The cell lining materials and rubbing behaviors against the cell wall suggest that Ctenoplectra bees use floral oil mainly for cell lining materials. [source] The functional significance of multiple nest-building in the Australian Reed Warbler Acrocephalus australisIBIS, Issue 3 2006MATHEW L. BERG The vast majority of bird species build a nest in which to breed. Some species build more than one nest, but the function of most multiple nest-building remains unclear. Here we describe the unusual nest-building behaviour of the Australian Reed Warbler Acrocephalus australis, and test experimentally the hypotheses that multiple nest-building is related to individual condition or territory quality, and plays a role in mate assessment. Australian Reed Warblers built two types of nest structures: ,type I' nests, which were used for eggs and nestlings, and ,type II' nests, which were structurally distinct from type I nests, did not support eggs, nestlings or adults and were not essential for successful breeding. The number of type II nests built in each territory varied. Type II nests were only built before breeding had commenced in a territory and females were not observed participating in their construction, supporting a role in female mate choice. Birds provided with supplementary food built significantly more type II nests than control birds. However, supplementary-fed birds did not have greater pairing success, and the addition of further type II nests to territories did not increase the pairing rate or type II nest construction in those territories. There was no relationship between the presence of type II nests and either reproductive success or likelihood of nest predation. We discuss the implications of these results in light of previous suggestions regarding the function of multiple nest-building in birds. [source] Regression modelling of correlated data in ecology: subject-specific and population averaged response patternsJOURNAL OF APPLIED ECOLOGY, Issue 5 2009John Fieberg Summary 1.,Statistical methods that assume independence among observations result in optimistic estimates of uncertainty when applied to correlated data, which are ubiquitous in applied ecological research. Mixed effects models offer a potential solution and rely on the assumption that latent or unobserved characteristics of individuals (i.e. random effects) induce correlation among repeated measurements. However, careful consideration must be given to the interpretation of parameters when using a nonlinear link function (e.g. logit). Mixed model regression parameters reflect the change in the expected response within an individual associated with a change in that individual's covariates [i.e. a subject-specific (SS) interpretation], which may not address a relevant scientific question. In particular, a SS interpretation is not natural for covariates that do not vary within individuals (e.g. gender). 2.,An alternative approach combines the solution to an unbiased estimating equation with robust measures of uncertainty to make inferences regarding predictor,outcome relationships. Regression parameters describe changes in the average response among groups of individuals differing in their covariates [i.e. a population-averaged (PA) interpretation]. 3.,We compare these two approaches [mixed models and generalized estimating equations (GEE)] with illustrative examples from a 3-year study of mallard (Anas platyrhynchos) nest structures. We observe that PA and SS responses differ when modelling binary data, with PA parameters behaving like attenuated versions of SS parameters. Differences between SS and PA parameters increase with the size of among-subject heterogeneity captured by the random effects variance component. Lastly, we illustrate how PA inferences can be derived (post hoc) from fitted generalized and nonlinear-mixed models. 4.,Synthesis and applications. Mixed effects models and GEE offer two viable approaches to modelling correlated data. The preferred method should depend primarily on the research question (i.e. desired parameter interpretation), although operating characteristics of the associated estimation procedures should also be considered. Many applied questions in ecology, wildlife management and conservation biology (including the current illustrative examples) focus on population performance measures (e.g. mean survival or nest success rates) as a function of general landscape features, for which the PA model interpretation, not the more commonly used SS model interpretation may be more natural. [source] | ||||||||||